MSF
Technical Support Units
With the collaboration of
ICRC Assistance Division, Water and Habitat Unit
MSF–OCB, Logistic department, Technical support unit. – June 2016
NRJ@brussels.msf.org
Electrical Equipment and Installations in the Field
Rules and Tools
Acknowledgments
Many people helped me finalize this project. Some gave a hand on the technical side, some
on the writing side, some others on the management or sponsoring side.
The first to mention are the coordinators and other members of the MSF Logistics
Department in Brussels : Jean PLETINCKX and Francesc LOPEZ who must be thanked for
their great support, Anibal ORDENEZ, Jean-François VRAUX, Belkacem AIT YAHIA and
Elvina MOTARD who were good readers and gave such valuable feedback, Simon VAN
LEEUW who gave very good support to the department during the time that I was unavailable
because of this writing job, Philippe MAILLOT who gave valuable advice for the layout, and
also Eva KONG from the Communications Department who gave the right framework in
which to promote the final product.
Then comes the ICRC team: if this book was finalized in less than one year, it is mainly due
to their great support and involvement. Here we must thank Philippe DROSS, director of the
Wathab unit, Samuel BONNET and Alexander HUMBERT who coordinated the collaboration,
and Timothy GILES PITT who effectively corrected the first draft of the document. All of them
are wathab engineers at the ICRC.
I also have to thank so much all electricians who were and are still working in the field, both
expatriates and national staff. It is naturally thanks to their work and all experiences shared
with them during the last nine years that I learned so much about the specific challenges that
we have to face in the field. So, I have particularly to mention Popol Manzana and the Push
team in RDC, Julien Charlier, Robert Protka,, Agustin Mujica, Jim Cuts, Cypriaan Mujuri,
Ahmadou Wouna, and so many others – I apologize to those I have not been able to
mention!
And finally we have to thank a lot all technical referents from the other MSF sections who
supported the project and trusted a first release prior to any contents validation. First, Daniel
MANGEL from MSF Switzerland who really helped a lot when the project was discussed in
Geneva, and of course Jaap DOMENICUS and Danny WASSINGTON (Amsterdam), Benoît
DAL, Alfredo GONZALES and Gregory GAMBOA (Paris and Bordeaux) and finally Agusti
LOPEZ (Barcelona) – Maybe some of them don’t know that they helped me, but all
guidelines, tools and training documents that they made during the past years were of course
a good source of inspiration to compose this document. Somehow I also thank them in
advance for the feedback that will be needed in order to compose the next release…
Thanks to you all, the author,
Harold PRAGER,
MSF-OCB Technical Support Unit, Energy and temperature control.
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Foreword
The quality of the service offered to beneficiaries has always been a natural focus for
humanitarian activities. The latest evolutions of humanitarian issues and responses, projects
and actors are showing an increasing importance of the technical means that are deployed in
the field. The basic as well as the larger setups and more sophisticated equipments are
continuously needed , so that they have become more and more critical to satisfy the quality
of service required for our beneficiaries. It has always been a natural duty to ensure both for
beneficiaries and humanitarian workers safe reliable and efficient electrical setups.
Practical references and technical standards had become essential. We must simplify the
technical approaches, and ensure that all installations comply to clearly recognized
requirements ensuring the safety and reliability of the electrical installations and equipment’s.
The aim of offering to MSF and other agencies such a practical reference for internal
technical regulation of electrical installations in the field was already expressed for a long
time. Such a project was actually on the MSF workbench for several years.
It must be said that it is thanks to the interest of the ICRC about sharing such a reference
document that the job could be accelerated, and more resources could be mobilized for the
project. Thus, it is out of an exceptional collaboration between MSF and the ICRC that this
first version of “Electrical Equipment and Installations in the Field, Rules and Tools” was born
and will be widely released.
It is true and important to say that at the moment that this first version was finalized, the table
of contents and the principle of the building of such reference book that will be common to all
MSF sections and the ICRC have been validated, but not all technical contents, details have
been fully validated by all partners, nevertheless from an engineering perspective most of the
contents correspond to actual professional practice. One of the main purposes of this first
release is therefore to get all the feedback possible from the field. That will be the basis upon
which to build another version that can be submitted for a full validation by all partners.
It remains that all elements presented into this book are fully referring to international
standards, and all rules and recommendations that you will find here are largely in accord
with our experience and needs in the field. So, read it, use it, and discuss it, and you will find
how such a document is really the essential one, the one that was missing. Nevertheless, all
practical electricity courses, guidelines, training, and tools that are already used in the field
are still needed, but no one is offering yet the reference to rules that this “Electrical
Equipment and Installations in the Field, Rules and Tools” is now doing. You will discover,
page after page, how much this book is of interest not only to the engineer or the technician,
but also to the supplier, the project manager, and anyone in charge of the ownership or the
supervision of any electrical work needed to ensure the safety of individuals, the protection of
equipment and the continuity of service. In any case, we must insist from now on that you are
the main user of this project: we need your feedback to build the next version!
Jean Pletinckx - MSF-OCB, Logistic department director.
Philippe DROSS - ICRC, Water and Habitat unit director.
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Executive summary
This reference book is divided into four main parts. After an introduction giving the scope of
application of the document, two chapters give all information about the worldwide regulatory
framework, local regulations, and situations where internal rules must be applied within this
framework. Several subjects are developed. After some vocabulary and definitions, the
mission of the IEC (International Electrotechnical Commission) is explained as well as the
applicability of IEC publications. After this presentation, all main variations of standards
around the world are shown and discussed before explaining the field of applicability and
relevance of adopting internal rules.
In a second part, you will find all information about the phasing and management of electrical
projects. This matter is often missing in technical documents, but because it is one of the
most important conditions to ensure that such work is organized and followed in a way
ensuring the good running and results of the projects, it has been found of importance to
include this chapter into the document.
The following parts are more technical: The 5th chapter explains all requirements about
safety, including the presentation of various grounding systems and explanations about all
protection devices. The next chapter is exclusively dedicated to the quality requirements for
electrical equipment: Cables, junctions, enclosures, switchgears, breakers and terminals,
including lighting systems. After you will find a chapter about setup design. This matter is the
most observed by electrical installers. Each country has – or hasn’t – its own way of defining
the size and rates for lighting and socket circuits, the wiring and protection of wet areas, the
way to establish a protective grounding. This last chapter will be particularly helpful for
electrical designers and installers.
The last part is a listing of tools and templates illustrating the subjects presented or explained
in the first seven chapters. A lot of annexes also follow offering additional in-depth
information, mainly about international references.
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Table of Contents
ACKNOWLEDGMENTS ................................................................................................................................................... 5
FOREWORD ..................................................................................................................................................................... 7
EXECUTIVE SUMMARY .................................................................................................................................................. 9
TABLE OF CONTENTS ................................................................................................................................................ 11
1.
INTRODUCTION ..................................................................................................................................... 15
1.1.
SCOPE OF APPLICATION ....................................................................................................... 15
1.2.
WHY ARE TECHNICAL STANDARDS NEEDED? ................................................................... 15
1.3.
THE FOUR FUNDAMENTAL PRIORITIES ............................................................................... 16
2.
2.1.
REGULATORY FRAMEWORK ............................................................................................................. 21
DEFINITIONS: NORMS, STANDARDS, REGULATIONS, RULES & RECOMMENDATIONS 21
2.2.
INTERNATIONAL STANDARDS ............................................................................................... 25
2.2.1.
The International Electrotechnical Commission
25
2.2.2.
The IEC Affiliate Country Programme
26
2.2.3.
What is the Content of the IEC Standards?
27
2.3.
NATIONAL STANDARDS AND INTERNAL RULES ................................................................. 29
2.3.1.
National Standards............................................................................................................................................ 29
2.3.2.
Internal Rules .................................................................................................................................................... 30
3.
VARIATION OF STANDARD MODELS AROUND THE WORLD.................................................. 33
3.1.
WORLD VOLTAGES AND FREQUENCIES ............................................................................. 33
3.2.
WORLD PLUG TYPES .............................................................................................................. 35
3.3.
WORLD CABLE COLOUR CODE ............................................................................................. 39
3.3.1.
AC Supply Colour Code for Electrical Cables
39
3.3.2.
DC Supply Colour Code for Electrical Cables
39
3.3.3.
General Colour Coding for Electrical Cables
41
3.4.
WORLD MEASUREMENT SYSTEMS ...................................................................................... 43
3.5.
VOCABULARY AND SYMBOLS ............................................................................................... 45
3.6.
IDENTIFICATION RULES ......................................................................................................... 49
3.6.1.
ROOM IDENTIFICATION
49
3.6.2.
ELECTRICAL COMPONENTS IDENTIFICATION
53
3.6.3.
USE OF TITLE BLOCKS
57
4.
MANAGEMENT OF ELECTRICAL PROJECTS .................................................................................. 59
4.1.
PROJECT DEVELOPMENT CYCLE ......................................................................................... 59
4.2.
ROLES AND RESPONSIBILITIES ............................................................................................ 61
4.3.
ELECTRICAL PROJECT TASKS AND OUTPUTS ................................................................... 63
4.4.
IMPLEMENTATION OF ELECTRICAL PROJECT.................................................................... 65
4.5.
CONCLUSION ........................................................................................................................... 66
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5.
SAFETY OF INDIVIDUALS: TECHNICAL RULES ............................................................................ 69
5.1.
THE DANGER OF ELECTRICAL CURRENTS ......................................................................... 69
5.2.
THE CLASSES OF EQUIPMENT.............................................................................................. 73
5.3.
PROTECTION FROM DIRECT CONTACT ............................................................................... 77
5.4.
PROTECTION FROM INDIRECT CONTACT ........................................................................... 79
5.5.
EARTHING SYSTEMS .............................................................................................................. 81
5.5.1.
DIFFERENT EARTHING SYSTEMS
81
5.5.2.
EXPLANATION OF THE THREE EARTHING SYSTEMS
82
5.5.3.
USE OF RCDs WITH THE DIFFERENT EARTHING SYSTEMS
89
5.5.1.
EARTHING SYSTEMS – EARTHING RODS
91
5.6.
EARTH LEAKAGE PROTECTION DEVICES ........................................................................... 93
5.7.
WORKING ON ELECTRICAL INSTALLATIONS: PROTECTION RULES.............................. 101
5.8.
FIRE SAFETY .......................................................................................................................... 103
5.9.
LIGHTNING PROTECTION..................................................................................................... 105
6.
EQUIPMENT: QUALITY AND USAGE REQUIREMENTS. ............................................................ 111
6.1.
CABLES ................................................................................................................................... 111
6.1.1.
CABLES: GETTING THE RIGHT QUALITY
111
6.1.2.
CABLES: GETTING THE RIGHT CABLE FOR THE RIGHT USE
115
6.1.3.
CABLES: GETTING THE RIGHT CONDUIT
125
6.2.
JUNCTIONS ............................................................................................................................ 127
6.3.
ENCLOSURES ........................................................................................................................ 133
6.3.1.
INGRESS PROTECTION RATINGS
133
6.3.2.
JUNCTION BOXES
134
6.3.3.
OTHER ENCLOSURES
136
6.4.
SWITCHGEAR AND CONTROLGEAR ................................................................................... 139
6.5.
CIRCUIT BREAKERS .............................................................................................................. 149
6.5.1.
DEFINITION
149
6.5.2.
FORMS
149
6.5.3.
QUALITY REQUIREMENT
151
6.5.4.
ASSIGNED CURRENT AND PROTECTION RATES
155
6.6.
TERMINALS ............................................................................................................................ 159
6.6.1.
DEFINITION
159
6.6.2.
SOCKETS AND SWITCHES: VARIOUS SHAPES AND RELATED USAGES.
159
6.6.3.
STANDARD SOCKETS FOR HOUSEHOLD COMMON USES
160
6.6.4.
HEAVY DUTY POWER SOCKETS
164
6.6.5.
SWITCHES
166
6.6.6.
LIGHTING AND LIGHTING FIXTURES
168
6.7.
VOLTAGE PROTECTION DEVICES ...................................................................................... 177
6.8.
CONCLUSIONS ABOUT QUALITY AND USAGE REQUIREMENTS .................................... 181
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7.
RECOMMENDATION ABOUT SETUP DESIGN.............................................................................. 183
7.1.
GENERAL ORGANISATION OF A DISTRIBUTION GRID ..................................................... 183
7.1.1.
SIZE OF A DISTRIBUTION AREA
183
7.1.2.
RATES OF THE MAIN DISTRIBUTION LINES.
185
7.1.3.
POSITION OF THE MAIN BOARD
190
7.1.4.
ROUTING OF THE MAIN CABLES
191
7.1.5.
THE PROTECTIVE EARTHING NETWORK
193
7.2.
DISTRIBUTION BOARDS ....................................................................................................... 197
7.2.1.
PLACEMENT OF DISTRIBUTION BOARDS
197
7.2.2.
DESIGN OF DISTRIBUTION BOARDS
198
7.3.
PLACEMENT OF CONDUITS AND JUNCTION BOXES ....................................................... 203
7.3.1.
UNDERGROUND CABLES .................................................................................................................................203
7.3.2.
CABLES AND CONDUITS INSIDE A BUILDING ..................................................................................................205
7.4.
PLACEMENT OF TERMINALS ............................................................................................... 210
7.5.
SIZES AND AREAS OF DISTRIBUTION OF FINAL CIRCUITS............................................. 211
7.5.1.
SIZE OF CIRCUITS
211
7.5.2.
AREAS OF DISTRIBUTION
211
7.5.3.
NUMBER OF POINTS IN GENERAL CIRCUITS
212
7.5.4.
SPECIAL CIRCUITS
212
8.
TOOLS AND TEMPLATES .................................................................................................................. 223
8.1.
8.2.
8.3.
8.4.
8.5.
8.6.
8.7.
8.8.
8.9.
8.10.
8.11.
8.12.
8.13.
9.
TOOL: GROSS BUDGET CALCULATION.............................................................................. 225
TEMPLATE: GENERAL MAP OF A COMPOUND .................................................................. 229
TEMPLATE: GENERAL MAP OF A BUILDING ...................................................................... 231
TEMPLATE/ TOOL: ASSESMENT.DOC................................................................................. 233
TEMPLATE: POSITION DIAGRAM ......................................................................................... 247
TOOL: LOAD STUDY SHEET ................................................................................................. 249
TEMPLATE: POSITION DIAGRAM MAIN DISTRIBUTION (Visio) ......................................... 255
TEMPLATE: ELECTRICAL DIAGRAM MAIN BOARD (Visio) ................................................ 256
TEMPLATE: POSITION DIAGRAM FINAL CIRCUITS (Visio) ................................................ 257
TEMPLATE: ELECTRIC DIAGRAM FINAL CIRCUITS (Visio) ............................................... 258
TEMPLATE: ELECTRIC DIAGRAM FINAL CIRCUITS (Excel) .............................................. 259
TEMPLATE: ELECTRIC AND POSITION DIAGRAM FINAL CIRCUITS (Excel) ................... 260
TOOL: REPORT WORKS FOLLOW-UP ................................................................................. 261
ANNEXES ................................................................................................................................................ 265
ANNEX 1: Listing of full and associate IEC members ........................................................................ 265
ANNEX 2: Reference table: Listing of the IEC affiliate countries and adopted IEC norms ................. 266
ANNEX 3: Reference table: Socket and plug types around the world. ............................................... 267
ANNEX 4: Reference table: Wire colour codes around the world ....................................................... 273
ANNEX 5: Reference table: Electrical symbols and vocabulary around the world ............................. 275
ANNEX 6: Electrification rates around the world ................................................................................. 278
ANNEX 7: Reference table: Main features of national/local standards around the world ................... 279
TABLES ........................................................................................................................................................... 285
FIGURES .......................................................................................................................................................... 285
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1. INTRODUCTION
1.1. SCOPE OF APPLICATION
Alongside their core activities around the world, international humanitarian organisations are
also confronted with the technical management of numerous premises such as offices,
warehouses, workshops and residences. The electrical installations in these premises are a
source of frequent problems, some of them extremely serious. Several cases of electrocution
and fires have been experienced, particularly during the last 5 years. Humanitarian
organisations are very conscious about the safety of their teams and fully aware of their duty
of care towards their staff. MSF has already taken certain steps to correct the potential short
comings in the electrical installations. MSF and ICRC have jointly confirmed their
commitment that all premises under their responsibility should comply with recognized
minimal technical standards and rules.
Officially, almost all countries have technical standards and rules defining what practices
should be respected when designing and implementing electrical installations. However, in
many countries where humanitarian organisations are operating, effective control procedures
do not exist, and there is a lack of certified technicians and good quality electrical equipment.
Hence, unfortunately in many cases the electrical installations do not comply with the
country’s technical standards and rules. Additionally, national standards and rules can be
obsolete, outdated or not adapted to humanitarian operations. In such contexts, humanitarian
organisations should impose upon themselves appropriate technical standards and rules,
and make sure that the correct resources are made available to ensure that the electrical
installations in premises are implemented, maintained and operated correctly.
The purpose of this paper is to present a set of internal rules that MSF and ICRC should
apply as a minimum standard for all electrical installations in field premises. For MSF, field
premises are considered to include: offices, residences, warehouses, workshops, hospitals
and health centres. For ICRC, field premises are considered to include: offices, residences,
warehouses, workshops and orthopaedic centres.
1.2. WHY ARE TECHNICAL STANDARDS NEEDED?
Using technical standards and rules helps ensure that the essential safety aspects are taken
into account. They also help simplify the definition of projects, and facilitate the
implementation of similar solutions throughout the world. Following technical standards and
rules is also the simplest way to satisfy quality requirements. A large variety of technical
standards are used to varying degrees around the world, including a number of
internationally established standards. However, as a result of specific situations, many
countries only partly apply the requirements of the variety of national and international
standards.
As international organisations working in such countries, MSF and ICRC must clearly define
how best to respect the relevant standards, whilst taking into account their limitations. MSF
and ICRC should develop additional rules to correct the absence or limitations of local
regulations in order to satisfy the specific levels of safety, quality and continuity needed in all
their electrical installations.
By preference, MSF and ICRC electrical projects are managed primarily in the field, and
hence field staff must be properly equipped to assume this responsibility. The continued
trend in electrical projects becoming larger and more complex, in turn makes the task of the
field teams increasingly more complex. The correct application of appropriate technical
standards can make a significant contribution to the effective management of electrical
projects, which produce safe, reliable and good quality electrical installations.
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1.3. THE FOUR FUNDAMENTAL PRIORITIES
The objective of technical standards and rules is to ensure the respect of certain fundamental
priorities in terms of electrical installations. When dealing with electrical installations one must
keep in mind the following fundamental priorities:
st
1 Priority: Safety of Individuals
Protection against electrocution and fire
(Saves lives and assets)
ALL STANDARDS AND RULES RELATED TO THE SAFETY OF INDIVIDUALS
ARE CRITICAL REQUIREMENTS
2nd Priority: Protection of Devices
Protection against fire, power instability and effects of lightning
(Saves assets)
ALL STANDARDS AND RULES RELATED TO THE PROTECTION OF DEVICES
ARE ESSENTIAL REQUIREMENTS
3rd Priority: Service Continuity
Protection against service breakdown, failure of power sources or effects of any
other interruption
ALL STANDARDS AND RULES RELATED TO CONTINUITY OF SERVICE
ARE FUNCTIONAL REQUIREMENTS
4th Priority:
Cost Control and Environmental Care
Aspects that lead to the most accurate choice and sizing of the power sources, and
control of the power demand
Even if the 4th priority is related to major financial and ecological issues that are also
critical at a certain point and must anyway be kept in mind, compared to the matter of
the first priorities, it is considered that
GUIDING PRINCIPLES RELATED TO COST CONTROL AND ENVIRONMENTAL
CARE ARE OPTIONAL REQUIREMENTS
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The service continuity: an operational objective
Noted above as a functional requirement, the importance of service continuity can effectively
become an essential or even critical requirement – for example in the case of the electrical
installation for an emergency operating theatre or any lifesaving medical facility.
Each fundamental priority is linked to specific requirements. Technical standards and rules
are mainly concerned with the critical and essential requirements of protection of individuals
and equipment. However, they also contribute to the functional requirement of service
continuity, by reducing service interruption due to the tripping of protection devices.
Considering priorities is of course helpful when it is needed to figure out some essentials.
Each priority is linked to specific threats problems and solutions. All of them will be largely
presented and explain into these pages. The next page gives a complete figure of the
priorities linked with those specific threats, problems and solutions.
However, as presented here these priorities cannot be an absolute: operational priorities are
often forcing to a momentary acceptance for bad electrical installations. It is most specifically
the case during emergency operations, while it is necessary to deploy a functional setup as
fast as possible. But this doesn’t mean that emergencies are allowing safety essentials to be
forgotten! Specific electrical equipments for fast deployment have therefore been developed
and will be preferably used when possible. In every case, and even more if the electrical
installations used during a first phase of an emergency are not fair, the situation must be
corrected and stabilized as soon as possible, and a special attention must be accorded to
avoid the “syndrome of the accepted nightmare”: It is very common in some unsafe poor or
degraded contexts that unsafe installations are considered as a natural part of the context,
and as far as they are functional they are accepted, without any consideration for their unsafe
state. There is no way to add danger to the dangers, and it is a duty to offer to the
humanitarian workers the best conditions to ensure their safety and the comfort needed to
make their job with the best conditions. And such a comfort is certainly even more important
when the contexts are already unsafe and stressing.
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Safety of individuals
Protection of devices
Priorities
Service continuity
Cost control and environmental care
Threat /
danger
Electrocution
Fire
Problem
Direct or indirect
contact
Short-circuit,
overload, bad
junction
Faulty power
supply
Faulty user
device
Solution
Insulation,
grounding,
terminals,
residual current
breaker devices
Breakers and
cable rates,
junctions,
terminals
Voltage
limiters,
stabilisers,
lightning
arresters
Correct
selection,
installation,
use and
maintenance
Scope of
intervention
Costs and
benefits
High fuel and
power
consumption
No backup
Wrong load
study
Backup
generator
and UPS
Generator sizing,
Optimisation of
power sources
and power
demand
Damaged user device
Electrical setup/ Technical intervention
90 % of investment costs
Power
break
down
10 % costs
High human benefits
Device
Management
No costs
Setup design, economy
Low costs
Cost reduction
High financial payback
Figure 1: Overview of priorities with linked threats and solutions.
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Throughout this paper, where appropriate, the underlying issuing being addressed will be
highlighted with the use of icons, as follows:
Electrocution
Protection of Individual
Fire Risk
Danger for Devices (Unprotected Devices)
Protected Devices
Risk of Lightning
Power Continuity
Power Interruption (Power Discontinuity)
More general icons, are also highlighting
Critical information, information of interest
Do / don’t indications ,
Good / bad practices
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2. REGULATORY FRAMEWORK
2.1. DEFINITIONS:
NORMS, STANDARDS, REGULATIONS, RULES & RECOMMENDATIONS
It is not unusual for the same term used in different languages to have different meanings, or
for different terms to actually mean the same thing. For example the terms ‘Normes’ in
French, ‘Standards’ in English and ‘Code’ in American English, can all mean essentially the
same thing. This can be illustrated with some typical examples in French and English:
French
English
Norme
Standard
Standard – pratiques habituelles
Standard - usual/ common practices
Régulation – règlementation
Standard, Regulation, Code (USA)
Règles
Rules
Recommandations
Recommendations
It is also common, even within official documents, for many of the above terms to be used
interchangeably. These terms are also frequently translated into other languages where their
sense may not be exactly the same as originally intended. Additionally, these terms can be
partly synonymous and their meanings can overlap one another.
This document is intended to be used worldwide by MSF and ICRC and very often by people
whose mother language may not be English or French. With this variety in mind, it is
essential that MSF and ICRC adopt some internal conventions clearly defining the key terms
used in this document. These conventions are set out below:
Normative Standards (Common References, Norms)
Normative standards are specifically related to normalised definitions, units, values, sizes,
tolerances and tests protocols. They are intended to be universal standardised (normalised)
references used in data sheets, declarations of specifications and technical exchanges
between engineers. In English, the term ‘Standard’ is almost always used in the same sense
as the term ‘Norm’ in French.
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Example:
The normative standards defining the specifications of an electrical circuit breaker are
regulated by the International Electrotechnical Commission/ European Norm 60947-2.
A modular breaker satisfying all the
requirements set out in the Norm can be
considered to be certified for that Norm. All
given values must have been tested in
accordance with the definitions given by the
Norm. In addition, the technical specifications
related to the product must mention a
complete listing of values and specifications.
Typically, certification to a specific Norm is
indicated on the product.
Figure 2: indication of standard
references on an electrical device.
For example, the breaker illustrated here is
certified to the IEC/EN 60947-2 Norm (as well
as the National Electrical Manufacturers
Association NEMA - AB1 Norm).
All products complying with the same Norm have theoretically achieved similar results in
the same normalised tests and are rated accorded to the same reference.
Practical Standards (Usual and Common Practices)
Practical Standards are common choices made to facilitate usages. A Practical Standard
frequently refers to a set of normative standards, (norms, regulation, or code) but can also
refer to practices that are not included in such a standard. We will use the term ‘common
practice’ to designate common uses that are applied as “standards” these last being official
or not.
Example:
15A is a standard rate for circuit breakers in the United States, while 13A is a standard
rate in UK and breakers are rated 16A in France & Germany.
However, all four countries refer to the IEC Norm (IEC 60947-2) that defines the testing
protocols and specifications for all rates of low voltage circuit breakers.
Regulation Standards (Official Standards, Codes)
Regulation Standards (Official Standards, Codes) are administrative decisions that oblige the
use of a common standard in regards to a specific issue. Most of the time, when a Regulation
Standard has been adopted, further controls are organised by the administrating authority in
order to verify that the regulation has been respected. It is unlikely that a Regulation
Standard would be fully respected if an effective system of control is not in place. The control
and verification that Regulation Standards are respected is unfortunately sometimes
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inadequate in countries where MSF and ICRC operate. In these situations, internal
Regulation may be the most appropriate option.
Example:
A number of countries have prohibited the use of incandescent bulbs, requiring instead
the use of energy saving bulbs. This is a Regulation, not a Norm, nor a Standard.
‘National standards’ (such as the British Standards – BS or the “Norme Française” –
NF- ) for the design and implementation of electrical installations are in fact, in this
terminology, national Regulations. They set out which standard (such as circuit
breaker rating) has to be respected in which situation (domestic, public, industrial,
commercial areas, etc.)
Rules
A Rule is a practical tool that helps to guide calculations and decisions in the design or
implementation of an electrical installation. Rules can be viewed as a simplified method of
ensuring compliance with the chosen Norms, Standards or Regulations.
Example:
MSF’s internal “Rule of 15 meters” gives an easy and practical method to assist in the
design of an electrical installation. This simple rule influences the design of the main
distribution system (including the positioning for all earthing poles and consumer units)
in a way that ensures that the electrical installation complies with the relevant Norms
and Standards.
Recommendations
A recommendation is a practical advice that helps in making decisions about the product
selection, the design of a setup or the organisation of works. It does not necessarily relate to
compliance with a specific Norm, Standard or Regulation.
Example:
When installing a generator it is recommended to consider providing good ventilation, to
ensure effective cooling and hence efficient operation of the generator.
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2.2. INTERNATIONAL STANDARDS
Many international institutions are continually developing international standards in numerous
different domains. One of the principle actors in the field of international standards is the
International Organisation for Standardisation (ISO). ISO works on a wide range of issues
creating a range of international standards, commonly referred to as ISO standards (or
Norms). The ISO also frequently works with other more specific organisations specialised in
specific issues. The IEC –International electrotechnical commission - is one of these
specialist organisations that deals primarily with the development of international standards
related to electrical equipment and installations.
2.2.1. The International Electrotechnical Commission
The international standards for electrical and electro-technical issues have been developed
principally by the International Electrotechnical Commission (IEC). The IEC’s over-arching
objective is to promote co-operation on all issues concerning standardisation in the domain of
electricity and electronics. IEC is promoting the idea of worldwide normalisation
standardisation, and develops technical Norms and documents in accordance with the
requirements of ISO. As such, the IEC is widely recognised as the international reference for
electro-technical equipment and installations, and many countries are willing to be part of
such international regulation. Currently 60 countries are Full members of the IEC, 26 are
Associate members, and 83 are Affiliate members. Full and Associate members both have
access to all the technical activities, however Associate members have restricted voting
rights. The Affiliate membership is particularly relevant to the humanitarian context, and as
such is discussed in more detail in section 2.2.2.
The IEC standards are largely based on European practices, and as such adoption of IEC
standards within Europe has been particularly strong. It is not uncommon for IEC and
European standards to use the same reference, for example IEC 60947-2 and EN 60947-2
both deal with ‘Low-voltage Switchgear and Controlgear’, and both contents are completely
similar.
However, many other countries still do not officially recognise or follow the IEC international
standards. There is also unfortunately the situation where some countries officially recognise
the IEC standards but do not implement them. In addition there is sometimes the situation
where the IEC standards contradict regional/ national standards or practices. A good
example of this last situation is the United States. The US is a full member of the IEC, but it
still uses the North American standard which does not conform completely to the IEC
standard.
The IEC has developed numerous standards, definitions and publications dealing with
electrical and electro-technical issues. For example, the IEC has developed definitions for the
range and limits of use of electrical equipment, and recommendations for best practices for
the design and implementation of electrical installations, and many countries have adopted
these publications. However, the IEC publications tend to be very detailed technical
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documents, mainly intended to guide manufacturers, and to give a framework to national
standards. As such, they are not necessarily useful as simple practical reference standards
for designing and implementing simple electrical installations.
A list of the countries participating with IEC as Full, Associate or Affiliate members is included
in ANNEX 1: Listing of full and associate IEC members on page 265.
2.2.2. The IEC Affiliate Country Programme
Started in 2001, the IEC Affiliate Country Programme offers developing and newly
industrialised countries around the world a form of participation in the IEC without the
financial burden of full or associate membership. The Affiliate Country Programme promotes
the use and adoption of IEC International Standards in these countries. It also helps develop
trade with these new markets, as participants adopt the IEC's International Standards and
use its conformity assessment systems.
The countries participating in the Affiliate programme is potentially very interesting for MSF
and ICRC, as many of the countries where MSF and ICRC operate are participating in this
programme. Knowing which international standards a particular country has officially adopted
is a good starting point when considering the design or implementation of an electrical
installation. Figure 3 below illustrates the countries participating in IEC and the level of their
membership. For more details, the list of countries participating in the Affiliate programme,
and the standards that they have adopted, is given in ANNEX 2: Reference table: Listing of the
IEC affiliate countries and adopted IEC norms on page 266. More extensive details are available
on the IEC website (http://www.iec.ch/dyn/www/f?p=103:9:0 ).
Full members
Associate members
Affiliate Members
Figure 3: IEC Membership around the World
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2.2.3. What is the Content of the IEC Standards?
To date, the IEC works with 97 technical committees, 77 sub committees and has published
approximately 7,000 documents. The content of the IEC standards can be divided into three
categories.
1st - General Interest
This category deals with the standardisation of: technical terms, definitions, vocabulary,
identification methods and rules, classes of equipment and protection levels.
For MSF and ICRC operations throughout the world, whatever the local uses of terms, it is
important to utilise the same vocabulary and identification methods everywhere. The IEC
standards should hence form the reference for standardising the terms and definitions used
in technical design and implementation of electrical installations.
2nd - Quality, Performance and Testing of Electrical Devices
This second category addresses the standardisation of the quality of electrical equipment.
The IEC sets standards for the quality of electrical equipment, and certifies manufacturers
and their products that meet these quality standards. Electrical equipment certified to IEC
standards is effectively ensured to be of good quality. Given the questionable quality of
locally produced or unregulated equipment, MSF and ICRC should only use equipment that
complies with international standards – specifically IEC standards. Compliance with IEC
standards should only be exempted in cases where there is an established regional or
national strong preference for another recognised international standards system. This is only
likely to occur in regions or countries that are strongly attached to the United States’ National
Electrical Code, using preferably references to ANSI, NEMA or UL certifications
Hence, our first internal rule comes out of the issue of the quality of electrical equipment.
1.1 To ensure the reliability of electrical equipment, only equipment referring at
least to IEC certification should be purchased and installed.
In specific instances, compliance with other recognised international standards, such as
the United States National Electrical Code,NEMA, UL may be accepted in lieu of IEC
compliance.
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3rd - Rules and Recommendations for the Design of Installations
The IEC has also developed recommendations about good practices for the design and
implementation of electrical installations. MSF and ICRC are often directly in charge of
designing or implementing electrical installations, hence the IEC’s recommendations are
potentially very pertinent.
In summary, MSF and ICRC need to take into account international standards for electrical
equipment and installations in order to ensure the quality of their electrical installations and
projects. In particular, MSF and ICRC should:
•
•
•
Use internationally recognised terms and symbols.
Purchase only internationally certified electrical equipment
Follow internationally authorised recommendations
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2.3. NATIONAL STANDARDS AND INTERNAL RULES
2.3.1. National Standards
Many countries have some form of national standards related to electronics and electrical
installations. In a lot of cases, these national standards have been heavily inspired by
national standards from certain developed countries – for example British Standards, French
Standards, US Standards and German Standards. In some cases, mainly the most
developed countries, the national standards comply with, or are very close to, the IEC
standards. In other countries their national standards may be based on outdated foreign
standards. This is particularly common in ex-colonial countries where the national standards
are frequently based upon the ex-colonial country’s standards at the time that the country
gained independence. In each individual context it would be useful to know whether the local
national standard has been based upon a foreign standard (such as British, French, US or
German), and if so – which one. Short-comings in the national standards could then
potentially be compensated by referring to the source foreign code. For example, a short
coming of the Pakistan national standard could be resolved by referring to the most recent
version of the British Standard.
Unfortunately some countries which do have national standards, do not actively enforce them
allowing the space for organisations to use whatever standards they want. International
development activities are sometimes contributing to this situation. A prime example of this is
Afghanistan where the heavy presence of international development donors has created a
mix of standards being followed (American, British, and German). Other countries may have
no formal national standards and also not be officially following a specific foreign or
international standard. In these situations the quality of electrical equipment available locally
is principally influenced by the business market.
It is worth bearing in mind that standardisation is principally an approach being promoted by
developed countries, and is slowly trickling down to other countries. In the countries where
MSF and ICRC typically work, the status and enforcement of national standards is likely to be
particularly confused and chaotic.
Even for countries where strong national standards do exist, there can be significant
differences between national standards from different countries. Most of these differences
are related to the power supply voltage and frequency used, the type power sockets outlets,
and colour of wiring. Other differences can relate normalised rates of protection, cable sizes,
and specific provisions related to the use of particular equipment or installations in particular
areas.
Where national standards exist, MSF and ICRC must respect all provisions of these
standards. However, an important condition is that following the national standards must not
cause the electrical installation to fall below the standard of the MSF/ ICRC Internal Rules.
MSF and ICRC can implement electrical installations that surpass the requirements of the
local national standards, but should never implement electrical installations that do not at
least meet the MSF/ ICRC internal rules.
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2.3.2. Internal Rules
As outlined earlier, the purpose of this document is to set out a harmonised approach that
MSF and ICRC should follow throughout the world when developing electrical installation
projects. This is achieved primarily through the development of Internal Rules. Internal Rules
are developed throughout this document and are highlighted in text boxes marked with an .
The first Internal Rule was presented in section 2.2.3, and the next Internal Rules are
presented below. Text boxes marked with an A. are highlighting Advice notes that are also
developed throughout this document.
Internal Rules are set by MSF and ICRC to control their own programmes. There is no
formal, legal connection between these Internal Rules and the specific requirements of IEC
(or any other) international standards. In the strict legal sense, there is no obligation to follow
these rules. However, MSF and ICRC have voluntarily imposed these rules upon themselves
– and hence there is an obligation for MSF and ICRC personnel to follow these rules.
There will undoubtedly be some differences between such internal rules and local official
standards or regulations. Some technical solutions that may be allowed under national
standards may not necessarily be allowed by the Internal Rules. Where national standards
are more onerous than Internal Rules, the requirements of the national standard should be
applied. The intention is that the Internal Rules ensure an adequate level of safety and even
if local national standards are inadequate.
Considering the potential interaction of local national standards with the MSF and ICRC
approach, leads to our next Internal Rule:
2.1 Everything being compulsory or forbidden under the authority of local national
regulations must be applied, even if not compliant to our internal regulations /
recommendations.
2.2 When a local regulation is not compliant to our internal recommendations, all
ensuing inconveniences made to the respect of our priorities must be balanced by the
definition and application of additional protection measures.
2.3 Everything being accepted by local authorities, included established conventional
way of working is acceptable unless not compliant to our internal regulations /
recommendations.
2.4 Everything being matter of regulation or recommendation which is not regulated
by any local authorities is exclusively under the authority of our internal regulations /
recommendations.
2.5 Unless not applicable, all internal standards / rules / recommendations that are
defined and that are applied are referring to the international standards, rules and
recommendations made by the IEC.
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3. VARIATION OF STANDARD MODELS AROUND THE WORLD
3.1. WORLD VOLTAGES AND FREQUENCIES
One of the most important differences between individual standards is the voltage and
frequency used. While the IEC stipulates 220V-240V 50 Hz systems, the American NEC
uses 100-127V 60Hz systems. In rare cases some particular countries also have 220-240V
60 Hz systems (such as Korea, and the Philippines) or 100-127V 50Hz systems (such as
Madagascar). The distribution of voltage/ frequency systems is summarised in Figure 4
below:
Figure 4: Voltage and Frequencies around the World
This map clearly shows that, with the notable exception of South America, the vast majority
of countries where MSF and ICRC are operational use the 220-240V / 50 Hz system. Most of
the standard equipment sent to the field by humanitarian organisations complies with the
standard voltage and frequency used in the organisation’s country of origin, and most
equipment only complies with one specific voltage and frequency system.
As can be seen from Figure 2, in the majority of cases, equipment purchased in Europe
would be appropriate for installation in the field – at least in terms of voltage and frequency.
However, particular attention should be paid when working in countries which do not follow
the 220-240V / 50 Hz system. Or when purchasing equipment manufactured in countries
using other voltage/ frequency systems – for example the United States.
Voltage can easily be adapted using transformers. However, frequency can only be adapted
by using costly frequency converters, or a double conversion UPS with programmable
frequency output. Using the wrong frequency particularly effects devices such as
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compressors, pumps, fridges, and motors. The main effects of a wrong frequency on such
equipment are: loss of performance, overheating, and reduced lifespan.
Hence the use of equipment in a country with another voltage/ frequency system is not
simple, and this leads to the first Advice note in this publication. Advice notes highlight certain
key issues that project managers should consider in the design or implementation of an
electrical installation.
Advice note ( always highlighted in text boxes marked with an A.)
1.1
Check the voltage and frequency of your equipment
Before installing any electrical appliance, always read the specifications mentioned on
the identification plate or into the user manual and check if it is fully compliant with the
local standard.
Multistandard appliances: Theoretically, only electronically regulated equipment such as
phone chargers, AC adapters for laptops and some other equipment (which use DC voltage
generated by embedded electronics) can be used with all systems. Most of the time their
identification plate will at least mention ‘Input: 100–240V 50/60Hz’.
Data plate for an AC/DC
adapter complying with
50/60Hz frequencies and 100240V voltage range
Data plate for an air
conditioner, with a voltage
range of 208-230V and
frequency of 60 Hz
Figure 5: Examples of Voltage/ Frequency
Data Plates
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3.2. WORLD PLUG TYPES
Another of the important differences between individual standards is the type of plug and
socket used in electrical installations. There are many different types of plugs and sockets
and there usage varies throughout the world, as illustrated in Figure 4.
Figure 6: Plug Types around the World
The most common types of plugs and sockets are explained below, and additional details of
socket and plug types around the world are contained in ANNEX 3: Reference table: Socket and plug
types around the world., on page 267.
Type A
Commonly called the ‘American Socket’
Max 15A
100 – 127V
Ungrounded
Only Class II Devices
Socket Type A can only be used with plug Type A
•
•
•
•
•
Type B
•
•
•
•
Commonly called the ‘American grounded Socket’
Max 15A
100 – 127V
Grounded
Socket Type B can be used with plug Types A & B
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Type C
Commonly called the ‘European Hotel Socket’
• Max 2A
• 220-240V
• Ungrounded
• Pin Dia. 4mm
• Only Class II Devices
• Socket Type C can only be used with plug Type C
• Plug Type C can be used in socket Types E & F.
• This type of socket is usualy installed inside of bathrooms, mostly
into hostels. They are commonly supplied by an insulation transformer and are mainly
intended to be used with electric shavers.
Type E
Commonly called the ‘French Socket’
•
•
•
•
•
•
Max 16A
220-240V
Grounded
Pin Dia. 5mm
Socket Type E can only be used with plug Types C & E
Plug Type E cannot be used in socket Type F
Type F
Commonly called the ‘German or Shuko Socket’
•
•
•
•
•
•
Type E/F Hybrid
Max 16A
220-240V
Grounded
Pin Dia. 5mm
Socket Type F can only be used with plug Types C & F
Plug Type F cannot be used in socket Type E
Commonly called the ‘Universal European Plug’. Ungrounded type.
•
•
•
•
•
•
Max 16A
220-240V
Ungrounded
Only Class II Devices
Plug Type E/F Hybrid can be used in socket Types E & F
Mainly used for portable electrical tools
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Type E/F Hybrid
Commonly called the ‘Universal European Plug.’ grounded type.
•
•
•
•
Type G
Max 16A
220-240V
Grounded
Plug Type E/F Hybrid can be used in socket Types E & F
Commonly called the ‘British Socket’
•
•
•
•
Max 13A
220-240V
Grounded
Socket Type G can only be used with plug Type G
Local national standards for socket and plug types should be respected. Additional measures
should be taken to adapt equipment fitted with other types of plugs, in order that they can be
used correctly with the type of socket used in the country where the project is being
undertaken. Our next internal rules come out of this point.
3.1
The national standard for electrical plugs and sockets must be respected.
In particular all fixed domestic power outlets or sockets must be in accordance
with the local standards.
3.2
Travel adapters can only be used for occasional use of low power Class II
devices which do not need a grounding connection.
3.3
All electrical plugs fitted to fixed equipment must be fitted with a plug
complying with the local standard. Adapters are not acceptable and electrical
plugs should be removed and replaced with the correct type as necessary.
3.4
The only exception to rule 3.3 is in the case of equipment that is moved
frequently between countries with different plug & socket standards. In this
instance dedicated adapters should be purchased.
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When travelling, or using non local standard devices
“Universal”
traveler
socket
adaptors…
Most of them don’t have any
connection for the earth pin!
Only agreed for occasional use with
low power class II equipment!
This figure shows a
French
standard
multiple
outlets
equipped with a British
standard plug… The
most reliable adapter
for use of French
standard plugs in a
country equipped with
British
standard
sockets.
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3.3. WORLD CABLE COLOUR CODE
A third important difference between individual standards is the colour of electrical cables
used in an electrical installation.
Accorded to the IEC standards (IEC 60446), the following colours are permitted for electrical
cables:
Black
Brown
Red Orange Yellow
Green
Blue Violet Grey
White
Pink Turquoise
Striped cables using these colours are also permitted.
There are also some widely accepted systems for cable colours, as outlined in the following
sections.
3.3.1. AC Supply Colour Code for Electrical Cables
In fixed installations, two main families of systems are common:
Colour codes
IEC/EN 60446 : 2001
BS 7671 since 2004
Former British
Standard
BS 7671
Neutral
Blue
Brown
Phases
Black
Protective Earth
Grey
Green/Yellow
Black
Red
Yellow
Blue
Green or Green/Yellow
The following one is also commonly used in some British influenced countries. It is a
simplification of the former official British system.
Colour codes
Also common
Neutral
Black
Phases
Red
Red
Protective Earth
Red
Green or Green/Yellow
3.3.2. DC Supply Colour Code for Electrical Cables
DC supply cables must also comply with a colour coding system. There is a general
agreement about the basic colour coding system to be used.
Standard cable colours for DC supply
Applied in most countries for DC
supplies
Positive
Negative
Forbidden
Red
Black
Green or
Green/Yellow
However, considering the increased use of DC systems within MSF and ICRC, such a colour
coding system should be developed further. The following is a proposed colour coding
system for MSF and ICRC to adopt for DC supply electrical installations.
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INTERNAL PROPOSAL
The normal colour coding system for all DC voltages uses Red (+) and Black (-) cables
for negative grounded systems, and Blue (-) and White (+) for positive grounded
systems.
It is proposed for MSF and ICRC to use the specific colours for the most common DC
voltages. These colour cables should be available, at least through international
purchasing. However, in the case where the correct colours are not available, the
standard colour coding system should be used – and the cables should be marked with
tape of the correct colour and stickers identifying the voltage of the system (if it is
different than 12V). These stickers will use shape “0V” for the ground wire, and
‘+xxVDC’ or ‘-xxVDC’ for non-grounded wires (for example +12VDC, +24VDC, -12VDC, 24VDC).
NEGATIVE GROUND
VOLTAGE
POSITIVE
+12 V
Red
+24V
Orange
+48V
Violet
POSITIVE GROUND (Rare)
NEGATIVE
-12 V
Blue
-24V
Brown
-48V
Black
GROUND
FORBIDDEN
Black (-)
GROUND
FORBIDDEN
White (+)
A detailed listing of the different colour codes, including for flexible power cords, and some
historical ones (which could be encountered in old installations) is given in ANNEX 4:
Reference table: Wire colour codes around the world on page 273
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3.3.3. General Colour Coding for Electrical Cables
Important remark: Actually, many installations do not respect any colour coding system sometimes simply because the desired colour was not available on the market at the time the
installation was made. It also happens that colours are mixed: a wire entering a cable conduit
may have a different colour at the entry side than the one at the exit side. In such situations,
the correct identification of the cables is vital.
As a basic principle, everything confusing in the electrical cabling must be avoided. All
identification must be clear, and the colour coding system used should make such
identification easy. It is very important to respect the colour integrity of cables all along their
circuit. The colour coding system used must facilitate the layout and execution of distribution
boards making them easy and quickly understood. Whenever unidentified or confusing
coloured cables are found, they should be marked immediately at the time of their
identification. Wires having confusing colours should be marked by wrapping clearly the ends
of their insulation with tape of the correct colour. If relevant for the purpose of identification,
the cable may also need to be marked at additional locations or even along its entire length.
If certain wires of the incorrect colour cannot be replaced in a short term, marking them with
very visible and strong permanent identification tape is even more important.
Consideration of colour coding systems for electrical cables, leads to the next set of Internal
Rules.
4.1
The national standard colour coding system should be respected.
4.2
To ensure the integrity of installations, when former versions of colour codes
have been used and are still allowed in existing installations, all identifications,
repairs or replacement works made into such installations must be made
according to this former colour code.
4.3
All new installations and extensions to old installations must respect the most
recent local colour coding system.
4.4
If several colour codes are acceptable for new installations in a given country, the
colour coding system which is the closest to the IEC system should be selected.
4.5
Whatever the colour coding system used, the integrity of the colour identification
code and other identification of cables must be respected all along their circuit.
4.6
Identification of cables should be controlled and corrected at the time of the
primary assessment works of any existing electrical installation.
4.7
As a specific means to ensure electrical boards are made very clear, the use of the
right colour codes for all internal wiring of the boards is particularly important.
4.8
Ideally all cables that do not respect the applicable colour coding system should
be replaced with the correctly coloured cables. If the extent of work needed to
achieve this is considered unreasonable, the incorrectly coloured cables should,
as a minimum, be clearly marked with tape of the correct colour. Additional
identification methods may also be required.
Colour codes are only a part of the identification methods and rules that must be used to
ensure the clarity of electrical drawings and installations. Other identification methods and
rules are developed throughout this publication.
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3.4. WORLD MEASUREMENT SYSTEMS
The two principle measurement systems used throughout the world are the metric system
and the imperial system. The map in Figure 7 below shows when countries adopted the
metric system, and which countries are not using the metric system. Figure 6 makes it clear
that the majority of the world now follows the metric system. However there are countries that
use the imperial system (shown in black) and countries that have not officially confirmed
which system they follow (shown in grey). This last case is of particular interest, as it
represents a number of countries where MSF and ICRC are operational.
Figure 7: The Metric and Imperial System around the World
In fact, considering electrical equipments, the imperial system is most effectively represented
by the American Wire Gauge (AWG) system, defining the standard sizing for the cross
section of wires. As a consequence, the metric and imperial systems are defining differently
the rates of circuit breakers commonly accorded to minimal cross section of wires. These
differences are illustrated in the following tables.
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Comparison between American Wire Gauge and Metric Systems – Cable Minimal
Cross Sectional Areas/ Max Circuit Breaker Values/ Temperature Rise
For applications in accordance to UL 489
and CSA C22.2 Standard (NEC)
16
(15
14
(13
12
(11
10
(9
8
(7
6
(5
4
(3
2
(1
Max circuit
Minimal
breaker
cross
rate
section mm² (assigned
current)
1,3 mm²
10 A
1.6 mm²)
2,1 mm²
15 A
2.6 mm²)
3,3 mm²
20 A
4.2 mm²)
5,3 mm²
30 A
6.6 mm²)
8,4 mm²
40 A
10.6 mm²)
13,3 mm²
50 A
16.8 mm²)
21,1 mm²
80 A
26.6 mm²)
33,6 mm²
110 A
42.2 mm²)
0 - 1/0
00 - 2/0
53,5 mm²
67,4 mm²
150 A
175 A
000 - 3/0
85 mm²
225 A
0000 - 4/0
107 mm²
250 A
250
127 mm²
300 A
350
177 mm²
350 A
400
203 mm²
400 A
500
253 mm²
500 A
AWG No.
For applications in
accordance to IEC 60947-2
Standard
Max circuit
Minimal
breaker rate
cross section
(assigned
mm²
current)
1.5 mm²
10 A
2.5 mm²
16 A
4 mm²
20 A
6 mm²
25 A
10 mm²
40 A
16 mm²
63 A
25 mm²
80 A
35 mm²
50 mm²
100 A
125 A
70 mm²
160 A
95 mm²
200 A
120 mm²
250 A
150 mm²
320 A
185 mm²
400 A
240 mm²
500 A
Indicative
cable
temperature
rise ( noninsulated
single round
copper wire
into the air)
36 °C
30 °C
41 °C
35 °C
36 °C
27 °C
41 °C
23 °C
36 °C
27 °C
28 °C
34 °C
36 °C
28 °C
34 °C
26 °C
24 °C
31 °C
30 °C
24 °C
35 °C
23 °C
31 °C
26 °C
34 °C
30 °C
28 °C
35 °C
30 °C
37 °C
34 °C
Table 1: Metric and AWG wire cross sections
Common Rates of Circuit Breakers Used in Each System (Amperes)
Imperial: 6, 10, 13, 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 110, 125, 150, 175, 200, 225 A
Metric:
6, 10, 16, 20, 25, 32, 40, 50, 63, 80, 100, 125, 160, 200, 250, 320, 400 A
It is not uncommon in countries where there is no strong and/or precise technical regulation
for a mixture of imperial and metric systems to be used. This situation can be encountered in
Nigeria, Kenya, Uganda, Tanzania, Sudan, Egypt, South Africa, Zimbabwe, Malawi, Zambia,
Pakistan, Thailand and Cambodia.
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3.5. VOCABULARY AND SYMBOLS
When talking or writing about technical matters, each language naturally uses its own
vocabulary. The symbols used in diagrams and drawings can also vary significantly between
regions, countries and languages. It is beyond the scope of this publication to present the
whole variety of electrical terms and symbols used throughout the world. However, more
information on the main symbols and vocabulary used globally is presented in Annex 5.
For practical reasons it is always useful to know the local terms and symbols in order to
communicate effectively with local contractors. Nevertheless, for internal communications
and documents, MSF and ICRC should use the same vocabulary and symbols everywhere.
Here are the main electrical symbols and related terms in English and in French.
Terms and Vocabulary
ENGLISH
Circuit, Line, Feeder
Main circuit
Main distribution circuit
Final circuits
Auxiliary circuit
Command circuit
Diagram
FRENCH
Circuit, ligne, alimentation
Circuit principal
Circuit de distribution principal
Circuits terminaux
Circuit auxiliaire
Circuit de commande
Schéma
Terms, Vocabulary and Symbols
POWER SOURCES
AC source
SOURCES D’ENERGIE
Source AC
DC source
Source DC
Transformer
Transformateur
Single Phase Generator
Générateur monophasé
Three phases Generator
Générateur triphasé
Batterie
Battery
CABLES
Phase wire
CÂBLES
Fil de phase
Neutral wire
Fil de neutre
Earthing wire
Fil de terre
2 conductors cable without
earthing (1 N +1P)
3 conductors cable with earthing
(1 N +1P+1G)
Câble 2 conducteurs sans terre
(1 N +1P)
Câble 3 conducteurs avec terre
(1 N +1P+1G)
Three phases + neutral cable (1
N +3P)
Câble triphasé avec neutre (1 N
+3P)
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Three phases + neutral +
earthing cable (1 N +3P +1G)
Câble triphasé avec neutre et
terre (1 N +3P +1G)
Three phases cable without
neutral nor earthing (3P)
Câble triphasé sans neutre ni
terre (3P)
TERMINALS
POWER OUTLET / SOCKETS
TERMINAUX
PRISES DE COURANT
Single phase socket without
earthing
Prise monophasée sans terre
Single phase socket with earthing
Prise monophasée avec terre
Watertight single phase socket
with earthing
Prise monophasée étanche avec
terre
Watertight three phases socket
with earthing
Prise triphasée étanche avec
terre
SWITCHES
One way switch (general symbol)
INTERRUPTEURS
Interrupteur (symbole général)
Two way switch
Interrupteur va-et-vient
Single pole switch
Interrupteur monopolaire
Bipolar switch
Interrupteur bipolaire
Watertight (bipolar) switch
Interrupteur étanche (bipolaire)
Change-over switch
Inverseur de source
LIGHTING
ECLAIRAGE
Lighting bulb (hanging)
Lampe à ampoule (plafonnier)
Lighting bulb (on a wall)
Lampe à ampoule (Murale)
Watertight lighting bulb
Lampe à ampoule étanche
Single fluorescent tube (TL)
Tube fluorescent simple (TL)
Double fluorescent tube (TL)
Tube fluorescent double
Watertight fluorescent tube
Tube fluorescent étanche
Autonomous emergency lighting
unit
DISTRIBUTION UNITS
BOARDS AND BOXES
Consumer unit / fuse box
Junction/ derivation box
Bloc de secours autoalimenté
COMPOSANTS
DISTRIBUTION
DE
TABLEAUX ET BOÎTIERS
Tableau de distribution
Boîte de jonction / dérivation
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PROTECTIONS
PROTECTIONS
Circuit breaker (general symbol)
Disjoncteur (symbole général)
Thermal element
Élément thermique
Magnetic element
Élément magnétique
Thermal – magnetic circuit
breaker (MCB)
Single pole MCB
Disjoncteur magnéto thermique
Dual poles MCB
Disjoncteur bipolaire
Three poles MCB
Disjoncteur tripolaire
Four poles MCB
Disjoncteur tétra polaire
Residual current circuit breaker
(RCCB)
Residual current circuit breaker
with overload protection (RCBO)
Four poles RCBO
Interrupteur différentiel
Disjoncteur monopolaire
Disjoncteur différentiel bipolaire
Disjoncteur différentiel tétra
polaire
parafoudre
Lightning protection
PROTECTIVE EARTHING
Protective Earth
PE
PROTECTIONS
EQUIPOTENTIELLES
Protection équipotentielle
Earthing ( US: Grounding)
Terre
Frame / body
Masse / châssis
MISCELANEOUS
AC Voltage stabilizer
DC power supply / battery
charger
Power inverter
Pump / compressor
Air conditioner
Heater
Washing machine
Dryer
Water heater
EQUIPEMENTS DIVERS
Stabilisateur de tension AC
Alimentation DC / Chargeur de
batteries
Onduleur
Pompe / Compresseur
Air conditionné
Chauffage
Machine à laver
Séchoir
Chauffe-eau
Table 2: Main electrical symbols
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3.6. IDENTIFICATION RULES
3.6.1. ROOM IDENTIFICATION
For small premises there is no need to use a normalised method of identification. Most of the
time, functional identifications such as Admin Office, Kitchen, Room 1, Room 2, Bathroom,
etc. will be sufficient for plans and diagrams. When considering larger premises such as large
offices or big compounds, a more rational room identification method is needed.
Identifications are often still the name, or the function of a room. However, as the function of
the room may well change over time, it is advised to also give each room a unique and
constant identification reference.
Here is a proposal for a rational identification method:
Depending upon the configuration, each building, part of a building, or functional group of
buildings is identified by a zone letter (for example A, B, C, etc.).
Each room inside of a zone is identified by a number following the identification letter of the
zone (for example A1, A2, A3, B1, B2, B3, etc.).
As far as practical, identification letters and numbers are allocated in a clockwise direction
starting at the entry side of the compound, zone or building. On sites with a linear distribution
of buildings or zones, identification letters cannot be allocated in a clockwise manner – a
linear approach should be used.
Corridors, access areas and passages are identified by preceding the identification code with
an ‘X’ (for example, XA1, XA2, XB1, XB2, etc.).
Stairs are identified by preceding the identification code by a ‘W’ (for example WA1, WA2,
WB1, WB2, etc.).
Corridors, access areas, passages and stairs linking two zones (or building, part of a
building, or functional group of buildings) with different identification letters are identified with
the same ‘X’ followed by the two letters of the linked zones (for example XAB, XBC, WAB,
WBC, etc.).
Outdoor spaces are identified by preceding the identification code by a ‘Z’ (for example ZA1,
ZA2, ZB1, ZB2, etc.).
TO AVOID ANY CONFUSION WITH NUMBERS, THE CHARACTER I(i) and O(o) ARE NOT
USED FOR ZONE IDENTIFICATION (for example the identification I1 should not be used)
RESERVED LETTERS (W, X, Z) ARE ONLY USED FOR THE FUNCTIONS DESCRIBED
ABOVE, THEY ARE NOT USED AGAIN FOR IDENTIFYING ROOMS OR ZONES (for
example the identification WW1 should not be used)
This identification method is best illustrated with some examples.
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Figure 8: Example of Zone Identification for a Large Compound
Figure 9: Example of Room Numbering (Zone B within the Same Compound)
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Figure 10: Example of Zone Identification for a Large Building
Into this example, letters could not be assigned in a clockwise system, due to the linear
nature of the building. Instead, they were assigned in a linear approach from right to left, like
the usual writing sense in the country
Figure 11: Example of Room Identification Numbering (in zones A and B of the same
building)
To aid clarity, all identification references should be written on the doors or door jambs of all
rooms, and the entries of passages or stairways, etc. There is no need to use large signs to
mark these identification references, they should remain small and discrete.
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3.6.2. ELECTRICAL COMPONENTS IDENTIFICATION
As a basic requirement for every electrical installation, circuits should be clearly identified
inside the breaker boards. For small installations, functional identifications should be
sufficient. Small stickers mentioning ‘Kitchen’, ‘Room 1’, etc. will be enough to help identify
which circuits are protected by which breaker in the breaker panel. For large installations, the
desired clarity can only be obtained by following rational identification rules, as explained in
the preceding section.
In addition, the Identification Reference of each terminal must be indicated on the terminal
itself. This dedicated identification gives the entire path from the mains to the terminal: it
contains the ID of the main line, the ID of the concerned final board, the ID of the circuit and
the position of the terminal along the circuit.
Whatever the size of the installation, all identifications are marked on both the position
diagram and on the single line electric diagram. In order to facilitate the job of any electrician
that must intervene, a copy of these diagrams must be located with the concerned board.
Here are these identification rules and examples.
Main boards:
The power panel, containing the commutation devices for the power sources should be called
PP, while the main distribution panel should be called MB (in English) or TG (in French).
For these boards, let’s feel free to call them
PP, MB GP, P0, B0, GB or whatever, it is not
of importance, so, let’s do as they use to do
locally : it is after the main board that it is
recommended to apply a standard
identification method.
Figure 12: identification of main panels
Main lines:
Always use a CAPITAL LETTER – A, B,
C… don’t use “I” “O” “X” “Z”…
Figure 13: identification of main lines
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Figure 14: The Electrical Diagram of a Power Panel and Main Distribution Boards – Using the
Same Identification Rules
Panels on the main lines: Use an indication number according to the position of the panel
along the main line. Hence, the complete identification of a final board is given by the letter of
its supply line (feeder), and the number of its position: the 1st panel on line A is A1, the 3rd
panel on the G line is G3, etc.
Figure 15: identification of distribution panels
Remark about main line and panel identification: The proposed identification
method is suitable for a distribution structure with a single main panel and a
number of final boards. In some instances, installations are organised using
intermediary distribution panels. However, where ever possible, such
structures should be avoided as using intermediary panels can make it difficult to
choose the correct rate for the breakers. In situations where such intermediary
panels are already installed and must be maintained, the identification reference
should use additional letters to identify intermediary panels and lines, as explained
below.
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Intermediary panels: The same identification method should be applied, with sub-distribution
lines identified by a capital letter following the identification of the upstream panel. For
example, the line ‘B’ out of the panel A2 will be ‘A2B’. The panels supplied by this secondary
line will be identified by adding a number to the identification of their feeder line, for example
A2B1. Following these rules means that all identification references for feeder lines end with
a letter, while the identification references for panels end with a number.
Figure 16: identification of intermediary panels
Final circuits out of the final boards: Use numbers rather than letters, as there could be more
than 25 circuits out of a panel. Use the small letter ‘c’ to indicate that this is a final circuit, for
example c1, c 2, c3, etc.
Figure 17: identification of final circuits
Terminals: Use the following letters to identify the kind of terminal:
Power sockets: P
Switches: S
Lights: L
Junctions: J (if needed)
For less common terminals, other letters can be used – but should be clearly defined in the
legend of the design or diagram.
Terminals should also be identified with a number, indicating their position on the circuit, for
example P1, P2, S1, S2, L1, L2, etc. In this way, the complete identification reference of a
terminal describes the complete path from the main board. For example terminal B3c1P2 is
the 2nd socket on the 1st circuit from the 3rd panel on the main line B. In large installations,
this identification reference should be physically written on the terminal.
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For small boards supplying only a few terminals, the identification numbering should be
continued from one circuit to another: Power sockets on c1 will be P1, P2, P3, P4, P5, and
power sockets on c2 will be P6, P7, P8, etc. This will allow a simplified identification system
to be used on the position diagram. On drawings and designs, in order to keep them simple
and legible, only the final part of the indication reference should be shown, as illustrated in
the example below.
Figure 18: Identifications on a single line diagram
For large boards supplying a lot of terminals, the same continuous numbering method should
not be used, as it makes it difficult to cross check against drawings and diagrams. Instead,
the numbering is reinitialised from 1 on each circuit: Power sockets on c1 will be P1, P2, P3,
P4, P5, etc. and power sockets on c2 will also be P1, P2, P3, etc. In this case, the
identification reference given on the position diagram must also include the number of the
circuit: for example c1P1, c1P2, c1P3, c2P1, c2P2, c2P3, etc.
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3.6.3. USE OF TITLE BLOCKS
Not only the rooms and electrical components must be identified. Plans and diagrams also
need to be clearly identified, and Title Blocks should be included on all plans and diagrams to
achieve this.
As a minimum, a Title Block should indicate the Owner, Date, Project Title, Document
Identification, Document Type, Subject, and Author), as shown in the example below:
OWNER / client
Date
Revision
COUNTRY :
PROJECT :
TITLE
Subject 1
Subject 2 Subject 3
Doc Type :
Author:
Contact
:
Figure 19: example of a title block
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4. MANAGEMENT OF ELECTRICAL PROJECTS
The objective of this chapter is to contextualize the Protocol for the Management of
Construction Projects (PMCP) into electrical projects. The PMCP enhances management
of electrical projects by outlining and explaining each step of the project development and
clarifying the roles and responsibilities of each stakeholder.
Following the steps of the PMCP, this chapter describes the different steps of a project cycle,
and the prerequisites and deliverables particular to electrical projects.
By applying the following rules, stakeholders will ensure consistency of the project, therefore
contributing to the compliance of the works with technical standards and to the satisfaction of
the end users.
5.1: Electrical projects, regardless of their size, must be managed according to the
principles of the PMCP, and the guidelines further described in this chapter.
5.2: Each step of the project development must be validated by the project owner prior to
starting the next one. Such validation is necessary to ensure that the project is in line with
the project owner’s needs.
5.3: Unless force majeure events obligate to revise the project, changes in information
validated beforehand must be avoided.
4.1. PROJECT DEVELOPMENT CYCLE
Regardless of their nature and scale, electrical projects, as one of the core activities in
construction, follows a similar cycle of development as described below:
Vision
Handover
Feasibility
Construction
Design
Procurement
Figure 20: The project development cycle
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• Vision
Identification of the needs and project scope definition as expressed by the
end user, further named in this document Project Owner.
• Feasibility
Examinations of the conditions under which the project shall be carried out
and of major variables in regulations, standards and technology in order to
come up with technical options.
• Design
Development of technical solutions and specifications compliant with the
needs and requirements defined at vision and feasibility steps.
• Procurement Preparation of contract documents for tender procedure based on the
design documents and selection of the contractor, and/or purchase of the
materials and tools if works are carried out in-house.
• Construction Execution of the works under constant supervision throughout the
implementation of the works in order to ensure compliance of the
installations with the design and standards.
• Handover
Final inspection and testing of the works in order to proceed to the takeover of the works. Preparation of an operation and maintenance plan.
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4.2. ROLES AND RESPONSIBILITIES
Throughout a project development cycle, two main players are involved in an electrical
project and their role and responsibilities varies as the project develops. Below is listed some
of the major responsibilities of each party.
The Project Owner is responsible for describing the scope of an electrical project (Vision).
He owns the works when completed and handed-over, and therefore participates in the
selection of most appropriate options when submitted by the Project manager. Either one or
a group of persons can represent the project owner. Hence, the Project Owner shall:
•
•
•
•
•
•
•
•
Assist the project manager is gathering all relevant information and authorizations,
Provide a listing of the needs, as extensive as possible but not necessarily technical,
Review and endorse the design at each step of its development in order to confirm
that the design are in line with the scope of the project,
Choose alternatives among several options if requested by the project manager,
Provide all information should it be required by the project manager,
Validate that the works complies with the needs at handover step,
Develop together with the project manager an operation and maintenance strategy,
Notify any defect that may appear after the works have been taken over during the
warranty period, if any,
The Project Manager is responsible for ensuring that the steps of the project development
cycle are observed and that consolidated inputs are provided by the various stakeholders. He
ensures that the project is carried out in line with the project owner’s needs and in
compliance with technical standards. Depending on the technical complexity of the electrical
project, the Project Manager, although represented by one person, may involve other
specialist or technicians. Hence, the Project Manager shall:
•
•
•
•
•
•
•
•
Advise the project owner on technical issues related to the project proposal,
Carry out necessary technical assessments and investigations,
Gather all missing information in terms of electrical needs, and produce a complete
and consolidated listing of the needs with technical information,
Get the project owner’s validation at each step of the project development,
Provide various technical options and associated diagnosis,
Coordinate the design of the project in line with the project owner’s needs and
compliant with technical standards,
Submit designs and clarify the possible implications of alternatives to the project
owner, taking into consideration safety, sustainability, maintenance, cost, service
continuity and environmental aspects,
Identify and select the consultants, suppliers, technicians, contractors, personnel
required to carry out the design and the works,
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•
•
•
•
Manage the budget and timeframe of the project, order necessary material and
equipment, and administrate the contract for works if any,
Organize and supervise the works, ensuring compliance with the technical design
documentation and technical standards, but also taking into consideration specific
requirements in terms of service continuity,
Organize the commissioning of the works, including all relevant tests and as-built
documentation, and certify that the works have been completed in line with the
technical design documents and technical standards;
Organize the taking over of the works, and follow up the correction of defects noted at
the completion of the works;
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4.3. ELECTRICAL PROJECT TASKS AND OUTPUTS
The following schedule details the phases and steps of a project development cycle accorded
to the PMCP (Protocol for the Management of Construction Projects). Such project
development cycle should be followed for all electrical projects regardless of their technical
complexities or financial implications.
In addition, deliverables and outputs specific to each phase are also listed, keeping in mind that
they must be approved by the project owner prior to stepping into the next phase as mentioned
in rule 5.1.
VISION
•
•
•
•
Description of the problem and the needs (including the list of equipments to be
maintained or moved);
General description and state of the existing installations, if any;
Description of the projected situation (reasons and scope of intervention);
Identification of the project owner and project manager.
FEASIBILITY
•
•
•
•
•
•
•
•
•
•
Feasibility study and Preliminary Design
Detailed assessment of the existing installations, if any; (user's satisfaction, compliance
with technical standards, state and/or obsolescence of the installations, etc.)
Description of the constraints and the means;
Sketches, technical options diagnosis and alternative proposals if relevant;
Draft description of project organization in terms of HR, budget, time and procurement
strategy;
Area, building and room identification (refer to section 3.6.1 on page 49 for
identification rules);
Comprehensive listing of the electrical consumers (user's devices, needs) including
available electrical specifications (power, cos phi,...) and usage factors);
Draft listing of the user’s needs (number and position of all electrical terminals needed,
list of equipments and devices, schedule of use, etc.);
Position diagram (copy of the needs list on drawings showing exact location of all
terminals and fixed equipment)
DESIGN
•
Project Proposal as expressed by the Project Owner
Developed Design and Technical Design
Load calculation, power sources and back-up sizing, distribution sizing, protection
devices sizing;
Position diagram of main panel board and division boards indicating their
distribution areas, and the position of the main distribution lines;
Position diagram of the main grounding (equipotential) network and surge protection
devices;
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•
•
•
•
•
•
•
Single line diagram of the main distribution (from power sources and main board(s)
to the head protection of final distribution boards;
Single line diagram of the final boards and related circuits and terminals;
Numbering of the terminals made on the position diagram, to cross check with the
related single line diagram;
Additional information on position diagram (i.e. manholes, channels, junctions,
specifications related to the conduits and their placements)
Material specifications (refer to catalogs and supply lists, brand, model, references);
Tools and specific equipments required for the works if works are done internally;
Listing of auxiliary finishing works;
PROCUREMENT
•
•
•
•
Time program of the works;
Preparation of tender documentation (Quantity estimation, Contract draft, etc.);
Purchasing of materials, tools and equipments;
Identification of the team or the company in charge of the works;
CONSTRUCTION
•
•
•
•
•
•
•
Construction Supervision and Contract Administration
Site reports and meeting minutes;
Payment certificates;
Site supervision with constant monitoring of the works implemented
HANDOVER
•
Construction Procurement
Substantial Completion and Taking-Over of the Works
Final evaluation of the works (Conformity of the works with the project and technical
standards);
Commissioning report (Testing), Taking-Over certificate and Punch-list;
Final Completion certificate (after corrections are made and guarantee period)
As-built drawings;
Operation and Maintenance plan;
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4.4. IMPLEMENTATION OF ELECTRICAL PROJECT
The development of appropriate and consistent design is the most important point that will
ensure a good execution. However, adequate preparation and supervision of the works to be
implemented is key in the success of a project.
Before starting the implementation works, the project manager should keep in mind the
following points:
•
•
•
•
•
•
Technical design has been technically approved by the project manager and endorsed
by the project owner;
The supplies, materials and tools have been delivered and are stored into a dedicated
warehouse, and an inventory has been made if the works or part of the works are
done in-house,
The Contractor has been designated and a contract for works has been signed if the
works are outsourced,
The phasing of the works has been prepared.
The project supervision team has been identified, and the distribution of tasks and
responsibilities is clear,
Everything has been organized so that the people working / living into the place where
the works have to be done is feeling comfortable,
When starting the works, the project manager should keep in mind the following points:
(About the site and follow-up preparedness)
• All equipment and pieces of furniture that must be moved to free the space are moved,
stored in a correct place, and protected as required, in accordance with the people
living or working on the site of the works.
• Dedicated secure places must be found to store the supplies and tools on site.
• All movements of supplies between the central warehouse and the onsite storage
must be recorded in a journal.
• Small additional supplies will be anyway needed along the ongoing works. A purchase
journal is needed to follow these.
• All working hours of the implementation team members must be recorded as well.
When executing the works, the project manager should keep in mind the following points:
(About the order of the successive operations)
•
•
•
•
Everything that must be removed or dismantled is removed and dismantled,
The exact position of all terminals and boards is clearly marked on site,
All mounting blocks (empty plastic boxes that will hold the terminals) are put in place
with their cable entries set in right number and position,
All boards (breaker boxes etc.) are prepared. Accorded to the size and weight of the
boards different ways are possible: Empty boxes are installed at the same time as the
mounting blocks of terminals are installed, or they can be prepared in advance, all
modular devices being already put in place on their rails, and all internal wiring of the
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•
•
•
•
•
•
•
board being prepared in advance. Then, the boards will be put in place with all their
equipment already set in place. But it is often easier to place empty boards first,
All junction boxes, channels, pipes, trunks are put in place between the board and all
mounting boxes of terminals,
All cables and wires are put into the pipes and trunks,
All identifications of wires are always made along the progression of the works,
All terminals are installed and wired into their mounting boxes,
All wires entering into the breaker board are connected to the modular devices,
All identifications are reported on the modular devices,
According to the situation, circuits can be tested one per one along the progress of the
works, or can be tested after that all wiring jobs have been made.
When completing the works, the project manager should keep in mind the following points:
•
•
•
•
•
•
All identifications are updated,
All drawings and diagrams are updated,
A copy of the concerned updated position and electrical diagram is placed inside of
each board. (These diagrams are only concerning the area and circuits supplied by
the board),
The site of the works is completely cleaned off and all remaining tools, supplies,
accessories, and wastes are evacuated.
While all remaining tools supplies and accessories are back into the warehouse a final
inventory is established,
Same for the inventory of the tools. A listing of the tools that have been damaged or
lost must be established. It is also the right time for those to be cleaned, controlled and
maintained, even if this must also be made during the works.
4.5. CONCLUSION
The PMCP and guidelines introduced in this chapter per se are obviously not a magic wand
that solves all the problems and challenges that may occur during the life of a project. As
every project management tool, one of its most important aims is to foster multidisciplinary
teamwork as the condition for success and satisfaction.
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5. SAFETY OF INDIVIDUALS: TECHNICAL RULES
5.1. THE DANGER OF ELECTRICAL CURRENTS
According to their level and duration, the effects of electrical currents on human beings can
be very dangerous. A current of only 10mA creates a serious shock, and values over 30mA
can potentially have irreversible effects (such as serious internal burns) or can be fatal due to
respiratory or cardiac arrest. The following table gives some indications of the potential
effects of different levels of current and contact time.
INTENSITY
DURATION
EFFECTS
0,5 to 1 mA
-
Perception threshold
8 mA
-
Shock to the touch, backlash
10 mA
4m 30s
Limbs muscles contraction, lasting crispation
20 mA
60 s
Tetanisation start of the rib cage
30 mA
30 s
Ventilatory paralysis
40 mA
3s
Ventricular fibrillation
75 mA
1s
Ventricular fibrillation
300 mA
110 ms
Ventilatory paralysis
500 mA
100 ms
Ventricular fibrillation
1A
25 ms
Cardiac arrest
2A
instantaneous
Damage to nervous system
Table 3: Danger of electrical currents
Whether they are minor or serious, all incidences of electrocution have the same origin.
Because all flows in electrical circuits are current loops that are returning to their source,
electrocution occurs when a person, or a part of a person, is inserted into one of these loops.
In this way an electrical circuit is established by simultaneous contact with two conductive
objects having a difference of voltage and being inserted into the same electrical circuit.
Hence:
 Electrified objects must be unreachable
 Voltage differences between objects being simultaneously touchable (frames,
earth) must be suppressed.
This danger is obvious for anybody touching at the same time both active wires of different
polarity (poles) of an electrical system (double contact). The other case of dangerous contact
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is when a person is simultaneously in contact with an electrified object and the earth (simple
contact).
Simple contacts are dangerous too because we need to give to the electrical network a
voltage reference that is stable, close to the environment and close to 0 Volts. Most of the
time, to achieve this, one pole of the electrical source is earthed (grounded). This
earthed pole is called the neutral or the 0 V while the poles that are not earthed are called the
phases (P), or the live (L).
This permanent connection to the earth has two main intended effects:
 For all materials that are insulated from the earth, and particularly the conductive ones,
the development of electrostatic charges reaching high voltage levels compared to the
ground can be dangerous for people (sudden static discharges through persons) and
for the devices (sudden static discharges through electrical insulations). Objects which
are connected to the earth cannot accumulate electrostatic charges, as these will flow
to the ground as they are developed. The reference voltage of the object will remain
close to the voltage of the ground. (It is the OV reference)
 Because it is connected to the earth, the neutral will collect all currents (losses) from
circuits (accidentally) in contact with the earth, and transmit them back to the power
source.
People are in almost permanent contact with the ground. As a result of the relation between
the earth and the neutral, the earth is also the primary conductive object connected to the
electrical circuit. Every non-grounded object with an exposed conductive part that is in
contact with the phase (live) pole of the electrical source is dangerous in the situation where
someone has a simple contact with it.
 With an earthed neutral, all simultaneous contact with the earth and a conductive part
connected to the phase of a circuit are highly dangerous.
Figure 21: Current flow in case of a direct simple contact with live conductor
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Simple contacts with electrified objects are of two kinds:
1. Direct simple contacts: A contact with an active live part of an electrical system (phase
wire, junction, etc.)
2. Indirect simple contact: A contact with an exposed conductive part (e.g. user device
frame) that is accidentally in contact with a live active part of an electrical system.
In practice, if no protection means are installed, both a direct and an indirect contact have the
same effect - the person is electrocuted.
Not all exposed parts of electrical devices are equally dangerous: Depending on their design
and conditions of use, electrical devices have very variable safety levels.
 The IEC made a classification of equipment related to their specific dangers and
related specific requirements. It is required that the class of insulation of the electrical
equipment in use is identified, and that the specific requirements of the class to which
they belong are respected.

To meet these requirements even in case of damaged, incorrect or faulty devices or electrical
installation, three specific aspects of safety precaution have been established and are
compulsory:
 The protection against direct contacts: Electrified objects (bare parts of wires,
junctions) must be untouchable.
 The protection against indirect contacts: The voltage of all exposed conductive parts
(ECP) must be reduced to the surrounding (reference) voltage by the mean of
earthing.(Grounding)
 Ground Fault Circuit Interrupters (GFCIs) must interrupt the power in case of
dangerous losses.
The main strategies for addressing these key aspects of safety precaution will be discussed
in the following sections. (5.3 to 5.6,on page 76 and following)
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5.2. THE CLASSES OF EQUIPMENT
According to the level of protection that equipment provides against electrical shocks, the IEC
has defined the following protection classes (IEC 61140). These class definitions are used to
differentiate between the protective-earth connections requirements of the equipment.
Class 0
These appliances have no protective-earth connection and have only a single level of
insulation between live parts and their metal frame. With such equipment, a single fault could
cause an electric shock or other dangerous event without triggering any fuse or circuit
breaker. Even though such equipment is forbidden by most local regulations, they can still be
found in some countries.
Example: Metallic light bulb holders.
Class 0 equipment are strictly forbidden.
Class I
Class I Symbol
These appliances must have their frame connected to the electrical protective earthing (PE)
by a separate earth conductor. The earth protective conductor must be included in their
power cord, which has 3 conductors. The power cord must be connected to a power outlet
equipped with a protective earth. No single failure can result in a dangerous voltage being
produced in the frame of the appliance - that might cause an electric shock. If a fault occurs,
a breaker device can trigger and interrupt the supply to the faulty appliance.
In case of a contact between a live conductor and the casing: If the earthing (grounding)
resistance is low enough, the faulty current will trip an over-current device (fuse or circuit
breaker). In any other situations, when it reaches the rated protection threshold, the faulty
current will trip any ground fault breaker (RCCB or RCBO).
Example: Most fixed appliances and some mobile appliances such as: Fridges, waterheaters, washing machines, coffee machines, micro waves, copy machines, printers, desktop
computers, some laptop adaptors, etc.
All class 1 equipment must be connected to the earth protective conductor (Yellow
green - grounding). Otherwise their use is strictly forbidden.
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Class 0I
Class 0I Symbol
These appliances have their frame connected to earth with a separate terminal. The
connection to the protective earth is made with a separated single conductor not included in
the mains cable. In effect this provides the same automatic disconnection as Class I.
Example: Generators
If correctly connected to the protective earth, all class 0I equipment are similar to
class I equipment.
Class II
Class II Symbol
A Class II or double insulated electrical appliance is built in such a way that it does not
require a connection to the protective earth (ground). No single failure inside of a class II
equipment can result in a dangerous voltage in the external body of the equipment, as the
electrical insulation has been doubled or reinforced by other means. Class II equipment must
be labelled ‘Class II’ or ‘double insulated’. The double insulation symbol is generally present
on the data plate of the equipment.
Do not confuse ‘Class II’ with ‘Class 2’ equipment as defined by the UL standard. ‘Class II’ is
a protection class as per IEC standards (IEC 61140), whereas ‘Class 2’ determines a range
of voltage output of power adaptors as per UL standards.
Example: Most of the light mobile equipment, such as: Phone chargers, DC power adapters
for small laptops, drilling machines, grinders, portable electric saws, grass mowers, cooking
mixers, etc.
Class II equipment do not need a connection to the protective earth. All mobile
equipment, and more specifically mobile tools, small domestic appliances and some
electro medical appliances must be at least Class II appliances.
Note that medical equipment must also comply with other requirements!
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Class III
Class III Symbol
A Class III appliance is designed to be supplied from an internal or separate safety
extra-low voltage (SELV) power source (<48V DC).
In every case, no contact with the supplied voltage is dangerous.
SELV conditions have additional requirements
All active parts must be:
Double insulated from any electrical part of other installations (e.g. primary input voltage
of the LV/ SELV power adaptor
Insulated from the protective earthing wire. If there is a ground fault there is no risk of a
SELV conductor becoming electrified because of contact with the faulty protective earth.
We have 2 main kinds of class III equipment
Supplied by a separated power adapter/generator with a Class III output
Supplied by internal battery cells
Example: Most of the equipment supplied by DC adapters and portable equipment,
such as:
Laptop computers, IT accessories (switches, modems), phones, all battery powered
portable tools, torches, battery powered lights, etc.
For many medical devices - at least the ones in contact with the patients - even
compliance with Class III is not considered sufficient protection, and further
more-stringent regulations must apply.
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Note about ELV and SELV: The following table gives the voltage classification as defined by
the IEC (IEC 60338 and 61000-3-6):
Code
Name
AC
DC
(S)ELV
Extra Low Voltage
Norm : U <50V
= 48V dry 24V wet
Norm < 120V
= 72V dry 36V wet
LV A
Low Voltage A
50V < U < 500V
120V < U < 750V
LV B
Low Voltage B
500V < U < 1000V
750V < U < 1500V
MV
Medium Voltage
1kV < U < 35kV
1.5kV < U < 50kV
HV
High Voltage
35kV < U < 230 kV
50kV < U < 500 kV
EHV
Extra High Voltage
U > 230kV
U > 500kV
Table 4: The voltage classification
ELV max voltage varies according to the situation. In practice the recommendation is:
Dry areas: 48VAC / 72VDC
Wet areas: 24VAC / 36VDC.
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5.3. PROTECTION FROM DIRECT CONTACT
!
This concerns the protection against direct contact with electrified
parts of the electrical system, such as bare wires and uncovered junctions.
When properly installed, insulations, covers, caps, doors and other mechanical protection
offer the only correct protection against the danger of direct contact.
This involves:
-
Insulation (sheathing) of the cables
Cover to boxes (distribution, junctions, or protection boxes or panels)
Front covers of switches, sockets, etc.
Insulation of lighting fixtures, and any kind of user devices
Too often, the physical barriers which prevent direct contact with live electrical parts are
damaged or missing. It is therefore necessary, before any other operation, to verify and reestablish these physical protections. This concerns the components of the electrical
distribution systems as well as the appliances/devices/equipment supplied by these lasts. All
components and appliances must be of an appropriate quality and in good condition – no
deterioration of their protective qualities is acceptable.
In the case of enclosures with doors that anyone can freely open, there are some additional
specific requirements:
-
An additional protection must be installed inside of the enclosure.
In the case of breaker panels, an additional protection layer must cover all
junctions of the breakers, and only the part with the handle of the breaker should
be accessible.
For boards that do not have these additional inner protections of the electrical junctions,
access must be restricted only to qualified electricians. These boards should be located into
a closed technical room with restricted access, and otherwise access panels or doors should
include locking mechanisms that can only be opened with a specific tool or dedicated key.
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5.4. PROTECTION FROM INDIRECT CONTACT
When a conductive (e.g. metallic) frame is in contact with a live electrical component
because of a default of the device, touching this frame is as dangerous as touching the
electrical component itself. This is called indirect contact, as the person is not touching the
electrical component directly. Indirect contacts are as dangerous as direct contacts.
The main protection against indirect contact is to connect all frames to an ‘equipotential
earthing’ hence ensuring that the external surfaces of all objects that can be touched have
the same voltage as the environment. The wiring system that connects all frames together in
this way is called the protective earthing wire (PE).
The following figure illustrates the principles of an equipotential protective earthing system.
Losses
GROUND
Losses
Figure 22: general principle of an equipotential bounding.
Connecting all bodies and frames of devices to the ground reduces the potential (voltage)
between the touchable parts of the appliances and the ground to close to zero volts – and
hence reduces the risks associated with indirect contact. All losses due to a fault between
phase and ground will be collected through the protective earthing wire and will go back to
the neutral of the generator (or other power source), which is also earthed. The route of the
losses is called the ‘fault loop’.
L
N
PE
The loss is collected
by the neutral of the
generator
G
EARTH STAKES
THE
LEAKAGE
CURRENT
PASSES
THROUGH
THE FRAME
AND THEN
TO THE
EARTH
WIRE
P
FAULT
CONTACT
BETWEEN
PHASE AND
FRAME!
EARTH
Figure 23 : Figure of a fault loop.
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Two different equipotential wiring systems are connected to the earth:
1. The protective earthing of the electrical system (all earth wires coming from the electrical
terminals)
2. The protective earthing of the building (all protective wires coming from non-electrical
objects which are conductive such as pipes, metallic carpentries, doors, windows, etc.)
This is the general principle of the establishment of an equipotential of the frames and
collection of losses through a protective earthing wire. However, different kinds of earthing
systems are allowed, each of them having advantages and disadvantages. They are
described into the next chapter, 5.5: The Earthing Systems.
With a protective earth, most of the current losses pass by a controlled network of wires: the
protective earthing system. Because it refers to the earth potential, if the loss is not too high,
the contact voltage (voltage between a faulty device and the surrounding earthing) is
decreased to an acceptable voltage of under 50V. But this voltage varies according to the
conditions of the losses.
If, compared to the total resistance of the fault loop (R (Phase wire) + R (fault)) + R (contactNeutral)) the resistance (R (Phase wire) + R (fault)) is very low, the contact voltage can
increase over 50V. This is caused if R (fault) is very low, or if R (contact-Neutral) is too high.
This contact voltage will also increase if the resistance between the surrounding earthing and
the neutral is reduced (wet areas, bare feet, etc.).
This means that the protection against dangerous contacts must include ground fault
breakers. Requirements about Ground Fault breakers are explained in Section 5.6, Earth
Leakage Protection Devices.
The practical installation of an earthing system must also follow some rules. These will be
detailed in the chapter about setup design and execution.
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5.5. EARTHING SYSTEMS
5.5.1. DIFFERENT EARTHING SYSTEMS
The need to install protective earthing systems has been clearly explained in the previous
section about indirect contacts. We know that the neutral of the source and all frames must
be connected to the earthing system. Different options are possible and must be examined.
Whichever option is selected, the fundamentals of the protective earthing system remain the
same:




The pole of the power source that refers to the earth is called the Neutral
It is defining the ‘0 Volt reference’ of the system
It collects all losses coming back to the power source through the earth.
All protective earthing systems include the interconnection of all metallic frames to an
equipotential earthing. Any object of a given environment must refer to the potential of
the ground (OV)
Three main earthing systems are defined by the IEC (IEC 60364),
They are called IT, TT, TN
It is important to make the right choice for the earthing system of an installation.
The two letters used to define earthing systems have the following meaning:
The first letter is related to the neutral of the power source.
o ‘I’ means that the neutral of the power source not directly connected to the earth.
It is Isolated or is has an Impedant connection to the earth. (connection by the
mean of an impedance - resistor or coil)
o ‘T’ means that the neutral is connected to the earth (‘T’ comes from the French
‘Terre’ meaning earth)
The second letter is related to the frames of the user devices.
o ‘N’ means that the frames of the user devices are connected to the neutral
o ‘T’ means that the frames of the user devices are connected to the earth
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5.5.2. EXPLANATION OF THE THREE EARTHING SYSTEMS
The IT earthing system
For large installations, this system is rarely used and is difficult to manage. It concerns very
small class II installations, or installations requiring a high level of continuity.
Advantage: The first fault is never dangerous. In case of a single fault the service can be
maintained. This is the reason why this system is for instance mandatory in sophisticated
western medical operation theatres.
Disadvantage: The insulation must be constantly controlled. The first fault must be detected
and corrected before a second fault occurs and trig a protection breaker.
Note: The IT earthing system is actually the one used by many very small generators (< 2
kVA) typically running to supply a small number of preferably class II users in a provisional
and/or very small installation. It is acceptable because light portable generators often do not
have any grounding connections (They are also Class II equipment). Additionally, with a
small number of user devices the probability of a double fault is very low.
The TT earthing system
With the TT earthing system the neutral of the power source is earthed and the frames of the
user devices are earthed separately. This system is the most common and it is often imposed
when connecting to a public power distribution system.
The neutral of the power source is connected to its frame which is then connected to an
earthing rod. At the level of the power source the neutral and the earth are the same. On the
side of the user devices all frames are connected to a separate earthing pole.
The following figure illustrates the
principles of a power distribution setup
using a TT earthing system.
Only the active wires
are distributed
Earthing of the neutral
Earthing of the user devices
Figure 24 : figure of a TT earthing system
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Advantages:
-
The intensity of the collected losses is limited by the earth resistance
-
Each user is responsible for their own protective earthing system
Disadvantages:
-
Because the intensity of the losses is reduced by the resistance of the ground only
Ground Fault Circuit Interrupters (GFCI), Residual Current Devices (RCD), Residual
Current Circuit Breakers (RCCB), and Residual Current Circuit Breaker with Overload
protection (RCBO) devices can protect against faulty circuits.
-
If the ground resistance is very high (sand, dry season etc.) the losses cannot be
collected and GFCI devices would not be able to trip in case of an insulation fault
occurring.
-
On public grids the quality and resistance of the earthing is also related to the earthing
on the supply distribution side. If the earth on the supply side is not correct, even with
a perfect earthing on the user’s side, the resistance of the ground loop or fault loop will
not be correct. In this case the quality of the grounding can only be corrected if the
faults on the distribution side are corrected.
-
In the case of a lightning strike, and depending upon the earth resistance, high
voltages between user device frames and electrical system could be produced –
damaging the the user devices.
When using a TT earthing system:
The earthing of the neutral and of the user devices are independent.
The losses are passing through the ground.
It is necessary to install residual current protection devices.
If the ground resistance is too high the protection against losses is not effective.
Voltage surges caused by lightning are more significant.
The principles of the TT earthing system are illustrated in the figure following on next page.
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TT
10 Ω < Earth resistance < 30 (100) Ω
Figure 25: principle diagram of a TT system
Earth resistance, GFCI and contact voltages in TT:
• A 300mA GFCI will trip on a fair 230V fault (contact frame – phase) if the earth loop
resistance is lower than 500 Ohms
• A 30mA GFCI will trip on a fair 230V fault (contact frame – phase) if the earth loop
resistance is even lower than 5000 Ohms
• A 300mA GFCI will trip on a resistive fault (resistive contact frame – phase) with a contact
voltage of 30V if the earth loop resistance is lower than 100 Ohms
• A 30mA GFCI will trip on a resistive fault (resistive contact frame – phase) with a contact
voltage of 30V if the earth loop resistance is even lower than 1000 Ohms
• For these reasons the max earth loop resistance that is allowed is 100 Ohms, but it is
recommended that the resistance of the earth loop is always lower than 30 Ohms.
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The TN earthing systems
within TN earthing systems the neutral of the power supply and the user devices frames are
connected to the same earth.
Advantages:
•
•
•
The fault loop has a permanent very low resistance.
Protection devices are very sensitive and reliable
Theoretically no need for Ground Fault Circuit Interrupter or Residual Current Device
Disadvantages:
•
Fair faults (défaut franc in French) are short-circuits.
There are a number of variations of the TN earthing system, designated by a third letter. TN
systems can be ‘C’ (Combined Earthing) or ‘S’ (Separated Earthing). The three main variants
are explained below:
TNC System (The most basic one)
In the TNC earthing system the neutral and the protective earthing are the same wire. This
wire must be GREEN YELLOW and is called ‘PEN’.
Its use is not recommended. It is only suitable for min 16mm² cables in industrial installations.
The principles of the TNC earthing system are illustrated in the following figure.
TNC
Figure 26 : Diagram of a TNC System.
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Advantages:
-
Very low cost
Disadvantages:
-
No breaker devices allowed on the neutral pole
The neutral wire carries current and losses – a GFCI (RCD) device cannot be installed
Important currents can pass into user device frames and the equipotential wiring,
creating poor equipotential
The PEN wire must be green-yellow. All junctions of the PEN are first made to the frame and
only after from the frame to the neutral pole of the active electrical junctions.
Some existing domestic installations are still wired with a TNC system, or similar.
Such installations must be rewired with a separate protective earthing wire.
TNS System (The most stable one)
The earthing of the neutral is still the same as the earthing of the user device frames (TN),
but in this case the Neutral and PE have each their own wire. Losses are only carried through
the PE wire, and the equipotentiality of the frames is preserved.
Use: Every kind of installation except those that must continue to function after the first fault.
These should be protected with an IT system (as described earlier) as it provides a higher
level of continuity. However, for reasons linked to the danger of lightnings, large size
installations are requiring more than 1 earthing pole. Some limitations must therefore be
made in case of large provisional emergency installations for which a TT system is most of
the time more adapted, and are even mandatory if the cross section of the cables is lower
than 16mm².
TNS
Figure 27: diagram of a TNS System.
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Advantages:
-
Very high reactivity of circuit breakers on fair faults.
-
Very high reactivity of RCD’s on resistive faults.
-
Higher selectivity than TT systems because MCB are tripping on fair faults.
-
The contact voltage of faulty devices always remains very low.
-
Better protection of user devices in case of lightning (single voltage reference).
Disadvantages:
-
The selectivity of too sensitive DDR must be increased.
-
Fair faults can produce short-circuit currents, which can be destructive for the faulty
devices.
Constraints:
The TNS earthing system is only suitable if you also control the earthing of the neutral at the
power source.
The TNS earthing system is the most suitable when the electrical installation is only powered
by a generator. If the electrical installation is supplied by both the public grid (TT earthing
system) and backup generators - there is no problem to run the generator with a TNS
system. However, care must be taken to ensure that the neutral of the city power is not
connected to the TNS earthing system through the neutral of the generator. In this situation,
the pole(s) and the neutral wire of the unused source must be disconnected from the mains
when operating the change-over switch.
TNC-S System (The most affordable one)
A TNC-S earthing system consists of a TNC system between the power source and the main
board, and a TNS system after the main board.
A TNC-S system is gives all the advantages of TNS system for a lower cost, as no separated
PE needs to be installed between the power source and the main board.
Remarks about TNC-S systems:
•
•
As in a TNC system, the neutral wire from the power source to the main board must
be at least 16mm², and the PEN wire must be green-yellow.
It is strictly forbidden to go back to a TNC system after that it has passed to a TNS
configuration.
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A TNC_S System is a TN system beginning in TNC and ending in TNS:
TNC-S
Figure 28: Diagram of a TNC-S System.
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5.5.3. USE OF RCDs WITH THE DIFFERENT EARTHING SYSTEMS
Each of the 3 recognized earthing systems have advantages and disadvantages.
Incomplete earthing systems or non-recognised earthing systems are also often
encountered. These have to be replaced or improved in order to comply with recognised
earthing systems and to satisfy the safety requirements.
Only fully functional earthing systems are reliable.
Whatever the earthing system used, protections against short-circuits must always be very
fast and reliable. Their sensitivity must be accorded to the value of the potential short-circuit
currents. But it is even more a concern in a TN system because fair faults are short-circuits.
•
•
•
•
•
In TT the RCD is breaking for faulty current remaining low even in case of fair faults.
In TN, fair faults between phase and PE are shorts circuits. It becomes an additional
reason to have well rated fast and reliable breakers. The breakers must trip
immediately to avoid or reduce the damage that can be caused by short circuit
currents at the level of a faulty contact with a frame.
In TT, you have less selectivity than TN on fair losses that are most often breaking a
general protection: most of the RCD are installed as general protection of boards, and
only a few are used for the protection of final circuits, Because of their high cost.
In TN, fair losses are breaking the final circuit protection, not the general one.
The selectivity is higher with TN systems:
RCD must also be installed in TN systems:
•
•
•
•
Circuit breakers only detect fair faults. RCD are needed to detect resistive faults.
Fair faults most often occur after resistive ones. Because of their high sensitivity to
resistive faults in TN systems, RCD will prevent most of them.
Defaults are detected very soon.
To maintain the selectivity on fair faults, RCD’s installed as general protection must be
of the selective type ‘S’ – delayed.
Some commonly found problems with earthing systems, and suggestions on how to address
these problems, are given in the section ‘Tools and Templates’.
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Summary about the different earthing systems
Safety
Losses/
Protection
1st fault Yes
2nd fault No
No loss on
1st fault
IT
With Insulation
controller
Good if RE+
Ru < 30 
Low losses.
Dist (EarthInto PE
TT
User) <
Need RCD
15m
ShortCircuit
Lightning
IT
TN
Earth Dist
(C & S) (Earth-User)
< 15m
TNC
TNS
Random:
No RCD
Wiring
MCB
Wiring
MCB
On fair faults, Losses
are local short-circuits
into frames.
Protection with MCB
Into PEN and
Wiring
frames.
and
Unprotected
frames
on low losses.
Into PE.
Very good
RE=RU < 1  On low
losses:
RCD
Wiring
Floating
Higher risk
for devices.
Need SPD
Power
Range
< 2000W,
Class II
> 2000W,
Class II
Installation
Cost
Low
Small <
15m
Very high
All
Public grid.
Long
distances
Medium
Bad.
Need SPD
> 16mm²
Cu
Allowed
between
source and
main board.
Low
Very good.
Lower
surges.
Need SPD
> 15m
All
All
Medium
Table 5: Main features of the various earthing systems
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5.5.1. EARTHING SYSTEMS – EARTHING RODS
In the previous section, earthing rods were mentioned in relation to the different earthing
system used. A TT earthing system uses two earthing rods (1 at the power source and 1 for
earthing the user device frames). A TN earthing system only uses 1 earthing rod (at the
power source). However, beside these basic differences in the earthing systems, the effects
of ground voltage caused by lightning also vary according to the number of earthing rods and
the distance between them. Installations in countries with frequent thunderstorms must be
protected against voltage surges linked to ground currents caused by lightning.
Earthing systems and configurations are consistent only if the size of the installation is such
that the distance from the earthing rod to the most remote point of the installation is less than
15 meters. In situations where this distance is further than 15m, steps should be taken to
improve the earthing system.
-
In TT systems, if the distance between the earthing of the neutral and the earthing of the
user devices is more than 15 m, surge protection is needed to protect sensitive devices.
In almost all TT installations there is more than 15m between the earthing rods – hence
the majority of TT systems will need to be equipped with surge protection devices (SPD).
-
In TN systems, if the distance between the earthing rod and the user devices is more
than 15m, an additional earthing rod must be installed (closer to the user devices).
Voltage surges will remain lower than in TT systems, but when an additional earthing rod
has been installed, surge protection devices will also be needed.
Only the reduction of the distance between user devices and earthing stake can mitigate the
risk for people to be electrified by a frame in case of a lightning strike close by.
Installations with more than one voltage reference must be protected against the variation of
the ground voltage caused by lightning – which can cause voltage surges between frames
and electrical systems. The difference of voltage between several earthing components can
be reduced if these earthing components are linked to each other. Anyway when we have
more than one earthing rod, lightning arresters must be installed at the level of all
earthed ends (generators and boards)
It is common to use the PE wire of the main distribution to interlink the earthing rods.
However, at the moment of a lightning strike significant currents can be produced in this
cable, causing it to burn out (particularly if it is less than 16mm2 in cross section). This
situation can be improved by using underground PE interlinks instead of a PE wire included
in the distribution cable. Such an underground interlink must be made with a bare conductor.
It can be a 35mm² flat tinned copper braid, or a flat 100mm² galvanized steel ribbon.
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Finally, making such an underground interlink between earthing rods, included the one of the
power source - even in a TT configuration - will have the same effect as having a TT
configuration with a very low earth resistance, even if the quality of the soil is very resistive.
Such an enhanced TT setup will definitely correct and stabilize too high earth resistances that
we can observe in some regions during the dry season. This is of course much more the
case in dry sandy soils. On the other hand, such an improvement of a TT system will turn it
similar to a TN one, because the fault loop will have the same very low resistance. In other
terms, underground interlinks of all earthing rods is making a very good TT system which is
completely similar to a TN system. In that case, all requirements specific to TN systems must
be respected. The next figure shows the principle of such an improvement.
Figure 29: Use of underground links to improve the earth resistance.
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5.6. EARTH LEAKAGE PROTECTION DEVICES
An earth leakage protection device is a security device that will break off the power in case of
losses: Accorded to the various local vocabularies they can be called ‘Ground Fault Circuit
Interrupters’ (GFCI), ‘Residual Current Devices’ (RCD), ‘Residual Current Circuit-Breakers’
(RCCB), ‘Leakage Current Breakers’ or ‘Safety Breakers’. All are protection devices which
turn off circuits if the measured losses are higher than their rating.
PROTECTIONS inside
the distribution board
GENERATOR
L
L
1
L
2
3N
DEFAULT
A300 mA GFCI
installed into
the breaker
board will
detect the loss
and will break
the circuit.
User Device
Loss > 300mA
GROUND
Figure 30: The use of earth leakage protection devices
These devices will detect losses and shut down the faulty circuits. They are very important for
the majority of electrical installations, even if a protective earthing system is correctly
installed.
How are they functioning? - In practice, in a power supply circuit, the sum of electrical flow
(forward + backward) must be zero. If this is not the case, it means that there is a loss in the
system. The Residual Current Device measures this current value which ‘escapes’ the
current flow system and returns to the generator by taking another route: whether it is via the
earthing cable or through the ground itself.
The requirements for RCDs are defined by: IEC 60755 (general requirements), IEC 61008
(RCCBs – Residual current circuit breakers), and IEC 61009 (RCBOs residual current circuit
breaker with overload protection).
An RCD can detect low leakage currents that could flow through the body of a person. It thus
provides additional protection if the normal protection means fail, e.g. old or damaged
insulation, human error, etc. This can also be referred to as the ultimate protection because it
can interrupt the current even if the other devices have failed.
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The use of a 30 mA RCD on all circuits supplying socket-outlets up to 20 A is now
mandatory, as per IEC 60364-4-41 (Electrical installations in buildings: Protection for safety:
Protection against electric shock). Note that an RCD does not limit the instantaneous current
flowing through the body, but does limit the time for which the current flows. Note also that for
a direct contact with a 230 V phase conductor, the current flowing would be approximately
150 mA. RCDs with 10 or 30 mA ratings let the same current through. The two ratings
provide equivalent protection. However, the 30 mA threshold provides a cost-effective
compromise between safety and continuity of service.
Downstream of an RCD, it is possible to supply a number of loads or circuits as long as the
leakage current does not trip the RCD. For a given leakage current, a reduction in the
threshold makes it necessary to increase the number of protective devices.
Protection against indirect contacts
An RCD is the only solution to protect against indirect contacts on a TT system because the
dangerous fault current is too low to be detected by overcurrent protective devices. It is also
a simple solution for the TN-S and IT systems. For example, when the supply cable is very
long, the low fault current makes it difficult to set the overcurrent protective devices. And
when the length of the cable is unknown, calculation of the fault current is impossible and use
of an RCD is the only possible solution. Under these conditions, the RCD operating threshold
must be set to somewhere between a few amperes and a several tens of amperes.
Protection against fire hazards
IEC 60364-4-42 (Electrical installations in buildings: Protection for safety: Protection against
thermal effects) also recognizes RCD effectiveness in protecting against fire hazards by
requiring their use with a maximum operating threshold of 500 mA. This threshold will likely
be reduced to 300 mA in the near future, as already recommended by certain national
standards such as NF C 15-100 in France.
In practice, almost no national regulation requires a protection threshold of 30mA for
socket circuits as it is however required by IEC 60364-4-41. The most common
requirement is to have a 300mA RCD as a general protection of a distribution board,
and a 30mA protection on circuits supplying wet areas (bathrooms, outdoor circuits,
laundries…)
Unless local requirements are more demanding, (E.g. the US NEC, requiring 5mA
protection on each socket) our internal rule is therefore to follow this common
requirement, provided that all requirements about the protection against direct
contacts and the first requirements about the protection against indirect contacts,
meaning an efficient earthing of all frames, are fully respected.
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Residual current devices: symbol, values and types.
1. SYMBOL :
Figure 31: Detailed Symbol of a RCD
2. VALUES:
RATE OF A RESIDUAL CURRENT DEVICE = value of the loss permanently admissible
without any risk of triggering the RCD. Every loss having a greater value will trigger the RCD.
ADMITTED CURRENT = maximum value of the user current permitted, and maximum rate of
the upstream breaker
3. TYPES:
RESIDUAL CURRENT CIRCUIT BREAKER (RCCB):
Autonomous operation downstream of a circuit-breaker. Good choice if the upstream breaker
is protecting several residual current circuit breakers, or is installed into an upstream panel.
Example:
Four Pole 300mA Residual Current
Breaker with an admitted current up to 63A
Figure 32: Mounting scheme of a RCCB
! THE ADMITTED CURRENT MUST BE EQUAL TO OR HIGHER THAN THE RATE OF THE
UPSTREAM BREAKER
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RESIDUAL CURRENT CIRCUIT BREAKER WITH OVERLOAD PROTECTION (RCBO):
Combining the function of residual current protection with the function of a circuit breaker.
The symbol to be used is adapted to the corresponding type:, it combines the symbol of a
circuit breaker with the symbol of a residual current device.
Figure 33: figure of a RCBO
RCBO are space saving devices, but they have a limited ruggedness, and you have a limited
choice about the short-circuit protection type (curve of the magnetic trigger).
RESIDUAL CURRENT TRIGGER DEVICES:
Residual current tester mechanically linked to an
associated upstream breaker. The symbol shows the
measurement device and the system of mechanical
coupling.
Figure 34: symbol of a residual current trigger
device
Easy to mount. It is possible to choose the breaker
curve type.
The Residual Current Trigger Device is keyed, so that
only a breaker from the same brand and having a rate
equal to or lower than the current admitted by the
residual current device can be linked to it.
Figure 35: mounting of a trigger
RCD
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DIFFERENT TYPES OF RCD ARE ALSO PROPOSED ACCORDED TO THEIR
SELECTIVITY AND IMMUNITY.
AC Class
Triggering is ensured for sinusoidal, alternating currents, whether they be quickly applied or
slowly increase.
A Class
Triggering is ensured for sinusoidal, alternating residual currents as well as for pulsed DC
residual currents, whether they be quickly applied or slowly increased.
Application: loads with electronics, rectifiers, and instruments.
‘si’ type
Reinforced continuity of supply on disturbed networks with:
A high risk of nuisance triggering: successive lightning strikes, presence of electronic
ballasts, presence of switchgear that incorporates interference filters i.e. lighting, microcomputing, etc.
Sources of blinding: presence of harmonics or high frequency rejection, presence of DC
components: diodes, thyristors, triacs.
‘SiE’ type
The RCCB/ID ‘SiE’ types are particularly suitable for use in humid environments and/or
environments polluted by aggressive agents, for example swimming pools, marinas, the foodprocessing industry, water treatment plants, industrial sites.
They also incorporate RCCB/ID ‘si’ functions.
Instantaneous
Ensure instantaneous triggering (no time-delay).
Selective
(Time delayed) Total discrimination can be achieved using a non-selective residual current
device placed downstream. They should be chosen for the general leakage current protection
when in a TN configuration, or an enhanced TT configuration with a very low fault loop
resistance. If fair defaults are occurring in such configuration, they will ensure discrimination
with downstream circuit-breakers
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TESTING OF RCD’s
Figure 36: Testing of a RCD
Residual current devices have a
test button. This button should be
pushed every month to verify if
the differential is functioning
correctly.
Note that this test is only a
mechanical test of the RCD. Only
RCD testing devices can verify
the actual behavior of an RCD
when there is a loss.
Requirements about RCD uses
Accorded to the situation, the right class or type of RCD must be selected.
-
RCCBs are always the best choice. It is not advised to use RCBOs.
-
The ‘SiE’ type is the most adapted to the conditions typically encountered in most
of the countries where humanitarian interventions are needed.
-
Evidently, the selective type is always preferable for the general protection of an
installation, or the general protection of boards supplying user devices requiring a
high continuity of service, specifically with a TN or similar configuration.
Where to install RCD’s, and what rates to use
•
General protection of a setup
Head protection of a main board for current rates > 63A
The correct rate is between 1% and 2% of the rated current of the installation.
•
General protection of a final board, or installations with a current rate < 63A
Unless the use of 30mA RCD is required by local authorities, 300mA is the max rate allowed
for the general (head) protection of final boards.
If needed, the selectivity can be increased by installing several RCDs, each protecting up to
15 final circuits, or a supplied surface of 150m².
•
Specific protection of final circuits
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Unless the use of 5mA or 10mA RCD is required by local authorities 30mA is the max rate
allowed for the individual protection of circuits supplying some specific user devices or areas:





Bathrooms
Water heaters
Washing machines
Outdoor circuits
Every Class I user device using water or being installed in wet or potentially wet areas
The use of RCDs provides a very high level of safety for individuals and an excellent
protection against fire, and for this reason RCDs are required in all electrical installations. But
whatever the sensitivity and quantity of RCD that are installed, the primary means of ensuring
the safety of people remains the complete protection against direct contact and the
installation of a complete earthing system.
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5.7. WORKING ON ELECTRICAL INSTALLATIONS: PROTECTION RULES
Certified Electricians
Technical interventions on electrical systems should only be performed by certified
electricians, or by an electrician apprentice supervised by a certified electrician. The
certification of the electrician must be according to the voltage level of the circuits where the
intervention must be performed. In practice we never have to work with voltages higher than
600 V, but if it is needed to work on circuits with higher voltages, an electrician certified for
medium or high voltages must be called, even if the concerned circuits are out of power.
Turning the power off
For all works inside distribution boards, the main breaker of the distribution board must be set
in the OFF position.
For all works on circuits, the closest upstream circuit
breaker must be turned off.
When the power has been turned off it must always be
verified with a voltmeter that the power is actually off.
It must be avoided that anyone could accidentally turn the breaker back into
the ON position while working is going on. The breaker must be blocked by a
padlock, or the door of the board must be locked with a key, or the room
where the board is installed must be locked.
If it is not possible to lock the breaker, the door or the room, all other means that can avoid
an accidental reconnection of the concerned circuits must be used: the breaker can be
blocked with a piece of tape, or the outgoing wires can be disconnected from the breaker and
wrapped with tape (to avoid any contact with other circuits).
Signalization
In each case, and particularly when the circuit breaker that has been
turned off to ensure safety cannot be readily seen by the worker while
he is working - a warning panel, and/or a signalization tape, must be
installed and easily visible indicating that an electrician is working on
the system.
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In every instances, and for certain if there is even a small probability that the
circuits where it is needed to work can be accidentally reconnected during the time of
the works, an ultimate safety measure is to connect to the ground all live wires
supplying the worksite by the mean of thick cables equipped with alligator clips.
In that case, any attempt of reconnection will resume in a triggering of the upstream
protection device and the transient voltage will be reduced close to the earth voltage.
Works on electrified parts
If it is unavoidable to work on live parts the technician must wear
1000 Volts insulated gloves. Insulated gloves are not very strong
and can suffer cuts or tears easily, and must be checked thoroughly
prior to use. In order avoid damaging them, it is recommended to
wear strong gloves over the insulated ones.
Even when working with insulated gloves touching electrified parts
with the hands must be avoided. It is always preferable to use
insulated tools instead.
A protection against sparks must also be worn. They
consist in a helmet to protect the hair and a transparent
protective mask to protect the face and the eyes.
Additional protection can be given by wearing safety shoes,
and or standing on an insulated carpet.
Use of insulated tools.
Even when working on circuits that are insulated from the mains, only dedicated electrician’s
tools should be used. Electrician’s tools are almost completely covered with an insulating
material. They must be 1000V insulated and compliant to EN/IEC 60900.
Figure 37:
insulated electrician handtools
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5.8. FIRE SAFETY
Electrical sparks and overheating of components is a very common origin of fires. It is
believed that in developed countries, 40% of fires are caused by electrical defaults, as
illustrated below:
Explosion 1%
Lightning 1%
Electricity 41%
Bare flame 37%
Accident 7%
Other 7%
Cigarette 6%
Figure 38: statistics about fire origins
Fires not only damage goods and materials, they also present a significant risk of death or
injury. Apart from the direct dangers posed by electrical installations, fires caused by
electrical faults are a significant indirect risk from electrical installations. Fires can be caused
by a wide range of electrical issues, such as overloaded circuits, short circuits, poor quality or
inappropriate equipment (cables, breakers, etc.) or poor quality of workmanship in installing
the system.
It is possible to speculate that people are more often affected by fires caused by electrical
problems than they are affected directly by electrical faults (such as electrocution).
Additionally, fires can potentially affect a large number of people at the same time, whereas
electrocution frequently only affects a single person at a time.
Even if strongly related to the safety of people, technically protection against fire is
considered as part of the protection of equipment. The next chapter deals with electrical
equipment and specific requirements regarding their protection. It includes all standards and
rules needed to avoid fires due to faults in electrical installations.
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The cause of many electrical fires is a significant short-duration temperature rise or electric
arc due to an insulation fault. Unfair or corroded junctions are also important causes of
sparks, overheating, and fire. The risk increases with the level of the fault current.
It also depends on the level of fire or explosion hazard specific to the room (storage of
flammable materials, presence of volatile hydrocarbons, etc.). Many electrical fires are
caused by a combination of factors: old installation, wear of insulation, bad junctions, losses,
accumulation of dust and humidity, etc.
Leakage
current
Carbonised
insulation
and dust
Small
discharges
Figure 39: Process resulting in a fire
These are additional reasons to investigate for weak points of electrical installations and
user devices, and to correct all problems found. Well installed and correctly rated RCDs are
also an important and compulsory protection against the dangers of fire.
It is also too common that people consider that the installation of smoke detectors, fire
alarm systems and fire extinguishers is the correct way to ensure fire safety. However,
alarms and extinguishers only help a faster reaction and to reduce the consequences
of a fire – once it has already started.
Whilst it is always good to mitigate the consequences of an existing risk, no alarm
system or extinguisher has ever avoided an electrical fire starting. The only way to
avoid an electrical fire is to have a well-designed and well-constructed electrical
system using good quality and appropriate equipment.
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5.9. LIGHTNING PROTECTION
Lightning is a major cause of accidents concerning
people and equipment. The consequences of
lightning mostly affect the ongoing operation of an
electrical installation.
Protection against lightning should be according to:
•
•
The factor of risk, which is related to the ‘keraunic level’ (yearly lightning intensity – in
hits/km²/years or days of thunderstorm/ year).
The operational criticality and cost of the assets and equipment that could be
damaged by lightning.
The following figure illustrates the annual frequency of thunderstorms throughout the world.
Figure 40: Map of the annual frequency of thunderstorms
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There are three types of accidents related to lightning strikes.
Fire
As a direct effect of lightning striking flammable materials (roof, wooden poles, etc.)
The next sketch shows where theoretically are the points most likely to be hit by
lightning strikes – these are represented by the red areas. 90% of the lightning
strikes can be expected to hit these areas.
These areas can be identified by considering a hypothetical sphere, 100m in diameter, rolling
across the surface of the ground (presented by the light blue circles in the figure). Where this
sphere could come into direct contact with the surface represents the areas vulnerable to
lightning strikes (areas shown in red, with yellow figures of lightning).
Figure 41: Potential lightning sites on a landscape profile
Lightning rods are designed to work in the same way as these red areas
represented into the sketch. They will attract lightning and hence decrease the
danger of lightning strikes in the surrounding area. A lightning rod which is 15
meter over the surrounding landscape will avoid lightning hits up to a distance of 35 meters.
R= 50m
Lightning rod, h=15m over
the surrounding landscape
Protected zone
h=15m
d=35m
Lightning rods do not have any effect on
the protection of electrical installations,
in fact it is the contrary. Because they
attract lightning, lightning rods increase
the number of hits received by the site.
Their unique protective effect is related
to the danger of fire, as they decrease
direct hits on surrounding roofs and
other objects that could potentially catch
fire.
Figure 42: area of protection of a lightning rod
If lightning rods are installed, the
protection of the electrical installation against the effects of lightning must be increased, at
least in areas close to the lightning rod. For this reason, it is rarely advisable to install
lightning rods. Only specific equipment, such as high antennas, that are ‘natural’ lightning
rods - should be considered in more detail to reduce the risk of damage by lightning strikes.
Such ‘attracting objects’ like high antennas should be located as far as possible away from
the electrical installations. For other structures, such as a corrugated sheet roof, if they are
connected to the earthing system, the danger of fire is already significantly reduced.
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Electrocution of people
When there is a lightning strike, very sudden and significant currents radiate into
the ground from the initial point of impact. This means that the voltage can vary by
several thousand volts within a few metres. In this situation, the voltage within the
protective earthing close to the lightning strike can suddenly become significantly different
from the voltage in remote parts of the site. If the distance to the closest earthing stake is
large, the voltage of all frames connected to the protective earthing can become very
different from the voltage of the physical site where the frame is installed. Hence, anyone
standing close to a frame connected to a remote earthing stake could be electrified.
For this reason, it is recommended that the distance from any location inside the area of
distribution of an electrical system to the closest earthing stake must be less than 15 metres.
There are three ways to decrease the danger from lightning strikes:
-
Have earthing stakes in close proximity
-
Increase the equipotentiality of the site. The more conductive and well connected
the site is to the ground, the lower will be the voltage difference between different
parts of the site.
-
When a lightning rod is present, it should be correctly connected to the protective
earthing. To increase the equipotentiality (and hence the safety) of a site, all
earthing grids (building, electrical, radio, lightning rods, etc.) must be connected
together.
Destruction of equipment
We have seen in the previous point that people are protected from being
electrified by indirect effects of lightings by installing close earthing stakes. On
large sites, this means that you will have several earthing stakes. If there is a
voltage difference between the earthing of the neutral (on the side of the source) and the
local earthing of the electrical system, ground currents caused by lightning could induce a
high voltage between equipment frames and the electrical system. High voltages between
the earthing and the electrical system are a major source of equipment damage.
There are three means to help avoid such voltage surges:
-
Again, by ensuring the equipotentiality of the site. Earthing belts and underground
mesh in the foundations of the building (min 5m x 5m) are a good solution to help
ensure this equipotentiality.
-
The installation of surge protection devices in breaker boards.
-
The installation of local surge protection devices to protect critical and sensitive
materials.
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Installation of surge protection devices
Surge protection devices (SPDs) connect all active and protection wires at the
site where they are installed. They constantly monitor the voltage between active
wires, and between active wires and the earthing. In case of voltage surges they
create a short-circuit between the concerned conductors. This short circuit reduces the
voltage surge to an acceptable value.
SPDs employed as part of the structure’s fixed installation are classified according to the
requirements and loads on the installation sites as surge protective devices Type 1, 2 and 3
(or class I, II, III) and tested according to IEC 61643-1.
These three levels of protection are according to different protection zones:
-
Type1 (class I) for main electrical boards in highly dangerous areas.
Type 2 (class II) for average danger – protection in sub distribution boards.
And type 3 (class III) for protection at the level of the consumer.
The concept of lightning protection zones (LPZ) according to IEC 62305-4 for power supply
systems are stipulated in IEC 60364-5-53/A2 (IEC 64/1168/CDV: 2001)
In practice:
a. In breaker boards close to a lightning rod, or in main electrical boards installed in
areas with high risk of lightning
In this case the surge protection devices must be able to resist a current up to 100kA (max
direct current of a lightning strike), and a Class 1 SPD must be installed. However, their cost
is very high (more than $500 per pole). This is one of the reasons to avoid having lighting
attractors too close to electrical installations. However, in case costly critical user devices are
installed, Class 1 SPD can be a good statistical investment. Class a1 SPD also protect class
2 SPD otherwise installed in the other boards of the installation.
b. In other breaker boards
In most countries, Class 2 SPD must be installed in all breaker boards which have their own
associated earthing stake. They can withstand short-circuits currents up to 10 – 45kA
(depending upon the length of the surge). Note that the distance of protection is limited to 15
meters, and additional protection must be installed if necessary to avoid exceeding this
distance. Other rules are associated to this factor of distance, and reference should be made
to Chapter 7. The cost of a Class 2 SPD is about $50 per pole.
c. In sockets supplying sensitive equipment
This level of protection devices are not able to manage high surges and must be protected by
upstream Class 1 or 2 equipment, and within a distance of 15m. They can also be installed
inside sensitive devices.
An important feature of SPDs is that they have a ‘Follow current extinguishing capability’.
When they trip, SPDs make a short circuit during the time of the surge. But the source
(generator) also supplies the short circuit during that time. This current from the source which
is not interrupted after the surge has ended is called ‘the follow current’ and if this short –
circuit current coming from the source is too high, the SPD cannot return to its resting
position and it burns out. The current extinguishing capacity is about 300A For Class 1
protection and 150A for Class 2 protection. In the case where the upstream breaker has a
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higher rate, the SPD must be protected by a dedicated 250A (Class 1) or a 125A (Class 2)
fuse or circuit breaker. In every case, the SPD must be installed downstream from the main
breaker of the breaker board where it is installed.
(fuse,
300A)
LPZ 1,
Type 1 SPD
(fuse,
125A)
LPZ 2,
Type 2 SPD
LPZ 3,
Type 3 SPD
Figure 43: Installation diagram of lightning protections accorded to protection zones
The above figure illustrates the 3 zones and classes of protection. MEBB means ‘main
earthing bonding bar’, and EBB means ‘Earthing bonding bar’. The figure does not show the
circuit breakers.
F1 is the main overload protection at the SEB (Service entrance board).
F2 are 300A fuses to protect Class 1 SPDs if the upstream CB is bigger than 300A.
F3 are 125A fuses to protect Class 2 SPDs if the upstream CB is bigger than 125A.
In a situation where the SPD cannot extinguish the ‘follow current’ an upstream fuse or circuit
breaker must be able to trip and interrupt the short
circuit current.
Because SPDs can be damaged after severe and
repeated shocks, they are equipped with indicators if
they are still in a good state or not. Some have
auxiliary contacts that can act on warning lights or
other alarm system when the device needs to be
replaced. SPDs must be regularly inspected, and
damaged ones replaced. It is recommended to
maintain a stock of spare SPDs cartridges in order to
facilitate rapid replacement of damaged ones.
Figure 44:
Modular surge protection device
This SPD is a 4 pole modular device with
replaceable cartridges. The green windows show
that it is in a good state.
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6. EQUIPMENT: QUALITY AND USAGE REQUIREMENTS.
Electrical installations are only made up of cables, junctions, enclosures, switchgears, and
protections.
Cables must be according to the situation and usage requirements. Their type, size, and
colour are defined in accordance with technical requirements, local features and regulations.
The section 6.1 is dedicated to cables and wires.
Junctions connect cables together or with terminals. Junctions must also be according to the
situation and usage requirement. They will be discussed in section 6.2
Enclosures are needed to protect various parts of the installations. Requirements for
enclosures are presented in section 6.3
Switchgear are switching and isolating the main distribution circuits when required. They can
be general switches, or change-over switches, and must also meet specific requirements.
They will be discussed in section 6.4
Circuit-breakers are exclusively dedicated to the protection of the cables. Their quality and
correct protection rating will be discussed in section 6.5
6.1. CABLES
All the electrical power supplied to sockets, lights and other user terminals is delivered
through a network of cables and wires. Hence, cables and wires are the most important part
of an electrical installation.
6.1.1. CABLES: GETTING THE RIGHT QUALITY
For most of the uses, the wire core must be pure, bare or tinned copper (Tin offers a better
protection against corrosion)
 Be very vigilant: Some fake/counterfeit cables are made with coppered steel!
How to check if a cable is made of copper or steel?
Steel wires are easy to recognize. Steel is a hard metal while copper is a soft one. Steel
is more rigid than copper, and if you bend slightly a steel wire it will come back into place
like a spring. If you do the same with copper, you need much less strength to bend the
wire and it will stay bent.
However it is not as easy when considering stranded wires. The thinner the individual
strands making your stranded wire, the more flexible will be the wire. There will no longer
be this spring effect even if the wire is made of steel. But very thin steel wires are
burnable, and corrosion (rust) might be visible at the end of the wire.
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Aluminium is also very common. It is cheaper than copper and it is therefore increasingly
used, especially when large cross sections are needed. Such usage must be reserved for
cross sections starting from 35 mm². Compared with copper, aluminium is lighter, but it is
less conductive. To obtain a cable resistance equivalent to copper, its cross section must be
doubled. (35mm² Al = 16mm² Cu)
It is sometimes used for underground cabling, but the most frequent use of aluminium is for
aerial lines, because of its light weight.
Provisions when installing aerial lines
Except for short distances, aerial cables cannot support themselves. They must be
carried by a carrier line, generally made with galvanized steel. The electrical line is then
hung from this supporting wire, which carries all the weight loading between the
supports.
Aerial lines must be protected against the effects of lightning, particularly when the
distances are large. With thick cross sections it is easier to use several single conductor
wires instead of a multi-conductor cable. To reduce the effects of voltage surges in
aerial lines, the cable must be twisted, having 3 turns per meter. If multi-conductor cable
is being used, it must be verified that the conductors are twisted inside the cable. Single
conductor wires can be twisted manually.
The uses of the different metals for electrical works:
Aluminium
Aluminium
/Copper
Plain Copper
Tinned
Copper
Coppered
Steel
Fake
cables,
braid,
earthing
material
Cable
(mainly aerial
lines)
Junctions of
aerial lines
to copper
wiring
Cable, braid,
earthing
material
Cable,
braid,
earthing
material
For Cable
core > 35²
Must be
protected
Recommended
if strands are >
0.20mm²
Mandatory if
strands are
< 0.20mm²
NEVER
The surface
of bare
aluminium is
always
oxidised. It
must be
cleaned
before a
junction is
made
Aluminiumcopper
junctions
must be
made with
dedicated
junction
pieces, and
must be
protected
Large cross
sections are
very expensive.
Very thin
strands can be
vulnerable to
corrosion
Tin protects
the copper
from
corrosion
The copper
accelerates
the
corrosion of
the steel
Cheap
Cheap
Expensive
Expensive
Expensive
effects
Steel + Zinc
Earthing
material
Only for
earthing
equipment
The zinc
protects the
steel from
corrosion
(grounding
stakes,
grounding
belts
(galvanized
steel ribbons)
Cheap
Table 6: Use of different metals in electric works
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Steel, Copper, Zinc, Aluminium
– Solutions related to inter-metallic junctions
When different kinds of metal are in contact one with another, corrosion effects can be
very destructive, especially in humid conditions. In the case of bimetallic junctions, some
provisions must be taken, and some associations must be completely avoided.
Coppered Steel: Is often found in fake copper cables, and is also commonly used for
earthing rods, and braided earthing belts. Copper does not protect steel against
corrosion, in fact it is the opposite. Once the protective copper coating is damaged,
corrosion of the steel begins very quickly. Iron oxide is more voluminous than iron and it
will spall off the copper, thereby exacerbating the corrosion of the steel. Coppered steel
should not be used, and grounding rods made from coppered steel are not reliable.
Copper – Aluminium Junctions: Aluminium is only authorised for power cables starting
from 35mm², and it is used primarily for aerial lines. Aluminium exposed to the air is fast
oxidising on the surface, and this layer protects aluminium from further contact with the
air, preventing further and deeper corrosion. Copper cables join the aluminium aerial
lines to the local distribution system. Copper will exacerbate the corrosion of aluminium
surfaces in contact with it. Corroded junctions mean losses and overheating caused by
their reduced conductivity.
Junctions between copper and aluminium are allowed, but they must be made with
dedicated junctions and protected against air and moisture. Tinned cable shoes or tin
solder applied to the copper surface before joining the copper wire with the cleaned
aluminium will decrease the reaction. The pressure between surfaces must be
maintained by screwed brass cage terminals. Several layers of car paint finalising the
work will help ensure a good junction.
Zinc Plated Steel: Is a very good association as zinc protects the steel even if the zinc
plating is damaged. Like steel, zinc is less conductive than copper, but its corrosion
protection of steel makes it a better option than Coppered Steel. Pure copper is evidently
a better conducting material, but its price often makes it an impractical for earthing
installations. Zinc plated steel is a good compromise between price, durability and
conductivity and hence it is highly recommended that earthing installations use zinc
plated steel if copper is not an option.
Insulation:
A lot of different insulation materials having varying characteristics are proposed by cable
manufacturers. The most commonly used types of electrical insulation are: PVC (of various
types) PE (polyethylene), and rubber. Most of the time, both the insulation of the wire and – if
existing - the external coating of the cable are made out of PVC or PE. Rubber and other
elastomers (silicone, flexible PVC) are used for flexible cables. PVC meets most of the
qualities required for standard applications.
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The thickness and arrangement of the insulation layers varies depending upon the voltage
and environmental stress. For example, provisional installations must have cables with a high
level of mechanical resistance, and hence only flexible cables with a thick rubber coating
(min 3mm) can be used. Armoured cables are used in fixed installations, when a higher
mechanical resistance is needed, specifically for underground cables, or for sites having
higher mechanical stresses.
Verification of the insulation quality
The mechanical integrity and resistance of the insulation must be verified (elasticity,
flexibility, no cracks).
If corrosion appears at the end of the wire, it must be verified that the insulated part of
the core is not corroded inside of the cable.
It must be verified that the insulation is not adherent to the conductor. Adherence
between the insulation material and the core means that the quality of the cable is
probably not acceptable. This is sometimes due to bad quality material or production
process, but it also occurs when cables have reached a too high temperature
(overloaded second hand cables, storage temperature).
Adherence between the insulation layers (core insulation, filling material, external
coating) is also a sign of bad quality or overheated cables.
Adherence is a sign of potential danger and causes technical difficulties. If it is a
consequence of a precedent overheating, the regularity of the thickness and original
physical properties of the insulation material is not ensured anymore, and could weaken
the insulation properties.
Insulation grade: Must be rated 600-700V and tested 2000V. Even if the rated voltage is
only 400/230V the insulation must be able to face higher voltages. Surges due to events on
the network (thunderstorms, disconnection of inductive loads) that could reach more than
1000V are very common, and it is not admissible that the insulation material could be
destroyed by such events.
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6.1.2. CABLES: GETTING THE RIGHT CABLE FOR THE RIGHT USE
I. RIGID OR FLEXIBLE
According to IEC standards (IEC 60228), cables are sorted into 4 classes of rigidity:
Class 1: Solid (plain) core: Solid conductor, the core is formed by one single wire with a
diameter up to 6 or 10 mm2 (also denoted by the letter U).
Class 2: Wired (stranded) core: Stranded conductor intended for fixed installation. For cores
with a diameter over 6 or 10 mm2, the core is usually formed by a number of thin wires (also
referred to by the letter R).
Class 5: Flexible Wired (stranded) core: The core is formed by a large number of thin wires.
Class 6: Very Flexible Wired (stranded) core:
RIGID CABLES
Cables
Class 1
Class 2
FLEXIBLE CABLES
Wired
Core
Class 5
Flexible
Core
Class 6
Very
Flexible
Strands < 0.20mm²: tinned copper is preferred
Solid Core
mm²
(1 strand)
1.5
2.5
BEST USE
4
6
10
N strand
max
AVOID
Cross
section
VERY
RIGID
35
50
70
95
120
150
185
240
BEST USE
25
NOT AVAILABLE (TOO RIGID)
16
s max
/strand
mm²
N strands
min
s max /
strand
mm²
N strands
min
s max /
strand
mm²
7
0,21
29
0.053
76
0.020
7
0,36
48
0.053
125
0.020
7
0,57
54
0.075
200
0.020
7
0,86
80
0.075
174
0.035
7
1,43
77
0.13
290
0.035
7
2,29
122
0.13
463
0.035
7
3,57
190
0.13
723
0.035
7
5,00
266
0.13
1012
0.035
19
2,63
380
0.13
663
0.075
19
3,68
344
0.20
928
0.075
19
5,00
466
0.20
1260
0.075
19
6,32
588
0.20
1591
0.075
19
7,89
735
0.20
1988
0.075
19
9,74
907
0.20
1402
0.132
19
12,63
1176
0.20
1819
0.132
Table 7: Classes of cables
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a. RIGID CABLES
Features/ quality requirements:
Single core (solid cable, class 1) up to 4/6 mm²
Stranded wires are made out of several twisted solid wires (the strands)
For cables from 6/10mm², stranded wires of class 2 must be used.
The criteria of rigidity reported in the table above are indicative. Practically, it is the rigidity of
the wire which is the factor of importance. Too thick strands make the cable too rigid, and it
cannot be bent. Too thin strands make the cable too flexible, and it cannot be used anymore
in fixed installations, unless special provisions are applied for the junctions (See section on
flexible cables).
Solid core rigid
single conductor cable
Solid core rigid
multiple conductor cable
Figure 45 : several kinds of rigid cables
Wired rigid conductor – strands
are thick enough to get a ‘rigid’
cable but they allow that it can
be curved in position
Use of rigid cables:
6.1 Rigid cables are allowed for fixed installations, indoor and outdoor.
-Are allowed for circuits wiring and internal board wiring.
6.2 Rigid cables cannot be used with portable or moving equipment
- Cannot be used to supply equipment subjects to vibrations
- Cannot be used as an extension cord or power cord for any electric device
Each cable also has a minimum bending radius. If the bending radius is too small, the
cable can be damaged. The thicker and more rigid a cable, the higher the minimum bending
radius. For example, solid single conductor cables have a minimum bending radius of 5 x the
cable diameter, whereas armoured cables have a minimum bending radius of 15 x the cable
diameter.
5 < R/d <15
(Pending the
type of cable)
R
d
Figure 46: bending radius of
cables
Too small bending radius the cable is damaged
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Limits of use with rigid cables. Carrying out wiring internally within a board is very difficult
with rigid cables when the cross section is over 6mm². In this situation, flexible wires will
facilitate the job and can be used instead, provided that the wire ends are equipped with
cable terminals. More details are given in the sections dealing with flexible cables, junctions
and about boards.
b. FLEXIBLE CABLES
Features/ quality requirements:
Thin wire strands are easier to use, but they are more vulnerable to corrosion than thicker
ones. Good insulation must prevent exposing the wire strands to external agents. Some
insulation material can become porous when age. Also, in poor quality cables sometimes a
thin space is left between conductor and insulation. Both of these defaults can induce
corrosion. It is also the case that at the ends of the cable, the conductor is most of the time
exposed to the air, and problems of corrosion may appear faster with thin strands. Tinned
copper offers a good level of corrosion protection for thin strands. Cable ends of non-tinned
copper wires can be protected with tin solder, or specific insulation grease. More information
and execution details concerning cable ends are given in the section about junctions.
Flexible wire – strands are
so thin that the cable is
very flexible. Strands are
tinned to protect the core
against corrosion.
Flexible multiple conductors
cable for light use.
0.6mm insulation
1mm PVC coating
Flexible multiple conductors
cable for heavy use.
1mm insulation
3mm rubber coating
Figure 47 : Various types of flexible cables
Use of flexible cables:
7.1 Must be used in provisional and mobile installations, indoor and outdoor.
7.2 Must be used for extension cords or power cords for any electric device.
7.3 Must be used for any portable or mobile equipment.
7.4 Must be used for the wiring of mobile machinery, or devices subject to vibrations.
•
•
•
Flexible wires are make it easier to do the internal wiring of boards and panels.
Flexible cables are allowed for every usage for which rigid cables are allowed
Flexible cable terminations must be equipped with cable terminals
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All flexible cable terminations must be equipped with cable terminals. Unless
junctions are especially dedicated to accept flexible wires, do not connect flexible
wires to any kind of junctions (screws, cages, etc.) without respecting special
provisions to reinforce cable ends, even inside of plugs and sockets (see section on
junctions).
II. SINGLE CONDUCTOR OR MULTIPLE CONDUCTORS CABLE
a. SINGLE CONDUCTOR CABLES
Insulation for 230V: min 1mm PVC
Figure 48: single conductor cable
Use of single core cables:
8.1 Single conductor wires can only be used if they are protected by an external
enclosure. Unsheathed multi-conductor cables must be considered as being single
conductor wires. They can be placed: Inside a board; Inside a dedicated conduit, pipe,
duct or trunking.
8.2 Wires belonging to distinct separate circuits cannot be placed in the same conduit,
unless mechanical separations are included.
(A circuit is defined as the cabling downstream of a protection device. Wires protected by
different circuit breakers are consider to belong to separate circuits.)
It is very common to use single wire conductors with PVC pipes. PVC pipes can be flexible
(ringed) or rigid (smooth). Multiple conductors/ cables can also be placed into protective
pipes/ sleeves
Three single core wires placed into a
ringed PVC pipe
Ringed flexible PVC for underground
sleeve (RED)
Figure 49: various kinds of rigid and
flexible pipes
Rigid smooth PVC pipe
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Use of tubes and pipes for electrical conduits:
9.1 The minimum diameter of a round pipe used as electrical channel is 2cm (3/4”)
9.2 The minimum diameter of a round pipe used as electrical channel should be at least
twice the diameter of the wires or the cable passing through it.
b. MULTIPLE CONDUCTOR CABLES
Insulation requirements: minimum 0.6mm + external coating (sheath)
Use of multiple conductor cables according to their external coating (sheathing):
10.1 For fixed uses (preferably rigid cable) without external conduit, the coating must
have 2 layers.
10.2 So far as their terminations are reinforced with cable terminals, flexible cables with
a double PVC sheathing are also allowed in fixed installations.
10.3 Flexible cables with only 1mm PV sheathing cannot be used in fixed installations.
Such cables are dedicated for power cords or extension cables, and should not be used
in fixed installations. If no other solution could be found they could eventually be used in
restricted circumstances, but they must be protected with a pipe (same provision as
single conductor wire).
10.4 Flexible cables with 3mm rubber or PVC coating can be used in the same way as
rigid or flexible cables with a sheathing built in 2 layers. However, such cables should
be reserved for provisional outdoor installations (they are much more expensive than
multiple conductor rigid cables designed for fixed installations).
The purpose of having 2 layers is to reinforce the mechanical resistance of the cable and to
avoid any damage to the insulation of the wires while unsheathing the cable. While
unsheathing a cable, only the plain and smooth external coating must be cut with the knife or
with the unsheathing tool. The internal coating (filling) can easily be torn and will be removed
afterwards without using any cutting tool, ensuring that the wire insulation is not cut during
the unsheathing operation.
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Plain PVC or PER
outer coating
(sheath)
Tearable
inner coating
(filling)
Plain Copper
0.6 mm
single core (solid
PVC or PER
cable)
insulation
Thick coating, flexible:
recommended for provisional
installations and allowed for fixed
installations
Double coating, rigid:
Recommended for all fixed
installations
Thin coating, flexible: Recommended for
power cords and extensions. Allowed
with provisions (in conduits) for fixed
installations
Figure 50: Features and uses of multiconductor cables
III. ARMOURED OR UN-ARMOURED CABLES
Armoured cable are primarily intended for underground lines. They are also recommended in
areas with high mechanical stresses, or in locations where vehicles, heavy machines or
pieces of equipment can move, for example workshops, external lines along walls, etc.
Technically they do not require any additional conduits. However, a conduit could still be
useful, for example the cable can be replaced without need to re-dig a trench.
Armour and shields are not the same.
A shield is a protection against magnetic interferences, and is mostly used in data cables.
Shields are generally made out of braided copper. A simple shield is not armour, as it does
not offer any mechanical protection.
Shielded cable (aluminum foil) No
mechanical protection is offered.
Shielded cable (braided tinned copper)
No mechanical protection is offered.
Figure 51: Shielded cables
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Armour offers mechanical protection against shocks, pressures, tension, cuts, and various
other mechanical constraints. Armour is generally made out of galvanized steel wires or steel
tapes wrapped around the cable. Many use a combination of steel wire and tape. Armour will
also act as a shield against magnetic interferences. Shields and armour must be grounded.
Armoured cable (steel tape.)
Armoured cable (steel wires)
Figure 52: Armoured cables
Please note that armoured cables are very heavy and rigid. They are not easy to
install, so reserve their use for where it is really needed. Be very careful when
unsheathing armoured cables. Cutting steel wires and tapes requires specific tools,
and tools intended for cutting copper are not suitable. Please also notice that when
they have been cut, armour edges are very sharp and can be a safety issue for
personnel working with the cable.
IV. ROUND OR FLAT CABLES
All the above described multi-conductor cables are round cables. Another type of cable, the
flat cable, can also be found in some installations. Flat cables are mostly used for visible
installations, as their flat profile is more adapted for such installations, but there are a number
of provisions and restrictions that must be pointed.
They can be of different types, and their use must be restricted in accordance with their
characteristics.
Figure 53: flat cables without coating
Two conductor flexible flat cables without
external coating are forbidden in fixed
installations. They can only be used as power
cords for some light applications (double
insulated bed lights or lightweight hanging lights,
light DC uses like doorbells, audio uses like
loudspeakers etc.). The use of such cables is
never recommended.
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Cables with an external coating are stronger. However, if they
do not have a protective earth conductor they can only be used
in the same way as two conductor flat cables without external
coating.
Figure 54: flat cables with coating
Flat cables with an external coating and a bare copper
protective earth conductor are also forbidden.
Figure 55:
Flat cables with bare protective conductors are forbidden
Flat cables with an external coating and an insulated
protective earth conductor, with the same cross section as
the active conductors, are not recommended. Never the
less, they are allowed for visible use in indoor and outdoor
fixed installations, and in areas without any mechanical
constraints or and danger of due to the activities around (but
only if stronger cables are unavailable). Note that flat cables
never have a double protective external coating.
Figure 56:
Flat cables with external coating and insulated protective
Even if they could be protected in a pipe, it is forbidden to use flat cables for embedded
installations. Installation of a flat cable in a pipe or conduit is in any case difficult.
All provisions concerning the use of flexible and rigid cables must be respected regardless of
whether they are flat or round. Like round rigid cables, flat rigid cables are completely
forbidden for power cords, extension cords and mobile applications.
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Use of flat cables:
11.1 Flat two conductor flexible cables without external coating are only allowed when
used as power cords for light applications that do not need a protective earthing (class 2
equipment). They are forbidden for any fixed installation.
11.2 Flat two conductor flexible cables with an external coating are only allowed for the
same use as flat flexible two conductor cables without external coating.
11.3 Flat cables with a protective earthing conductor thinner than the active conductors
are forbidden.
11.4 Flat cables with a bare protective earthing conductor are forbidden.
11.5 Rigid coated flat cables with equally sized protective and active insulated
conductor are allowed for apparent uses in indoor and outdoor areas provided that there
are no mechanical constraints and stresses.
11.6 Flat cables cannot be used for embedded installations.
11.7 Following the above rules the use of flat cable is allowed, but is not recommended
in any fixed installations.
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6.1.3. CABLES: GETTING THE RIGHT CONDUIT
Conduits, channels, trunks, pipes, are a complex matter. We have already seen that some
cables require mechanical protection, others do not.
According to the situation and types, only some types of conduit can, or should be used. The
subject of the right choice and placement for conduits will be developed in the chapter about
the design of installations. But it is also necessary to define the accordance between cables
and conduits.
Inside of walls
Aerial
Bare
conducto
r wire
Single
core
insulated
wire
Not
recom
mended
YES, if
twisted.
Needs a
carrier
without
conduit
NO
NO
Single
coating
NO
NO
Double
coating
Not
recom
mended
YES
On
walls,
with
appare
conduit
nt
Single conductor
NO
YES
NO
NO
Multiple conductors
Not
recom
NO
mended
YES
YES
Armoure
NO
YES
NO
YES
d
Flat
cables
NO
NO
NO
NO
without
coating
Flat
Not
Not
cables
recom
recom
NO
NO
with
mended mended
coating
Table 8: Accordance between Cables and Conduits
On trays,
inside of
false
ceilings
Underground
without
conduit
with
conduit
NO
NO
NO
NO
YES, if
core
sections >
25mm²
NO
NO
NO
YES
NO
YES
YES
YES
YES
NO
NO
NO
NO
NO
NO
NO
Remarks:
Aerial lines are not recommended except for long distribution lines in sites where no other
solution is possible, for example rocky sites where it is not possible to dig. In any case,
special provisions must always be made in case an aerial line must be established.
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Protection against rodents: Rodents are very common in false ceilings, and are also
commonly living underground: underground sleeves and manholes could be visited by them.
Only armoured cable is offering in itself a protection against rodents. Rigid PVC pipes do not
provide protection against rodents, but ringed soft flexible PVC pipes do give protection (as
rodents do not gnaw soft materials).
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6.2. JUNCTIONS
Junctions are a very critical part of the electrical installation. The junctions must be well made
and well fastened. Poor or loose connections are often the origin of fires because they can
heat up or cause sparks. The junctions must be clean and free of corrosion. Corrosion is also
often a source of overheating, and a cause of problems. According to the function and
situation, each type of wire requires a proper junction. A lot of different kinds of junctions are
possible, but not all of them are acceptable.
Restriction on use of junctions:
12.1 No junction can be made outside of protective enclosures.
12.2 No junction is suitable to provide a tensile mechanical connection (e.g. hanging light
fitting).
12.3 Unless they are mechanically sealed in-situ, non-insulated junctions are never
permitted.
12.4 Junctions made by twisting wires together (either with or without insulating tape) are
forbidden.
12.5 For 230V wires fixed into screwed junctions, a minimum distance (as well as an
isolating separator) must be kept between the junctions. The separator must prevent any
metal tool or object from touching adjacent junctions at the same time.
12.6 Unless they are equipped with specific crimped wire terminals, no flexible wiring is
allowed in junction terminals specifically designed to allow only rigid wires.
Junctions inside of junction boxes, and other protective enclosures:
Insulated spring caps can be used to tight twisted rigid conductors
together.
Push-in block spring terminal are adapted to single strand rigid wires
Lever block spring terminal are adapted to rigid and flexible wires
Figure 57: Various types of junctions
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Insulated spring caps, push-in block spring terminals, or lever
block spring terminals are the most adapted for wires up to 4
mm² inside of junction boxes. The lever block spring terminals
are also suitable for flexible wires. Insulated spring caps and
push in block terminals are never suitable for flexible wire,
even if these are fitted with wire terminals.
Figure 58: junction of flexible
wires inside of a junction box
Lever blocks are suitable
for flexible wires.
Junction boxes should preferably be constructed from
insulating material (PVC, PE, PE). Metal boxes are only
needed in harsh environments, where hard mechanical
shocks are possible.
Junctions of for wires with larger cross sections should be
made with heavy duty screwed cage terminals.
Heavy duty screwed cage terminals can be installed on DIN rails
inside large junction boxes or breaker boards.
Non-insulated junctions sealed in place inside junction boxes are
often used for wires thicker than 4-6 mm².
Figure 59: Heavy duty screwed junctions
Screwed junctions are only suitable for rigid wires, or flexible wires equipped with rigid wire
terminals. Not all screwed junctions are recommended.
The most common screwed cage junction is the plastic block screwed junction.
If no other junction type is available, they can be
used in enclosures but note that they are not
recommended.
Figure 60:
Use of plastic block screwed junctions
In case that they are used, the stripped length of
the wires coming from each entry of the terminal
must overlap each other inside of the terminal,
ensuring that all wires are tightened by both
screws.
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Junctions with flexible cables:
•
•
•
To be used in screwed cage junctions, flexible wires must be fitted with cable
terminals.
Only lever block spring terminals are adapted to receive flexible wires without cable
terminals
Push-in block spring terminal are only adapted to single strand rigid wires and cannot
be used with flexible cable, even if they are fitted with cable terminals
It is recommended that unless the junction is specifically designed to receive flexible cables,
when using flexible wires all junctions must be reinforced with cable terminals.
Figure 62: Straight crimp terminals
for use with flexible wire in screwed
cage terminals
Figure 63: Crimping Plier
Terminals must be crimped with
special pliers
Figure 61: Various types of crimp terminals
Each type is adapted to a specific use and
junction type
Figure 64: : Junctions inside of a
generator.
All cables are fitted with cable shoes.
crimped with a dedicated plier
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Junctions inside breaker panels:
Most modular protection devices are equipped with 35 mm² screwed cage terminals. They
can accept any rigid wire from 1.5mm² to 35 mm² in cross-section. When wires have been
inserted and tightened, their fitting must be tested by pulling on the wire. If needed, more
than one wire can be fastened into the same junction. However, with some types of cage
terminals, if there are multiple cables not all of them might be adequately secured. In this
case, the core of the several wires can be twisted together before being fasten inside the
junction. Alternatively, several cables can be connected together with a push-in or a lever
spring block terminal, and then connected to the breaker with an additional piece of wire.
The wiring of boards
must be made very
carefully
and
precisely. No bare
part
of
the
conductors should
be visible, the wiring
is straight and clear,
the junctions are
fair.
Figure 65: Wiring of a breaker board
The earthing busbars shown here above gather together all earthing wires inside of boards.
Figure 66: Earthing busbars
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Various junction types are also used for the earthing protection system
Copper rods need
specific junction
Main equipotential
bounding.
This pipe clamp is
connecting the earthing
protection to metal pipes.
Figure 67: Various types of earthing junctions
Galvanized steel
rods often have a
‘flag connector’ to
join several earthing
conductors. The
junction is made with
specific screwed
junctions using a
lead piece to press
the wire.
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6.3. ENCLOSURES
6.3.1. INGRESS PROTECTION RATINGS
The IP codes give universal values for the rates of ingress protection for enclosures.
The IP code is given using 2 digits:
 A number from 1 to 5, related to ingresses of solid objects.
 A number from 1 to 8, related to the ingress of water.
It is mandatory to always use enclosures with an IP protection rate according to the situation.
When modifications (holes, cable glands, etc.) are made and/or accessories are added to
enclosures, the original protection rate must be reconsidered according to the new state of
the enclosure.
The IP coding system is explained in the following table:
.
IP .
First digit:
Ingress of solid objects
IP.
.
Second digit:
Ingress of liquids
0
No protection
0
No protection
1
Protected against solid objects
over 50mm (e.g. hands, large
tools).
1
Protected against vertically falling
drops of water or condensation.
2
Protected against solid objects
over 12.5mm (e.g. hands, large
tools).
2
Protected against falling drops of
water, if the case is installed at an
angle of up to 15° from vertical.
3
Protected against solid objects
over 2.5mm (e.g. wire, small
tools).
3
Protected against water spray from any
direction, even if the case is installed at
an angle of up to 60° from vertical.
4
Protected against solid objects
over 1.0mm (e.g. wires).
4
Protected against water splashes from
any direction.
5
Limited protection against dust
ingress (no harmful deposit).
5
Protected against low pressure water
jets from any direction. Limited ingress
permitted.
6
Totally protected against dust
ingress.
6
Protected against high pressure water
jets from any direction. Limited ingress
permitted.
7
Protected against short periods of
immersion in water.
8
Protected against long, durable periods
of immersion in water.
Protected against close-range high
9k pressure, high temperature water
spray.
Table 9: The ingress protection ratings (IP code)
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Protection against ingresses: A specific issue
Not only dust or water entering an electrical enclosure is problematic: Many kind of
insects, and even small lizards like to make their nest in all sorts of spaces. They are often
found inside of electrical conduits and enclosures like junction boxes, where they can
degrade the installations and can be a source of problems and even fires. All openings,
even very small, that can offer a mean of access to conduits, junction boxes or other
electrical enclosures must be found and carefully sealed.
6.3.2. JUNCTION BOXES
When it is necessary to join underground lines, junction boxes
can be placed underground, preferably inside of manholes. In
this situation the junctions must be at least IP66, and should be
filled with an insulation gel. This gel can easily be removed if
repairs are needed to the junctions. Such gel should be used
inside junction boxes placed in humid environments.
An electrical installation must last for at least 25 years. We
never know what can happen during such a period. A lot of
events and external factors can damage essential parts of the
installation, and even more when they are installed in tropical
environments. Junction boxes are potentially one of the most
fragile parts of an instalation. Whatever their size, they must be
strong enough to resist these environments.
- All junction boxes must at least be IP 55.
- They must be large enough to accommodate comfortably
the required number of junctions.
- The entrance points must be equipped with sealing systems
adapted to the cable size and the environment.
- For indoor use, rubber sealing systems are generally good
enough to ensure that the junction box is protected against the
ingress of humidity or any solid foreign objects (dust).
Figure 68: Junction boxes
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For outdoor use, in wet areas, or technical areas (subject to movement, grease deposits,
dust or other volatile dirt - like laundries, mechanical workshops, or warehouses) stronger
seals must be used. Cable glands are much more watertight and stronger than standard
rubber seals. In such areas, the IP rate must be at least IP 66.
A lot of different size and types of cable glands are available, each according to specific
conditions of use. Standard PVC ones are frequently used in the most common situations.
The following images illustrate different types of cable glands.
Figure 69: Various types of cable glands
Cable glands also reinforce the mechanical strength and attachment of the cable to the
enclosure, ensuring that in case of tension on the cable it will not displace the cable and not
put tension on the junction itself.
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6.3.3. OTHER ENCLOSURES
All other electrical enclosures must also meet certain specific requirements. For example:
•
•
Electrical boards in dry areas must be at least IP44.
Electrical boards placed outdoors or in technical areas must be at least IP66.
Covers and doors must also ensure that the IP ratings are maintained. Closing systems,
hinges and gaskets must be effective and in a good condition. It is preferable that electrical
boards are manufactured from non-conductive materials (such as polycarbonate, polyester,
PVC or ABS). However, larger boards which need additional structural strength may be
fabricated from metal. The following images show some examples of electrical boxes:
This board is not adequate it has no door and is made
from weak materials.
These enclosures are adequate - they are made with
thick rigid PVC and have strong transparent doors.
Figure 70: Various types of plastic boards
Many cheap boards are too flexible and fragile. If a board deforms because of the
mechanical stresses weight when equipped and installed, most of the time the cover doors
will not close properly. Cheap boards that are constructed from thin plastic are also easily
cracked or damaged when drilling holes, installing cable glands, or even when installing thick
cables. All enclosures must be rigid and thick enough to resist to such mechanical stresses
without any deforming or cracking.
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Very large enclosures (access door >1m²)
should preferably be constructed from steel.
However, metal enclosures are subject to
corrosion, which weakens their ruggedness
and watertight properties. Metal enclosures
have to be properly protected with an
anticorrosive layer (zinc coating or other
antirust paint). A thick layer of epoxy or
polyurethane will add the final protection, and
also protect the board from most mechanical
damage that could in turn damage the anticorrosion layer.
Figure 71:
Steel enclosure for large boards
Din rails offer an easy way to mount and organise electrical boards. Breaker boards with
horizontal Din rails are preferred.
Din rails offer the most affordable solution for easy mounting and wiring of breaker boxes.
Figure 72: Boards equipped with DIN rails
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6.4. SWITCHGEAR AND CONTROLGEAR
‘Switchgear and Controlgear’ is a general term covering switching devices. It refers to all
devices designed to connect or disconnect electrical mains, including:
 Their combination with associated control, measuring, protective and regulating
equipment,
 Assemblies of such devices and equipment with associated interconnections,
accessories, enclosures and supporting structures
Switchgears are intended in principle for use in connection with generation, transmission,
distribution and conversion of electric energy.
Controlgears are intended in principle for the control of electric energy consuming equipment.
They must comply with IEC standards and they can be:
•
•
•
Main switches of an electrical installation, or branch. Including change-over switches.
(IEC60947-3)
Electromechanical Contactors and motor-starters. (IEC 60947-4-1)
Circuit breakers. (as per IEC 60947-2)
Circuit breakers as per IEC 60698 and switches as per IEC 60669 are dedicated for other
uses (Household and similar fixed electrical installations) and they are not considered to be
switchgear or controlgear. They will be described in Section 6.5 ‘Circuit Breakers’ and In
Section 6.6 ‘Terminals’.
CLASSIFICATION OF SWITCHGEAR ACCORDING TO THEIR ABILITIES AND
USES
Switch.
IEC 60947-1
‘Mechanical switching device capable of making, carrying and breaking currents under
normal circuit conditions including operating overload conditions’. A switch is provided for
frequent opening and closing of circuits under load or slight overload conditions. It must be
combined and coordinated with a protective device against overloads and short-circuits, such
as a fuse or a circuit breaker.
Contactor
IEC 60947-4-1
‘Switch having only one position of rest, operated otherwise than by hand’.
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The IEC standard defines utilisation categories depending on the load and the control
functions provided by the contactor. The class depends on the current, voltage and power
factor, as well as contactor capacity in terms of frequency of operation and endurance.
Disconnector.
IEC 60947-3
‘Mechanical switching device which, in the open position, complies with the requirements
specified for the isolating function’. A disconnector serves to isolate upstream and
downstream circuits. It is used to open or close circuits under no-load conditions or with a
negligible current level. It can carry the rated circuit current and, for a specified time, the
short-circuit current.
Switch-disconnector
IEC 60947-3
‘Switch which, in the open position, satisfies the isolating requirements specified for the
function of a disconnector, and which can break the circuit under load conditions’. A switchdisconnector serves for switching and isolation. The switch isolates the circuit. Protection is
not provided. It may be capable of carrying short-circuit currents if it has the necessary
carrying capacity, but it cannot break short-circuit currents.
Combined fuse-switch
disconnector
/ switch disconnector-fuse
Switch disconnectors with a fuse used as
switching device, or combined with a fuse in
series with the switching devices.
Switchgears can include overload
protection fuses
Figure 73: Fused switch disconnector
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In addition to not having any protection against direct contacts,
this switchgear is a ‘disconnector’ not a ‘switch-disconnector’.
If it is turned off under load, the contacts will arc and are
quickly damaged.
It is not safe nor reliable and must be replaced by a correctly
insulated ‘switch-disconnector’.
Figure 74: Old model of a single disconnector
This kind of changeover switch is also a
‘disconnector’. It should be replaced by a
‘switch- disconnector’.
Figure 75: "blade" change over switch
Damages linked to the use of a disconnector
instead of a switch-disconnector are often a
cause of fire.
Figure 76: Disconnectors damaged by fire
Switchgear are a critical part of electrical installations. Currents in the main distribution
system are higher than in final circuits, but it is the need for switchgear to be able to both
connect and disconnect circuits under load which is the most stringent. With inductive loads,
high voltage transients can cause significant arcing across mechanical switching. The
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disconnection of currents is much more significant source of arcing than the connection of
currents. The design of switchgear must be made in a way that electric arcs will not destroy
the contacts, or overheat or damage the casing. Contacts damaged by repetitive arcing can
be a source of many problems, such as: poor contacts, current instability, overheating,
intermittent or permanent arcing, and start of fires. Damaged or inappropriate switchgear are
unfortunately a common cause of fire.
Use of Switchgears
13.1 Switchgear must comply with IEC 60947-1
13.2 The use of disconnectors that are not switch-disconnectors is forbidden.
13.3 All switchgear must be able to switch off mixed loads at full load without destructive arcing
(cos = 0.65).
13.4 They must be able to support short-circuit currents during a ‘short time’.
CIRCUIT BREAKERS THAT CAN BE USED AS SWITCHGEAR
The difference between standards IEC 60898-1 and IEC 60947-2.
IEC 60898-1
• Relates to the ac. low-voltage circuit breakers (MCBs) found in homes, schools,
shops, and offices. For use in final distribution electrical switchboards of buildings
where nominal current does not exceed 125A.
• They are intended for use in indoor, pollution and humidity-free conditions
• They can be used by untrained people and do not need maintenance.
• Pollution degree 2, Temperatures up to 30°C.
• Impulse voltage 4kV, isolation voltage is the same as nominal voltage 400V.
• THEY CANNOT BE USED AS SWITCHGEAR for the general switching,
disconnection, or protection of mains, or branches of a main distribution.
IEC 60947-2
• Defines additional requirements to IEC 60898-1 and relates to industrial, harsh or
outdoor applications that require pollution degree 3, higher voltages, and higher power
rates.
• 30°C is not enough for industrial applications where the temperature in a switchboard
can reach 50°C and higher. Manufacturers usually supply temperature rating tables
which show the nominal current for different temperatures. For example for a 63-amp
circuit breaker, it may be 70 amps at 30° and 56 amps at 70°C.
• The rated voltage currently required in industrial-use CBs is 440, 690 volts or higher.
• Impulse voltage is 6 or 8kV.
• THEY CAN BE USED AS SWITCHGEAR, BUT NOT SPECIFICALLY AS SWITCHDISCONNECTORS IF NOT MENTIONED (frequent manual operation must be
allowed as per 60947-3).
• While IEC 60898-1 clearly describes B, C and D curves with ratio to rated current, in
IEC 60947-2 the instantaneous tripping release may be adjustable according to the
need of the user or pre-defined by manufacturer with ±20% tolerance.
• This is the reason why manufacturers in addition provide a wide scope of different
curves for 60947-2 CBs: K, Z, and MA.
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Table 10: Comparison between IEC 60898-1 and 60947-2
The most appropriate solution is to use MCBs certified
to both standards as their performance meets
requirements of use for residential installations, as
well for industry and infrastructure applications. In
practice, only IEC 60947-2 breakers are accorded to
most of our context. Unless indicated, they cannot be
used for frequent manual operations like ‘Switchdisconnectors’.
Utilisation categories of IEC 60947-2 circuit breakers
According to IEC 60947-2, the utilisation category of a
circuit breaker shall be stated with reference to whether
or not it is specifically intended for selectivity by means of
an intentional time delay with respect to other circuit
breakers in series on the load side under short-circuit
conditions.
Some circuit-breakers are
also suitable to be used as
switch-disconnector
Figure 77: MCCB (Molded
Case Circuit Breaker)
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Utilisation category A
Without an intentional short-time delay for selectivity under short-circuit conditions and
therefore without a short-time withstand current rating.
Utilisation Category B
With an intentional short-time delay (which may be adjustable) provided for selectivity to
downstream breakers under short-circuit conditions. Such circuit-breakers have a short-time
withstand current rating. They are also called current-limiting circuit breaker. They are circuitbreakers with a break-time short enough to prevent short-circuit currents reaching otherwise
attainable peak values.
If a higher discrimination and selectivity is needed Cat B breakers can be installed upstream
of Cat A ones. Cat A breakers are allowed in all situations (unless a higher selectivity is
required), and there are no safety issues if only Cat A breakers are used, as there is
instantaneous tripping.
GENERAL REQUIREMENTS FOR ALL SWITCHGEAR
(for use in LV Installations)
•
•
•
•
•
•
Insulation rates: Must be 500V min.
Rated or assigned voltage: For use with 230 / 400V systems, must be 450 or 690V
Rated or assigned current: The max admitted permanent current under normal
conditions must be at least 2 x the average rated current of the installation, or (for
switchgear other than breakers) 2 x the rate of the upstream breaker.
Breaking capacity: The breaking capacity of switches must be at least 2 x the max
rated current. Breakers must be able to break off short-circuit currents - their breaking
capacity should be at a minimum of 6kA. This breaking capacity must eventually be
increased, accorded to the actual calculation of short-circuit currents.
Rated number of operations: The life time of the switching device, in number of
operations. Switchgear are not supposed to be turned on and off every day, but in
many situations in the field, they are. Their life time should be at least 5000
operations.
Utilisation category: The kind of loads for which the switching device has been
designed must be in accordance with the actual load connected to the switchgear.
Some switches are only able to connect or disconnect resistive loads, while others are
designed to switch inductive loads (such as motors, pumps, fluorescent tubes with coiled
ballasts etc.). If they are switch-disconnectors, they are supposed to be able to disconnect
loads with a power factor of 0.6 at full load without problems. Oversized switches may be
needed for fluorescent tubes with inductive ballasts, as they often have a power factor of
about 0.35.
It is mainly for electromagnetic contactors that the right class of utilisation must be selected.
For general use it is recommended that they are able to work with slight inductive loads (0.6).
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Utilisation Category and Type of Application (mainly used for contactors)
AC-1
Non-inductive or slightly inductive loads, example: resistive furnaces, heaters
Cat AC-1 is a very common category of utilisation. If the current rate is divided by 2 they can be used
for general circuits included with more inductive loads.
AC-2
Slip-ring motors: switching off
AC-3
Squirrel-cage motors: starting, switching off motor during running time
Cat. AC-3 is the most suitable for switching on and off mixed inductive and resistive loads without
any problems if a high ability for switching inductive loads is required.
AC-4
Squirrel-cage motors: starting, plugging, inching
AC-5a
Switching of discharge lamps
AC-5b
Switching of incandescent lamps
AC-6a
Switching of transformers
AC-6b
Switching of capacitor banks
AC-7a
Slightly inductive loads in household appliances: examples: mixers, blenders
AC-7b
Motor-loads for household appliances: examples: fans, central vacuum
AC-8a
Hermetic refrigerant compressor motor control with manual resetting
overloads
AC-8b
Hermetic refrigerant compressor motor control with automatic resetting
overloads
The following categories define the category of utilisation in household appliances
AC-20
Connecting and disconnecting under no-load conditions
AC-21
Switching of resistive loads, including moderate overloads
AC-22
Switching of mixed resistive and inductive loads, including moderate
overloads
-> Best switches for household appliances
AC-23
Switching of motor loads or other highly inductive loads
Cat A
(IEC 60947 circuit breakers) Protection of circuits, with no rated short-time
withstand current
Cat B
(IEC 60947 circuit breakers) Protection of circuits, with a rated short-time
withstand current
Table 11: utilisation categories of switchgears
Before selecting switchgear it is useful to verify the rated category of utilisation to ensure that
it is suitable for the intended use. Very often the required category of utilisation is very mixed
and only a few categories are complying with mixed uses. Hence, the most common and
universal categories of switchgear used are: AC-1, AC-3, AC22, and AC-23.
With multipole switchgear it is very important that all poles are coordinated. Unless they are
only operating off-load, all poles must switch and un-switch at exactly the same time.
This is particularly the case if they are four-pole switchgear. If the neutral pole is not
coordinated with the phases poles, it will be a cause a momentary supply of incorrect voltage
that could damage the downstream devices. Another important requirement of switchgear is
the mechanical strength of the junctions, for example, cheap equipment often have weak
junction terminals.
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CHANGE-OVER SWITCHES
The picture on the right shows a model of
a manual change over switch (pressure or
cam contacts) that is widely reliable and
adapted to more stringent uses.
Other kinds of change-over switches are
also available and could be more
appropriate for some uses.
Figure 78: Manual change-over switch
Change-over switches can also be made with
two electro-magnetic contactors. In this case,
the command is given by an auxiliary switch
that selects the contactor that should be
active. The command button can be installed
remotely, or the command can be a part of an
automated selection system.
Figure 79:
Electro-Magnetic change-over switch
Automated
change-over
switches,
or
automated transfer switches are another kind
of source selector. They typically monitor
whether or not the public network is operating
and has the correct voltage. Depending up the
status, it will either switch automatically to the
‘city power’ or start a backup generator.
Automated change-over switches can be
programmed for different waiting times,
depending upon the situation. When the ‘city
power’ is back, a timer is also activated, and
will reconnect the city power only after the
supply voltage has been acceptable during the
sample time.
Figure 80: Automated change-over or
Automated Transfer Switch (ATS)
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It is worthwhile recalling the main points for switchgear and controlgear:
 Switchgear must be able to switch and un-switch at normal circuit conditions
including operating overload conditions and a cos φ of 0.65 without destructive
arcing. They must be ‘switch-disconnectors’ according to IEC 60947-3.
 Switchgear must be able to carry slight overloads (1.2 x rate) without excessive
heating.
 Switchgear must be able to carry short-circuit currents during a short time.
 Unless they are circuit breakers, switchgear are not able to disconnect shortcircuit-currents.
 Unless they are circuit-breakers or have embedded protections, they must be
protected by upstream IEC 60947-2 circuit breakers.
 If they are not circuit-breakers, it is advised that the rated current of switchgear is
a minimum of 150% of the protection rate of the upstream circuit-breaker.
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6.5. CIRCUIT BREAKERS
6.5.1. DEFINITION
A circuit breaker is a ‘Mechanical switching device, capable of making, carrying and breaking
currents under normal circuit conditions and also making, carrying for a specified time and
breaking currents under specified abnormal circuit conditions such as those of short-circuit’.
Circuit-breakers are the device of choice for protection against overloads and short-circuits.
6.5.2. FORMS
Many different forms of circuit-breakers have been developed for the protection of low
voltage circuits. However, not all of them are acceptable. Two main formats are the most
commonly used, and are becoming the standard reference everywhere: MCBs and MCCBs.
MCB stands for ‘miniature circuit-breaker’ or ‘modular circuit-breaker’. Their size is
normalised accorded to a standard module width of 17.5 mm.
This standard size is according to the use of 35mm ‘DIN’ rails installed in dedicated electrical
enclosures.
Figure 81: Standard size of MCBs and DIN rails
MCBs can be 1 to 4 poles.
Single pole breakers are only
allowed
for
low
power
applications situated inside
the breaker board (pilot lamps
etc.). 3 poles breakers are
only allowed for 3 phase
systems without a neutral. For
Figure 82: Modular or miniature circuit breakers (MCB)
all other uses (because if
there is a neutral it must be also protected) it is required to use only 2 poles or 4 poles
breakers. All MCBs should have a maximum of 1 pole per module.
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MCCB means ‘moulded case circuit breaker’. MCCBs commonly relate to bigger circuitbreakers, used for the general protection or switchgear. Their size varies in accordance with
their rate. Most are too large to be placed on a 35mm DIN rail and need to be installed in
boards bigger than commonly used for final distribution boards.
Figure 83: Various models of MCCBs
Various sizes of MCCB are available, from
63A up to 630A or more. Some have an
adjustable rate and delay. Some can
include RCD features, also adjustable in
rate and waiting time (‘S’ function for
discrimination/ selectivity).
Figure 84: Adjustment panel on a MCCB
MCCBs are often used as switchgear and for general protection of installations, branches of
an installation, or as final protection for heavy equipment (> 63A). But it must be repeated
that unless it is mentioned that they are ‘switch disconnector’ they are not suitable for
frequent manual operation.
As the main features of switchgear has been discussed earlier, this section will look more
specifically at the features and requirements for MCBs circuit-breakers that are used in
common switchboards for household installations.
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6.5.3. QUALITY REQUIREMENT
The previous section showed that there are two IEC standards which define two different sets
of specifications for low voltage circuit-breakers. Many companies offer MCBs that only
comply with IEC 60898-1, meaning that they are only suitable for indoor applications in
humidity and pollution free environments up to a temperature of 30°C. This does not match
the reality of the conditions in many of the contexts where MSF & ICRC are operating.
Hence, higher specification MCBs must be used: they must comply with IEC 60947-2.
How to recognise an IEC 60947-2 compliant MCB
One of the requirements of IEC 60947-2 compared to IEC 60968-1 is that many additional
indications must be written on the device. These include details of the standards that the
item meets, along with useful indications about their technical features.
Figure 85: Mandatory indications as per IEC 60947-2
•
•
•
•
•
•
•
•
Manufacturer’s trademark
Compliance with standard IEC/EN 60947-2
Selectivity category (Cat A)
Rated voltage (500V)
Rated impulse withstand voltage (U imp = 6kV)
Rated short-circuit breaking capacity (Icu = 15kA @ 440V)
Tripping curve (C curve)
Reference temperature (if different from 30°C) - 50°C
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•
•
•
•
Pollution degree (3)
Rated insulation voltage (Ui = 500V)
Suitability for isolation (should show even when circuit breaker is installed)
Clearly marked ‘ON’ (red) and ‘OFF’ (green) positions (should show even when circuit
breaker is installed)
Main features of a MCB
Some values are common to all MCBs that are compliant with IEC 60947-2, but related to the
rate of a specific model, some values will vary. It is important to make the right selection,
bearing in mind the most important values that must be according to the intended use:
The rated voltage (Ue): Must be according to the service voltage. 450V or 500V are correct
values for 230 / 400 volts systems.
The breaking capacity (Icu): Can vary from 6kA to 15kA and more. 6kA is enough for most of
the situations encountered in the fields.
The rated current (In): Value of the permanent current that can flow without any tripping of
the device. Common values are 2A, 6A, 10A, 13A, 16A, 20A, 25A, 32A, 40A, 50A, 63A. The
tripping time will vary according to the situation.
In case of overload, the tripping time is according to the severity of the overload, and ambient
temperature. All MCBs are designed to allow a certain overload during a rated waiting time. It
is the thermal sensor of the device (bimetal) that will finally trip the contacts.
With an overload current I = 2 x In, the tripping time is normally close to 1 minute, but the
allowance for overload varies a lot according to the rating of the MCB. The higher the rating,
the shorter the waiting time.
Figure 86: tripping curves of circuit breakers
In case of a short-circuit, the current threshold that will trip the magnetic sensor vary with the
rate (In) and the tripping curve: B, C, or D.
•
•
•
B curve will trip the sensor for currents between 3 x and 5 x In
C curve will trip the sensor for currents between 5 x and 10 x In
D curve will trip the sensor for currents between 10 x and 20 x In
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Prospective
fault-current peak
Rms value of the
prospective fault current
Current peak limited by
the breaker
In case of a short-circuit, the tripping time
must be as short as possible. If Cat A, it is
never more than 0.005 sec, but high current
peaks are most often limited after less than
0.003 sec, which is necessary to limit the
energy that the device should dissipate
during a short-circuit.
The arcing that occurs after the opening of
the contacts can also last a few
milliseconds before that it is blown by the
device, which has an arcing chamber to do
so. Low quality circuit-breakers most of the
time have a longer reaction time and do not
have an effective arcing chamber: they are
much less safe to use.
Tf: Delay before opening
Ta: Arcing time
Ttc: Total fault clearance time
Figure 87:
Tripping curve in case of a short circuit
Main parts of a breaker
1. Manual lever switch and position
indicator
2. Actuator mechanism that forces the
contact together or apart.
3. Contacts
4. Screwed cage junction terminals
5. Bimetallic thermal sensor. In case of
overload this sensor deforms with the
temperature and acts on the actuator.
6. Adjustment screw – only for purpose of
fine adjustment by the manufacturer.
7. Magnetic sensor. In case of high current
rush, the solenoid acts on a magnetised
piston that triggers the actuator.
Figure 88: Internal view of a circuit breaker
8. Arcing chamber - which helps
extinguish the arc in a very short time.
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Counterfeit MCBs
Depending upon the country, as for cables and other technical equipment, circuit breakers
that are purchased locally do not always meet the quality requirements. Many comply with
IEC 60898-1. There are also counterfeit items which claim to be compliant with every
required standard, but in fact do not comply with any.
Some international brands of quality electrical equipment offer good quality devices,
complying with the most stringent criteria of safety and quality of the IEC 60947-2 standard
(such as ABB, LEGRAND, HAGER, SCHNEIDER). Unfortunately, counterfeit copies of these
brands are also frequently sold on local markets, even by official distributors of international
brands. Electrical protection is very important, so unfortunately it means that only additional
controls or international purchase can ensure that original good quality parts are purchased.
How to control the quality of a circuit-breaker

Their packaging must be in good state. It must be as strong as the original one is
supposed to be and all indications and references must be clear and complete.
Specification sheets, installation manual and some accessories (labels, etc.) must
also often be present in the packaging.

Appearance: the quality of the plastic moulding, aspect, colour, sometimes
indicates that the device is not original.

Indications: if printed values and references are missing or look rough or irregular,
the device is probably not original. Same for bar codes, or holograms that are
supposed to be present.

The weight can sometimes indicate the quality of the equipment. Surprisingly light
devices are sometimes found and they must be avoided

Their mechanical robustness and precision when operating the lever switch is also
sometimes a good indication - even the sound of the mechanical operation.

The strength and material of the screwed junction cages is also an indicator.
Sometimes, signs of corrosion indicate that the metal is poor quality.

If there is still doubt, the casing can be opened to verify that all the components
are present (bimetal, solenoid, and arcing chamber) and appear to be of good
quality.
Unfortunately, even after making these tests and observations, it is still difficult to be
sure that the equipment is the correct quality. Increasingly counterfeits can appear
very similar to original equipment. The only way to be completely sure is through
further testing, or international purchasing.
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How to test the electrical features of a MCB
 Tests must be related to the specifications of the circuit-breaker.
 Its behaviour and waiting time in case of overload can easily be tested by connecting a
load with twice the rate of the breaker. The tripping time must be between 10 sec and
1 minute.
 To test the durability and sustainability of the breaker in case of multiple trips, the test
must be repeated several times, with a rest of two minutes between tests.
 The normal behaviour of the device must remain the same after several repetitions.
 The ability to reconnect as easily and firmly as for the first test must also be observed.
No excessive heating or colour change of the casing must be observed.
 The same test can be made for short circuits. According to the tripping curve, the
minimal short-circuit current must be applied (5 x In for B curve, 10 x In for C curve.)
The breaker must trip immediately.
 To test the breaking capacity, higher currents must be applied.
 As for overload test, repetitions are a part of the test, and the same signs must be
observed: stability and constancy in behaviour, ability to reconnect, no excessive heat,
and colour variation of the casing.
 After testing the device, it can be opened in order to examine the condition of the
components.
 However, such tests are not always easy to do.
Influence of temperature
The specifications at higher temperatures up to 50°C (for IEC 60947-2) do not reduce the
quality requirements, but a derating must be applied. Practically, this derating means that at
higher temperatures there is a higher sensitivity of the overload protection, because the
thermal sensor of the device has a higher temperature. This is not really a problem, because
the wires that are protected also have a higher temperature in such conditions, and it is good
that their protection devices are also tripping in accordance with the surrounding temperature
and not only the temperature produced by the current into the wires. This is an important
feature, because circuit breakers are protecting the downstream cables against the danger of
too high temperatures. The choice of the correct rate is closely related to the cable that must
be protected.
6.5.4. ASSIGNED CURRENT AND PROTECTION RATES
Three factors influence the dissipation of the heat produced by the current passing through a
cable. These factors determine the maximum temperature rise of the cable for a given
current rate.
•
•
•
The type of cable (number of active conductors, insulation and coating material - PVC,
PE, armour, etc.).
The placement of the cable, (in the air, embedded, in technical channels, false ceiling,
insulating material, single cable or multiples cables).
The ambient temperature.
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In practice, the next table gives rates that have already been assigned to most of the
encountered conditions in hot countries. More precise adjustments and calculations could
give results that could potentially allow a reduction of the size of the cables. However, unless
it is a very big installations (where the financial impact of such a reduction could be large), it
is easier and better to respect the given values, which were calculated with a security factor
that will be appropriate to most of the MSF & ICRC field situations.
This table has already been presented in an earlier chapter to illustrate the differences
between AWG and metric system as they apply to the cross section of cables. It is repeated
here to highlight the correct rates that must be applied for circuit-breakers.
American Wire Gauge/ Metric conversion table/ Minimal cross section & max circuit
breaker values & temperature rise.
For applications in accordance to UL 489
and CSA C22.2 Standard (NEC)
Max circuit
Minimal
breaker rate
cross
(assigned
section mm²
current)
1.3 mm²
10 A
1.6 mm²)
2.1 mm²
15 A
2.6 mm²)
3.3 mm²
20 A
4.2 mm²)
5.3 mm²
30 A
6.6 mm²)
8.4 mm²
40 A
10.6 mm²)
13.3 mm²
50 A
16.8 mm²)
21.1 mm²
80 A
26.6 mm²)
33.6 mm²
110 A
42.2 mm²)
AWG No.
16
(15
14
(13
12
(11
10
(9
8
(7
6
(5
4
(3
2
(1
0 - 1/0
00 - 2/0
53.5 mm²
67.4 mm²
For applications in accordance to IEC
60947-2 Standard
Minimal cross
section mm²
Max circuit breaker
rate (assigned
current)
1.5 mm²
10 A
2.5 mm²
16 A
4 mm²
20 A
6 mm²
25 A
10 mm²
40 A
16 mm²
63 A
25 mm²
80 A
35 mm²
50 mm²
100 A
125 A
70 mm²
160 A
95 mm²
200 A
120 mm²
250 A
150 mm²
320 A
185 mm²
400 A
240 mm²
500 A
150 A
175 A
000 - 3/0
85 mm²
225 A
0000 - 4/0
107 mm²
250 A
250
127 mm²
300 A
350
177 mm²
350 A
400
203 mm²
400 A
500
253 mm²
500 A
Indicative cable
temperature rise
(non-insulated
single round
copper wire in the
air)
36 °C
30 °C
41 °C
35 °C
36 °C
27 °C
41 °C
23 °C
36 °C
27 °C
28 °C
34 °C
36 °C
28 °C
34 °C
26 °C
24 °C
31 °C
30 °C
24 °C
35 °C
23 °C
31 °C
26 °C
34 °C
30 °C
28 °C
35 °C
30 °C
37 °C
34 °C
Table 12: Cable size - AWG to metric conversion
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In case of a long length of cable, the size of the cable has to be corrected. The
calculation must ensure that the voltage drop at full load does not exceed 3% of the
rated voltage. As a reminder, with an ampacity of 1 Amp/ mm² the voltage drop is
about 1 Volt every 50 meters for a single wire, 1 volt every 25m within a two wires
circuit. With 5 Amp/ mm², in a 2 wire circuit, the voltage drop is as much as 1 volt
every 5 m.
• The values given in the preceding table are established by applying a correction factor
of about 0.5 - which is enough to foresee most of the worst conditions.
• This factor is based on the typical situation in hot countries. Without knowing the
quality of the cables that will be used, it was also assumed that no cable could exceed
a temperature of 70°C.
•
There is no need to oversize any circuit-breaker, even if the cross section of the
downstream cable has been oversized. The lower the rate, the higher the safety. The
rate will therefore be calculated according to the expected maximum load of the circuit.
•
Permanent current in a conductor should not be more than 75% of the assigned
current of the circuit. Produced heat is then 60% of the heat produced at 100% load.
•
Short-circuit protection curve: The ‘C’ Curve is the most usual curve. Icc = 7 – 10 x In.
MSF & ICRC installations are often powered by generators, which have low shortcircuit currents (only twice their rated current), and hence the C curve cannot satisfy
the requirements. Therefore, B curve breakers must be selected. They have a
sensitivity to short-circuit current between 3x and 5x the assigned current.
•
For the same reason, to ensure their instantaneous tripping in case of a short-circuit,
the rate for the head protection of branches (main distribution cables going to final
boards) will preferably be limited to a rate of 1/3 of the rate of the generator.
If all calculations are made appropriately, miniature circuit breakers complying with IEC/EN
60947-2 and designated CAT A, will meet these requirements, both with ensuring that their
quality is also accorded to our requirements.
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6.6. TERMINALS
6.6.1. DEFINITION
Terminals are the fixed devices at the end of the final distribution of electrical circuits. In this
sense they are the main objective of an electrical installation. Terminals are fixed socket
outlets, fixed switches and fixed lighting appliances.
6.6.2. SOCKETS AND SWITCHES: VARIOUS SHAPES AND RELATED USAGES.
INDOOR AND OUTDOOR USE, FLUSH OR APPARENT MOUNTING
Flush mounting of indoor sockets and switches is always preferred, not only for aesthetical
reasons. Apparent mounting is more fragile, because any fixed object protruding from a wall
can be easily damaged by passing people or equipment, especially in high-traffic locations
such as corridors. The following images illustrate several examples of both flush and apparent
mounting terminals.
Figure 89: Terminals and flush mounting blocks
Various types of flush mounting blocks are available: they vary in size (for 1, 2 or 3 devices),
they can be vertical or horizontal, and some are dedicated for hollow walls (round shape) while
others for solid walls (square shape). They are standardised in size so that most devices can
be mounted in them easily. Two standards of depth are generally available, 40mm and 65mm.
The deeper boxes are preferred when possible.
Apparent mounted sockets and switches are preferable for
outdoors or wet environments, as it is easier to make them
watertight. In outdoor situations the terminals need to be
more robust and capable of resisting not only water
ingress, but also the effects of UV, and even physical
impact. The use of cable glands is often required to
ensure the waterproofness of enclosures, and if not
correctly installed, the ingress protection can be
compromised.
Figure 90: Apparent mounted terminals for outdoor use
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6.6.3. STANDARD SOCKETS FOR HOUSEHOLD COMMON USES
I.
USAGE REQUIREMENTS
As discussed in early sections, the shape of the socket used depends upon the local
standards and regulations, and these local standards must be respected in MSF and ICRC
electrical installations. However, it is not only the shapes of sockets that varies. Standards
also define different current and voltage rates, such as:
•
•
•
•
2.5A/250V (EC type C, class II, ungrounded)
13A/250V (UK type G, grounded)
15A/135V (US type A , class II, ungrounded) & B, grounded),
16A/250V (EC type E & F, grounded),
The protection rates of the circuits must be according to the current rating of the sockets.
However, some local regulations are allowing exceptions to this rule, but not all of them are
acceptable.
-
Type C sockets can be supplied by an insulation transformer, with a max power of
300VA. These transformers can be supplied by standard 10 / 16A circuits. Such an
insulation transformer is mandatory for ungrounded sockets installed into a bathroom.
Some European regulations allow 20A protection rate for 16A sockets. We
recommend to use a rate of max 16A, more particularly into hot countries.
- The British and British inspired
regulations
(BS 7671, 2004) allows 13A
2.5mm²
switched sockets that can be installed in
32A Ring
two specific ways:
Circuit,
RING
Spur
20A
Radial
Ring circuits are
not allowed
Ring circuits have a cabling system
(2.5mm²) making a ‘ring’ and coming back
to a 32A circuit-breaker. There can also be
individual ‘spur’ lines (2.5mm²) that must be
individually protected by 13A fuses if the
spur line has more than one socket. This is
in conjunction with the use of plugs that
also have an imbedded 13A fuse.
RING
Branch
RADIAL
Figure 91:
"Ring Circuits" following the British Standards
Not
allowed!
13A Fuse
Unit
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For safety reasons, and better accordance with IEC recommendations (even if allowed by
British Standards), ring circuits are not allowed by the MSF/ ICRC internal rules. Fused
sockets or plugs are also not allowed.
Radial circuits are the second option permitted under British Standards. They are also
permitted under MSF/ ICRC internal rules – but with some minor (but important) differences
with the British Standards. The most important of these differences is related to the current
protection rating – with MSF/ ICRC internal rules limiting the protection rating of standard
household sockets to 16A.
Type G sockets (the British system) often incorporate switches. However, these switches are
a potential point of weakness: mechanical problems (because they are rarely operated)
corrosion, and poor contacts that can produce arcing and overheating. It is hence
recommended to use sockets without switches.
Some type G sockets have an embedded 13A circuit-breaker. This is better than a fuse, but
such sockets are much more expensive than unprotected sockets. If the circuit is correctly
protected by 13 or 16A circuit-breaker, there is no need to install sockets with an embedded
circuit breaker.
Ring circuits will also be discussed in more detail in the next chapter on installation design.
Depending upon which socket system is used, other standards may need to be followed:
•
•
•
US sockets (A & B types) - compliant to UL 231: Should be used with 15A circuitbreaker protection. According to local regulations, they might include 5mA GFCI
devices.
German sockets, ‘Shuko’ (F types) – must be according to CEE 7, DIN 49440
French sockets, (E type) must be according to CEE7/5 (FR1-16R) NF / CEBEC
German and French sockets must be installed on standard 16A protected circuits.
II. QUALITY REQUIREMENTS
All plugs and socket outlets must comply with IEC Standards (IEC 60884-1).
Ingress protection rate: Sockets must include ‘children protection’ measures that avoid the
introduction of any metallic object inside of the socket when no plug is inserted. At least IP 4x
is requested.
For sockets (as for other equipment), references to quality standards are not always genuine
and if the quality is in doubt, it is advisable to carry out some tests. Here are some criteria
that can be helpful to assess the quality of typical household electrical sockets:
Appearance: general appearance, thickness and quality of plastic casing, cover plates,
mechanical parts, fixations. The weight of the device is also an indicator.
Mechanical and electrical behaviour must meet the following requirements:
Mechanical:
•
Fixation to the mounting blocks must ensure that the appliance remains fixed in place
when subjected to a perpendicular traction of 20 Newton.
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•
•
Spring push in junctions or screwed cage junctions must resist traction on the wires up
to 5 Newton. Flat screwed junctions are not recommended unless used with washer
wire terminals on flexible wires.
Distance and separation between poles must ensure that there is no possibility to
make contact between the poles with any straight conductive object.
Electrical:
•
•
Spring push in junctions or screwed cage junctions must fit with twin 2.5mm² rigid
wires (for parallel mounting of several sockets) - or flexible wires with dedicated
terminals.
Electrical contacts must be made with brass or any other conductive material with a
contact surface and pressure such that no excessive heat can be observed with either
a permanent current of 25A, or a current of 40A applied during 30 sec. The resistance
to a short-circuit is proven if a current of 160A (10 x In) with a duration of 200ms does
not cause damage to the contacts or the casing (melting, burning, etc.).
All these requirements are adapted to all electrical consumers that are in the range of use of
the sockets and related circuit breakers (permanent current < 80% x In and < 45 minutes).
All electrical consumers with a potentially
permanent
(more than
45
minutes)
consumption higher than 60% of the socket
rate must be connected with dedicated power
lines. This is concerning circuits which are
supplying only one socket/ device. It must be
the case for water heaters, hoven, washing
machines, dryers, air conditioners and other
fixed powerful devices.
Figure 92: Single switch disconnector for
heavy loads
The connection device will then be a heavier duty socket, (industrial sockets) or a dedicated
junction box. In that case, this junction box must include a switch disconnector, a contactor or
a breaker, with a manual operated system. If installed in countries where frequent periods of
under voltage are observed, also preferably with the addition of a under voltage coil triggering
system. If the breaker box and circuit breaker that is protecting the circuit is at a distance of
less than 5 meter from the supplied equipment, it is acceptable that its junction box is only
equipped with screwed junction terminals and is not equipped with any disconnection device.
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6.6.4. HEAVY DUTY POWER SOCKETS
Not all electrical consumers need less than 13 or 16A. For higher demands where it is
necessary to use a socket, specially designed models must be installed.
The IEC Standards (IEC 60309) define a wide range of single phase and three phases
connectors from 16A up to 125A that are now recognised almost worldwide. This system is
organised in such a way that each standard voltage and frequency (American, European) is
related to a unique shape and colour of plug or socket. Standard references are available for
16A, 32A, 63A and 125A, with 3, 4, or 5 pins (single phase, three phase delta without neutral,
and three phase star with neutral). Models are available with IP ratings from IP44 to IP68.
The differentiation key between the various types is made according to the position of the
grounding pin. This position is expressed in terms of its equivalent position on a clock face.
(The hour indication in the following table) The main available configurations compliant with
the international and North American standards are shown here below.
Table 13:Heavy duty industrial IEC sockets
In practice, in most cases it will be the 3 pins single phase 230 V (blue) and the 5 pins three
phases + neutral 230/400 V (red) that are used. As shown in the following images, models
are available for mobile plugs, wall mount, panel mount, with a straight or inclined shape, and
for both female and male connectors. This large range of products offers solutions for a wide
variety of mobile (plugs) and fixed (sockets) needs.
Figure 93: Most common Heavy duty IEC "industrial" plugs and sockets
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6.6.5. SWITCHES
Switches for household and similar fixed electrical installations must comply with IEC
Standards (IEC 60669-1). Most of the requirements are similar to the requirements for
sockets outlet.
The most common standard current and voltage rating is 10A 250V. Usually standard lighting
circuits are therefore wired with 1.5mm² cables and protected with 10A circuit-breakers. If it is
necessary to supply lighting circuits with 16A (2.5mm²) circuits, all switches installed on the
circuit must be rated 16A, even if the lights downstream to the switch require less than 16A.
This requirement is related to the fact that switches must be able to withstand short-circuit
currents whose level and duration are according to the rating of the protection and cross
section of the wires.
Mixed socket and lighting circuits: If 10A switches are installed on socket circuits, or
branches of socket circuits, it is required that the socket circuits are protected by a 10A circuit
breaker. Switches on 16A socket circuits must be 16A switches.
For switches (as for sockets), references to quality standards are not always genuine and if
the quality is in doubt, it is advisable to carry out some tests. Here are some criteria that can
be helpful to assess the quality of typical household electrical switches:
Appearance: general appearance, thickness and quality of plastic casing, cover plates,
mechanical parts, fixations. The weight of the device is also an indicator.
Mechanical and electrical behaviour must meet the following requirements:
Mechanical:
•
•
•
Fixation to the mounting blocks must ensure that the appliance remains well fixed
when subjected to a perpendicular traction of 10 Newton.
Spring push in junctions or screwed cage junctions must resist traction on the wires up
to 5 Newton. Flat screwed junctions are not recommended unless used with washer
wire terminals on flexible wires.
Distance and separation between poles must ensure that there is no possibility of
making a contact between poles with any straight conductive object.
Electrical:
•
•
•
•
•
Spring push in junctions or screwed cage junctions must fit with twin 1.5mm² rigid
wires - or flexible wires with dedicated terminals.
When the contact is established, they must support permanently their rated current in
normal conditions and in conditions of overload, i.e. they are able to support such
conditions without excessive heat.
All switches must be able to connect, support and disconnect 1.25 x their rated current
under a voltage of 1.1 x their rate (e.g. 250V + 10%)
The acceptable overload is: 1 minute for 2 x the rate, and 15 seconds for 4 x their rate.
The resistance to a short-circuit is proven if a current of 10 x In (100A or 160A) with a
duration of 200ms does not cause damage to the contacts or the casing (melting,
burning, etc.).
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Recommended maximum load on switches:
Even if switches are tested to ensure their ability to withstand 1.2 x their rate without
excessive heating, these tests are only relevant for short term behaviour. To help ensure the
long life of switches, the acceptable permanent load (more than 45 min) should not exceed
60 % of their rating. The action of disconnection is the most critical function of a switch.
Switches are supposed to be able to disconnect inductive loads (such as TL tubes with coiled
ballast) without destructive arcing. Inductive loads always produce high transient voltages
and electrical arcing at the moment of the disconnection. Household switches rarely have an
arcing chamber, so it is highly recommended to limit the inductive load to a level that is lower
than if it was a resistive load.
In practice, to calculate the maximum rate that must be applied to downstream lighting
circuits - the square root of the cos Φ is multiplied by the rate of the switch.
Example: calculation of the maximum power (in watt) of TL tubes (cos Φ 0.35) that
can be installed on a 10A switch:
 (0.35)0.5 x 10 A = 0.6 x 10A = 6A.
 True power in watt : 0.35 x 6A x 230V = 480 W
 Permanent use = 60% X 480W = 288W = 16 TL tubes of 18W, or 8 TL tubes
of 36W
This is one of the reasons why it is recommended to avoid using loads with a low power
factor. Frequently, TL tubes must be balanced with capacitors, or, much better, only TL
fixtures with electronic ballast (and therefore also a wider input voltage range) should be
purchased.
It is also more and more common to use remotely controlled stepping switches (also
known as ‘uni-selectors’ or ‘stepping relays’). They are installed in breaker boards
and are controlled by low voltage or very low voltage impulses sent by remote
commands buttons. All requirements made for the manual switches can be extended
to the quality and usage requirements needed for these switches (must comply with
IEC 60947-5).
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6.6.6. LIGHTING AND LIGHTING FIXTURES
There are several different IEC standards that each deal with specific aspects of lighting and
lighting fittings, such as:
•
•
•
•
•
•
•
TL tubes (IEC 60081 & 60901)
Ballast for TL tubes (IEC 60920)
Glass bulbs (IEC 60887)
Bayonet lamp holders (IEC 61184)
Safety of lamp holders (IEC 60061)
LED lighting (IEC 62471 & 62717)
Performance of lighting devices (IEC 62722)
These have their equivalences in national regulations such as British standards and
American codes.
Common to these are some fundamental requirements that must be respected in MSF &
ICRC electrical installations.
III. CLASSES OF EQUIPMENT, EARTHING PROTECTION
Fixed lightings: All ungrounded lighting fixtures should be class II equipment – in particular all
external parts of bulb holders should be made from nonconductive material.
Exposed conductive parts of lighting fixtures: If they cannot be connected to a protective
earthing, should be double insulated from all electrified parts of the device. Junction blocks
must be inside an insulated nonconductive compartment. Conductive channels (decorative
tubing, etc.) containing wires and cables must be insulated on the inside. All cables must be
mechanically protected from conductive parts that could damage the cable in case of friction,
traction, or movement (common for some types of lighting fixtures). It is recommended that
even if the fixture (exposed conductive parts) is connected to an earthing protection, the
preceding requirements should still be respected, in order to help minimise insulation-related
problems.
Mobile lighting: It is recommended that all mobile lighting is at least class II equipment. Plugs,
cords and ‘on-cords’ switches must be verified.
IV. INGRESS PROTECTION
All lighting fixtures must be at least IP 41 (no possibility of ingress of solid objects over 1mm).
External lighting and lighting fixtures must be at least IP66. It is preferable that the frame of
external lighting or lighting fixtures is made with strong nonconductive material. This
requirement is principally to avoid the effects of possible corrosion of steel frames installed
outdoors on ingress protection rating. It is also necessary that all external lighting and lighting
fixtures are protected against possible impact from moving objects, vehicles or persons. This
protection can be ensured by placing the lighting in a location aware from such potential
impacts, or by ensuring that they are capable of resisting such impacts.
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V. PROTECTION AGAINST HEAT
According to the technology used and the power rates, some lighting can produce significant
heat. All fixtures or exposed parts of lighting equipment that can reach temperatures higher
than 45°C must be protected from being touched by a person. This protection can be a fixed
metal protection mesh or any other mean that can produce the same protective result. Higher
temperatures are allowed for parts or lighting equipment that cannot be reached. It must also
be avoided that the heat projected by some powerful lighting can damage any surrounding
object. The distance between lighting equipment and any surrounding objects must ensure
that no danger or damage can be caused by the projected heat.
VI. PERFORMANCE
The lighting requirements must be defined prior to any considerations about the performance
of lighting systems. Standard requirements of illumination are defined by ISO 8995-1:2002.
These standards are considering 3 factors:
The illumination level (Lux, lx)
The ‘Lux’ is the illumination level given by 1 Lumen on 1 m² (1lx=1lm/m²).
The table below shows the levels of natural lights and needs accorded to areas and activities.
Natural light
Moonless clear night sky with airglow
Quarter moon
Full moon on a clear light
Full moon overhead at tropical latitudes
Dark limit of twilight with a clear sky
Very dark overcast day
Sunrise or sunset on a clear day
Full daylight (not direct sun)
Direct sunlight
Illumination needs - general
Outdoor
Basement
Corridor / warehouse
Restroom, sleeping room
Kitchen, Office, workshop - light job
Office, workshop - precise, intensive job
Very precise working
Illumination needs - medical facilities
Night lighting
Corridors
Bedrooms
Waiting room
Examination room
Laboratories
Operating rooms
Operating table
Min
5
25
50
100
250
400
1000
Min
10
50
100
200
200
300
300
3000
LUX
0.002
0.01
0.27
1
3,4
100
400
10000-25000
32000-130000
Good
Optimum
15
25
50
75
100
150
200
300
325
400
700
1000
2500
4000
Good
Optimum
20
40
100
150
200
400
350
500
400
600
500
1000
500
1000
5000
8000
Table 14: iIlumination levels- facts and needs
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The illumination level is not the only important factor to give the required comfort and clarity
of vision. The luminance, which describes the brightness of a source of light and the colour
temperature, also influences the feeling of comfort provided by a lighting system. For some
specific activities, it is also very important to consider the colour rendering index, as this
determines which colours will be clear, bright and discernible by the observer.
The luminance (Candelas, Cd)
The luminance is the value of the brightness of a source of light at a given distance. Roughly,
it is proportional to the number of lumen emitted by a source divided by the apparent surface
of the source, and to the distance between the light source and the observer. Very bright
small sources can give the same quantity of light (lumen) as less bright larger sources. But
the first one will dazzle you more than the second. Very bright sources are and are more
stressful for people, and tend to attract more insects. The luminance of a light source can be
reduced if it is surrounded by a diffusing glass or plastic globe.
The colour temperature (Degrees Kelvin - K)
Figure 94: The scale of the colour temperature
‘True white’ is considered to be around 6500K. In practice, we consider that:
•
•
A ‘warm white’ colour is given by lighting with a colour temperature between 2400K
and 3000K (2400K - very warm, 2700K - medium warm, 3000K - slightly warm).
A ‘cold white’ colour is given by lighting with a colour temperature between 3400K and
6500K (3400K - slightly cold, 4500K - medium cold, 6500K - very cold)
Figure 95:
Colour temperature of usual lighting sources
There is no difference in brightness between warm and cold colour light sources (if their
power is the same), but it makes a difference to the feeling and mood provided by the
lighting. Warmer lights are preferred in areas of rest, where it is good that people feel
welcomed with conviviality, warmth and friendliness. Colder lights are preferred in areas of
activity, work, where there is a need for precision, accuracy and concentration.
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Of course, both the resulting brightness and colour of a given lighting system in a particular
place is influenced a lot by the colours of the surrounding walls, floor, and ceiling. However, it
is still important (where available) to choose lighting systems that provide colour
temperatures adapted to the nature of the room being served.
This is also true for outdoor security lights: a warmer light makes a soothing atmosphere
while colder lights will produce more stress. So, it is better to use warmer lights to decrease
the stress at perception level. In the case of security lights it is also better to decrease the
luminance of the sources, and to use several less powerful sources rather than a single
powerful one. However, in the case of intrusion very bright cold light projectors could be
beneficial.
A last point about colours relates to insects. It appears that most are more attracted by blue
lights (colder) than by yellow lights (warmer).
The colour rendering index (CRI - in %)
The CRI is a comparison to the colour spectrum of natural white light. A CRI of 100 means
that all colours are perceived in true colour, because the intensities at each wavelength from red to violet - are similar to the ones of a natural light. A CRI of 0 means that the light
source is monochromatic and only one colour is perceived in its true colour. For example,
sodium lamps produce orange light and only orange appears the correct colour with sodium
lamps.
The following images show some examples of lighting sources with different CRIs:
Figure 96: The colour rendering index of usual lighting sources
According to the type of activity being undertaken, the need to be able to clearly
distinguishing between colours varies. Medical examination and surgery requires not only a
good illumination level, but also a CRI> 90. For indoor use, only light sources with CRI class
1 (>80) should be used.
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The adjacent graph shows ranges of
colour rendering related to usage of
the room being illuminated. This
graph uses the value Ra – which is
an average rendering value for the
first 8 samples (from the 11
considered as a reference for CRI).
Figure 97: typical usages related to CRI requirements
Whatever the lighting source used
(TL tubes, bulbs, Halogens, LED), it
must be marked with certain data.
This should indicate not just
electrical data (power, voltage) but
also the temperature colour (in
Kelvin) and the colour rendering
index (in %).
These latter items not only help in choosing an appropriate light source, but can also be a
useful indicator of the quality of the product (a fake copy is less likely to have appropriate
data for colour temperature and colour rendering). Figure 95 illustrates the coding system
used for data information marking on light sources.
POWER
(WATTS)
CRI :
9: > 90
8: > 80
7: > 70
CCT
Kelvin
27= 2700
30 = 3000
40=4000K
Figure 98: Information data on lighting devices
Key performance criteria are related to both technical and economic aspects, namely:
1.
2.
3.
The electrical performance - ratio electrical power/lighting power in watt/lumen,
The cost and lifetime
The ecological impact
A complete table with specific features and requirements for common types of light source is
given in the table 9 below.
Otherwise, some additional important remarks about some lighting and lighting fixture
components:
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Bulb holders: Must be made from insulating material. Do not mix bayonet (B) and screwed
(E) bulb holders. The choice should be based upon the local regulations or common
practices.
Tube fixtures: Must be made from insulating and strong material. They are most effective if
used in conjunction with reflectors and transparent diffuser covers (polycarbonate).
Coiled ferromagnetic ballasts. These do not compensate the voltage/ frequency variations.
Failed ignition of the starter when voltage is too low, reduced lifetime of starters, weaken and
reduce the lifetime of the tube, unstable light (blinking), sensitive to corrosion, overheating
and losses to frame/ earthing. Very bad cos . If many are installed, must be compensated
with capacitor.
Electronic ballasts. These are more expensive than ferromagnetic ballasts but provide better
insulation, good regulation with voltage variation (less failed starts) no blinking, better lifetime
of tubes. They avoid the need for a starter. They are lighter, but not as robust as coiled ones.
Should be used in preference to ferromagnetic ballasts.
Starters: (for tubes). They are only needed with coiled ballasts. They are suffering a lot when
they try to ignite tubes under too low voltages . They are very dangerous inside of areas with
flammables (high voltages & arcing during ignition).
Incandescent bulbs: These use a lot of energy and have a short life span. Can be very hot
and pose a fire risk. Sensitive to shocks and overvoltage.
Halogen: These use less energy but have very hot surfaces. Mainly used as spot lights. Very
sensitive to voltage variations and can be damaged simply by being touched.
Fluorescent tubes: X5 - X10 less energy consumption, but fragile and contain mercury. Most
recent versions are very efficient and contain less mercury.
Compact fluorescent lamps: In theory, 5 x less energy consumption. Various shapes (spiral,
bulb, etc.) but do not always fit as a direct replacement for incandescent bulbs (bigger and
heavier). Fragile and contain mercury. Some are made with reduced quantities of mercury.
All kind of high and low pressure gas lamps for outdoor use: For large spaces. The choice for
the correct siting, installation of lamps, and type of ballast is more stringent than with other
lamps. Need a long time to warm up but can become very hot. Fragile - when switched off
must wait until they have cooled down before moving or manipulating them. Vulnerable under
frequent switching.
LED: Various efficiencies and forms available. The choice is particularly interesting if the
efficiency is over 85 Lm/watt (preferably 100 Lm/watt). Light, robust, and some are dimmable.
Still expensive, but very low cost over the long term.
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Direct
Warm
Starter
dangerous
with
flammable
s
Heat/
consumpti
on / short
life
Initial Cost
/ pleasant
light.
Consumpti
on
Direct
Very hot
Warm
nice light
Less
consumer
Very hot
fragile
Fragile
Temperate
No
Low cons /
Mercury
Low cons
ECO:
Mercury,
bad cos F
Starter
dangerous
with
flammables
Temperate
No
Low cons /
Mercury
Low cons
ECO:
Mercury
Can be
dangerous
with
flammables
Temperate
No
Low cons /
Mercury
Low cons
ECO:
Mercury
Can be
dangerous
with
flammables
Temperate
No
Low cons /
Mercury
Low cons
ECO:
Mercury
Can be
dangerous
with
flammables
Remark
Frequent
On/Off
Yes
need
specific
fixture
General
10
78 - 2700 35000
6500
4
96
1
2
10
0.06
need specific
fixture
General
Short
0.08
Short
13
Short
1,6
Short
General
1
warm up
need
specific
fixture
82 - 2700 6500
85
dimmable
General
0.14
Good
allowance
Ambient,
spot
need
specific
fixture
18
Good
allowance
General
low cost
1,4
Good
allowance
Use
low cost
1
High
sensitivity
Holder/
fixture
Cost/lume
nX
lifetime
Cons
Watt
/1000
0.2
weak
lumen
Initial
Cost
(1000
lumen)
20
Doesn't
like
voltages
peaks
Cos
1
Sensitivity
voltage
variation
CCT
Kelvin
70 - 2700 0.35
6500
95
CRI 1-100
2
Lifetime
(Hours)
63
Eff. Lm/W
4
No
2950 0.95
6000
No
1
No
143
No
1
ye
s
Eco
Advantage
s
Disadvant
age
Heat
Yes
0.95
Ye
s
2700
Incandescent
7
1000
100
Halogen
16
2000
100
Fluorescent Tube
T8 Mag ballast
50
5000
Fluorescent Tube
T8 electron
ballast
55 10000
71 - 2700 6500
95
Fluorescent
TubeT5 low eff
80 20000
Fluorescent Tube
T5 high eff
Lighting
Systems
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Heat
Frequent
On/Off
Eco
Advantages
Disadvanta
ge
Remark
Temperate
Low cons /
Mercury
Low cons
ECO:
Mercury
Can be
dangerous
with
flammables
Temperate
Low cons /
Mercury
Low cons
COST:
Initial. ECO:
Mercury
Can be
dangerous
with
flammables
Hot
Low cons
Low cons
COST:
Initial.
Can be
dangerous
with
flammables
Hot
Low cons
Low cons
COST:
Initial.
Very low
CRI
Temperate
Low cons
Long life
COST:
Initial.
Need to
make good
choice
Specific,
expansive
Outdoor,
powerful
High Pressure
Sodium (HPS)
85 16000
22
1900
0.9
8
12
0.5
Specific,
expansive
Outdoor,
powerful
Light Emitting
Diodes (LEDs)
10
50 - 2700 50000
6500
0
95
1
8
10
0.16
low cost
general
Direct
0.5
Long
19
Long
6
Medium
0.9
Medium
2900 4100
warm up
8196
dimmable
General
53 12000
Good
allowance
Specific,
costly
Ceramic Metal
Halide
Medium
allowance
0.3
Medium
allowance
General
14
Good
allowance
Use
low cost
4
Bad
Holder/
fixture
0.9
Sensitivity
voltage
variation
Cost/lumen
X lifetime
82 - 2700 6500
90
Lifetime
(Hours)
CRI 1-100
CCT Kelvin
Cos
Cons Watt
/1000 lumen
Initial Cost
(1000
lumen)
69 12000
Eff. Lm/W
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Yes
CFL nonintegrated ballast
(Y
es)
No
0.3
No
No
18
No
No
3
No
No
0.9
No
Compact
82 - 2700 55 10000
Fluorescent (CFL)
4100
90
Lighting
Systems
Table 15: performances and typical specifications of various lighting systems
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6.7. VOLTAGE PROTECTION DEVICES
Breakers and RCDS protect people and equipment from the dangers of electrocution,
overloads, short-circuits and fires. The quality requirements for equipment have also
been defined and are an important factor for their durability. However, in the contexts
where MSF & ICRC work there is often the problem and effects of voltage variations in
the mains electricity supply. Most of the time the problem is that the voltage is too low,
so that some devices do not work properly, and some others (motors, fridge
compressors, etc.) are forcing and overheating. It happens also that there are too high
voltages, for example during periods of lower load on the city grid (night time), and
sometimes faulty voltage because of poor operation of the system (reversed junction
of neutral and phase), or because the neutral has been disconnected. Sudden voltage
peaks can also occur following heavy loads being suddenly disconnected from the
grid, or as a consequence of thunderstorms.
This reference document would not be complete without addressing the matter of
protection against voltage variation.
1. Devices that are able to deal with voltage variations:
Some devices are more able of supporting voltage variations than others:
•
•
Many DC adapters for class III equipment are built to be ‘universal’ – meaning
that they can work both in 50 and 60Hz, and with a voltage input between 90
and 265V. This represents a wide operating range, but such appliances will still
not be able to withstand sudden peaks in excess of 400V.
Electronic ballast for fluorescent tubes are also resistant to some voltage
variations. It has already been recommended elsewhere in this paper that all
fluorescent tubes should be equipped with electronic ballasts. But once again,
electronic ballasts are not able to withstand sudden peaks in excess of 400V.
2. Voltage monitoring devices
•
•
•
If the voltage of the power source is not reliable, it
should be monitored, and the power should be cut
when the voltage is outside the acceptable
operating range.
The acceptable voltage range is typically between
205 and 245V.
It is possible to find ‘Automatic voltage switchers’
that are able to ensure this function for various
power ranges. An example is the AVS from the
brand ‘Sollatek’, which can be found in many
countries. Note that the power switching devices
embedded in such equipment can be quickly
damaged by electrical arcing between contacts if Figure 99:
they are used at full power, so it is recommended Automatic Voltage Switcher
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•
to use them for a maximum of 50% of their rated max power.
If there is a need for a centralised voltage control, it is better to use industrial
voltage control relays in association with AC3 power contactors. A full range of
good quality industrial control relays are
available on the market and are very
useful. They can monitor single and three
phase systems monitor the voltage
symmetry between phases, and even the
phase sense if needed. To suit the specific
site conditions, it is always more reliable
and accurate to compose your voltage
monitoring and switching system out of
industrial voltage control relays associated
with power contactors.
The following figures present two examples
of such control relays: for single phase
systems, Schneider is offering the
Figure 100:
RM17UBE and for three phase system they
Industrial voltage control relays
propose the model RM35UB330.
3. Stabilisers
Stabilisers are very frequently used in the field. They can correct voltages in a
range of +15% -15% (which is correct for voltages between 190 and 250 Volts).
There can be a lot of problems if low cost/ poor quality stabilisers are used. Many
of these low cost stabilisers are unsafe, and frequently do not even have an
earthing connection. The general criteria for selecting good quality stabilisers are
the same as for other equipment, but here are some more specific points to
consider:
•
•
•
•
The weight, the price, the presence of an earthing junction, and the range of
use are important points. Only a limited (and appropriate) number of devices
should be connected to each stabiliser – particularly for small stabilisers.
It is frequently a better option to install a central stabiliser for an entire
compound.
It is also important to consider carefully the voltage range of the stabiliser.
The rated output power of a stabiliser (the power value given by the
manufacturer) does not reflect the max power that the stabiliser should be able
to deliver whatever the conditions. The actual max power is related to a max
input current. When the input voltage decreases, the stabiliser must increase
the input current to maintain the same output power. If the voltage decreases
by 25%, the input current needs to increase by 25%. As the actual limit of a
stabiliser is the input current, the max delivered power will be decreased
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•
•
•
accordingly. If the input voltage to a stabiliser rated 230V 10 kVA is 25% lower
than 230V, the actual max output power of the stabiliser is decreased to
7.5kVA. Stabilisers must be oversized according to the input voltage range.
As for many types of electrical equipment, especially in hot climates, it is
advisable to use stabilisers at half of their official rating. For example if a supply
of 50kVA is needed, install a 100kVA
stabiliser. In this situation it will last longer,
it will not overheat, and there is some
reserve capacity if the power demand
increases.
Stabilisers made using copper coils are
very sensitive to power cuts. Low quality
ones often produce voltage surges when
the power cuts, in effect acting in the same
way as ignition coils. Hence, it is important
that surge arresters are installed at the Figure 101: Low cost stabilizer
- which does not have an
input and output side of the stabiliser.
earthing connection.
Note that anyway electronic stabilisers are
lighter and more reliable.
4. UPS
Modern UPS are now all of the type ‘double conversion’. They will perform as an
UPS if batteries are installed, and most of them will act alike stabilisers if there are
no batteries installed. Their range is much wider than the range of copper coiled
stabilisers. A typical double conversion UPS is
able to work over a range between -35% to
+30%. This range can increase to -55% to
+30% if the normal load is 50% of the rated
power. The same advice as for normal
stabilisers is applicable, use them at the half of
their rate, and they will have a long life.
Figure 102: Example of a 6kVA double conversion UPS
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6.8. CONCLUSIONS ABOUT QUALITY AND USAGE REQUIREMENTS
Meeting the usage requirements of an electrical installation is under the responsibility
of the MSF & ICRC teams. The MSF & ICRC teams also have the responsibility to
choose the correct equipment. However, this choice is often limited by the availability
of suppliers and manufacturers. Whilst local purchase is preferred for many good
reasons, it is often a challenge to find the required quality.
Here are some tips to find the correct supplies:
•
Look for the representatives and official suppliers of international brands.
•
Look for national distributors and ask them who are their main clients and local
suppliers.
•
Look for consumers having similar needs and requirements and ask them
where they found the right products, and the right services.
•
When national distributors cannot meet your specific requirements (e.g. B curve
breakers, etc.) the delivery time can be very long.
•
Always make orders using the original reference code from the brand.
•
If there is any doubt on the quality or authenticity of a supply, always prefer
international purchase.
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7. RECOMMENDATION ABOUT SETUP DESIGN
The setup design includes either the organisation, or structure of an electrical
distribution system and practical details of execution. It concerns the position and
hierarchy of the components, and it speaks about rates, sizes, distances, and their
correct placement in various types of area.
These recommendations concern the user’s installation, from a single final board to all
terminals in all areas. The user’s installation is the one that the ‘client’ will see and use
every day. Behind the user’s installation, we also have a main distribution system
installed between the source and the final board. This can range from a single cable
between the meter of the electrical company and a single board, to an expensive and
extended network of cables supplying numerous boards from various power sources
on a large setup. Recommendations about the design of the main distribution system
are presented in the first section of this chapter.
7.1. GENERAL ORGANISATION OF A DISTRIBUTION GRID
As described in Chapter 4 the first step of the ‘electrical project’, is to establish the
position of the distribution board(s), and, if several are to be installed, a position
diagram with their related areas of distribution. The structure and position of the main
distribution system must be established according to the position of these areas. But
the sizing and position of the distribution areas first needs to be established.
7.1.1. SIZE OF A DISTRIBUTION AREA
The position of distribution boards and size of the distribution area is established
following several criteria. The first ones are the ‘rules of the 15 meters’.
Distances.
14.1. The distance between every location inside an electrified setup, and
the related grounding stake must be less than 15 meters.
Reasons:
The level of voltage surges between device frames and the environment in case of
lighting must be limited. This helps ensure the equipotentiality of all frames connected
to the main earthing junction and all surrounding objects or persons in contact with the
ground. The potential of the protective earthing must be close to the potential of the
area and occupants, even in case of lightning.
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14.2. The maximum length of a final circuit is ideally 15 meters.
Reasons:
1. Reduce distances from terminals to their breaker panel.
2. Make smaller panels.
3. Simplify the wiring of the installation.
4. Reduce the lengths and costs of final cables.
5. Reduce number of cables, size and cost of ducting.
7. Ensure that the surge arresters are giving protection to all terminals.
In practice, the circuits are longer than the direct distance from the board to the
terminals. In order to limit the length of final circuits to 15 meters, the distribution area
should be inside a circle of radius 10 meters from the distribution board. The
distribution board must be close to both the main earthing junction and to the arrival
point of the mains (which is rarely at the centre of a distribution area). In ordinary
residences or offices, according to the size and arrangement of rooms and floors, an
average distribution area is between 100 and 200 m². According to their use, larger
spaces should preferably have more than one distribution board. According to the
needs, some individual rooms should have their own board, for example workshops,
laboratories, or technical areas. Final circuits that need to be longer than 15 meters
should preferably only be used for class II or unreachable class I or 0I equipment, for
example to supply remote outdoor lightings, or submerged pumps. For houses and
offices, as a rough indication, the total installed power of an average distribution area,
should not exceed 10 – 15 kVA.
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7.1.2. RATES OF THE MAIN DISTRIBUTION LINES.
14.3. To ensure the instantaneous reactivity of the main protections in
case of a short-circuit, the maximum rate of the circuit breakers of main
distribution lines is 1/3 of the rate of the generator breaker. B curve
breakers are mandatory.
Reasons:
1. In case of a short circuit, alternators are not able to deliver more than 2x their max
current.
2. In case of a short-circuit the most sensitive breakers (B Curve) react between 3.5
and 5x their rated value. To ensure an immediate tripping we must consider that we
need a short-circuit current of 5x the rate. The breaker of the generator is correctly
rated in case of overload (full rate) but is naturally oversized in case of short-circuits,
because the short-circuit current never reaches a value of 5x the rate of the generator,
but it can reach the value of 5x the rate of a B curve breaker rated 1/3 of the generator
rate.
14.4. The maximum rate for main distribution lines must be limited to 63A
(minimum cross section cable 16mm²).
Reasons:
1. Stay within the range of domestic breakers (cheaper, and easier to find).
2. 16 mm² cables are still easy to move and install. They are still light and flexible
compared to larger cross sections.
3. Reduce as much as possible the breaker rate due to the limited short-circuit current
produced by a generator. A 63A B curve breaker is suitable for short-circuit currents
produced by generators of 125kVA or above. But this breaker cannot react when
using smaller generators. With smaller generators, the rate of the breakers has to be
reduced in accordance with the short-circuit current, respecting the previous rule.
14.5. Preferably use several main distribution lines, up to 16 main lines
or more on a large setup if required.
Reasons:
1. More main lines mean main breakers of lower rates.
2. More lines will increase the selectivity in case of a breaker tripping.
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3. The total quantity of cable will decrease, because doubling the cross section of a
cable does not double the current that it can carry (due to heat dissipation).
4. More selectivity in case of a damaged cable – smaller areas are affected in case of
a tripping protection or having a cable that has to be fixed or replaced.
14.6. Reduce the number of steps (subpanels) between the main
distribution panel and the final panels. Ideally, no steps would be the
best, i.e. all final panels directly supplied along the main distribution
lines.
Reasons:
To decrease the rating level and quantity of protection devices, and ensure their
reactivity and selectivity. Multiplying steps means that breaker rates have to increase
from downstream to upstream at each step. Hence it is easy to reach rating levels that
are too high, or to have rates too close together between upstream and downstream
protections
14.7. Do not install more than 3 to 5 final boards on a main line –
depending upon the power rates of these panels.
Reasons:
1. More boards on the same line will decrease the selectivity in case of a main breaker
tripping.
2. The rate of the head protection of each board remains correct whilst still respecting
the right conditions to ensure enough selectivity.
14.8.
On panels having more than 20 final circuits, divide the panel
into several parts each having their own head protections.
Reasons:
1. Dividing a board in several parts will allow a decrease in the rate of the head
breaker.
2. This increases the reactivity and the selectivity of the protections, mostly for the
main RCD.
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In practice: Capacity of distribution and installed power
Use of devices
Simultaneity
% installed loads/
distribution capacity
Board
Permanent
Intensive
Average
Light
Rare
Total
High
Average
Low
Never
40%
50%
80%
100%
120%
Range for a max installed power of
Phases
Amps
3
40
11 kVA
14 kVA
22 kVA
28 kVA
33 kVA
3
32
9 kVA
11 kVA
18 kVA
22 kVA
26 kVA
3
25
7 kVA
9 kVA
14 kVA
17 kVA
21 kVA
1
40
4 kVA
5 kVA
7 kVA
9 kVA
11 kVA
1
32
3 kVA
4 kVA
6 kVA
7 kVA
9 kVA
1
25
2 kVA
3 kVA
5 kVA
6 kVA
7 kVA
This table shows the installed power, the type of use and a related range of the
distribution capacity for boards rated between 6 and 28 kVA.
It gives a better idea of the sizing of boards and areas of distribution.
Table 16: Distribution capacity and power of user's devices
The load study
It is the load study that will finally be the best base to give correct sizes of boards and
areas, avoiding the need for too large boards and rates for the general breakers of
boards. Boards and local Installations are easier to install and manage when the
number of circuits is between 10 and 20. If it is sometimes necessary to distribute
more circuits from one board. For example, for some technical areas with a lot of
powerful equipment, or other specific areas where it is necessary to have fewer larger
boards instead of more smaller ones. In these situations, the main protection of the
board can be divided into several protection devices, (main CB and RCD) each
controlling a proportion of the circuits. This will decrease the rates and increase the
selectivity and discrimination of the main protections. The sizing and protection rate of
a single board is a part of the sizing and organisation of the entire installation.
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Distribution capacity of upstream and downstream circuits
The next example shows a hierarchical tree and sizing of an installation and gives an
idea of comparison between the rate of the power supply (100%), the average load
(50%), and the total installed power (160%). It shows that the sum of the power rates
of the distribution boards and circuits is finally 200%, 400% and 1400% of the total
installed power of the user devices to supply.
Figure 103: Circuit rates compared to their actual loads
Important points in this example:
•
In this example the generator is correctly sized to supply a load between 23%
and 57% of the total installed loads and can supply peaks up to 63% of the
loads (max simultaneity). The distribution grid is largely able to supply all loads
at 100% simultaneously.
•
The selectivity (discrimination upstream downstream) of the protections against
short circuit and overloads is ensured.
•
Overloads on the main distribution lines and main protections are highly
unlikely.
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•
Overloads of the generator are avoided in this example, but other situations
could require supply peaks of up to 100%, and hence need a bigger generator.
It is only in situations with relatively few consumers that the simultaneity rate
can be 100%. In larger setup there is no need for a generator able to supply all
consumers at the same time. For usual big installations, it is common that the
power of the generator is between 30% and 50% of the power of the installed
consumers. But the distribution grid must be able to carry much more.
Two other methods are commonly used to size a final distribution system:
Both are intended to give an idea for the sizing of the final distribution, not for the
sizing of the power source. They are considered to be reasonably accurate in the case
of ‘standard western installations’. But the density of power demands, number of user
devices and number of terminals vary significantly between locations, and between
western references and field situations. These methods can provide a good
comparison, but cannot be used without adjustments.
Method using the floor areas of rooms:
The distribution capacity is calculated in W/m², according to the usual rates for
different areas: 20W or 50W/m² is commonly used for corridors or warehouses;
100W/m² for bedrooms and living rooms; 200W/m² for offices; 400W/ m² for kitchens;
etc.
Method with the number of terminals
The distribution capacity is calculated in watt per terminal: 300w/ socket; 200w/ switch.
For both methods some fixed heavy consumers are added (water heater, washing
machine, heaters, air conditioners, etc.).
These two methods are more approximate than a model based on a more analytical
need study and preceding rules and examples. But in the case of ‘average’ or ‘usual’
installations it is sometimes useful to crosscheck the results coming from the analytical
method and compare with the results from these two methods.
In practice: The selectivity and the use of C curve breakers for high starting
currents.
If C curve breakers are used instead of B curve ones, their maximum rate should be
1/6 of the rate of the generator breaker. It is recommended to use C curve breakers
only for devices with high starting currents. However, the selectivity (discrimination)
with an upstream B curve breaker is effective only if its rate is more than twice the rate
of the C curve downstream breaker. In that case a higher rate B curve is sometimes
the solution.
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Discrimination on short-circuit
NO discrimination on short-circuit
Discrimination on short-circuit, but the head CB must be oversized
Discrimination on short-circuit, but thicker cable to load.
Figure 104: Circuit Breakers : choice of tripping curves and discrimination
7.1.3. POSITION OF THE MAIN BOARD
Thick main cables are expansive, and hence the main board must be positioned
strategically. The main cable of a 100 kVA generator (our example) must be able to
carry 3 x 150A. This means that the cable will be at least 4 x 50 mm², better 4 x 70
mm². This cross section must also be increased for distances over 100 m.
Additionally to their high cost, the installation of heavy cables is not an easy job. It is
unavoidable that the main cable sometimes needs to be very big, but its length must
be reduced to a minimum thanks to the structure of the power distribution system from
the source to the terminals. It must be designed so that the main distribution panel is
not too far from the source and in a good position to supply the final distribution panels
with suitably sized main distribution lines.
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7.1.4. ROUTING OF THE MAIN CABLES
The routing of the main cables
between the main board and the
final
distribution
board
is
according to the best positions
that have be found for all final
distribution boards.
It is usual that a large part of the
main lines are installed in
trenches (underground lines) or
alternatively as aerial lines. If
only used for a single cable,
trenches and aerial lines are
more expensive than the cable.
•
The routing must be organised in such a way that will use the minimum length
of trenches or aerial lines.
•
To reduce the cost, several cables can be grouped together in the same trench
or aerial line, even if this adds slightly to the length of the cable.
•
When a new building is constructed, some trenches or ducting are also used for
other services networks (e.g. water distribution, waste water, data network,
outdoor lighting, etc.). If excavation works are made for one services network, it
is useful to consider combining several services in each trench. There is no
problem to have water pipes and electrical conduits in the same trench. The
correct placement of underground services is one of the first jobs to do in
virtually all construction projects. The placement of underground services must
be coordinated the surface water drainage system and the construction of
roads or footpaths.
•
Use the external walls as a support. Placing cables on a wall is much cheaper
than underground.
•
When it is necessary to cross a building, it is important to first try to find an easy
way of passing through the inside of the building (e.g. in a false ceiling or
existing services ducting). This is likely to be cheaper than installing the
electrical cables in trenches passing around the outside of the building.
More details on the placement of boards are giving in section 7.2, and more
explanations about underground technical sleeves and cable placement in section 7.3.
The figures following next page show examples of adequate and inadequate routing of
main cables.
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MANY TRENCHES
HAVE BEEN DUG TO
REDUCE THE CABLE
LENGTH. But the cost
of trenches is higher
than the cost of
cables.
Length of aerial lines
can also be reduced.
TO REDUCE THE COST
SEVERAL CABLES ARE
INSTALLED INTO THE
SAME TRENCH. Where
possible the cables
have been placed on
the walls.
Aerial lines have been
reduced to a
minimum.
Figure 105: Examples of main cable routing
To reduce the number and total length of trenches also reduces the risks of accidental
damage to underground lines.
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7.1.5. THE PROTECTIVE EARTHING NETWORK
The equipotentiality of a site cannot be ensured with only grounding stakes, even if all
conductive parts of the building (steel carpentry, plumbing, steel beams etc.) have
been correctly connected to the main earthing junction, close to the earthing stake. In
countries where thunderstorms occur, ensuring the equipotential of the ground will
greatly reduce the dangers linked to lightning strikes. In new buildings, the
reinforcement bars inside the concrete will be connected to the protective earthing,
and an earthing belt established around the building. This should be installed on all
new buildings constructed by MSF and ICRC. This type of earthing system should
also be added to existing buildings that are more than 10 meters long. Such a belt can
be made with flat braided copper, 35 mm² (which is a very good conductor but is
expensive) or with galvanized steel tapes of 100 mm².
Figure 106: Grounding belt around a large building.
The green triangles are the grounding stakes and the junctions to the reinforcement bars.
An earthing belt around a building must be connected to the reinforcement bars of the
slab every 5 meters. Earthing belts that are close to one another (less than 15 meters)
must be interconnected.
Earthing stakes should be used to reinforce the system at each corner of the building.
In most of the situations, 3m long stakes is the recommended length. Humid soils
always offer a better ground conductivity, but humidity always varies: when designing
an earthing network,
the driest situation will be considered, and sometimes,
depending upon the conductivity of the ground, additional or longer stakes are needed
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to ensure a good grounding of the site. More humid soils can sometimes be found
deeper, but not always. With large buildings of more than 15-20 meters, it is advised
to add stakes every 5 meters, preferably at the point where the belt is connected to
the reinforcement bars.
Board enclosure
Protective earthing of electrical circuits
Same cross section as circuits
Earthing junction bar
Main
earthing of
electrical
circuits
Same cross
section as
internal
wiring of
distribution
board.
Min 10 mm²
SPD Surge
protection
device
‘lightning
arrester’
Main earthing wire of electrical
circuits. (< 3m)
Without SPD: Same cross section
as previous. (Min 10 mm²)
With SPD: min 25 mm² is advised
Main earthing junction
Non
electrical
earthing
(protection
of building
- plumbing,
metal
frames)
6 mm²
Main
earthing
conductor
Min 16 mm²
With SPD:
Min 25 mm²
35 mm² is
advised
Figure 107: Earthing wires and junctions
Earthing stake or
earthing belt
Earthing junctions in buildings
The main earthing junctions for the electrical boards must also be connected to a
stake, in addition to the belt, if existing. It is frequently installed outdoors on an exterior
wall, and brings together the earthing connection from the board and all other earthing
protections in the area (inside and outside of the building). The max recommended
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distance between board and main earthing junction is 3 meters. The junction and
cross section of the earthing wires is shown into the figure below.
An earthing network of a building has 3 main branches
1. The ‘ground’ earthing (background, underground, site reference)
a. Earthing stake (rod, pole) X profile galvanized steel 3 m deep
b. Earthing belt
c. Building foundations/ bars / steel mesh / Basement
All elements should be 35 mm² copper or 100 mm² galvanised steel.
2. The building earthing
a. Conductive elements, corrugated iron roofs (6 – 16mm²)
b. Metal frames, pipes, bathrooms (6 mm²)
The earthing wire must be continuous (no breaks) up to the main earthing junction.
Lights
(10 -25
mm²)
(2.5 mm²)
Electrical
Local
(6mm²)
distribution
electrical
board
earthing
(2.5 mm²)
Main
Socket,
Metal bath/
(6mm²)
electrical
metal
frame
bath
drain
earthing wire
Main Earthing Junction
Test terminal/
disconnector
(16-35
mm²)
Junction to
concrete bars
(35 mm²)
(6 mm²)
Non
electrical
earthing
Junctions
to pipes
(water,
gas, fuel)
Earthing stake/
belt
Figure 108: Earthing junction in buildings
3. The electrical earthing
a. Protective earthing of electrical terminals/ devices/ distribution cables/
bathrooms.
b. All electrical protective earthing wires are connected to the earthing
junction bar inside the breaker board.
c. The frames within a bathroom (e.g. bath tub, pipes, drains, etc.) can be
connected in one of three ways:
• 6 mm² wire to a local socket/ junction box (reconnect to
electrical network earthing).
• 6 mm² wire to the earthing junction bar in the breaker box.
• 6 mm² wire to the main earthing junction.
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Main earthing junction:
Branches ‘2’ and ‘3’ are connected to the main earthing junction:
-
The building earthing wires join the main earthing junction (6-16mm²).
The main electrical earthing wire joins the main earthing junction (1025mm²).
The bathroom protective wire may join the main earthing junction (6 mm²).
The main earthing junction is connected to Branch 1.
-
The main building earthing wire (16-35mm²) joins the main earthing junction
to the ground earthing network (stake, belt).
Test terminal/ disconnector:
This is optional and commonly installed for testing or measurement purposes.
Grounding stake
Main earth
conductor
Inspection port
Clamp: (Cable shoe,
bolt or pierced
galvanised bolt, lead
washer, flat washer,
nut)
10 cm
Corrosion
Protection
X shape
galvanized
steel
2m – 3m
deep
Figure 109: placement of an grounding stake
•
The least expensive and most durable results are obtained with galvanised
steel.
• The total external surface area can be improved by using a ‘X’ profile stake.
• Humid sites work better.
• The dispersion conductivity can be improved by adding a conductive compound
for 30cm around the stake (e.g. charcoal powder works well and is not
expensive).
Do not use salt or any other corrosive material to improve the conductivity.
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7.2. DISTRIBUTION BOARDS
7.2.1. PLACEMENT OF DISTRIBUTION BOARDS
Rules of placement for electrical boards
•
The final boards are positioned strategically inside their area of distribution.
• The area of distribution is within a radius of 10 m maximum from the board
supplying that area.
• Apart from some exceptional excursions out of the area (long outdoor circuits,) the
area of distribution can be smaller, not bigger.
• The main earthing junction (stake, underground belt) is preferably at a max
distance of 3 meters from the board (length of main earthing wire)
• In new buildings, it is the architect that must design a dedicated embedded place
and associated technical ducting for the placement of the distribution board.
• According to the situation the boards must be in a dedicated room, or accessible
for the users.
• When boards are installed in a closed room, the access to the (key) room must be
possible 24/24, for technical staff on duty.
•
All accesses and passages to the boards are kept free.
•
In particular, boards cannot be hidden by shelves or other pieces of furniture.
• Boards must not create an obstacle for any movement in corridors or other
passages, doors or stairs.
•
A minimum distance of 1 meter must be kept between a board and a window.
•
Boards cannot be placed in front of doors or windows.
• Boards must be installed in dry places. When boards are installed outdoors, they
must be IP66, the floor must be a dry slab or any other dry floor above the outdoor
ground surface. They must be protected from the rain with appropriate roof and walls
at least 2 meters around. If required the area around the shelter must be drained. The
access to an electrical shelter must remain clear.
• The top third of an electrical board should ideally be placed at a height of between
150 and 200 cm.
Large boards (height bigger than 1.5m) must be placed on the floor
• Must preferably be placed on a stand, (masonry, or steel feet) to ensure that the
bottom of the board is at a height of 20 cm above the floor.
•
They must be fastened to a wall.
• All provisions must be made so that no water could enter even when the floor is
covered in water.
•
No equipment can be installed in a board below a height of 40 cm above the floor.
• A battery powered autonomous emergency lighting must be installed in order to
provide lighting of the board and surrounding area in case of a power cut.
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7.2.2. DESIGN OF DISTRIBUTION BOARDS
The sizing and structure of distribution board has been presented in the preceding
chapter. But not only the electrical aspects of sizing are important, the general layout
of distribution boards must also follow some rules.
A distribution box must be clear.
 In a single glance anyone should be able to understand the general structure of
a distribution board. It must be easy to identify where are the entry, the general
protections and the outgoing circuits.
All circuits should be identified or numbered. Printed copies of the position and
electrical diagrams should be included inside the board, or in a sealed file close to the
board. These diagrams must of course be up to date.
MAINS
GENERAL
BREAKER
GENERAL
RESIDUAL
CURRENT
PROTECTION
DEVICE
LIGHTNING
AND SURGE
PROTECTION
AS FAR AS POSSIBLE, THE
GENERAL PROTECTION WILL
BE PLACED TOP LEFT.
THE WIRES ARE ENTERING
TO THE TOP OF THE DEVICES
AND COMING OUT FROM THE
BOTTOM OF THE DEVICES.
GENERAL PROTECTION
FINAL CIRCUIT
BREAKERS
Earthing junction
PROTECTION
OF THE FINAL
CIRCUITS
RESIDUAL
CURRENT
DEVICE 30mA
circuit
W/ 30mA
Protection
TO MAIN
EARTHING
JUNCTION
To the final circuits
Figure 110: General layout of a distribution board
A distribution box must be organised.
 It is usual to work from the left to the right and from the top to the bottom.
 Many board devices can work in the same way if they have their entries at the
bottom or at the top. However, the preferred rule of ‘from left to right, and from top
to bottom’. Should be applied to single board devices. The power should enter the
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device by the top, and exit by the bottom. The distribution of the power to a bank
of circuit breakers is also preferably made from the left to the right.
 It is not uncommon for incoming mains to enter a board at the bottom, and for
outgoing circuits to exit from the top of the board. This is not necessarily a
problem, and it is still possible to follow the prefer option of organising boards left
to right and top to bottom. It simply necessary to have enough space for the
incoming mains cable to cross the board in order to be connected at the top-left
section. Similarly for the outgoing circuits to cross to the lower right section.
 In some situations, it may still be easier to organise a board from bottom to top (or
in another manner). It is not the preferred way to do, but it can still be appropriate
according to the situation. The most important thing is that the board is clear,
‘square’, easy to understand, has remaining empty spaces, and is consistent with
the organisation of other boards within the specific installation.
A special attention to the sizing of the distribution wires is required.
It is unfortunately not rare that the wires coming from the main protection to
the final circuit breakers are not of the correct cross
section.
 The cross section of the wires
distributing the power to all final
circuits must be according to the rate
of the head breaker.
Figure 111: Wrong cross section
inside of a breaker board
DANGER!
2.5 mm² distribution
to the breakers
does not fit!
10 mm² 40A
feeder

With large boards having several
dozen outgoing circuits, it is better to
divide the board into several main parts,
ensuring that each part can be protected
by 32A protection. This will increase the
selectivity (discrimination) and decrease
the rate of head breakers and of
distribution wires inside of the board.
Figure 112:
Dividing the main protection of boards
In this example of a board, each rank
has its own general protection.
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 Using a maximum (if possible) rate of 32A for the head protection of boards, 6mm²
wires can be used to distribute the power to the final breakers. Wires of 6mm² are
still manageable, and not too difficult to manipulate. With higher breaker rates,
10mm² are required which are not so easy to manipulate.
 The best method for supplying a rank of breakers is to use connecting bars
(commonly called ‘connecting combs’ or ‘bus bars’) instead of wire bridges. They
are easier to install and take up less space inside the board.
Without Busbar
With Busbar
Various types of bus bars are available: single phase 1 pole, 2 poles, three phases 3
poles or 4 poles, and for all rates of currents.
Figure 113: Using bus bars to feed breakers
 It is recommended that 1/3 of a breaker board is left as free space. This will avoid
overheating, will allow addition of circuits, and will make everything much more
clear.
 For all boards, but more specifically large ones, it is important to define the space
where the wires will be installed, between the entrance to the board and the
connection to the board devices. They can pass behind the DIN rails or a special
section can be reserved at the sides of the board. It is better to tie all wires
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together in bundles, as they will take less space and help keep the board clear
and simple. Bundles of wires can also be routed between banks of board devices.
 It is important that all wires entering a board are long enough to allow correct
routing and easy connection to the board devices. When making the wiring of an
installation, let always an excessive length of wires at the level of the terminals,
junction boxes and boards. It is recommended that this excessive length is
equivalent to the height plus the width of the enclosure, plus 10 cm. The length will
then be adapted to the place of actual junction that will be made, but still having
an orthogonal routing and enough excessive length to allow some further
adaptation of the wiring.
Sometimes existing boards can be very
unsafe, and very complicated
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7.3. PLACEMENT OF CONDUITS AND JUNCTION BOXES
7.3.1. UNDERGROUND CABLES
protection cover
Warning tape
Backfill
Protection
mesh
Cable
inside of a
conduit

Underground cables
must be armoured, or must
be inserted into a flexible
tube, or a PVC pipe. PVC
pipes allow the placement of
several cables inside of the
same pipe, and facilitate the
addition or replacement of
cables.
Yellow sand

It is common on
construction
sites
that
service trenches are dug
Trench
40cm
around and through a site
Figure 114:
and installed with several
Arrangement of a trench for underground cable
PVC pipes of diameter 100120mm (provisional sleeves.) In this case, cables can be installed in these service
pipes later.
 If several cables (armoured or inside flexible conduits) are placed in the same
trench, the horizontal distance between cables should be 3-5cm.
 Do not over-tension buried cables. It is better that some slack remains in the cable
in order to resist possible small-scale land movements.
 The correct depth of a trench is 80cm and the correct depth for a cable is 60cm.
 The protection cover is often omitted. It is only mandatory when crossing roads or
pathways.
 According to the soil characteristics, during excavation of the trench shoring or
angled-back excavation may be needed to ensure stability.
 As for all below ground work, excavation of service trenches should be done
carefully bearing in mind what might be buried in the site.
 Yellow sand should be put under and above the cable. The colour is different from
the surrounding ground so if someone is digging in the vicinity it is easier to see the
presence of a cable. Many types of soil contain stones, and a surrounding of sand
prevents stony soil from damaging the cable or conduits. In addition, plant roots and
even rodents do not like to pass through sand.
 The protection mesh is not always used, but it does provide a good protection
against spades and other excavation tools.
 The backfill is generally the earth excavated from the trench.
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 The warning tape is placed at a depth of 15-20 cm below the surface of the ground.
Special tape is sometimes available, but otherwise a red/ white or a yellow/ black
stripped tape can be used.
Figure 115: Warning tape over underground cables
 Whatever what kind of sleeves are dug inside of a trench, some rules must also be
applied when routing these:
Max 25 m.
Manhole
Every 25 m. on
straight ways
Manhole
At every curve
Figure 116: Manholes along a trench
All kind of underground sleeves must also follow
other rules.
 Whatever it is water, gas, data or electricity, no
curve, nor T junction nor any kind of direction
change are allowed for underground sleeves.
Manhole
 At the site of each curve or junction, a manhole
must be placed.
 On straight ways, a manhole must be placed at
least every 25 meters.
 All sections between manholes are straight.
 Manholes are made with special PVC boxes, or in place, with
bricks or concrete. They are protected against the rain. They can
include junction boxes (IP 68 + Magic gel)
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Exiting of buried cables
When coming out of the ground, the electrical cables must
be properly mechanically protected. If cables are coming
vertically out of the ground, it must be beside a wall or a fixed
structure. All vertical cable against a wall must be protected
against shocks, specifically when installed outdoors. In such
situations, cables must be protected by a thick steel pipe up
to a height of 150cm. The top of the pipe should be fitted with
an elbow to prevent rain water from entering.
Figure 117:
Pipe arrangement to exit out of the ground
7.3.2. CABLES AND CONDUITS INSIDE A BUILDING
There are many ways to install cables and conduits inside buildings.
Apparent cables
General:
•
•
•
•
•
All vertical apparent cables should be installed parallel to surrounding walls.
They can be installed in the corner between walls.
All horizontal apparent cables should be installed parallel to the ceiling, at a
distance of 25-35 cm from the ceiling.
Apparent cables must be fixed with appropriate special hose clips.
Cable curves should be fixed at each end with a hose clip
Apparent cables fixed to the ceiling should be perpendicular to the wall from
which it comes.
Apparent cables without a conduit:
•
•
•
•
•
Apparent cables without conduits are less expansive but often do not look very
nice.
They are common in workshops or other technical areas.
In some situations mechanical protection of the cables is required and apparent
cables cannot be installed without conduits.
The distance between hose clips fixing straight cables should not exceed 50
cm.
In case several cables are following the same route, the minimum distance
between cables should be at least equivalent to the half of the cable diameter.
The distance between adjacent cables should be constant.
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Apparent cables in a circular conduit:
•
•
•
•
The distance between hose clips fixing straight smooth PVC tubes should not
exceed 60cm.
Only straight parts of the circuit should be in circular conduits.
If multi-conductor cable is used, bends can be made without using a conduit
between lengths of straight circular conduit.
If single conductor wires are used, bends must be formed with sections of
flexible conduit.
The preceding kinds of apparent installations are more adapted to warehouses or
workshops.
Apparent cables in square plastic trunking:
•
They have a better appearance than circular conduits and can be used in
houses or offices. They are more hygienic than other kind of apparent ducts
and can be used in medical facilities. They are often used inside of operation
theatres and laboratories.
•
They must be installed very carefully. All
junctions between sections of trunking must be
very precisely sized and placed, if not the
appearance can be rather ugly, and openings
can be a source of problems or dirt.
•
They can be used around doors, directly under
the ceiling, or along walls where they meet the
floor.
•
If several circuits made with single conductor
wires are to be installed in one cable trunking,
this trunking must have separation system to
segregate circuits from each other.
Figure 118:
Use of square plastic trunking
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•
Junctions can be made inside plastic trunking, in which case the need for
junction boxes is reduced.
•
Some brands have terminals that can be incorporated into the cable trunking.
Figure 119: terminals incorporated into square plastic trunking
•
Good quality plastic cable trunking can be expensive.
Fastening conduits to walls or other supports
A common problem with apparent cable or conduit installation is that they must be
fastened to the walls, and sometimes walls are so weak that the fastening system is
not strong enough.
Cable or tube clips with nails are only
effective in wood, and they are rarely
strong enough in plain walls.
Figure 120:
Various types of tube clips
Screws can be effective in plain walls
as long as the wall construction is
strong enough for a good fixing. Many
different types of tube clips are
available on the market, but the use of
plastic ties in screwed bases is the
best option.
Horizontal and vertical routing of conduits on the walls do not have the same
constraints. Horizontal channels will collapse easier than vertical ones. If only one
screw is weak, the two screw on either side will carry more weight, will perhaps also
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fail. This is the reason why after a time a horizontal conduit often bends in between
the remaining fixing points.
Another point is that horizontal channels accumulates dusts and grease. They cannot
be used into medical facilities requiring a high level of hygiene and sterilization.
Vertical channels have less problems. They do not collapse as easily or deform, and
they will not accumulate so much dirt.
Square plastic trunking have some advantages in terms of fixation. The location of
fixing screws is flexible, so it can be adjusted to take advantage of strong fixing points
on the wall. If the use of fixing screws is not possible, an adhesive could be used
instead. Additionally, sealing the space between the wall (or ceiling) and the trunking
with a putty will help reduce the build-up of dirt. However, in medical facilities the best
will be to have an embedded installation.
Cables on cable trays:
Cable trays provide a simple way of
supporting cables, and are frequently
used in technical areas or workshops.
If proprietary cable trays are not easily
available, they can be made locally
with thick steel wires, or even
reinforcement bars (if particularly
heavy cables are needed).
Figure 121: Cable tray
Hidden cables
Cables embedded into plain walls
Embedded cables must be installed inside plastic conduits. Preferably flexible
conduits should be used, but the use of rigid conduits is also possible. It is preferable
that only single conductor wires are installed in embedded conduits. Conduits should
be a minimum of 20mm in diameter. There is no need to make deep grooves, as the
depth of the groove should be 1 cm deeper than the diameter of the conduit. Conduits
can be fixed in place inside the groove by nails or quick-setting plaster. The
embedded conduit is covered thereafter with a 1cm layer of plaster.
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Embedded conduits should only run vertically or horizontally. By priority, there are
certain locations within a room that should be reserved for the installation of
embedded cables, as shown in the following figure:
Figure 122: Spaces reserved for embedded conduits inside of a room
Junction boxes should (by preference) be imbedded, but the cover must remain
visible. Passing embedded conduits and cables through walls is permitted. However,
in this situation additional consideration should be given to the strength and
arrangement of the conduit and cable.
Cables embedded inside hollow partition walls:
Multi-conductor cables, as well as single conductor inside conduits, can be installed in
hollow walls. There are no rules or conventions on the routing of cables inside of
hollow walls. If rodents are likely to be present, it might be useful to install even multiconductor cables in larger flexible conduits.
Cables in a false ceiling:
Installing cables within a false ceiling is often a good solution, as it avoids the
installation of cables horizontally in or on the walls. Inside of false ceilings, there is no
convention on the routing of cables. However, where appropriate it is better to group
cables together. To provide protection against rodents, all cables inside of false
ceilings must be installed in flexible plastic conduits. Junction boxes are allowed inside
of false ceilings, and it is recommended that they are IP 66, with cable glands. This to
helps ensure that they will remain closed, and are protected against insects and dust.
Cables under the floor:
In case there is a hollow floor or a basement, cables can be installed under the floor.
The same principles as for installations in false ceilings should be applied.
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7.4. PLACEMENT OF TERMINALS
Previous chapters have looked at the technical aspects of terminals. However, there
are also some rules about the location of terminals.
Floor sockets:
•
Minimum distance from corners: 50 cm
•
Minimum distance from a door frame: 20 cm
•
Height over the floor: between 20 and 30 cm. All sockets must be placed at the
same height!
•
Avoid the installation of sockets under windows.
•
Think about the use: double sockets are sometimes needed.
•
Distance between adjacent sockets: 150 cm.
Bench sockets, over-table sockets, workshops.
•
The recommended height is max 120 cm, but it should be according to the use.
•
The usual height above a bench or work table is between 15 and 30 cm.
Switches:
•
All switches must be at the same height. Between 90cm and 120 cm is the
standard height. Refer to the common use in the country.
•
Switches are often beside doors. But for special situations (outdoor light,
bathroom, etc.) the switch may be in another location.
•
The switch must be on the handle side of the door.
•
Minimum distance from the door frame: 20 cm.
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7.5. SIZES AND AREAS OF DISTRIBUTION OF FINAL CIRCUITS
The size of the different final circuits is defined by the number of points supplied (such
as sockets). The maximum number of points per circuit should be between 5 and 8
points. The choice of the area of distribution for a single circuit is also important: some
areas have particular requirements.
7.5.1. SIZE OF CIRCUITS
Good sense must help in making the appropriate choice for the size of a circuit.
Between 5 and 8 points supplied is an indicative maximum, and the actual number of
points (such as sockets) supplied must be according to the specific needs.
An office with a lot of equipment (such as printers, monitors and laptops) could be
connected to 8 sockets, plus a number of mobile multiple socket extension cables. But
consideration needs to be given to how frequently these sockets will be used. As a
reminder, the average actual load on final circuits is usually less than 10%, and a long
lasting or continuous load on a single circuit should never be more than 60-70%.
When sockets are constantly in use, they do not have the same status as sockets that
are simply available in case of need. A lot of appliances are constantly plugged in to
sockets, but may only actually be in use for a few minutes or hours per day (such as
photocopiers).
Circuits with sockets that are more intensively used, such as workshops or kitchens,
should be divided into several circuits equipped with less sockets. This will help
decrease the load on the circuit, and increase the continuity of service in the area.
Some specific fixed uses also require their own circuit, for example if they have
frequent high power demands (such as air conditioners, pumps, ovens, washing
machines) or some other critical use (such an alarm system or a critical
communication service).
7.5.2. AREAS OF DISTRIBUTION
The area of distribution of circuits must be defined in a way that minimises the
problems of power unavailability in case of one circuit breaks down. For example, if a
lighting circuit loses power, the situation is much easier to cope with if some lighting in
the area still has power.
Ideally, lighting circuits should be distributed in such a way that any circuit supplying a
particular area should not also supply the surrounding ones.
In some situations, even within the same room, lighting can be served by more than
one circuit. The same is also true for sockets. Special consideration should also be
given to supplying critical equipment (such as cold-chain and medical equipment).
Have more than one circuit supplying the area will help provide back-up resources in
the event of a circuit failure.
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7.5.3. NUMBER OF POINTS IN GENERAL CIRCUITS
Sockets circuits. (16A standard circuits, UK 13A, US 15A)
One socket = one point.
Double sockets are also considered as only one point.
Even if officially allowed in some countries, ring circuits are forbidden. Only radial
circuits are allowed.
Lighting circuits. (For standard 10A circuits)
One switch = one point.
Add one point for each tranche of 300 VA fixed lighting. This means that the maximum
power in a general 10A lighting circuit is: 1 switch + 7 x 300VA = 2100VA.
7.5.4. SPECIAL CIRCUITS
VII. Circuits for powerful fixed devices
These circuits only supply one device. One fixed device = one circuit.
These circuits supply fixed (powerful) devices such as ovens, washing machines,
air conditioners, heaters, water pumps, big photocopiers, carpentry machinery,
large computer servers, etc. These circuits must be specifically sized for their
intended use, with a minimum of 16A and 2.5mm² wires. It is however allowed
to supply two identical devices with a consumption rate lower than 1000VA from
the same the same circuit (e.g. two identical low power air conditioners, or
heaters).
VIII. Circuits for critical devices
These circuits also only supply one device. One critical device = one circuit.
A critical device can be many different types of equipment such as an alarm system,
security or emergency lighting, data storage, critical medical equipment, or critical
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laboratory equipment. It is important to consider the criticality of a device in relation to
other devices plugged into the same circuit. For example it would not be appropriate
that a critical medical device was supplied from a circuit that could be tripped by a
faulty hot water kettle. In the case of critical devices, it is not the power or the constant
use that is the main criteria for the sizing of the circuit, it is continuity. It will not be
always necessary to have a 16A circuit. But note that too thin wires are not
mechanically strong enough and manageable in a fixed installation, and hence even
for power rates lower than 10A the minimal cross section of wires into fixed
installations is 1.5mm².
IX. Bathrooms and other wet areas
Wet areas and particularly bathrooms must meet very specific requirements.
A wet area is an area where water is used in a way that the floor could become wet.
The two main wet areas are the laundry and the bathroom. A wet area is not an area
that can be underwater (like swimming pools) and other requirements are linked to
underwater electrical installations. Bathrooms are particularly critical because when
having a shower or a bath people are wet and are not wearing shoes (which can offer
protection against electrical contacts).
a. For all wet areas:
All terminals must be at least IP44.
All switches must be bipolar switches.
All circuits (including the lighting) must be protected by an AC type residual current
device with a minimal sensitivity of 30mA. It is sometimes required to have a RCD with
a sensitivity of 10mA. This is not technically needed (the threshold of current
hazardousness has been fixed to 30mA) – but is an additional precaution. In case a
10mA RCD is installed, do not put too many devices on the same RCD – an addition
of small insignificant losses could trip the RCD. Most of the losses are anyway
collected by the protective earthing connected to all frames that are therefore much
less dangerous for people in case of a loss. But it remains that any faulty device must
trip a protection before causing a risk of electrocution.
All provisions made for wet areas also concerns equipment using water, even if
installed in a ‘dry area’. Such as the case of washing machines and water heaters,
that must be also protected by a RCD with a sensitivity of 30 (10) mA.
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b. For bathrooms:
In addition to the provisions made for all wet areas, a bathroom is divided into specific
zones based on distances from the tub or the shower, and specific requirements have
been defined for each of these zones.
The ‘Zone 0’ is the inside of the bath or shower.
The ‘Zone 1’ is the zone immediately above the bath tub or shower up to a height of
2.25m
The ‘Zone 2’ is the extension of Zone 1 by 60 cm each side, and 75 cm above (up to a
height of 3.00 meters.) Even if it is not defined as such in all official regulations, all the
area 60cm above and around the sink is considered zone 2.
Figure 123:
Zone division and safety levels into a bathroom
The ‘Zone 3’ is the remaining areas of the bathroom, up to a height of 2.25 m, 3.00 m
if above Zone 1. The rest of the bathroom does not technically have a zone, however
it is preferable to consider that the entire bathroom is at least in Zone 3. (30mA RCD is
mandatory)
It is highly recommended that electrical terminals or devices in
bathrooms are only allowed in Zone 3 or non-zoned areas.
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This concerns sockets as well as switches and lighting fixtures. Even lighting fixtures
are only allowed in Zone 3.
The general switch(es) for the lighting must be bipolar and must be placed outside of
the bathroom. All additional lighting or service sockets inside of the bathroom (e.g. a
‘razor socket’ or lighting above the sink) must be as well controlled by the general
external lighting switch of the bathroom.
If there is a service socket around the sink, and the distance is less than 40cm from
Zone 2 it must be insulated from the mains with a max 100W insulation transformer.
This socket is only for class II equipment and must be free of an earthing junction.
Other service sockets able to supply more powerful appliances (hair dryers, etc.) must
be placed at a distance of more than 40 cm from Zone 2. Some official regulations
require that such a socket is equipped with a 5mA RCD. (e.g. US regulations).
If the ceiling of the bathroom is lower than 2.25 meters, only class II or class III lighting
is allowed. For class III lighting devices supplied by an external SLV transformer, the
transformer must be class II and situated in Zone 3 or outside of the bathroom.
In case of a false ceiling, if it cannot be opened, it is considered out of the volume of
the bathroom even if it is lower than 2.25 or 3 meters.
The case of water heaters and washing machines inside of bathrooms.
Some would prefer to not allow such devices to be installed in bathrooms. Particular
attention to the junction of such devices to the protective earthing is mandatory, and it
must be remembered that 30mA RCD are required in every case. Modern washing
machines and heaters are covered with an insulating material, which significantly
increases the safety. If any sign of corrosion of the bodies of water heaters is
observed they should be discarded. If a few corrosion appears on washing machines
or fridges, it should be removed and painted, but if they are more corroded or if losses
are observed during an electrical measurement of their insulation, it must be decided
to better discard than repair and maintain such degraded devices.
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X. Outdoor Circuits
All equipment installed outdoors must meet the same requirements as for every wet
area, but additional requirements must also be respected.
All equipment, including junction boxes, and all terminals must be at least IP 65. Cable
glands and all entries of equipment must be made with a particular attention to their
function as dedicated protection against ingresses and the mechanical reinforcement
of cable entries. A cable gland must enable the cable to resist a tension of at least 10
Newton. Special attention should be paid to the cover of junction boxes. More
generally attention also has to be paid to all mechanical fittings of outdoor electrical
devices (even in dry climates) to avoid damage by sand and dust. All outdoor circuits,
including outdoor lighting, must be protected by a 30mA sensitivity AC type RCD. All
outdoor circuits, even sockets, must be switched by double pole switches, and the
switch should preferably be installed indoor. The rate of the overload and short-circuit
protection of switched sockets must be accorded to the rating of the switch, which
most of the time is 10A. If 16A outdoor socket circuits are required, it must be verified
that the switch is also rated at 16A.
Because of the sensitivity of the required RCD, do not put too much outdoor lighting
on the same circuit. In case a lot of lighting points are required, it is preferable to have
several separated circuits, ensuring that even in case of a tripping of a RCD, you can
still give enough light to the areas where it is needed.
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XI. Emergency, Fast Deployment and Provisional Installations
All provisional installations must meet the same requirements as outdoor installations.
They are intended to be installed outdoor as well as indoor but all equipment must be
at least IP66. The type of equipment that should be used is very similar to those used
for outdoor worksites, or outdoor music festivals. All cables must be flexible cables
coated with rubber or similar flexible, watertight and mechanically resistant material.
The installation must be ‘plug and play’ – During an emergency it is not relevant to
spend time with building and wiring breaker boards on site. All breaker boards and all
cables are purchased complete and equipped with plugs and sockets.
Figure 124:
Boards dedicated to fast deployment and provisional installations
Not only the boards and cables are specific, outdoor lighting terminals with pedestal or
hanging systems are a part of all provisional installations, and are installed outdoors
as well as indoors.
As long as the power requirement is relatively low, and the area of installation is not
too extended, small provisional installations are still easy to install. When installations
need to provide more power, or to cover extended areas, the same method as for
fixed installations must be applied.
A site plan is needed, with the required terminals and
associated power needs, the position of the main and local
distribution boards, as well as the position of the
distribution cables. As soon as there are more than a few
boards and cables, it is necessary to identify them. Boards
must have a number, and cables must have a ‘flag’ at each
end, with the number of the source board, and the number
of the circuit. It can rapidly become very difficult to manage
and operate a provisional installation if cables have not
been adequately identified.
Figure 125:
32A extension on a reel.
Distances are also important in provisional installations. In
particular for the final circuits, avoid using chains of
extensions to cover long distances, as well as chains of
multiple outlet extensions. There should not be too many
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junctions on one circuit, and a complex system of multiple extensions can make it
difficult to identify where a circuit has been disconnected. In practice, it is advisable to
have a final distribution boards every 20 meters. Final boards should be small boards
with a few circuits (about 4 is generally enough) and embedded socket outputs. Their
protection rate is generally about 1 x 32A, and they are preferably linkable - they have
a main input and output allowing several boards to be supplied from the same line.
They can be supplied from three phase 32A boards or from three phases 32A to 3 x
single phase 32A splitters. Also from larger 50A or 63A breaker boards able to supply
several lines in 3 x 32A. The rates and number of boards must naturally depend upon
Typical structure of a provisional
electrical distribution grid
FINAL
DISTRIB
FINAL
DISTRIB
FINAL
DISTRIB
Main
Distribution
FINAL
DISTRIB
FINAL
DISTRIB
FINAL
DISTRIB
FINAL
DISTRIB
FINAL
DISTRIB
FINAL
DISTRIB
Main
Distribution
the size and power requirements of the provisional setup.
It must be pointed that even installed indoors, the constraints on provisional
installations are heavier than the constraints on fixed installations. Indoor provisional
installations should be replaced by fixed installations as soon as possible.
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In some situations where MSF and ICRC operate, provisional installations may be
required to operate for extended periods of time. For example, large installations on
refugee camps for instance may never be replaced by fixed installations. In this
situation, all cables should be replaced every 2 years, and regular controls must be
made for all boards, plugs, and lighting.
Figure 127: Boards and lightings used in provisional installations
Because of these specific requirements and particularly the extended use of rubber
flexible cable, plugs, sockets, and boards designed for outdoor use, the price of a
provisional electrical installation is between 2 and 3 times the price of an equivalent
fixed installation. The principle advantage of provisional systems is the rapidity with
which they can be installed.
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XII. Storage of flammable materials
This is the case of fuel storages, but also of other chemicals like oils,
paints solvents, and some chlorine based products.
Such storage spaces must of course meet other specific requirements, like
ventilation, segregation, minimal distance from heat sources, limited
volumes, humidity control (e.g. chlorine).
Electrical installations in such areas should normally require ‘ATEX’ equipment. But
this is intended more for poorly ventilated areas with a potential for explosive gases, it
is very expensive, and some other solutions can be recommended.
•
•
•
Protective earthing in flammable materials storage areas:

Particular attention must be paid to the installation of junctions of conductive
frames to the earthing protection.

Frames of conductive shelves (steel shelves) must also be connected to the
protective earthing.

It is highly required that fuel storage tanks made from conductive materials are
properly connected to the earthing protection. Local earthing stakes will
improve the local equi-potentiality of the site.
Lighting in flammable materials storage areas:

If possible, lighting systems should be installed out of the area and light the
area via transparent windows.

No switch is allowed inside of a flammable materials storage area. Switches
must be installed outside of the area.

If lighting fixtures must be installed inside the area, they must meet the
following requirements :

They must be at least IP 66

Fluorescent tubes and any other low or high pressure gasses lamps are
forbidden.

LED lighting is the preferred solution.
Other electrical devices in flammable materials storage areas:

No electrical junction box belonging to local circuits or to any other circuits are
allowed.

No service sockets are allowed. If an electrical supply is needed e.g. to execute
some works, it should be supplied with an extension cord plugged into a remote
socket.

If electrical power tools are required inside the area, it is recommended to use
preferably sealed class III devices. (E.g. battery powered drilling machine, etc.).
If it is required to have permanently an electrical supply inside the storage area
(e.g. small office, reception), a dedicated shelter or separate area must be built
inside the storage area, and have its own ventilation.
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8. TOOLS AND TEMPLATES
Most of these documents are simply excel sheets, listings, and
examples of plans and diagrams, made with excel or visio. These excel
sheets and visio documents are available, adaptable, and can be used
and modified according to the needs. They are only examples, and some
may prefer to make or use other models. In fact each electrical installation
project has produced its own documents, which can potentially be used
as a reference or template.
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8.1. TOOL: GROSS BUDGET CALCULATION
Tool. Excel Sheet "Gross budget electrical works calculation.xls"
The calculation is based on the following data:
1. The surfaces
2. A value giving the type, or level of installation
3. A percentage according to the scope of the works.
4. The local cost of supplies compared with the original price, and local cost of HR can be adjusted
It can be used
For a global project of rehabilitation including several building
For a more detailed gross estimation for a single house.
1
Detailed explanation
All yellow cells can be modified
Surfaces: Consider indoor and associated equipped areas. The gross calculation sheet does not consider specific
needs for large outdoor spaces, but they should be added on one line. (Example 2)
2
Type
3
Scope:
4
Daily costs of national and expat staff can be adjusted also
Level
Example
1 Light
warehouses, buildings with basic electrical installations
2 Medium
Light offices, residences, wards, meeting rooms…
3 Complex
Intensive office, technical rooms, operation theatre, laboratories, server rooms…
1, 2, 3 are giving a good idea about what it can be, but this range from 1 to 3 can be extended:
The value must be chosen as close as possible to a "real gross feeling"
The actual situation could be at a level of 0.2, 0.5, 2.5 or 4 if it is your feeling.
You can cross check your feeling with an additional criteria to attribute a "level": the number of points/10m2
1
0-1 points /10 m²
2
1-2 points 10/m²
3
3-6 points /10m²
100% Is considering a complete replacement of existing, or a new installation
0% Is when no works are needed.
rate local cost % brut import
100%
The cost rate of imported supplies (price + taxes)
compared to their original price can be adjusted
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1a EXAMPLE: GROSS BUDGET ASSESMENT FOR SEVERAL BUILDINGS
DATAS
Supply and RH Gross assessment
%
Surface type
RH
rehab
Site
type 1,
Supplies
m2
0-100
national expat
2, 3
Man days
20 $/J 500 $/J
rate local cost % brut import
Price
$
Total
Budget
100%
Index
Actual Index
$/m²
100%
90 $/m²
$
Offices
600
2
60
$25.200
90,0
72,0
18,0
$10.440
$35.640
59 $/m²
$
59.400
Residence
200
2
30
$4.200
15,0
12,0
3,0
$1.740
$5.940
30 $/m²
$
19.800
Residence
250
2
40
$7.000
25,0
20,0
5,0
$2.900
$9.900
40 $/m²
$
24.750
Residence
250
2
80
$14.000
50,0
40,0
10,0
$5.800
$19.800
79 $/m²
$
24.750
Residence
300
2
25
$5.250
18,8
15,0
3,8
$2.175
$7.425
25 $/m²
$
29.700
Residence
150
2
25
$2.625
9,4
7,5
1,9
$1.088
$3.713
25 $/m²
$
14.850
Clinic
400
2
60
$16.800
60,0
48,0
12,0
$6.960
$23.760
59 $/m²
$
39.600
Labo
50
3
100
$5.250
18,8
15,0
3,8
$2.175
$7.425
149 $/m²
$
7.425
Warehouse
600
1
60
$12.600
45,0
36,0
9,0
$5.220
$17.820
30 $/m²
$
29.700
Workshop
300
3100
m²
2
50
$10.500
37,5
30,0
7,5
$4.350
$14.850
50 $/m²
$
29.700
Rate
52%
$103.425
369,4
295,5
73,9
$42.848
$146.273
47 $/m²
$
279.675
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1b EXAMPLE: GROSS BUDGET ASSESMENT FOR A SINGLE BUILDING
DATAS
Supply and RH Gross assessment
rate local cost % brut import
%
Surface type
RH
rehab
Total
Site
Actual Index
Budget
type 1,
Supplies
m2
0-100
national expat Total RH
$/m²
Man
2, 3
Days
20 $/J 500 $/J
$
$
100%
Index
100% =
$
Corridor
10
0,5
50
$88
0,3
0,3
0,1
$36
$124
12 $/m²
$
248
Terrasse
30
1
50
$525
1,9
1,5
0,4
$218
$743
25 $/m²
$
1.485
Dining room
20
2
60
$840
3,0
2,4
0,6
$348
$1.188
59 $/m²
$
1.980
Kitchen
15
2,5
100
$1.313
4,7
3,8
0,9
$544
$1.856
124 $/m²
$
1.856
Sleeping room
16
2
50
$560
2,0
1,6
0,4
$232
$792
50 $/m²
$
1.584
Sleeping room
20
2
50
$700
2,5
2,0
0,5
$290
$990
50 $/m²
$
1.980
Sleeping room
13
2
50
$455
1,6
1,3
0,3
$189
$644
50 $/m²
$
1.287
Dining room
20
1,5
100
$1.050
3,8
3,0
0,8
$435
$1.485
74 $/m²
$
1.485
Living room
35
2
60
$1.470
5,3
4,2
1,1
$609
$2.079
59 $/m²
$
3.465
Shelter
60
0,5
100
$1.050
3,8
3,0
0,8
$435
$1.485
25 $/m²
$
1.485
239 m² 100 % = 71 $/m²
$8.050
28,8
23,0
5,8
$3.335
$11.385
48 $/m²
$2.100
7,5
6,0
1,5
$870
$2.970
5 $/m²
$10.150
36,3
29,0
7,3
$4.205
$14.355
72%
Total indoor
Outdoor
600
0,1
100
TOTAL
$16.855
$
2.970
$19.825
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8.2. TEMPLATE: GENERAL MAP OF A COMPOUND
A
0
1
B
5
10
15
C
D
20
E
F
G
H
I
J
K
L
M
N
O
P
Q
30 meters
MAIN ENTRANCE
RADIO ROOM
GUARD ROOM
2
TRIAGE
New Building
MOSQUE
3
MORGUE
PHYSIOTHERAPY
TEMPORARY
SHELTER
MASS
CASUALTY
STORAGE
4
PANEL 3a
X-RAY
No line
6² To CMT and RTX
100A
No line
6² To X Ray generator
100A
100A
No line
100A
250A
PANEL 3a
ER
5 G 35² From Gen Room
5 G 25² to Panel 3a
PHYSIOTHERAPY
5
CARE TAKER'S SHELTER
LABORATORY
M H11
PANEL 3
16² To IPD 3
16² To Old ER
100A
6
16² To LAB
OT 1
100A
16² To Latrines 1
16² To IPD 2
100A
SCRUB
Panel M. II
16² To IPD 1
100A
OT 2
100A
16² Latrines 2
100A
16² To ?
100A
2
Panel M. I
ICU
STORE
5
OT
STORE
IPD 1
PREP
CLEAN
250A
PANEL 3
5 G 35² From Gen Room
5 G 25² to Panel 3a
M H4b
M H3
PREP
DIRTY
Latrines 2
ICU
1
RECOVERY
2
2
2
LATRINE
FEMALE
CHANGING
TOILET
MALE
CHANGING
IPD 2
5 G 16²
8
M H9
STERILIZATION
DRESSING
PANEL 4
M H7b
16² To IPD Fem 1
16² To Old Sterilisation
100A
100A
16² To Old Dressing
16² To OT
100A
100A
16² To IPD Fem 2
16² To Storet
100A
9
Latrines 1
7
M H4a
100A
16² To IPD Fem 3
100A
250A
5 G 35² From Gen Room
M H2
M H6
M H7
M H10
M H8
PANEL 4
IPD
FEMALE 1
POSSIBLE
EXTENTION
IPD 3
4
10
Admin
ICU
FIELCO
MALE
CHANGING
M H0
2
FEMALE
CHANGING
M H0
Med.
Office
ADMIN FIN
11
Med.
Office
PANEL 2
2
WATER PUMP
MAIN PANEL ( in generator room)
3
2
1
4
5
6
IPD
FEMALE 2
PANEL 2
4² To Pump
6² To Old Building
100A
6
Log Office
LOG
STORE
4
KITCHEN stock
Meeting room
and canteen
1
LOG
STORE
G1-165
G3- 65
MEETING
ROOM
16² To West
Basement
4 x 95² To panel M.II
5
KITCHEN
100A
250A
5 G 25² From Gen Room
Generators room
KITCHEN
100A
Transl.
office
3
12
100A
16² To ICU
LAUNDRY
GENERATORS
5 G 35²
To Laudry and offices
6
2
6
4 x 95² To panel M.I
5 G 35² To female IPD (DEAD END)
5 x 35² To panel 4
5 G 35² To panel 3
5 G 35² To panel 2
5 G 25² to previous guest house (DEAD END)
5 G 25² to previous guest house (DEAD END)
5 G 35² To Waste zone
FUEL
MSF OCB
G2 -165
27 07 2012
COUNTRY : AFGHANISTAN
PROJECT : KUNDUZ
6
STOCK
PANEL 1
ELECTRICAL DISTRIBUTION
13
Distribution lines
Boards
Groundings
Doc Type : general principle proposal
Author : Harold PRAGER - Tech ref - Brussels
Harold.prager@brussels.msf.org
14
WATSAN
STOCK
CARPENTRY
WORKSHOP
TEMPORARY
STORAGE
TEMPORARY
STORAGE
15
16
WASTE ZONE
TRANSFORMER
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8.3. TEMPLATE: GENERAL MAP OF A BUILDING
E
D
B
C
A
ZC1
XC3
ZB1
ZD1
E9
E10
XE3
E11
E8
E7
E6
E5
XA2
C2
C1
A1
XC2
D8
D9
D10
XD2
D11
D12
B1
B2
B3
B4
A2
B5
XB1
E0
XD1
XE1
XB2
XB4
XA1
A3
XC1
E4
D7
XE2
E2
D6
D5
D4
D3
D2
D1
B11
B10
XB3
B9
B8
B7
B6
E1
XA4
A7
ZD2
E3
XA3
ZB2
C8
A6
A5
A4
C3
XC4
M H4b
M H4a
M H3
C7
C4
MSF OCB
27 07 2012
COUNTRY : AFGHANISTAN
C6
C5
PROJECT : KUNDUZ
ELECTRICAL DISTRIBUTION
Distribution lines
POSSIBLE
EXTENTION
Boards
Groundings
Doc Type : general principle proposal
Author : Harold PRAGER - Tech ref - Brussels
Harold.prager@brussels.msf.org
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8.4. TEMPLATE/ TOOL: ASSESMENT.DOC
Checklist Electrical safety MSF facilities
This safety checklist is a tool that helps to provide safe electrical systems to MSF OCA facilities.
Every facility should be checked once a year. Everything connected to one main electrical
distribution box is regarded as one facility.
This checklist is designed as a form with questions. It guides the one who is executing the checklist
towards the right checks to carry out and it can be used as an historical log for the specific facility.
The checklist therefore should be stored in the appropriate binder from the LogAdmin kit.
Before executing the checklist
MAKE SURE THAT ALL POWER SOURCES ARE “DOWNSTREAM : BEHIND” THE MAIN
SWITCH AND/OR CAN BE SWITCHED OFF WITH THE MAIN SWITCH. IF YOU ARE NOT SURE
IF THERE ARE “HIDDEN” ALTERNATIVE POWER SOURCES, THE FACILITY IS TOO UNSAFE TO
EXECUTE THE CHECKLIST: CONTACT YOUR SUPERVISOR FIRST!
As you will need to cut power before executing the checklist, inform the end-users [= staff
members] of the facility and agree on a time to cut the power.
Only qualified1 personnel can execute the checklist.
Be sure your hands are dry and, when working on a live system, wear nonconductive gloves
and shoes with insulated soles.
Assure that all possible sources of electrical supply and cut-off switches are identified at
the facility you are about to check. Use diagrams/designs if possible or ask people that are
familiar with the system.
1’
Qualified’ is considered someone who has skills and knowledge related to the construction and
operation of the electrical equipment & installations and is able to recognize and avoid the
hazards involved.
On the OOPS KEY you can find several ‘How To’ that will help you to perform the checks mentioned
in this checklist.
1. Header information.
Project name:
Name of facility and location:
Date:
Name of person executing
checklist:
the
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Check 0: Do you have the appropriate tools to execute the checks?
A: Do you have insulated screwdrivers and cutting pliers, voltage tester and multimeter (RMS) and non-conductive gloves?
B: Are you wearing shoes with rubber soles?
Yes
No
Yes
No
C: Do you have appropriate warning material (see below for an example)?
Yes
No
 If any of the answers on A, B or C is “No”, report to your supervisor and await the arrival of
above equipment/ tools before continuing the checklist.
(If not available on site, you can make your own)
Check 1: feedback from end-users/appliances check
√ 1.1 Check with the end-users working in the facility if they experience specific problems? List
their answers below.
 If problems are reported by the end-users that cannot be fixed on the spot, decide with your
supervisor on a planning for improvement. The last part of this checklist [Plan for change] can be
used for a planning.
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√ 1.2 Check if any of the electrical appliances give a shock. Switch on the appliance, hold a voltage
tester to the metal casing –if present- of the machine - if the voltage tester is positive, you have an
appliance that gives a shock. Please record you results below.
Number of appliances tested:
Number of problematic appliances:
 If you encounter any appliance with a problem: please use “How to check earthing” to further
investigate the problem. If the problem cannot be fixed on the spot, decide with your supervisor on
a planning for improvement. The last part of this checklist [Plan for change] can be used for a
planning.
√ 1.3 Check all appliances connected to the electrical system.
A: Do all plugs fit the sockets (that means no adapters1 are used)?
Yes
No
B: Are all cables from appliances undamaged and well insulated?
Yes
No
C: Are all sockets fixed properly to the wall and are not coming out easily?
Yes
No
 If you have answered “No” for any of the above the situations should be improved, please use the
last part of this checklist to make a planning with your supervisor to improve the situation.
Check 2: Main board and distribution boxes.
Please locate the main board and the distribution boxes (if there are any) and answer the following
questions.
√ 2.1 Check if the main switch –on the main board- is accessible (is it known by the users where it
is located and can it be switched off immediately in an emergency)?
No
Yes
A: Is the main switch accessible?
B: Are end-users able to locate the main switch?
Yes
No
C: Do end-users know how to switch off the main switch?
Yes
No
 If the main switch is not accessible, change the layout. If this is not possible on the spot, discuss
with your supervisor, and plan for improvement.
 If the users do not know the location of the main switch, decide with your supervisor on best
approach: improved signing, training, etc.
√ 2.2 Check if there is an up to date overview present in the main box and the distribution boxes
indicating what fuse is used for what? (Switch appliances –if possible- and lights off and on and see
whether the overview is still up to date.) Please record your findings below.
1
Adaptors or adaptor plugs are often poor quality and do not have an earth connection
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Number of distribution boxes:
Number of distribution boxes with up to date
overview:
 If there are no overviews present, please make them. Please plan with your supervisor when
these will be completed.
√ 2.3 A Read the amperage (A) indicated on the fuses /breakers (exclude the ground fault
protection switches), and record below in ascending order, starting with the lowest amperage.
DANGEROUS TASK: MAKE SURE YOU IDENTIFY THERE IS NO POWER ON THE
WIRE YOU ARE ABOUT TO MEASURE. USE A VOLTAGE TESTER TO BE SURE!
√ 2.3 B Determine the wire size for each distribution box (with a wire size comparison board), of
the wire “leaving” the fuse/ is protected by the fuse. Indicate in the table below. If you encounter
different wire sizes leaving one size (A) fuse, indicate the different wire sizes.
Use Annex 1 - fuse/breaker and wire size comparison matrix- to judge whether the fuses/breakers
match the wire sizes. Only when the wires are too thin for the fuse used, it is a problem.
Location of distribution box (please fill):
Amperage
of Wire size(s) of wires leaving the fuses
fuses/breakers
in
ascending order:
Problem?
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Copy
this
table
if
need
ed to
allo
w all
distri
butio
n
boxe
s to
be
docu
ment
ed.
 If
you
No
Yes
have
identified any problems, contact your supervisor and decide on action to take. Please indicate the
plan of action in the planning section of this check list.
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MSF– ICRC Electrical Installations and Equipment in the Field: Rules and Tools. Version 0
√ 2.4 Please locate the ground fault protection breaker (differential switch or earth fault switch
also referred to as RCD, RCCB or GFCI) and perform the following checks:
Please press the “test button” of every ground fault protection breaker
√ A: Check if all the ground fault protection breakers switch off. If not replace the ground fault
protection breaker before continuing with B
√ B: Check if there is no more power in the system: none of the appliances or lights works.
A: Are ground fault protection breakers installed for all circuits2?
Yes
No
 If you answered ”No” for question A, plan for installation using the last part of this check list and
continue with check 2.5. If you have answered “Yes” continue with B and C.
B: Do all ground fault protection breakers switch off when the “test” button is
pressed?
C: Is there no more power on the system after all ground fault protection
breakers are switched off?
Yes
No
Yes
No
IF ANSWER NO FOR C, YOU MIGHT HAVE AN ALTERNATIVE POWER SOURCE
(E.G ANOTHER CONNECTION TO CITY POWER, OR A LINE FROM THE
NEIGHBORS, OR A CHARGER/ INVERTER) THAT IS NOT PROTECTED. IF YOU ARE
NOT SURE THAT THERE IS NO ALTERNATIVE POWER SOURCE, STOP ALL WORK
AND CONTACT YOUR SUPERVISOR, STATING THE ENERGY SYSTEM IS NOT SAFE
ENOUGH TO PERFORM THE CHECKLIST!
 If one of the answers on B or C is “No”, and you have taken the abovementioned warning into
account, please plan for improvements.
√ 2.5 Check if the distribution box/ boxes are properly protected and placed in a safe place. Please
answer the questions below:
Yes
No
A: Are the distribution boxes all in a dry place/under a roof?
B: Are the distribution boxes all in a box/cupboard that can be closed?
Yes
No
C: If the abovementioned is a metal box, is the box connected to an earth wire?
D: Are all distribution boxes at a safe distance (>6m) from flammable or explosive
materials?
Yes
No
Yes
No
2
The only exception allowed is a fixed appliance or wall socket that is grounded with a visible separate earth wire.
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 If you have answered “No” for any of the questions above, the distribution box should be
changed and or moved. Please use the last part of this checklist to make a planning with your
supervisor.
√ 2.6 Check if the cables or wiring between buildings, distribution box and generator(s) are
properly protected and have the correct wire size. Please answer the questions below:
A: Are all cables in-between buildings and generator(s) well protected and
No
Yes
insulated?
B: Do all cables in-between buildings and generator(s) have an appropriate wire
Yes
No
size 3?
 If you have answered “No” for any of the above, the situation should be improved. Please use the
last part of this checklist to make a planning with your supervisor to improve the situation.
Check 3: Earthing of system.
Please have a look at “How to check earthing” if you need more explanation.
3.1 Please perform the checks below for the following locations: workshops, kitchens, bathrooms,
operation theatres, sterilisation rooms and any other wet or humid places. Record your findings in
the table below.
√ Check 1: Is there an earth plug –with earth wire- between the plug and the appliance- on every
non-portable appliance?
√ Check 2: Are all portable appliances double insulated? Check for the following sign.
√ Check 3: Are all plugs directly connected to the sockets?
√ Check 4: Is an earth wire connected to the earth pin in the socket? (Open all the sockets)
√ Check 5: Is the earth wire connected to an earth pin in the ground? (Follow the earth line where
possible)
√ Check 6: Are the water pipes earthed?
Location 4
Workshop
Kitchen
Bathroom(s)
Present? Check1
Check 2 Check 3 Check 4 Check 5
Check 6
Y
Y
Y
Y
Y
Y
Y
N
N
N
N
N
N
N
Y
Y
Y
Y
Y
Y
Y
N
N
N
N
N
N
N
Y
Y
Y
Y
Y
Y
Y
3
See table in Annex 1
If more locations of the same kind are present [e.g. bathroom] please add an entry for each location in the table and
check the locations separately.
4
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MSF– ICRC Electrical Installations and Equipment in the Field: Rules and Tools. Version 0
N
N
N
N
N
N
N
 If you
answered
N
N
N
N
N
N
N
“No” for
Y
Y
Y
Y
Y
Y
Y
any of the
Sterilisation
checks,
room
N
N
N
N
N
N
N
the
Y
Y
Y
Y
Y
Y
Y
earthing
in
the
N
N
N
N
N
N
N
locations
Y
Y
Y
Y
Y
Y
Y
should be
installed
N
N
N
N
N
N
N
or
improved. We have had deadly accidents in the past for locations that were not properly earthed.
Please use the last part of this checklist to make a planning with your supervisor to improve the
situation.
Operating
Theatres
Y
Y
Y
Y
Y
Y
Y
3.2 Please locate the earth pin(s) in the ground by following the earth line(s) and answer the
questions below.
The amount of earth pins in the ground identified:
√ Check the earth pin connection by
answering the questions below. You can use
the picture on your right for clarification of
terms.
Please fill in a table with answers for each
separate earth pin.
Location of earth pin (please fill):
A: Is the connection of the earth conductor to the clamp on the earth pin visible?
B: Is the connection of the earth conductor to the clamp on the earth pin free of
corrosion?
Copy this table if needed to allow all earth pins to be documented
Yes
No
Yes
No
 If you have answered “No” for any of the above, the earth connection should be installed or
improved. Please use the last part of this checklist to make a planning with your supervisor.
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Check 4: Connections, sockets, light switches, and wires.
√ 4.1 Walk through every room of the facility, and check light switches, sockets, connections to the
wiring and visible wires from appliances. Open around 10 switches, sockets, and connections (in
total) to have a closer look, and answer the questions below.
Please record your findings:
Type
Sockets
Direct connections
Light switches
Amount in facility
Amount opened for check
Please, answer the following questions
A: Can you confirm that you did not find any signs of overheating?
B: Can you confirm that you did not find any dangerous situations related to
quality, placing or fixation (e.g. broken sockets with bare wires, uncovered
connections etc.)?
C: Are all wires in the sockets well connected?
D: Are all visible wires insulated?
Yes
No
Yes
No
Yes
No
Yes
No
 If you have answered “No” for any of the above the situation should be improved. Please use the
last part of this checklist to make a planning with your supervisor to improve the situation. NOTE:
The plan should include a check and where needed improvement of ALL connections, sockets,
switches and wires in every room of the facility!
Check 5: extension cables, multi sockets, adaptors and appliances
√ 5.1 Check all different make/brand of extension cables and multi sockets by opening them
Yes
No
A: Can you confirm that you did not find any signs of overheating?
B: Are all wires inside the cable of the right size for the maximum used wattage
Yes
No
mentioned on the cable?5
Yes
No
C: Are all wires in the sockets well connected?
D: Do all models with an earth connection indeed have an earth wire that is both
No
Yes
connected to the plug and socket(s)?
E: Can you confirm that you did not find any damage to the insulation of the
Yes
No
cables?
F: Can you confirm that you found no other reason to doubt the quality of the
Yes
No
cables and multi sockets?
G: Are the plugs in the extension cable of the same type as those of the appliances
Yes
No
connected to them (no adaptors or “workarounds”)?
H: Do plugs always make good contact immediately when plugged in the
Yes
No
extension cable?
5
See table in Annex 1
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MSF– ICRC Electrical Installations and Equipment in the Field: Rules and Tools. Version 0
 If you have answered “No” for any of the above, please use the last part of this checklist to make
a planning with your supervisor to improve the situation.
Check 6: Back-up systems.
√ Locate your UPS battery system(s) and answer the following:
How many different battery systems – a separate
pack of batteries on a location- did you locate?
A:
Are all ‘open’ (non-GEL or AGM or VLRA type) type batteries placed in well
ventilated rooms?
Yes
No
 If you have answered “No” on the question above, please use the last part of this checklist to
make a planning with your supervisor to improve the situation.
Check 7: Specific checks.
√ 7.1 Locate the shower (if there is one in the premises) and check if the electrical set up is safe:
Please use the picture below for explanation of the zones:
A: Is all electrical equipment outside zones 0, 1 and 2?
Yes
No
If you have answered “No” for question A, immediately inform your supervisor and remove the
equipment from the room or disconnect the equipment from the electricity until the situation is
improved.
B: Is all electrical equipment in zone 3 earthed?
Yes
No
If you have answered “No” for question B, please use the last part of this checklist to make a
planning with your supervisor to improve the situation.
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Plan for change.
This part of the check list is to be completed together with your
Please plan improvements for all problems encountered executing this check list.
# Problem
1
Agreed solution
Deadline
supervisor.
Responsible
2
3
4
5
6
Supervisor (name): ________________________
Date: ________________
Signature: _________________________________________
For the supervisor: make sure to update the deadlines in your standard Outlook 2007 agenda
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TOOL: LISTING OF USER'S NEEDS DOC
Excel sheet. Is the user’s part of the load calculation sheet. It also helps to calculate the sizing of the
distribution. It reports all fixed and mobile devices, as well as number of sockets per location. In this
example, power rates have already been allocated to the user’s devices (to calculate the load) and
terminals (to size the distribution).
The sheet contains a listing of sample devices including the most common associated values. It is
easy to copy each sample and insert it into a listing.
LISTING OF PREDEFINE USER DEVICES
Energy consumer
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
Location
Nbr.
/ remarks
Gross
unit
Power
(W)
P (W)
P (W)
total
total
(
(distributi
installed
on
power) capacity)
Type
cos φ
P (VA)
Total
Co ef.
P eak
(VA ) max
St art
t o t al
.
5 Devices with link to predefined 24H simulation values. These values can be changed from the project tag : se
Computer
1
Bulbs (indoor lighting)
1
Water heater
1
AC
1
Security lights
1
Other sample devices. All electrical values and
OXYGEN CONCENTRATOR
1
STAND FAN
1
SPOTLIGHT
1
Ceiling fan
1
MEDIPREMA FABIE-AMBIA
1
FANS
1
Ceiling fan
1
Agitator
1
Centifugal device
1
Cofee machine
1
Micro wave
1
Neon indoor
1
Bulbs
1
Fridge
1
Freezer
1
Bulbs
1
X RAY DEVICE
1
Lampe scialytique
1
MICROSCOPE
1
1
Washing machine
1
Outdoor lighting
Socket
1
65 W
65 W
130 W resistance
1
7W
7W
14 W resistance
1
1.500 W
1.500 W
3.000 W resistance
1
1.250 W
1.250 W
2.500 W compressor 0,8
40 W
40 W
80 W resistance
1
% for the 24 H simulation can be adapted individually.
400 W
400 W
800 W compressor 0,8
0,8
230 W
230 W
460 W Engine
100 W
100 W
200 W Engine
0,8
100 W
100 W
200 W Engine
0,8
1.300 W
1.300 W
2.600 W resistance
1
100 W
100 W
200 W Engine
0,8
25 W
25 W
50 W Engine
0,8
25 W
50 W Engine
0,8
25 W
0,8
55 W
55 W
110 W Engine
55 W
55 W
110 W Engine
0,8
55 W
55 W
110 W Engine
0,8
60 W
60 W
120 W resistance
1
23 W
23 W
46 W resistance
1
80 W
80 W
160 W compressor 0,8
120 W
120 W
240 W compressor 0,8
25 W
25 W
50 W resistance
1
2.500 W
2.500 W
5.000 W resistance
1
120 W
120 W
240 W resistance
1
20 W
20 W
40 W resistance
1
2.000 W
2.000 W
4.000 W Engine
0,8
1.000 W
1.000 W
2.000 W resistance
1
400 W
0W
800 W resistance
1
65
7
1.500
1.563
40
VA
VA
VA
VA
VA
1
1
1
5
1
65
7
1.500
7.813
40
VA
VA
VA
VA
VA
500
288
125
125
1.300
125
31
31
69
69
69
60
23
100
150
25
2.500
120
20
2.500
1.000
0
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
5
3
3
3
1
3
3
3
3
3
3
1
1
5
5
1
1
1
1
3
1
1
2.500
863
375
375
1.300
375
94
94
206
206
206
60
23
500
750
25
2.500
120
20
7.500
1.000
0
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
Remark : The power given to the sockets is only given to calculate the distribution capacity, not to calculate the power needs
The listing can be made by picking sample devices or creating them manually. Some values are
automatically associated with sample devices but all can be modified. The listing is clearer if it is
made room by room. At this stage not all values are completed to calculate the power load and to
size the distribution system. However, they are expected to be completed in the near future.
244
MSF– ICRC Electrical Installations and Equipment in the Field: Rules and Tools. Version 0
Energy consumer
Location / remarks
M AI N PAN EL
Generator room ( building 12)
Bulbs
Building 12 (generator room)
PAN EL A1
Building 14 (building in
construction)
Gross unit
Power
(W)
Nbr.
6
7W
4
15
400 W
7W
1
15
0
2
400 W
7W
1.500 W
2.600 W
2
30
1
1
7W
7W
2.000 W
400 W
1
1
22
1
1
1
0
8
200 W
65 W
7W
1.500 W
940 W
1.410 W
1
1
16
1
2
1
200 W
65 W
7W
1.500 W
1.410 W
400 W
2
1
26
1
1
8
0
200 W
65 W
7W
1.500 W
1.250 W
40 W
2
1
22
0
1
1
200 W
65 W
7W
Will be used for stock
Socket
Bulbs (in and out)
PAN EL A2
Building 15 (driver's room )
Socket
Bulbs (in and out)
Water heater
AC
Building
Building
Building
Building
PAN EL A3
Bulbs (indoor lighting)
Bulbs (out) security
Bulbs (out) security
Socket
To building 7
Socket
Computer
Bulbs (indoor lighting)
Water heater
AC
AC
Fridge
Bulbs (out)
PAN EL B2
Socket
Computer
Bulbs (indoor lighting)
Water heater
AC
Fridge
PAN EL C1
Socket
Computer
Bulbs (indoor lighting)
Water heater
AC
Bulbs (out)
Fridge
PAN EL D1
Socket
Computer
Bulbs (indoor lighting)
Water heater
AC
Fridge
15
15
15
15
Building 16 (guard house)
Building
Building
Building
Building
16
16
16
16
(guard house)
(guard house)
(guard house)
(guard house)
Building 7 ground floor
Building
Building
Building
Building
Building
Building
Building
Building
7
7
7
7
7
7
7
7
ground floor
ground floor
ground floor
ground floor
ground floor
ground floor
ground floor
common
40 W
Building 7 floor 1
Building
Building
Building
Building
Building
Building
7
7
7
7
7
7
floor 1
ground floor
floor 1
floor 1
floor 1
floor 1
Building 8 ground floor
Building
Building
Building
Building
Building
Building
Building
8
7
8
8
8
8
8
ground floor
ground floor
ground floor
ground floor
ground floor
common
ground floor
Building 8 floor 1
Building
Building
Building
Building
Building
Building
8
7
8
8
8
8
floor 1
ground floor
floor 1
floor 1
floor 1
floor 1
1.250 W
400 W
245
MSF– ICRC Electrical Installations and Equipment in the Field: Rules and Tools. Version 0
246
MSF– ICRC Electrical Installations and Equipment in the Field: Rules and Tools. Version 0
8.5. TEMPLATE: POSITION DIAGRAM
Excel sheet: “drawing tool for installation diagrams.xls”
This sheet contains all the needed symbols, pre-formatted sheets and sample of plans and
diagrams.
On this example we can see red circles of 10m radius centred on the distribution boards and
showing how the entire area is covered by well-placed distribution boards. The blue dashed lines
indicate the distribution areas. Because it is a simple installation, it is both the position diagram of
the main and the final distribution.
C
D
E
B
A
247
MSF– ICRC Electrical Installations and Equipment in the Field: Rules and Tools. Version 0
248
MSF– ICRC Electrical Installations and Equipment in the Field: Rules and Tools. Version 0
8.6. TOOL: LOAD STUDY SHEET
Same excel sheet as the one used for the listing of user’s devices. This last is completed by the
technician in charge of the load study. The load study is needed to size generators according to the
variation of load throughout the day, or the seasons. Two different tools can be used:
1. Estimate the load profile for the highest and lowest consumption period. In countries with
important seasonal variations, we should estimate the min and max load for the following
periods: day & night, during winter, mid-season, and summer. In other countries we need
only to estimate the min and max for day & night, weekends, and working days. The
intention is to visualise a load profile that could be realistic, and open to limited accepted
further development.
Energy consumer
M A IN P A NEL
Bulbs
P A NEL A 1
Location / remarks
Nbr.
Gen erat o r ro o m ( b u ild in g 1 2 )
Building 12 (generator room
6
Gross unit
Power (W)
7W
Bu ild in g 1 4 (b u ild in g in co n st ru ct io n )
Will be use for stock
Socket
Bulbs (in and out)
P A NEL A 2
Building
Building
Building
Building
P A NEL A 3
Bu ild in g 1 6 (g u ard h o u se)
To b u ild in g 7
Socket
Computer
Bulbs (indoor lighting)
Water heater
AC
AC
Fridge
Bulbs (out)
P A NEL B2
Building
Building
Building
Building
15
15
15
15
16
16
16
16
(guard
(guard
(guard
(guard
house)
house)
house)
house)
Bu ild in g 7 g ro u n d flo o r
Building
Building
Building
Building
Building
Building
Building
Building
7
7
7
7
7
7
7
7
groundfloor
groundfloor
groundfloor
groundfloor
groundfloor
groundfloor
groundfloor
common
Bu ild in g 7 flo o r 1
Socket
Computer
Bulbs (indoor lighting)
Water heater
AC
Fridge
Building
Building
Building
Building
Building
Building
Socket
Computer
Bulbs (indoor lighting)
Water heater
AC
Bulbs (out)
Fridge
Building
Building
Building
Building
Building
Building
Building
P A NEL C1
400 W
7W
1
15
0
2
400 W
7W
1.500 W
2.600 W
2
30
1
1
7W
7W
2.000 W
400 W
1
1
22
1
1
1
0
8
200 W
65 W
7W
1.500 W
940 W
1.410 W
1
1
16
1
2
1
200 W
65 W
7W
1.500 W
1.410 W
400 W
2
1
26
1
1
8
0
200 W
65 W
7W
1.500 W
1.250 W
40 W
Bu ild in g 1 5 (d river's ro o m)
Socket
Bulbs (in and out)
Water heater
AC
Bulbs (indoor lighting)
Bulbs (out) security
Bulbs (out) security
Socket
4
15
7
7
7
7
7
7
floor 1
groundfloor
floor 1
floor 1
floor 1
floor 1
Bu ild in g 8 g ro u n d flo o r
8
7
8
8
8
8
8
groundfloor
groundfloor
groundfloor
groundfloor
groundfloor
common
groundfloor
P (W) total
( installed
power)
42 W
42 W
%
Lower
period
Higher
Period
%
0%
0W
10%
4W
0%
0%
10%
0W
0W
11 W
10%
10%
60%
0W
0W
63 W
105 W
0W
0W
105 W
5 .3 0 5 W
40 W
0
105
0
5.200
W
W
W
W
2 .2 2 4 W
14
210
2.000
0
W
W
W
W
4 .3 8 9 W
0
65
154
1.500
940
1.410
0
320
W
W
W
W
W
W
W
W
4 .8 9 7 W
0
65
112
1.500
2.820
400
W
W
W
W
W
W
3 .3 1 7 W
0
65
182
1.500
1.250
320
0
2 0 .2 7 9 W
W
W
W
W
W
W
W
10%
10%
10%
30%
0
11
0
1.560
W
W
W
W
10%
60%
40%
40%
0
63
0
2.080
W
W
W
W
100%
0%
0%
10%
14
0
0
0
W
W
W
W
60%
100%
100%
10%
8
210
2.000
0
W
W
W
W
0%
5%
10%
30%
5%
5%
40%
5%
0
3
15
450
47
71
0
16
W
W
W
W
W
W
W
W
10%
40%
60%
40%
40%
40%
40%
100%
0
26
92
600
376
564
0
320
W
W
W
W
W
W
W
W
10%
5%
5%
30%
5%
40%
0
3
6
450
141
160
W
W
W
W
W
W
10%
40%
60%
40%
40%
40%
0
26
67
600
1.128
160
W
W
W
W
W
W
10%
5%
5%
15%
5%
10%
40%
0
3
9
225
63
32
0
W
W
W
W
W
W
W
10%
40%
60%
40%
40%
100%
40%
0
26
109
600
500
320
0
W
W
W
W
W
W
W
3 .2 8 9 W
9 .9 4 3 W
The percentages entered represent the anticipated % of use of each device during the periods of
lowest and highest demands. These will be considered as the average power that a generator must
be able to supply (around 50 – 60% of the generator rate). The next example shows the addition at
the end of a listing of 425 lines of devices for a large hospital. Compare the installed power with the
estimation of average running power along the periods.
249
MSF– ICRC Electrical Installations and Equipment in the Field: Rules and Tools. Version 0
Add
Running power
Running power
HOT Season
SDP
Energy consumer
Location
Nbr.
P (VA) total
Im
396 Lights
397 Frige
398 Fan
Mourge
Mourge
Mourge
4
2
2
399
400
401
402
Lights
AC
Submersible pump
Fan
Mosque
Mosque
Mosque
Mosque
403
404
405
406
407
408
409
410
411
412
413
414
415
AC
Lights
Air cooler
Fan
Boiler
Water dispenser
Water pump
Computer
Laptop
Frige
Copy machine
Printer
Security lights
Nursing
Nursing
Nursing
Nursing
Nursing
Nursing
Nursing
Nursing
Nursing
Nursing
Nursing
Nursing
Nursing
416
417
418
419
Incinerator
Boiler
Lights
Water cooker
Waist
Waist
Waist
Waist
420
421
422
423
424
Lights
Air cooler
Projector
Water cooker
Fan
Main
Main
Main
Main
Main
COLD Season
DAY
%
NIGHT
DAY
%
power
%
power
48 VA
2.000 VA
138 VA
0%
50%
50%
0 VA 50%
2.000 VA 50%
138 VA
0%
0%
50%
100%
0 VA
2.000 VA
275 VA
50%
50%
50%
30
2
1
16
720
4.500
2.500
2.200
VA
VA
VA
VA
0%
50%
20%
100%
0
2.250
500
2.200
VA
VA
VA
VA
30%
0%
10%
0%
216
0
250
0
3
31
1
18
2
1
1
3
2
1
1
2
10
5.625
744
688
2.475
3.000
688
625
900
130
150
620
1.500
1.000
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
50%
30%
100%
100%
50%
70%
20%
100%
100%
50%
15%
15%
0%
2.813
223
688
2.475
1.500
481
125
900
130
75
93
225
0
VA
20%
VA
0%
VA
0%
VA
0%
VA
50%
VA
50%
VA
10%
VA
0%
VA
0%
VA
50%
VA
0%
VA
0%
VA 100%
1.125
0
0
0
1.500
344
63
0
0
75
0
0
1.000
1
1
4
1
1.500
1.500
96
1.500
VA
VA
VA
VA
30%
50%
10%
30%
450
750
10
450
hut
hut
hut
hut
hut
38
1
2
1
1
1.368
375
1.000
1.500
1.138
VA
VA
VA
VA
VA
0%
100%
0%
30%
100%
0
375
0
450
1.138
425 Heater
Main gate/Guard hut
FUTURE INSTALL
( fill t he row 12, a nd clik t o " a dd" )
5
344 VA
0%
zone
zone
zone
zone
gate/Guard
gate/Guard
gate/Guard
gate/Guard
gate/Guard
0%
0%
20%
30%
0
0
500
660
VA 50%
VA 30%
VA
0%
0%
VA
VA 50%
VA 50%
VA 20%
VA 100%
VA 100%
VA 50%
VA 15%
VA 15%
VA
0%
2.813
223
0
0
1.500
344
125
900
130
75
93
225
0
%
NIGHT
power
%
power
48 VA
2.000 VA
0 VA
0%
50%
50%
0 VA 50%
2.000 VA 50%
0%
138 VA
VA 30%
VA
0%
VA
0%
VA
0%
216
0
0
0
0%
0%
0%
0%
50%
50%
10%
0%
0%
50%
0%
0%
###
0
0
0
0
1.500
344
63
0
0
75
0
0
1.000
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
DAY
0%
0%
20%
30%
0
0
500
660
VA
0%
VA 30%
VA
0%
VA
0%
VA 50%
VA 50%
VA 20%
VA 100%
VA 100%
VA 50%
VA 15%
VA 15%
VA
0%
0
223
0
0
1.500
344
125
900
130
75
93
225
0
VA
VA
VA
VA
%
power
VA 30%
VA
0%
VA
0%
VA
0%
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
48 VA
2.000 VA
0 VA
216
0
0
0
VA
VA
VA
VA
0%
0%
0%
0%
50%
50%
10%
0%
0%
50%
0%
0%
###
0
0
0
0
1.500
344
63
0
0
75
0
0
1.000
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
VA
0%
50%
30%
0%
0
750
29
0
VA
VA
VA
VA
30%
50%
10%
30%
450
750
10
450
VA
0%
VA 50%
VA 30%
VA
0%
0
750
29
0
VA
VA
VA
VA
30%
50%
10%
30%
450
750
10
450
VA
0%
VA 50%
VA 30%
VA
0%
0
750
29
0
VA
VA
VA
VA
VA
50%
VA
50%
VA 100%
VA
15%
VA
50%
684
188
1.000
225
569
VA
VA
VA
VA
VA
0%
0%
0%
30%
0%
0
0
0
450
0
VA 50%
VA
0%
VA ###
VA 15%
VA
0%
684
0
1.000
225
0
VA
VA
VA
VA
VA
0%
0%
0%
30%
0%
0
0
0
450
0
VA 50%
VA
0%
VA ###
VA 15%
VA
0%
684
0
1.000
225
0
VA
VA
VA
VA
VA
0 VA
70%
241 VA 50%
172 VA
0%
0 VA
686 kVA
6,0 %
VA
VA
VA
VA
VA
VA
VA
VA
MID Season
NIGHT
power
96 VA
4.000 VA
275 VA
school
school
school
school
school
school
school
school
school
school
school
school
school
Running power
326 kVA
DAY
0%
220 kVA
NIGHT
213 kVA
DAY
0 VA
179 kVA
166 kVA
NIGHT
0%
DAY
0 VA
150 kVA
NIGHT
8,0 %
% of loos
6,0 %
6,0 %
% of loos
6,0 %
6,0 %
% of loos
6,0 %
% of loo
6,0 %
784,88
% of loos
8,0 %
8,0 %
% of loos
8,0 %
8,0 %
% of loos
8,0 %
% of loo
8,0 %
250
MSF– ICRC Electrical Installations and Equipment in the Field: Rules and Tools. Version 0
2. In the second method, not only the maximum and minimum are calculated: it helps to estimate a complete load profile during 24 hours.
24 hour simulation 06 -> 18 (day), 19 -> 05 5 (night) FILL IN the %
The yellow cells can be changed directly, coloured ones are linked to specific figures
% for these specific figures. They will be automatically updated into the genera ltime tab
ON/OFF
Bulbs (indoor) 5%
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
Energy
Location /
consumer remarks
Ceiling fan
AC
AC
AC
Bulbs
Bulbs (indoor
Bulbs
AC
Bulbs
Bulbs
Bulbs
Bulbs
AC
AC
AC
AC
AC
AC
END OF LIS T
All rooms
NEONAT
EMERGENCIES
ISOLATION
OUTDOOR LAMPS
Nbr.
20
1
2
3
40
1
MODULAIRES
18
CRENI
2
CRENI
6
HOSPITALISATION
12
MATERNITE
12
ADMIN
12
BAT ADMIN
2
LABO
2
PHARMACIE
1
HOSPITALISATION
2
MATERNITE ACCOUC 2
MATERNITE SALLE SU 2
BACK
5%
5%
5%
5%
5%
5%
5%
5%
5%
5%
30%
60%
Security lights 100% 0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100%
Computer
60%
60%
60%
60%
60%
30%
20%
10%
5%
5%
5%
5%
10%
10%
10%
10%
10%
10%
10%
10%
10%
20%
30%
40%
40%
40%
40%
40%
40%
30%
15%
5%
5%
Water heater 40% 70% 40%
30%
20%
20%
30%
30%
20%
20%
20%
30%
40%
70%
60%
40%
30%
20%
10%
10%
10%
10%
10%
10%
AC
30%
60%
70%
70%
70%
70%
70%
70%
70%
70%
70%
70%
70%
60%
50%
40%
40%
40%
30%
30%
20%
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
100%
100%
100%
100%
100%
100%
100%
100%
100%
100%
100%
100%
100%
100%
100%
24-0
50%
40%
40%
40%
80%
30%
40%
40%
80%
80%
80%
80%
40%
40%
40%
40%
40%
40%
1
50%
40%
40%
40%
60%
20%
40%
40%
60%
60%
60%
60%
40%
40%
40%
40%
40%
40%
2
50%
40%
40%
40%
50%
10%
40%
40%
50%
50%
50%
50%
40%
40%
40%
40%
40%
40%
3
50%
30%
30%
30%
30%
5%
40%
30%
30%
30%
30%
30%
30%
30%
30%
30%
30%
30%
4
50%
30%
30%
30%
10%
5%
40%
30%
10%
10%
10%
10%
30%
30%
30%
30%
30%
30%
5
50%
20%
20%
20%
10%
5%
40%
20%
10%
10%
10%
10%
20%
20%
20%
20%
20%
20%
Gross unit
Power (W)
100 W
1.500 W
1.500 W
1.500 W
60 W
7W
60 W
1.500 W
60 W
60 W
60 W
60 W
1.500 W
1.500 W
1.500 W
1.500 W
1.000 W
1.500 W
5%
5%
20% 20% 20%
6
50%
20%
20%
20%
10%
7
50%
20%
20%
20%
10%
8
50%
20%
20%
20%
10%
5%
5%
5%
5%
40%
20%
10%
10%
10%
10%
20%
20%
20%
20%
20%
20%
40%
20%
10%
10%
10%
10%
20%
20%
20%
20%
20%
20%
40%
20%
10%
10%
10%
10%
20%
20%
20%
20%
20%
20%
40%
30%
10%
10%
10%
10%
30%
30%
30%
30%
30%
30%
30% 60% 70% 70% 70% 70% 70% 70%
30% 60% 70% 70% 70% 70% 70% 70%
30% 60% 70% 70% 70% 70% 70% 70%
10% 10% 10% 10% 10% 10% 10% 30%
5%
20%
60%
5%
20%
70%
5%
20%
70%
5%
20%
70%
5%
20%
70%
5%
20%
70%
5%
20%
70%
10%
10%
10%
10%
10%
10%
10%
10%
10%
10%
10%
10%
10%
10%
10%
10%
10%
10%
10%
10%
10%
10%
10%
10%
30%
30%
30%
30%
60%
60%
60%
60%
60%
60%
70%
70%
70%
70%
70%
70%
70%
70%
70%
70%
70%
70%
70%
70%
70%
70%
70%
70%
70%
70%
70%
70%
70%
70%
70%
70%
70%
70%
70%
70%
70%
70%
70%
70%
70%
70%
70%
70%
70%
40%
30%
20%
70%
40%
40%
40%
40%
70%
70%
70%
70%
70%
70%
70%
70%
70%
60%
60%
40%
70%
60%
60%
60%
60%
70%
70%
70%
70%
70%
70%
70%
70%
70%
80%
60%
40%
70%
80%
80%
80%
80%
70%
70%
70%
70%
70%
70%
70% 70% 60% 50%
70% 70% 60% 50%
70% 70% 60% 50%
100%
100%
100%
100%
60% 60% 60% 60%
40% 40% 40% 40%
70% 70% 60% 50%
100%
100%
100%
100%
100%
100%
100%
100%
100%
100%
100%
100%
100%
100%
100%
70%
70%
70%
70%
70%
70%
70%
70%
70%
70%
70%
70%
60%
60%
60%
60%
60%
60%
100%
50%
50%
50%
50%
50%
50%
In this sheet, a percentage is entered for each period of the 24 hours. The yellow cells must be completed manually. The coloured ones are
linked to a predefined schedule that can be modified in the 5 lines at the top - that show the schedule followed by all identical devices in the
listing.
The resulting values can be visualised on a graph, and the ideal size of generators is calculated. If the load variation shows important
differences of average loads between day and night, two sizes of ideal generators are proposed: one for the low load period, one for the
high load period.
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The green curve shows the average power consumption in kW. It is varying between 8 and 25 kW.
The plain blue curve shows the running periods and ideal rated power of the selected generators (here 25kVA and 53kVA).
GRAPH OF AVERAGE LOAD RURING 24 HOURS with generators capability
### peak
60
kW 24 h
vices
### min
### av
53 kVA peak
### ideal
### max
53 kVA max
50
### peak
53 kVA ideal
40
53 kVA av
53 kVA min
30
25 kVA peak
25 kVA max
25 kVA ideal
20
25 kVA av
25 kVA min
10
From
from2
2
Chosen Gen High 2
Chosen Gen low
0
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23 24-0 1
2
3
4
5
The dashed lines show the different running thresholds of the 53kVA generator in red, and of the 25 kVA in blue.
The threshold values, explanations and calculation made to size the generators are also given in the sheet.
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In this figure we have, out of the 24h diagram, an average use of 10.9 kW during the low period and 23.1 kW during the high period.
AVERAGE AND RATED POWER CALCULATION BOX
Average use
Active devices
Rated power of active devices
% Average use / active power
Lower on 24 H
higher on 24 H
10,9 kW
23,1 kW
140
140
35,5 kW
35,5 kW
39%
73%
Most powerful active device
1,5 kW
1,5 kW
Average is 60% of
18,1
18,1
18,0
18,1
18,1
18,1
Corr. most powerfull device
Corr. average / nbr devices
Correct range in kW of generator
temperature 25 °c
altitude 468 m
kVA Nominal
kVA Prime
kW
kW
kW
kW
kW
kW
25kVA
23kVA
7kW
11kW
14kW
18kW
20kW
Rated 60%
max>50% rated
Rated/ average
Rated
+ 0,0 %
+ 0,0 %
110%
100%
40%
60%
80%
100%
110%
38,5
38,5
27,9
38,5
38,5
38,5
kW
kW
kW
kW
kW
kW
53kVA
48kVA
15kW
23kW
31kW
39kW
42kW
user devices that are not turned to 0
Sum of the power of active devices
Average bulking applied
we must consider the power of the most powerfull devices that could be started
The average use must be around 60% of the rated power of the generator
Accorded to the most powerful device, the rated power has to be corrected
Accorded to the number of devices, the rated power has to be corrected.
The final value is accorded to the correction giving the highest rate.
Nominal rate / backup power
Prime power rate
Minimal constant load required
Ideal average load
Optimal load
Maximal constant load admitted
Peak load admitted 1h/24h
A lot of information is given in this sheet. We can see for instance that during the low period the selected size of generator will be ideal to supply
loads between 7 kW and 18 kW, with an average about 11 kW, an optimal at 14 kW, and an ability to give peaks up to 20 kW. We can also see the
corresponding values for the big generator. It is the kW that has been considered because the generator is first sized accorded to the real power
(thus in kW) that the engine must be able to deliver. If the Cos F remains higher than 0.8 (which is almost always the case) the alternator, which is
delivering apparent power in kVA, will never be undersized.
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8.7. TEMPLATE: POSITION DIAGRAM MAIN DISTRIBUTION (Visio)
From Visio file: 260614 Cantahay Electricity.vsd.
The visio template file “PUSH-TEMPLATE_2013-04-12.vst” is also available and already included in
all symbol libraries.
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MSF– ICRC Electrical Installations and Equipment in the Field: Rules and Tools. Version 0
8.8. TEMPLATE: ELECTRICAL DIAGRAM MAIN BOARD (Visio)
From Visio file: 260614 Cantahay Electricity.vsd.
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8.9. TEMPLATE: POSITION DIAGRAM FINAL CIRCUITS (Visio)
From Visio file: 260614 Cantahay Electricity.vsd.
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8.10.
TEMPLATE: ELECTRIC DIAGRAM FINAL CIRCUITS (Visio)
From Visio file: 260614 Cantahay Electricity.vsd.
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8.11.
TEMPLATE: ELECTRIC DIAGRAM FINAL CIRCUITS (Excel)
From an excel sheet: sample electric diagram.xls
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8.12.
TEMPLATE: ELECTRIC AND POSITION DIAGRAM FINAL CIRCUITS
(Excel)
From an excel sheet: sample electric diagram.xls
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8.13. TOOL: REPORT WORKS FOLLOW-UP
From the file « template debriefing report electrician.doc »
MISSION / PROJECT
What:
When:
Who
Contact
E mail
Phone
Ref Tech
Cell
Attached documents/ path
Current situation
Current step
Assessment /
Project
Preparation
Implementation
Evaluation
Level
Mission
Project
Object
Info
End of mission
Short description
% projected situation
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Version 0
Budget
Amount
Ref docs
Original Budget
Used Budget
Supply
Total Supply foreseen
Supply received
Used
In stock
Team
Number of people
Man * Days foreseen
Man * Days used
Man * Days still required
Problems Solved









-
Problems not solved









-
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Ongoing situation
Short description
Jobs to be completed





-
Corrections to implement





-
Follow-up & recommendation
Lesson learnt
Advantage
Disadvantage
   -
   -
Opportunities
Dangers
   -
   -
Advise about project improvement/ personal remarks






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9. ANNEXES
ANNEX 1: Listing of full and associate IEC members
IEC – INTERNATIONAL ELECTROTECHNICAL COMMISSION
The 60 full members and 26 associates:
Africa
Full: Algeria, Egypt, Libya, South Africa,
Associates: Kenya, Morocco, Nigeria, Tunisia,
Asia
Full: China, India, Indonesia, Japan, Korea (Republic of), Pakistan, Philippines (Rep. of the,)
Singapore, Thailand, Democratic People's Republic of Korea
Associates: Kazakhstan, Sri Lanka, Vietnam.
Europe
Full: Austria, Belarus, Belgium, Bulgaria, Croatia, Czech Republic, Denmark, Finland, France,
Germany, Greece, Hungary, Ireland, Italy, Luxembourg, Netherlands, Norway, Poland,
Portugal, Romania, Russian Federation, Serbia, Slovakia, Slovenia, Spain, Sweden,
Switzerland, Turkey, Ukraine, United Kingdom,
Associates: Albania, Bosnia & Herzegovina, Cyprus, Estonia, Georgia, Iceland, Latvia,
Lithuania, Malta, Moldova, Montenegro, the Former Yugoslav Rep. of Macedonia,
Middle East
Full: Iran, Iraq, Israel, Qatar, Saudi Arabia, Singapore, Thailand, United Arab Emirates,
Associates: Bahrain, Jordan,
Northern America
Full: Canada, Mexico, United States of America
Associates: Cuba
Southern America
Full: Argentina, Brazil, Chile, Colombia, Malaysia,
Associates:
Pacific / Oceanian
Full: Australia, New-Zealand,
Associates:
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ANNEX 2: Reference table: Listing of the IEC affiliate countries and adopted
IEC norms
Here below is the listing of the 83 affiliate countries, mentioning how many international
electrotechnical standards have been already adopted by each of them. This information
could be of a high interest when estimating the situation regarding the accordance to
international technical standardisation in a specific country. This listing is also published on
the IEC website. In addition, the website mentions for each country which IEC norms have
been adopted.
Afghanistan
(177)
Angola
(0)
Antigua and Barbuda (0)
Armenia
(0)
Azerbaijan
(2)
Bahamas
(0)
Bangladesh
(149)
Barbados
(15)
Belize
(0)
Benin
(169)
Bhutan
(51)
Bolivia
(22)
Botswana
(99)
Brunei Darussalam (74)
Burkina Faso
(0)
Burundi
(0)
Cambodia
(41)
Cameroon
(40)
Central African Republic (0)
Chad
(0)
Comoros
(0)
Congo Brazzaville
(0)
Congo Dem. Rep.
(52)
Costa Rica
(90)
Côte d’Ivoire
(168)
Dominica
(0)
Dominican Republic (2)
Ecuador
(289)
El Salvador
(0)
Eritrea
Ethiopia
Fiji
Gabon
Gambia
Ghana
Grenada
Guatemala
Guinea
Guinea Bissau
Guyana
Haiti
Honduras
Jamaica
Kyrgyzstan
Lao People's Dem. Rep.
Lebanon
Lesotho
Madagascar
Malawi
(319)
Mali
Mauritania
Mauritius
Mongolia
Mozambique
Myanmar
Namibia
Nepal
(21)
(248)
(0)
(0)
(0)
(387)
(0)
(0)
(0)
(0)
(169)
(0)
(7)
(0)
(0)
(50)
(374)
(0)
(0)
(0)
(0)
(48)
(53)
(0)
(0)
(0)
(0)
Niger
(0)
Palestine
(200)
Panama
(0)
Papua New Guinea (0)
Paraguay
(0)
Peru
(101)
Rwanda
(126)
Saint Kitts and Nevis (0)
Saint Lucia
(6)
Saint Vincent and the
Grenadines
(0)
Senegal
(24)
Seychelles
(0)
Sierra Leone
(27)
South Sudan, Rep. of (0)
Sudan
(139)
Suriname
(3)
Swaziland
(0)
Tanzania
(0)
Togo
(0)
Trinidad and Tobago (20)
Turkmenistan
(0)
Uganda
(213)
Uruguay
(117)
Yemen
(0)
Zambia
(107)
Zimbabwe
(71)
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ANNEX 3: Reference table: Socket and plug types around the world.
THE MOST COMMON ONES.
“American Sockets”
Mainly used in the USA, Canada, Mexico & Japan
•
15 A
•
Almost always 100 – 127 V
Type A
• Not grounded
(Only class II devices)
• Socket A is only for plug A.
Type B
• Grounded
• Socket B can be used with
plugs A & B.
Bahamas, Bangladesh, Bermuda, Bolivia, British Virgin Islands, Cambodia, Canada, China, People’s Republic of,
Colombia, Dominican Republic, Ecuador, El Salvador, Guatemala, Guyana, Haiti, Honduras, Jamaica, Japan,
Laos, Liberia, Mexico, Myanmar, Nicaragua, Panama, Peru, Philippines, Puerto Rico, Suriname, Taiwan,
Thailand, United States of America (USA), Venezuela, Vietnam, Virgin Islands (British), Virgin Islands (USA),
Yemen
“European Sockets”
Type C
Mainly used in Europe, South America & Asia
•
•
•
•
•
Not grounded (only for low power class II devices)
Max 2.5 A (pins diameter is 4 mm)
220 – 240 V
Socket C is only for plug C.
Plug C can be used in Sockets D, E, F (5mm hole)
• Plugs E & F cannot be used in socket C
• No grounding
• 5 mm pins should not be forced into 4 mm holes
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All countries using E or F type plugs.
Type E
Mostly used in France, Belgium, Poland, Slovakia & the Czech Republic
COMMONLY CALLED “THE FRENCH SOCKET”
•
•
•
•
•
Grounded
16 A (pins diameter is 5 mm)
220 – 240 V
Socket E can be used with plug types C & E
Plug E cannot be used on socket F
Belgium, Benin, Burkina Faso, Burundi, Cameroon, Central African Republic, Chad, Comoros,
Democratic Republic of Congo, Czech Republic, Denmark, Djibouti, East Timor (Timor-Leste),
Equatorial Guinea, France, French Guiana, Greenland, Guadeloupe, Laos, Madagascar, Mali,
Martinique, Morocco, Niger, Poland, Senegal, Slovakia, Syria, Tunisia.
Type F
Used in almost all other European countries, except the UK & Ireland
COMMONLY CALLED “THE GERMAN SOCKET” OR “SHUKO”
•
•
•
•
•
Grounded
16 A (pins diameter is 5 mm )
220 – 240 V
Socket F can be used with plug types C & F
Plug F cannot be used on socket E
Afghanistan, Albania, Algeria, Armenia, Austria, Azerbaijan, Belarus, Bosnia & Herzegovina, Bulgaria,
Cape Verde, Chad, Denmark, East Timor (Timor-Leste), Egypt, Estonia, Ethiopia, Finland, Georgia,
Germany, Greece, Greenland, Guinea, Hungary, Iceland, Indonesia, Iran, Italy, Jordan, Kazakhstan,
South Korea , Kosovo, Kyrgyzstan, Laos, Latvia, Lithuania, Luxembourg, Macedonia, Madeira,
Moldova, Monaco, Montenegro, Mozambique, Netherlands, New Caledonia, Niger, Norway,
Portugal, Romania, Russian Federation, Serbia, Slovenia, South Korea, Spain, Suriname, Sweden,
Tajikistan, Turkey, Turkmenistan, Ukraine, Uruguay, Uzbekistan.
PLUGS Type E/F HYBRID
THE “UNIVERSAL EUROPEAN PLUG” FOR GROUNDED 16A EQUIPMENTS
E Type Grounding
« French »
E Type Grounding
« French »
F Type Grounding
« German »
F Type Grounding
« German »
The power cords of electrical
equipment sold in continental
Europe and other countries is more
and more commonly equipped with
such “universal European plug”
usable on E and F type sockets.
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PLUGS Type E/F HYBRID FOR CLASS II EQUIPMENTS
THE “UNIVERSAL EUROPEAN PLUG” FOR NOT GROUNDED 16A EQUIPMENT
Designed for 16A (3600VA) double
insulated equipment (Class II)
Usable on E&F sockets
The main use is for portable electrical
tools (drilling machines, grinders, electric
saws, lawn mower etc.) and some
portable kitchen tools (mixers, etc.)
For safety reasons, all portable electrical tools must be double
insulated equipment (Class II.)
Type G Mainly used in the United Kingdom, Ireland, Malta, Malaysia & Singapore
COMMONLY CALLED “THE BRITISH SOCKET”
•
•
•
•
Grounded
13 A
220 – 240 V
Socket G is only for plug G.
Abu Dhabi, Bahrain, Bangladesh, , Bhutan, Botswana, Brunei, Cambodia, Cyprus, Cyprus North,
Dominica, Dubai, England, Gambia, Ghana, Gibraltar, Great Britain (GB), Guyana, Hong Kong, Iraq,
Ireland (Eire), Ireland, Northern, Isle of Man, Jordan, Kenya, Kuwait, Lebanon, Macau, Malawi,
Malaysia, Maldives, Malta, Mauritius, Myanmar, Nigeria, Northern Ireland, Oman, Qatar, Saudi
Arabia, Seychelles, Sierra Leone, Singapore, Sri Lanka, Tanzania, Uganda, United Arab Emirates (UAE),
United Kingdom (UK), Yemen, Zambia, Zimbabwe
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THE “EXOTIC” ONES
Type D
Mainly used in India
•
•
•
•
•
Grounded
5A
220 – 240 V
Socket compatible with plug types C & D
Unsafe compatibility with plugs E & F: No grounding connection
Bangladesh, Bhutan, Botswana, Chad, Congo, Democratic Republic of, Dominica, French Guiana,
Ghana, Guyana, India, Iraq, Jordan, Lebanon, Maldives, Martinique, Myanmar, Namibia, Nepal, Niger,
Nigeria, Pakistan, Saint Kitts and Nevis (officially the Federation of Saint Christopher and Nevis),
Senegal, Sierra Leone, South Africa, South Sudan, Sri Lanka, Sudan, Tanzania, Vietnam, Yemen,
Zambia, Zimbabwe
Type H
Used exclusively in Israel, the West Bank & the Gaza Strip
• 3 pins
• Grounded
• 16 A
• 220 – 240 V
• Socket compatible with plug types C & H
• Unsafe compatibility with plugs E & F : No grounding connection
Gaza Strip (Gaza), Israel, Palestine
Type I
Mainly used in Australia, New Zealand, China & Argentina
•
•
•
•
•
2 or 3 pins
2 pins: not grounded / 3 pins: grounded
10 A
220 – 240 V
Can only be used with plug type I
Argentina, Australia, China, People’s Republic of, East Timor (Timor-Leste), Fiji, Myanmar, New
Zealand, Papua New Guinea, Samoa, Tonga, Tuvalu, Vanuatu
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Type J
Used almost exclusively in Switzerland, Liechtenstein & Rwanda
•
•
•
•
•
3 pins
Grounded
10 A
220 – 240 V
Socket compatible with plug types C (flat model) & J
Jordan, Liechtenstein, Maldives, Rwanda, Switzerland
Type K
Used almost exclusively in Denmark & Greenland
• 3 pins
• Grounded
• 16 A
• 220 – 240 V
• Socket compatible with plug types C & K
• Unsafe compatibility with plugs E & F : No grounding connection
Bangladesh, Denmark, Faeroe Islands, Greenland, Guinea, Maldives, Senegal
Type L
Used almost exclusively in Italy & Chile
• 3 pins
• Grounded
• 10 & 16 A
• 220 – 240 V
• 10 A version socket can be used with plug types L & C (10 A)
• 16 A version socket compatible with plug type L (16 A version)
Chile, Eritrea, Italy, Libya, Maldives, San Marino, Syria, Uruguay, Vatican City
Type M
Mainly used in South Africa
• 3 pins
• Grounded
• 15 A
• 220 – 240 V
• Can only be used with plug type M
India, Lesotho, Mozambique, Namibia, Nepal, South Africa, Swaziland
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Type N
Used almost exclusively in Brazil
• 3 pins
• Grounded
• 10 & 20 A
• 220 – 240 V
• Can be used with plugs types N & C
Brazil, South Africa
Type O
Used exclusively in Thailand
• 3 pins
• Grounded
• 16 A
• 220 – 240 V
• Can be used with plug types O & C
• Unsafe compatibility with plugs E & F : No grounding connection
Thailand
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ANNEX 4: Reference table: Wire colour codes around the world
Standard wire colours for flexible cable
(e.g. Extension cords, power (line) cords and lamp cords)
Region or Country
Phases
Neutral
Protective earth/ground
European
Union
(EU),
Argentina, Australia, South
Africa (IEC 60446)
Australia,
New
Zealand
(AS/NZS 3000:2007 3.8.3)
,
Brazil
,
United States, Canada
,
(brass screw tip)
(silver screw tip)
(green) or
(green/yellow)
Standard wire colours for fixed cable
(e.g. In-, On- or Behind-the-wall wiring cables)
Region or Country
Most of IEC compliant
countries, European Union
(EU) (IEC 60446) UK from 31
March 2004 (BS 7671)
Phases
Neutral
,
,
,
(formerly)
UK prior to 2004
Still effective in India,
Pakistan, Kenya and other
former British colonies
Protective earth/ground
,
,
bare conductor,
sleeved at terminations
(formerly)
France, prior to 1970
Could be effective in some
former French colonies and
old installations
Any colours other than
(since about 1980)
Australia,
New
Zealand
(AS/NZS 3000:2007 clause
3.8.1, table 3.4)
single phase:
Or
bare conductor, sleeved at
terminations (formerly)
multiphase:
,
Brazil
South Africa
(until about 1980)
,
,
,
or
,
bare conductor, sleeved at
273
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terminations
(brass screw tip) (120/208/240
V)
United States and other US
inspired countries
,
,
(silver screw tip)
(120/208/240 V)
(277/480 V)
(277/480 V)
(green)
bare conductor
(ground or isolated
ground)
,
single phase
(isolated systems)
(120/208/240 V)
(green)
,
Canada
,‘
(600/347 V)
,
,
,
(three phase isolated systems)
,
(120/208/240 V)
bare conductor
(600/347 V)
(isolated ground)
,
274
MSF– ICRC Electrical Installations and Equipment in the Field: Rules and Tools. Version 0
ANNEX 5: Reference table: Electrical symbols and vocabulary around the world
AMERICAN
Wire gauge
Power
kW
Current
A
Voltage
V
Frequency
Hz
Service entrance panel (or fuse
Enclosure
Fuse
Circuit Breaker
Ground fault circuit interrupter
Equipment circuit breaker
Hot wire
Neutral wire
Ground wire
Single phase & neutral & ground
Triple phase & neutral & ground
Single pole 2 way switch
3 way switch
Push button
Single receptacle
Single grounded receptacle G
Switched grounded receptacle s
Duplex receptacle
Junction box
Emergency lighting unit
Building permit
Developer
Architect
Electrical consulting engineer
Specifications
BID
General contractor
Electrical sub-contractor
Electrical contractor
Wiring devices
ARABIC
CHINESE
ENGLISH
Cross-section
Power output
Current rating
Voltage
Frequency
Consumer unit
Cabinet or enclosure
Fuse
Circuit breaker
Residual current device
Isolator switch
Phase conductor
Neutral conductor
Protective conductor (earth)
Single phase + N + E cable
3 phase + N + E cable
One way switch
Two way switch, single pole
Push button
Socket outlet
Earthed socket outlet
Switched socket outlet, single
l
Double socket outlet
Junction box
E.L.U. (Emergency Lighting
Planning permission
Developer
Supervisor
Architect
Electrical consulting engineer
Specifications
Invitation to tender
Main contractor
Electrical work
Electrical contractor
Wiring accessories
mm2
kW
A
V
Hz
FRENCH
Section
Puissance
Courant
Tension
Fréquence
Tableau d’abonné
Armoire
Fusible
Disjoncteur
Interrupteur
Interrupteur
Conducteur
de
Conducteur
de
Conducteur
de
mm2
kW
A
V
Hz
Câble PH + N + T
Câble 3 PH + N + T
Interrupteur
Va-et-vient
Bouton poussoir
Prise de courant (PC)
Prise de courant
Prise de courant avec terre
commandée
Prise
de
courant
Boîte de jonction / Boîte de
dérivation
Blocs autonome d’éclairage de
sécurité (BAES)
Permis de construire
Maître d’ouvrage
Maître d’oeuvre
Architecte
Bureau d’études
Descriptif cahier des
Appel d’offre
Entreprise générale
Lot électricité
Installateur
Appareillage
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GERMAN
Querschnitt
Leistung
Strom
Spannung
Frequenz
Verteilung
Verteiler Schrank
Sicherung
Schutzschalter
FI-Schutzschalter
Trennschalter Trenner
Aussenleiter Phase
Neutralleiter Null
Schutzleiter PE
Leitung 1/N/PE
Leitung 3/N/PE
Schalter Ausschalter
Wechselschalter
Taster
Steckdose
Schutzkontakt-Steckdose
Schutzkontakt Steckdose abschaltabar
2-fach Steckdose
Abzweigdose
Sicherheits-leuchte
Baugehnehmigung
Bauherr
Bauleiter
Architekt
Elektroplaner
Pflichtenheft
Ausschreibung anfrage
Generalunternehmer
Elektrisches Gewerk
Elektroinstallateur
Installationsmaterial
A (mm²)
P [kW]
I [A]
U [V]
F [Hz]
ITALIAN
Sezione
Potenza
Corrente
Tensione
Frequenza
Centralino
Quadra generale
Fusibile
Interrutore automatico
Interrutore differenziale
Interrutore sezionatore
Conduttore di fase
Conduttore di neutro
Conduttore di protezione (terra)
Cavo di fase + neutro + terra
Cavo di fase + neutro + terra
Interrutore
Deviatore
Pulsante
Presa di corrente
Presa di corrente con terra
Presa di corrente con terra comandata
Presa di corrente doppia
Scatola di derivazione
Lampada d’emergenza
Licenza di costruzione (Edile)
Committente
Architetto
Studio tecnico (Engineering)
Capitolato
Richiesta d’offerta
Impresa generale
Parte elettrica
Installatore (Elettrico)
Apparecchiature elettriche
KOREAN
mm2
kW
A
V
Hz
PORTUGUESE/BRAZILIAN
mm2
kW
A
V
Hz
Secção
Potencia
Corrente
Tensão
Frequencia
mm2
kW
A
V
Hz
Quadro
Quadro geral de baixa tensão
Fusivel
Disjunctor
Interruptor diferencial
Interruptor seccionador
Condutor de fase
Condutor de neutro
Condutor de terra
Condutor de fase + neutra + terra
Condutor trifasico+ neutra + terra
Interruptor
Commutador de escada
Botão de pressão
Tomada de corrente
Tomada de corrente con terra
Tomada de corrente com interruptor
Tomada de corrente dupla
Caixa de derivação
Bloco autonomo de illuminacão de
i
Licença de construção
Promotor
Director de obra
Arquitecto
Gabinete de projectos de electrotecnia
Caderno de encargos
Consulta
Empreiteiro geral
Empreiteiro de electricidade
Instalador eléctrico
Aparelhagem electrica
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RUSSIAN
SPANISH
ENGLISH
Secciõn
mm2
kW
Potencia
kW
A
Intensidad
A
V
Tensiõn
V
Hz
Frecuencia
Hz
mm2
TURKISH
mm2
kW
A
V
Hz
Çap
-Toma de corriente con tierra -
Cross-section
Power output
Current rating
Voltage
Frequency
Consumer unit
Cabinet or enclosure
Fuse
Circuit breaker
Residual current device
Isolator switch
Phase conductor
Neutral conductor
Protective conductor (earth)
Single phase + N + E cable
3 phase + N + E cable
One way switch
Two way switch, single pole
Push button
Socket outlet
Earthed socket outlet
-
Switched socket outlet, single pole
Anahtarli priz
Doble toma de corriente
Double socket outlet
Junction box
E.L.U. (Emergency Lighting Unit)
Planning permission
Developer
Supervisor
Architect
Electrical consulting engineer
Specifications
Invitation to tender
Main contractor
Electrical work
Electrical contractor
Wiring accessories
Ikizler priz
Cuadro de abonado
Cuadro general
Fusible
Magnetotérmico
Interruptor diferencial
Interruptor seccionador
Conductor de fase
Conductor de neutro
Conductor de puesta a tierra
Conductor de fase + neutro + tierra
Conductor trifasico + neutro + tierra
Interruptor
Commutador
Pulsador
-
Caja de derivaciõn
Aparato autonõnomo de alumbrado de emergencia
Licencia de construcciõn
Propriedad promotor
Arquitecto
Estudio arquitectura ingeniera
Pliego de condiciones
Peticiõn de oferta
Constructora
Gremio elétrico
Instalador electricista
Material elétrico
Guç
Akim
Gerilim
Frekans
mm2
kW
A
V
Hz
Otomat kutusu
Pano
Kartus Sigortalar
Otomat
Kaçak akim koruma rölesi
Salter
Faz
Nötr
Toprak
Faz + nötr + toprak kablo
Üç faz + nötr + toprak kablo
Anahtar
Vavien
Zil butanu
Priz
Toprakli priz
Buat
Acil çikis ünitesi
Iskan
Müteahhitlik firmalari
Mimar
Projeve mühendislik bürosu
Kesif
Sartnäme
Insaat firmasi
Elektrik kesfi
Elektrik tesicatçisi
Elektrik malzemesi
277
MSF– ICRC Electrical Installations and Equipment in the Field: Rules and Tools. Version 0
ANNEX 6: Electrification rates around the world
1.6 billion people do not have electricity.
(From the Global electrical network - http://www.geni.org/index.html)
Afghanistan
Albania
Algeria
Angola
Argentina
Armenia
Australia
Austria
Azerbaijan
Bahamas
Bangladesh
Belarus
6%
100%
73%
15%
95%
100%
100%
100%
100%
100%
38%
100%
Belgium
Belize
Benin
Bhutan
Bolivia
Bosnia/Herzeg.
Botswana
Brazil
Brunei
Bulgaria
Burkina Faso
Burundi
Cambodia
Cameroon
Canada
Cent. Afric. Rep.
Chad
Chile
China
Colombia
Congo, Dem Rep
Congo, Pop. Rep
Costa Rica
Cote d'Ivoire
Croatia
Cuba
Cyprus
Czech Republic
Denmark
100%
90%
22%
11%
64%
100%
22%
93%
100%
100%
9%
2%
33%
46%
100%
3%
2%
95%
96%
92%
6%
9%
95%
20%
100%
82%
100%
100%
100%
Djibouti
15%
Dominican rep. 91%
East Timor
11%
Ecuador
80%
Egypt
98%
El Salvador
65%
Equt. Guinea 15%
Eritrea
20%
Estonia
100%
Ethiopia
13%
Finland
100%
France
100%
French
Guiana
88%
Gabon
74%
Gambia
15%
Georgia
33%
Germany
100%
Ghana
43%
Greece
100%
Greenland
90%
Guatemala
85%
Guinea
16%
Guinea-Bissau 12%
Guyana
60%
Haiti
31%
Honduras
45%
Hungary
100%
Iceland
100%
India
82%
Indonesia
63%
Iran
94%
Iraq
87%
Ireland
100%
Israel
100%
Italy
100%
Jamaica
70%
Japan
100%
Jordan
100%
Kazakhstan
100%
Kenya
15%
Korea, North 92%
Korea, South
Kuwait
Kyrgyzstan
Laos
Latvia
Lebanon
Lesotho
Liberia
Libya
Lithuania
Luxembourg
Macedonia
100%
100%
100%
39%
100%
98%
5%
5%
100%
100%
100%
100%
Romania
Russia
Rwanda
Saudi Arabia
Senegal
Serbia-Monten.
Sierra Leone
Slovakia
Slovenia
Somalia
South Africa
Spain
100%
100%
6%
85%
32%
55%
5%
100%
100%
10%
66%
100%
Madagascar
Malawi
Malaysia
Mali
Mauritania
Mexico
Moldova
Mongolia
Morocco
Mozambique
Myanmar
Namibia
Nepal
Netherlands
New Zealand
Nicaragua
Niger
Nigeria
Norway
Oman
Pakistan
Panama
Papua N. Guin
Paraguay
Peru
Philippines
Poland
Portugal
Puerto Rico
11%
3%
97%
11%
22%
95%
99%
100%
65%
7%
15%
26%
25%
100%
100%
70%
7%
45%
100%
98%
60%
73%
45%
54%
75%
75%
100%
100%
100%
Sri Lanka
Sudan
Suriname
Swaziland
Sweden
Switzerland
Syria
Taiwan
Tajikistan
Tanzania
Thailand
Togo
Tunisia
Turkey
Turkmenistan
Uganda
Ukraine
United Arab Em.
United Kingdom
United States
Uruguay
Uzbekistan
Venezuela
Vietnam
Yemen
Zambia
Zimbabwe
68%
19%
95%
6%
100%
100%
99%
100%
95%
9%
98%
15%
98%
100%
100%
9%
100%
100%
100%
100%
95%
100%
95%
80%
43%
20%
42%
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ANNEX 7: Reference table: Main features of national/local standards around the world
IEC
Country / state / territory
Single-phase
voltage
Frequency
(hertz)
Plug type
Abu Dhabi,
Afghanistan,
Albania,
Algeria,
American Samoa,
Andorra,
Angola,
Anguilla,
Antigua and Barbuda,
Argentina,
Armenia,
Aruba,
Australia,
Austria,
Azerbaijan,
Azores,
Bahamas,
Bahrain,
Balearic Islands,
Bangladesh,
Barbados,
Belarus,
Belgium,
Belize,
Benin,
Bermuda,
Bhutan,
Bolivia,
Bonaire,
Bosnia & Herzegovina,
Botswana,
Brazil,
British Virgin Islands,
Brunei,
Bulgaria,
Burkina Faso,
Burundi,
Cambodia,
Cameroon,
Canada,
Canary Islands,
Cape Verde,
Cayman Islands,
230 V
220 V
230 V
230 V
120 V
230 V
220 V
110 V
230 V
220 V
230 V
120 V
230 V
230 V
220 V
230 V
120 V
230 V
230 V
220 V
115 V
220 V
230 V
110 V / 220 V
220 V
120 V
230 V
230 V
127 V
230 V
230 V
127 V / 220 V
110 V
240 V
230 V
220 V
220 V
230 V
220 V
120 V
230 V
230 V
120 V
50 Hz
50 Hz
50 Hz
50 Hz
60 Hz
50 Hz
50 Hz
60 Hz
60 Hz
50 Hz
50 Hz
60 Hz
50 Hz
50 Hz
50 Hz
50 Hz
60 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
60 Hz
50 Hz
60 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
60 Hz
60 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
60 Hz
50 Hz
50 Hz
60 Hz
G
C/F
C/F
C/F
A/B/F/I
C/F
C
A/B
A/B
C/I
C/F
A/B/F
I
C/F
C/F
B/C/F
A/B
G
C/F
A/C/D/G/K
A/B
C/F
C/E
A/B/G
C/E
A/B
C/D/G
A/C
A/C
C/F
D/G
C/N
A/B
G
C/F
C/E
C/E
A/C/G
C/E
A/B
C/E/F
C/F
A/B
Closest
standard
Full
Assoc reference to be
Affil applied
Member
N/A
Affil
Assoc
Full
US
N/A
Affil
N/A
Affil
Full
Affil
N/A
Full
Full
Affil
Portu
Affil
Assoc
Spain
Affil
Affil
Full
Full
Affil
Affil
N/A
Affil
Affil
N/A
Assoc
Affil
Full
N/A
Affil
Full
Affil
Affil
Affil
Affil
Full
Spain
N/A
N/A
IEC / UK
IEC / D
IEC / D
IEC / D
NEC
IEC / D
IEC / D
NEC
NEC
IEC
IEC / D
NEC
IEC
IEC / D
IEC / D
IEC / D
NEC
IEC / UK
IEC / D
IEC
NEC
IEC / D
IEC
NEC
IEC
NEC
IEC / UK
IEC
IEC/NEC
IEC / D
IEC / UK
IEC/NEC
NEC
IEC
IEC / D
IEC
IEC
IEC / UK
IEC
NEC
IEC
IEC / D
NEC
279
MSF– ICRC Electrical Installations and Equipment in the Field: Rules and Tools. Version 0
Central African Republic,
220 V
Chad,
220 V
Channel Islands (Guernsey & 230 V
Chile,
220 V
China, People’s Republic of,
220 V
Christmas Island,
230 V
Cocos (Keeling) Islands,
230 V
Colombia,
110 V
Comoros,
220 V
Congo, Democratic Republic of,
220 V
Congo, People’s Republic of,
230 V
Cook Islands,
240 V
Costa Rica,
120 V
Côte d’Ivoire (Ivory Coast),
220 V
Croatia,
230 V
Cuba,
110 V / 220 V
Curaçao,
127 V
Cyprus, ,
230 V
Cyprus, North,
230 V
Czech Republic,
230 V
Denmark,
230 V
Djibouti,
220 V
Dominica,
230 V
Dominican Republic,
120 V
Dubai,
230 V
East Timor (Timor-Leste),
220 V
Ecuador,
120 V
Egypt,
220 V
El Salvador,
120 V
England,
230 V
Equatorial Guinea,
220 V
Eritrea,
230 V
Estonia,
230 V
Ethiopia,
220 V
Faeroe Islands,
230 V
Falkland Islands,
240 V
Fiji,
240 V
Finland,
230 V
France,
230 V
French Guiana,
220 V
Gabon (Gabonese Republic),
220 V
Gambia,
230 V
Gaza Strip (Gaza),
230 V
Georgia,
220 V
Germany,
230 V
Ghana,
230 V
Gibraltar,
230 V
Great Britain (GB),
230 V
Greece,
230 V
Greenland,
230 V
Grenada,
230 V
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
60 Hz
50 Hz
50 Hz
50 Hz
50 Hz
60 Hz
50 Hz
50 Hz
60 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
60 Hz
50 Hz
50 Hz
60 Hz
50 Hz
60 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
C/E
C/D/E/F
C/G
C/L
A/C/I
I
I
A/B
C/E
C/D/E
C/E
I
A/B
C/E
C/F
A/B/C/L
A/B
G
G
C/E
C/E/F/K
C/E
D/G
A/B
G
C/E/F/I
A/B
C/F
A/B
G
C/E
C/L
C/F
C/F
C/E/F/K
G
I
C/F
C/E
C/D/E
C
G
C/H
C/F
C/F
D/G
G
G
C/F
C/E/F/K
G
Affil IEC
Affil IEC
UK
IEC / UK
Full IEC
Full IEC
N/A IEC
N/A IEC
Full NEC
Affil IEC / F
Affil IEC / F
Affil IEC / F
N/A IEC
Affil NEC
Affil IEC / F
Full IEC / D
Assoc IEC/NEC
N/A NEC
Assoc IEC
N/A IEC
Full IEC / F
Full IEC
N/A IEC / F
Affil IEC / UK
Affil NEC
N/A IEC
N/A IEC
Affil NEC
Full IEC / D
Affil NEC
Full IEC / UK
N/A IEC
Affil IEC
Assoc IEC / D
Affil IEC / D
N/A IEC
UK
IEC / UK
Affil IEC
Full IEC / D
Full IEC / F
France IEC
Affil IEC
Affil IEC / UK
Palest IEC
Assoc IEC / D
Full IEC / D
Affil IEC / UK
UK
IEC / UK
Full IEC / UK
Full IEC / D
Danm IEC
Affil IEC / UK
280
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Guadeloupe,
Guam,
Guatemala,
Guinea,
Guinea-Bissau,
Guyana,
Haiti,
Honduras,
Hong Kong,
Hungary,
Iceland,
India,
Indonesia,
Iran,
Iraq,
Ireland (Eire),
Ireland, Northern,
Isle of Man,
Israel,
Italy,
Jamaica,
Japan,
Jordan,
Kazakhstan,
Kenya,
Kiribati,
Korea, North,
Korea, South,
Kosovo,
Kuwait,
Kyrgyzstan,
Laos,
Latvia,
Lebanon,
Lesotho,
Liberia,
Libya,
Liechtenstein,
Lithuania,
Luxembourg,
Macau,
Macedonia,
Madagascar,
Madeira,
Malawi,
Malaysia,
Maldives,
Mali,
Malta,
Marshall Islands,
Martinique,
230 V
110 V
120 V
220 V
220 V
120 / 240 V
110 / 220V
120 V
220 V
230 V
230 V
230 V
230 V
230 V
230 V
230 V
230 V
230 V
230 V
230 V
110 V
100 V
230 V
220 V
240 V
240 V
220 V
220 V
230 V
240 V
220 V
230 V
230 V
230 V
220 V
120 V > 240V
230 V
230 V
230 V
230 V
220 V
230 V
110 / 220 V
230 V
230 V
240 V
230 V
220 V
230 V
120 V
220 V
50 Hz
60 Hz
60 Hz
50 Hz
50 Hz
60 Hz
60 Hz
60 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 / 60 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
60 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 > 60 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
60 Hz
50 Hz
C/E
A/B
A/B
C/F/K
C
A/B/D/G
A/B
A/B
G
C/F
C/F
C/D/M
C/F
C/F
C/D/G
G
G
C/G
C/H
C/F/L
A/B
A/B
C/D/F/G/J
C/F
G
I
C
C/F
C/F
G
C/F
A/B/C/E/F
C/F
C/D/G
M
A/B>C/F
C/L
C/J
C/F
C/F
G
C/F
C/E
C/F
G
G
C/D/G/J/K/L
C/E
G
A/B
C/D/E
Franc
N/A
Affil
Affil
Affil
Affil
Affil
Affil
CN
Full
Assoc
Full
Full
Full
Full
Full
UK
UK
Full
Full
Affil
Full
Assoc
Assoc
Assoc
N/A
Assoc
Full
N/A
N/A
Affil
Affil
Assoc
Affil
Affil
N/A
Full
N/A
Assoc
Full
CN
Assoc
Affil
Port
Affil
Full
N/A
Affil
Assoc
N/A
Franc
IEC / F
NEC
NEC
IEC
IEC
NEC
IEC/NEC
NEC
IEC / UK
IEC / D
IEC / D
IEC / UK
IEC / D
IEC / D
IEC
IEC / UK
IEC / UK
IEC / UK
IEC
IEC
NEC
NEC
IEC / UK
IEC / D
IEC / UK
IEC
IEC
IEC / D
IEC / D
IEC / UK
IEC / D
IEC
IEC / D
IEC / UK
IEC
IEC/NEC
IEC
IEC
IEC / D
IEC / D
IEC / UK
IEC / D
IEC / F
IEC / D
IEC / UK
IEC / UK
IEC
IEC / F
IEC / UK
NEC
IEC
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Mauritania,
Mauritius,
Mayotte,
Mexico,
Micronesia, Federated States of,
Moldova,
Monaco,
Mongolia,
Montenegro,
Montserrat,
Morocco,
Mozambique,
Myanmar (formerly Burma),
Namibia,
Nauru,
Nepal,
Netherlands,
New Caledonia,
New Zealand,
Nicaragua,
Niger,
Nigeria,
Niue,
Norfolk Island,
North Cyprus,
Northern Ireland,
North Korea,
Norway,
Oman,
Pakistan,
Palau,
Palestine,
Panama,
Papua New Guinea,
Paraguay,
Peru,
Philippines,
Pitcairn Islands,
Poland,
Portugal,
Puerto Rico,
Qatar,
Réunion,
Romania,
Russia (officially the Russian Federation
Rwanda,
Saba,
Saint Barthélemy (Saint Barts),
Saint Kitts and Nevis,
Saint Lucia,
Saint Martin,
220 V
230 V
230 V
127 V
120 V
230 V
230 V
230 V
230 V
230 V
220 V
220 V
230 V
220 V
240 V
230 V
230 V
220 V
230 V
120 V
220 V
230 V
230 V
230 V
230 V
230 V
220 V
230 V
240 V
230 V
120 V
230 V
120 V
240 V
220 V
220 V
240 V
230 V
230 V
230 V
120 V
240 V
230 V
230 V
220 V
230 V
110 V
230 V
230 V
230 V
220 V
50 Hz
50 Hz
50 Hz
60 Hz
60 Hz
50 Hz
50 Hz
50 Hz
50 Hz
60 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
60 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
60 Hz
50 Hz
60 Hz
50 Hz
50 Hz
60 Hz
60 Hz
50 Hz
50 Hz
50 Hz
60 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
60 Hz
60 Hz
60 Hz
50 Hz
60 Hz
C
C/G
C/E
A/B
A/B
C/F
C/E/F
C/E
C/F
A/B
C/E
C/F/M
A/C/D/G/I
D/M
I
C/D/M
C/F
C/F
I
A/B
C/D/E/F
D/G
I
I
G
G
C
C/F
G
C/D
A/B
C/H
A/B
I
C
A/C
A/B/C
I
C/E
C/F
A/B
G
C/E
C/F
C/F
C/J
A/B
C/E
D/G
G
C/E
Affil
Affil
Franc
Full
N/A
Assoc
N/A
Affil
Assoc
N/A
Assoc
Affil
Affil
Affil
N/A
Affil
Full
Franc
Full
N/A
Affil
Assoc
N/A
N/A
N/A
UK
Assoc
Full
Full
Full
N/A
Affil
Affil
Affil
Affil
Affil
Full
N/A
Full
Full
US
Full
Franc
Full
Full
Affil
N/A
Franc
Affil
Affil
Franc
IEC
IEC / UK
IEC / F
NEC
NEC
IEC / D
IEC
IEC
IEC / D
IEC
IEC / F
IEC
IEC
IEC
IEC
IEC
IEC / D
IEC / D
IEC
NEC
IEC / F
IEC / UK
IEC
IEC
IEC / UK
IEC / UK
IEC
IEC / D
IEC / UK
IEC
NEC
IEC
NEC
IEC
IEC
IEC/NEC
IEC/NEC
IEC
IEC / F
IEC / D
NEC
IEC / UK
IEC / F
IEC / D
IEC / D
IEC
NEC
IEC / F
IEC / UK
IEC / UK
IEC / F
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Saint Helena,
Sint Eustatius,
Sint Maarten,
Saint Vincent and the Grenadines,
Samoa,
San Marino,
São Tomé and Príncipe,
Saudi Arabia,
Scotland,
Senegal,
Serbia,
Seychelles,
Sierra Leone,
Singapore,
Slovakia,
Slovenia,
Solomon Islands,
Somalia,
Somaliland,
South Africa,
South Korea,
South Sudan,
Spain,
Sri Lanka,
Sudan,
Suriname,
Swaziland,
Sweden,
Switzerland,
Syria,
Tahiti,
Taiwan,
Tajikistan,
Tanzania,
Thailand,
Togo,
Tokelau,
Tonga,
Trinidad & Tobago,
Tunisia,
Turkey,
Turkmenistan,
Turks and Caicos Islands,
Tuvalu,
Uganda,
Ukraine,
United Arab Emirates (UAE),
United Kingdom (UK),
United States of America (USA),
United States Virgin Islands,
Uruguay,
230 V
110 V / 220 V
110 V
110 V / 230 V
230 V
230 V
230 V
230 V
230 V
230 V
230 V
240 V
230 V
230 V
230 V
230 V
230 V
220 V
220 V
230 V
220 V
230 V
230 V
230 V
230 V
127 V / 230 V
230 V
230 V
230 V
220 V
220 V
110 V
220 V
230 V
230 V
220 V
230 V
240 V
115 V
230 V
230 V
220 V
120 V
230 V
240 V
230 V
230 V
230 V
120 V
110 V
220 V
50 Hz
60 Hz
60 Hz
50 Hz
50 Hz
50 Hz
50 Hz
60 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
60 Hz
50 Hz
50 Hz
50 Hz
50 Hz
60 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 / 60 Hz
60 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
60 Hz
50 Hz
50 Hz
50 Hz
60 Hz
50 Hz
50 Hz
50 Hz
50 Hz
50 Hz
60 Hz
60 Hz
50 Hz
G
A/B/C/F
A/B
A/B/G
I
C/F/L
C/F
G
G
C/D/E/K
C/F
G
D/G
G
C/E
C/F
G/I
C
C
C/D/M/N
C/F
C/D
C/F
D/G
C/D
A/B/C/F
M
C/F
C/J
C/E/L
C/E
A/B
C/F
D/G
A/B/C/O
C
I
I
A/B
C/E
C/F
C/F
A/B
I
G
C/F
G
G
A/B
A/B
C/F/L
UK
N/A
N/A
N/A
N/A
N/A
N/A
Full
UK
Affil
Full
Affil
Affil
Full
Full
Full
N/A
N/A
N/A
Full
Assoc
Affil
Full
Assoc
Affil
Affil
Affil
Full
Full
N/A
Franc
N/A
N/A
Affil
Full
Affil
N/A
N/A
Affil
Assoc
Full
Affil
N/A
N/A
Affil
Full
Full
Full
Full
US
Affil
IEC / UK
IEC/NEC
NEC
IEC/NEC
IEC
IEC
IEC / D
IEC / UK
IEC / UK
IEC / F
IEC / D
IEC
IEC
IEC
IEC / F
IEC / D
IEC
IEC
IEC
IEC
IEC / D
IEC
IEC / D
IEC
IEC
IEC/NEC
IEC
IEC / D
IEC
IEC / F
IEC / F
NEC
IEC / D
IEC
IEC
IEC
IEC
IEC
NEC
IEC / F
IEC / D
IEC / D
NEC
IEC
IEC / UK
IEC / D
IEC / UK
IEC / UK
NEC
NEC
IEC / D
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Uzbekistan,
Vanuatu,
Vatican City,
Venezuela,
Vietnam,
Virgin Islands (British),
Virgin Islands (USA),
Wales,
Yemen,
Zambia,
Zimbabwe,
220 V
230 V
230 V
120 V
220 V
110 V
110 V
230 V
230 V
230 V
240 V
50 Hz
50 Hz
50 Hz
60 Hz
50 Hz
60 Hz
60 Hz
50 Hz
50 Hz
50 Hz
50 Hz
C/F
I
C/F/L
A/B
A/C/D
A/B
A/B
G
A/D/G
C/D/G
D/G
N/A IEC / D
N/A IEC
N/A IEC / D
N/A NEC
Assoc IEC
US/UKNEC / IEC
US
NEC
UK
IEC / UK
Affil IEC / UK
Affil IEC / UK
Affil IEC /UK
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Tables
Table 1: Metric and AWG wire cross sections ....................................................................................44
Table 2: Main electrical symbols ........................................................................................................47
Table 3: Danger of electrical currents.................................................................................................69
Table 4: The voltage classification .....................................................................................................76
Table 5: Main features of the various earthing systems.....................................................................90
Table 6: Use of different metals in electric works .............................................................................112
Table 7: Classes of cables ...............................................................................................................115
Table 8: Accordance between Cables and Conduits ........................................................................125
Table 9: The ingress protection ratings (IP code) .............................................................................133
Table 10: Comparison between IEC 60898-1 and 60947-2 ..............................................................143
Table 11: utilisation categories of switchgears .................................................................................145
Table 12: Cable size - AWG to metric conversion ............................................................................156
Table 8:Heavy duty industrial IEC sockets .......................................................................................164
Table 14: iIlumination levels- facts and needs ..................................................................................169
Table 15: performances and typical specifications of various lighting systems .................................175
Table 16: Distribution capacity and power of user's devices.............................................................187
Figures
1. INTRODUCTION
Figure 1: Overview of priorities with linked threats and solutions........................................................18
2. REGULATORY FRAMEWORK
Figure 2: indication of standard references on an electrical device. ...................................................22
Figure 3: IEC Membership around the World .....................................................................................26
3. VARIATION OF STANDARD MODELS AROUND THE WORLD
Figure 4: Voltage and Frequencies around the World ........................................................................33
Figure 5: Examples of Voltage/ Frequency Data Plates .....................................................................34
Figure 6: Plug Types around the World ..............................................................................................35
Figure 7: The Metric and Imperial System around the World ..............................................................43
Figure 8: Example of Zone Identification for a Large Compound ........................................................50
Figure 9: Example of Room Numbering (Zone B within the Same Compound) ..................................50
Figure 10: Example of Zone Identification for a Large Building...........................................................51
Figure 11: Example of Room Identification Numbering (in zones A and B of the same building) ........51
Figure 12: identification of main panels ..............................................................................................53
Figure 13: identification of main lines .................................................................................................53
Figure 14: The Electrical Diagram of a Power Panel and Main Distribution Boards ............................54
Figure 15: identification of distribution panels.....................................................................................54
Figure 16: identification of intermediary panels ..................................................................................55
Figure 17: identification of final circuits...............................................................................................55
Figure 18: Identifications on a single line diagram ..............................................................................56
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Figure 19: example of a title block ..................................................................................................... 57
4. MANAGEMENT OF ELECTRICAL PROJECTS
Figure 20: The project development cycle ......................................................................................... 59
5. SAFETY OF INDIVIDUALS: TECHNICAL RULES
Figure 21: Current flow in case of a direct simple contact with live conductor .................................... 70
Figure 22: general principle of an equipotential bounding. ................................................................. 79
Figure 23 : Figure of a fault loop. ....................................................................................................... 79
Figure 24 : figure of a TT earthing system ......................................................................................... 82
Figure 25: principle diagram of a TT system ...................................................................................... 84
Figure 26 : Diagram of a TNC System. .............................................................................................. 85
Figure 27: diagram of a TNS System. ................................................................................................ 86
Figure 28: Diagram of a TNC-S System. ........................................................................................... 88
Figure 29: Use of underground links to improve the earth resistance. ............................................... 92
Figure 30: The use of earth leakage protection devices ..................................................................... 93
Figure 31: Detailed Symbol of a RCD ................................................................................................ 95
Figure 32: Mounting scheme of a RCCB ........................................................................................... 95
Figure 33: figure of a RCBO .............................................................................................................. 96
Figure 34: symbol of a residual current trigger device........................................................................ 96
Figure 35: mounting of a trigger RCD ................................................................................................ 96
Figure 36: Testing of a RCD .............................................................................................................. 98
Figure 37: insulated electrician handtools ........................................................................................ 102
Figure 38: statistics about fire origins .............................................................................................. 103
Figure 39: Process resulting in a fire ............................................................................................... 104
Figure 40: Map of the annual frequency of thunderstorms ............................................................... 105
Figure 41: Potential lightning sites on a landscape profile ............................................................... 106
Figure 42: area of protection of a lightning rod................................................................................. 106
Figure 43: Installation diagram of lightning protections accorded to protection zones ...................... 109
Figure 44: Modular surge protection device ..................................................................................... 109
6. EQUIPMENT: QUALITY AND USAGE REQUIREMENTS.
Figure 45 : several kinds of rigid cables ........................................................................................... 116
Figure 46: bending radius of cables ................................................................................................. 116
Figure 47 :Various types of flexible cables....................................................................................... 117
Figure 48: single conductor cable .................................................................................................... 118
Figure 49: various kinds of rigid and flexible pipes ........................................................................... 118
Figure 50: Features and uses of multiconductor cables ................................................................... 120
Figure 51: Shielded cables .............................................................................................................. 120
Figure 52: Armoured cables ............................................................................................................ 121
Figure 53: flat cables without coating ............................................................................................... 121
Figure 54: flat cables with coating.................................................................................................... 122
Figure 55: Flat cables with bare protective conductors are forbidden .............................................. 122
Figure 56: Flat cables with external coating and insulated protective ............................................... 122
Figure 57: Various types of junctions ............................................................................................... 127
Figure 58: junction of flexible wires inside of a junction box ............................................................. 128
Figure 59: Heavy duty screwed junctions ........................................................................................ 128
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Figure 60: Use of plastic block screwed junctions ............................................................................128
Figure 62: Straight crimp terminals ..................................................................................................129
Figure 61: Various types of crimp terminals .....................................................................................129
Figure 63: Crimping Plier .................................................................................................................129
Figure 64: Junctions inside of a generator. ......................................................................................129
Figure 65: Wiring of a breaker board ................................................................................................130
Figure 66: Earthing busbars .............................................................................................................130
Figure 67: Various types of earthing junctions..................................................................................131
Figure 68: Junction boxes ................................................................................................................134
Figure 69: Various types of cable glands .........................................................................................135
Figure 70: Various types of plastic boards .......................................................................................136
Figure 71: Steel enclosure for large boards......................................................................................137
Figure 72: Boards equipped with DIN rails .......................................................................................137
Figure 73: Fused switch disconnector ..............................................................................................140
Figure 74: Old model of a single disconnector .................................................................................141
Figure 75: "blade" change over switch .............................................................................................141
Figure 76: Disconnectors damaged by fire .......................................................................................141
Figure 77: MCCB (Molded Case Circuit Breaker) .............................................................................143
Figure 78: Manual change-over switch.............................................................................................146
Figure 79: Electro-Magnetic change-over switch ..............................................................................146
Figure 80: Automated change-over or Automated Transfer Switch (ATS) ........................................146
Figure 81: Standard size of MCBs and DIN rails ..............................................................................149
Figure 82: Modular or miniature circuit breakers (MCB) ...................................................................149
Figure 83: Various models of MCCBs ..............................................................................................150
Figure 84: Adjustment panel on a MCCB .........................................................................................150
Figure 85: Mandatory indications as per IEC 60947-2......................................................................151
Figure 86: tripping curves of circuit breakers ....................................................................................152
Figure 87: Tripping curve in case of a short circuit ...........................................................................153
Figure 88: Internal view of a circuit breaker ......................................................................................153
Figure 89: Terminals and flush mounting blocks ..............................................................................159
Figure 90: Apparent mounted terminals for outdoor use...................................................................159
Figure 91: "Ring Circuits" following the British Standards.................................................................160
Figure 92: Single switch disconnector for heavy loads .....................................................................162
Figure 93: Most common Heavy duty IEC "industrial" plugs and sockets .........................................164
Figure 94: The scale of the colour temperature ................................................................................170
Figure 95: Colour temperature of usual lighting sources ..................................................................170
Figure 96: The colour rendering index of usual lighting sources .......................................................171
Figure 97: typical usages related to CRI requirements .....................................................................172
Figure 98: Information data on lighting devices ................................................................................172
Figure 99: Automatic Voltage Switcher ............................................................................................177
Figure 100: Industrial voltage control relays .....................................................................................178
Figure 101: Low cost stabilizer .........................................................................................................179
Figure 102: Example of a 6kVA double conversion UPS ..................................................................179
7. RECOMMENDATION ABOUT SETUP DESIGN
Figure 103: Circuit rates compared to their actual loads...................................................................188
Figure 104: Circuit Breakers : choice of tripping curves and discrimination ......................................190
Figure 105: Examples of main cable routing ....................................................................................192
Figure 106: Grounding belt around a large building..........................................................................193
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Figure 107: Earthing wires and junctions ......................................................................................... 194
Figure 108: Earthing junction in buildings ........................................................................................ 195
Figure 109: placement of an grounding stake .................................................................................. 196
Figure 110: General layout of a distribution board ........................................................................... 198
Figure 111: Wrong cross section inside of a breaker board ............................................................. 199
Figure 112: Dividing the main protection of boards .......................................................................... 199
Figure 113: Using bus bars to feed breakers ................................................................................... 200
Figure 114: Arrangement of a trench for underground cable............................................................ 203
Figure 115: Warning tape over underground cables ........................................................................ 204
Figure 116: Manholes along a trench .............................................................................................. 204
Figure 117: Pipe arrangement to exit out of the ground ................................................................... 205
Figure 118: Use of square plastic trunking....................................................................................... 206
Figure 119: terminals incorporated into square plastic trunking ....................................................... 207
Figure 120: Various types of tube clips ............................................................................................ 207
Figure 121: Cable tray ..................................................................................................................... 208
Figure 122: Spaces reserved for embedded conduits inside of a room ............................................ 209
Figure 123: Zone division and safety levels into a bathroom............................................................ 214
Figure 124: Boards dedicated to fast deployment and provisional installations ................................ 217
Figure 125: 32A extension on a reel ................................................................................................ 217
Figure 126: Structure of a provisional distribution grid ..................................................................... 218
Figure 127: Boards and lightings used in provisional installations.................................................... 219
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Sources
IEC – International Electrotechnical Commission
US National Electrical Code
NF, BS, DIN Publications
Vinçotte : Household electrical installations
Schneider Group (Technical sheets)
ABB (Technical sheets)
Merlin Gerin : Technical Sheets
Legrand International guide
MSFF electricity support 2011
MSF OCG Electrical Safety Guide Line
MSF OCB Training document 2015
MSF OCB Memento of electrical systems protection
CICR - Electrical Safety Action Plan
CICR – Protocol for the Management of Construction Projects
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