ElectricalDesignGuideforthedevelopingworld
Developed and Compiled by Andy Engebretson, P.E. Staff Engineer Engineering Ministries International With Contributions from Jim Cathey, Kirk Singleton, Ed Lobnitz, Ruedi Tobler, Bob Gresham, Bill Wright, Larry Bentley Revised November 2014 1. Table of Contents
2. Introduction ................................................................................................................................ 2
3. Questions To Consider Before & During an EMI Trip ..................................................................... 3
4. Typical Electrical Design ............................................................................................................... 4
4.1 Electrical Symbols ......................................................................................................................... 4
4.2 Single line Diagram ....................................................................................................................... 4
4.3 Electrical Load Study..................................................................................................................... 4
4.4 Site Electrical Plan and Panel Schedules ...................................................................................... 5
4.5 Building Wiring Diagrams ............................................................................................................. 7
4.6 Panel Schedules ............................................................................................................................ 7
4.7 Circuit Breaker and Wire Size Determination .............................................................................. 8
4.8 Voltage Drop Calculation .............................................................................................................. 8
4.9 Grounding and Bonding................................................................................................................ 9
4.10 Written Report ............................................................................................................................. 9
5. Solar Design .............................................................................................................................. 10
5.1 Solar Sizing Concepts .................................................................................................................. 10
5.2 Rough Cost for Solar Equipment ................................................................................................ 10
6. Hospital Electrical Design ........................................................................................................... 11
6.1 Equipment List ............................................................................................................................ 11
6.2 Equipment Frequency Considerations ....................................................................................... 11
6.3 Air Conditioning and Heating ..................................................................................................... 11
6.4 Code Requirements .................................................................................................................... 11
6.5 Transfer Switches ....................................................................................................................... 12
6.6 Other Systems ............................................................................................................................ 12
Reference Documents
EMI Pre-Trip and During Trip Questions
Electrical Voltage & Output Worldwide Standards
EMI Diesel Generators Overview
EMI Electrical Power Density and Load Demand
Factors
EMI Electrical Report Example
EMI Site Electrical Load Study Example
EMI Solar vs Generator vs Utility Cost Comparison
EMI Wire Chart
Ground Conductor Sizing
Ground Rod Detail
Grounding & Bonding Diagram
World Solar Isolation Maps
Reference Drawings
Electrical Legend
Electrical One-Line Diagram
Generator Room Electrical Plans
Panel Schedules - MDP, PPG, PPPH
Panel Schedules - PPA, SPAG
Electrical Site Plan
Basement Lighting Wiring Diagram
Basement Power Wiring Diagram
Ground Floor Lighting Wiring Diagram
Ground Floor Power Wiring Diagram
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2. Introduction
Electrical Engineers on an EMI trip can expect to encounter a variety of unique design challenges that will
require creativity, flexibility and good engineering judgment. EMI projects are all different and it would be
impossible to try and address every design challenge that could be encountered. Therefore, this design
guide is created to give the designer an idea of the general format of an EMI electrical design. This design
guide will provide a lot of helpful information, but the designer must do their own research prior to the
trip and while on the field and use their best judgment based on the information gathered during the trip.
Data collected in the field that is different from this design guide shall take priority so long as safety of the
public is maintained. Numerous supplemental documents and drawings are referenced throughout this
design guide (see ‘Reference Documents’ and ‘Reference Drawings’).
Some countries have no established electrical code, so many of the design principles presented in this
document are adapted from the NFPA 70 National Electrical Code and are believed to be in accordance
with sound design. However, if there is any variance from any governing codes applicable to the site
location, the governing codes take priority and the installation shall follow the latest edition of those
codes regardless of any and all specifications explicitly or implicitly set forth in this document.
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3. Questions To Consider Before &
During an EMI Trip
Prior to embarking on an EMI trip the electrical designer should become familiar with the resources in this
design guide. The document labeled ‘EMI Pre-Trip and During-Trip Electrical Engineer Questions’ is a list
of questions that will help the designer understand and gather the pertinent information prior to and
during the time in-country.
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4. Typical Electrical Design
The example design in this design guide describes the basic elements of an EMI electrical design and
includes drawings and calculations.
4.1 Electrical Symbols
The drawing labeled ‘Electrical Legend’ shows the typical symbols that are used to represent electrical
devices. This is not an exhaustive list, so the designer may need to research the appropriate symbol if
it is not included on this drawing. Also, if the designer is able to acquire a local electrical drawing and
the symbols are different than shown on the EMI drawing, the symbols on the local drawing should be
used.
4.2 Single line Diagram
The drawing labeled ‘Electrical Single line Diagram’ shows a typical graphical representation of an
entire electrical system. A Single line is usually one of the first drawings created in a design as it
captures the information on an existing system and helps the designer quickly see how a system can
be modified. Power sources are shown at the top of the page and the loads are at the bottom. The
two power sources in this example are the public utility and a backup generator. A manual transfer
switch is used to transfer between the two sources.
The public utility through a transformer is the primary power source for the site. The transformer is
sized to accommodate the loads for the Phase 1 and Phase 2 buildings (see ‘EMI Site Electrical Load
Study Example’ for a description of the loads). Although the generator is the backup power source for
the entire site, it is only large enough to handle the Phase 1 loads. The client will need to upgrade the
generator or select the loads for which the generator will provide backup power (up to 100kW) when
Phase 2 is built. If the client had requested that only certain loads be included on the backup
generator, separate circuits and panels would need to be designed for the loads on back-up power.
Wire and breaker sizes to the Main Distribution Panel (MDP) and the main building panels (PPA and
PPPH) are shown on the single line diagram. The panels and sub-panels in each building are labeled
and shown in more detail on the ‘Wiring Diagram’ and ‘Panel Schedules’ drawings.
4.3 Electrical Load Study
Early in the design cycle a site electrical load study should be created to give the designer and the
client an idea of the overall size of the electrical system. The ‘EMI Electrical Load Study Example’
summarizes the loads for the facility being used as an example in this design guide. The design is
separated into Phase 1 and Phase 2. Phase 1 includes the first two levels (basement and ground
levels) of the accommodations building and all the site lighting and soccer field lights. Two additional
floors will be added to the accommodations building in Phase 2.
The general load for the building is calculated by multiplying the area of the building by the power
density for lights and outlets for a particular facility (see ‘EMI Electrical Power Density and Load
Demand Factors’ for power densities). These load densities are general guidelines and may not be
appropriate in some countries. The designer should try to measure lighting densities for similar
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facilities in the area and match the design to these. The “special loads” for each building are specified
in the last column and are calculated by multiplying the number of “special loads” (indicated in
parentheses) by their respective power consumption found in the ‘Device Power Consumption’ table
at the bottom of the spreadsheet. The maximum demand is the sum of the “general” and “special
loads”.
Once all the loads have been calculated, a demand factor must be applied. Referring again to the ‘EMI
Electrical Power Density and Load Demand Factors’, a 50% demand factor should be applied to all
“general loads” over 3kVA (apply 75% for hospitals) and a 100% demand factor to “special loads”. In
this example, a 75% demand factor is applied to the special loads because the client specified that no
more than 75% of the air conditioners (which are classified as “special load” devices) would be used
simultaneously. Pumps are listed below the demand factor and 100% of their load is added to the
total demand.
4.4 Site Electrical Plan and Panel Schedules
The drawing labeled ‘Site Electrical Plan’ shows all the main feeder cables and their routing on the site
in addition to all the site lighting. The names and locations of the main panels (MDP, PPG, PPA and
PPPH) are also specified on the ‘Site Electrical Plan’.
The drawing labeled ‘Generator Room Electrical Plans’ is a basic layout for the generator building and
shows the location of the MDP, PPG and Transfer Switch.
The drawing labeled ‘Panel Schedules – MDP, PPG, PPPH’ shows the layout of the main distribution
panel (MDP), the Generator power panel (PPG), and the pump house power panel (PPPH). The MDP
specifies all the main breakers feeding the subpanels. Picture 1 shows an example of a main
distribution panel layout.
Figure 1: MDP Layout
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PPG is a single phase panel schedule called a consumer unit (see Figure 2 below). Consumer units are
common in countries that have had European influence. The breakers mount to a din rail and the
main breaker feeds power to the branch circuit breakers through jumper wires or jumper bars.
Figure 2: PPG
PPPH is a three phase panel schedule. Picture 3 shows a three phase panel with the main breaker at
the bottom of the panel. Three phase panels can either contain bus bar like the one below, or they
may look more like the consumer unit with jumper wires or jumper bars connecting the main breaker
to the branch circuit breakers.
The load calculations for individual panels are described in section 4.6 ‘Panel Schedules’
Figure 3: PPPH
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4.5 Building Wiring Diagrams
The building wiring diagrams (see drawings ‘Wiring Diagram - Basement’ and ‘Wiring Diagram Ground Floor’) show the general location of all the electrical devices and how they are connected
together. The home runs to the panel board are also shown on the wiring diagrams. Each floor plan
will have two sheet of electrical wiring to avoid overcrowding the drawing. One sheet shows the
lighting wiring and the second shows the power wiring.
4.6 Panel Schedules
The drawing labeled ‘Panel Schedules - PPA, SPAG’ shows two typical three-phase panel schedules and
PPG is a typical single-phase panel schedule. PPA is the main panel schedule for the building and is
located in the Basement Worker’s Room. SPAG is the ground floor subpanel and is located in the
ground floor janitor room as shown on the building wiring diagrams. At the top of the panel schedule
all the pertinent information about the panel is displayed (Mark, Location, Main Breaker etc.). The
middle of the panel is a graphical representation of the 3-Phase bus bars and their connection to each
circuit breaker. Circuits #1, 3, 5 on panel PPA are shown with a line connecting them together to
represent a 3-phase circuit breaker. The total power consumption of the 3-Phase loads is evenly
distributed across the three phases. For example the total load on SPAG is 27.498kVA, or 9.166kVA
per phase. The wire size, circuit breaker size (CB Trip), load size (Wattage) and a description of the
equipment being served by that circuit are all shown on the panel layout.
The load on each circuit is calculated by summing up the power consumption of all the electrical
devices connected to that circuit. For example, circuit #2 on panel PPA is feeding two single phase air
conditioners for the small classrooms in the basement of the Accommodations. Each air conditioner is
rated at 1,232VA and they are connected to phase A, so 2,464VA is the value placed for phase A on
circuit #2.
PPA is a main panel with sub-panels connected to it so the total load on the panel is calculated in the
table labeled ‘Electrical Calculations (Accommodations)’ (reference spreadsheet ‘Panel Schedules PPA, SPAG’). The general load is calculated by multiplying the area of the building (the basement and
ground floors) by the power density for lights and outlets (reference ‘EMI Electrical Power Density and
Load Demand Factors’). A 50% demand factor is then applied to the general load. The special loads
are calculated and a 75% demand factor is applied to them. Usually special loads do not have a
demand factor applied, but in this case the client specified that no more than 75% of the “special
load” devices (primarily air conditioners) would be used simultaneously. The future loads are
estimated and added to the general and special loads to get the net total. In order to find the main
circuit breaker size for the panel, the current is calculated and multiplied by 1.25 in order to avoid
nuisance tripping. The next standard breaker size is then selected as the main breaker for the panel.
When significant loads will be added to a panel in the future, it is advisable to design panels, breakers
and wire sizes for future loads so that panels, breakers and wires do not have to be replaced when
future phases are added.
The ‘Summary’ table shows the total load (kVA) and current (Amps) on each phase. The total load on
the ‘Summary’ table will be larger than the ‘Electrical Calculations’ table because it does not include
the demand factor. The primary purpose of the ‘Summary’ table is to ensure that each phase has a
similar amount of load on it, thus creating a balanced load.
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4.7 Circuit Breaker and Wire Size Determination
In order to demonstrate how to determine the circuit breaker and wire sizes, circuit #2 on panel PPA
will be used as an example. The total load for circuit #2 on panel PPA in the drawing labeled ‘Panel
Schedules – PPA, SPAG’ is 2,464VA. The circuit breaker size and wire size can now be determined by
calculating the maximum current through the circuit:
Before selecting a breaker size, a safety factor of 25% should be applied to the maximum current to
avoid nuisance tripping:
The next standard breaker size larger than the final current calculated is then selected for the circuit.
In this case a 15Amp breaker would suffice. Circuit breakers generally come in standard sizes, so
during the trip the designer should determine the standard sizes available in the area.
With the breaker size selected, the wire size for the circuit must now be determined by referencing
the ‘EMI Wire Chart’. The circuit breaker is protecting the wire, so wire that is able to carry 15Amps of
current or more should be used on this circuit. In this example, 2.5mm2 wire was selected because
column 3 of the EMI Wire Chart shows that 2.5mm2 copper wire is capable of carrying 22 amps.
The same calculation above can be followed for the three-phase loads except the voltage would be
the phase to phase voltage (380V) and the current is calculated as follows:
The remainder of the EMI Wire Chart is explained as follows: Column 1 shows the American Wire
Gauge (AWG) sizes. Most countries use mm2 for wire sizes as shown in column 2. Column 3 shows
the current rating of copper wire that has an insulation rating of 75℃ since this is the most commonly
used wire internationally. Column 4 shows the current rating of aluminum wire with a 75℃ insulation
rating. The resistance factor used to calculate voltage drop is listed in column 5 and the physical
characteristics of the wire are shown in columns 6-10.
4.8 Voltage Drop Calculation
Voltage drop must be calculated in situations where the circuit conductors span large distances. If the
voltage drop is too great (greater than 4%), the conductor size must be increased to maintain the
voltage and current between the points. The calculations for a single-phase circuit and a three-phase
circuit are slightly different.
Single-phase voltage drop calculation:
D
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D
D%
S
RCE
Three-phase voltage drop calculation:
D
D
D%
S
VD
VD%
L
R
I
VSOURCE
RCE
= Voltage drop in Volts
= Percentage of voltage drop, but is commonly called “voltage drop”
= One way length of the circuits feeder (in meters)
= Resistance factor of the wire in ohms/kilometer (see EMI Wire Chart)
= Current in Amps
= Voltage of the circuit at the source of power (i.e. 110, 220, 380 V …)
If we continue with the example above using circuit #2 in panel PPA on drawing ‘Panel Schedules PPA, SPAG’ and assume a distance of 40 meters from the panel to the air conditioners and a 2.5mm2
wire, the voltage drop would be:
D%
Since the voltage drop is less than 4% on this branch circuit the wire size chosen is adequate.
4.9 Grounding and Bonding
The Reference Document ‘Ground Conductor Sizing’ shows the size of the ground conductor needed
for the corresponding feeder conductors. The ‘Ground Rod Detail’ shows a typical ground rod
installation, and the ‘Grounding & Bonding Diagram’ identifies the components of a grounded system.
4.10 Written Report
The document ‘EMI Electrical Report Example’ is an example of the electrical section of an EMI report.
Typically, the electrical section of the report is around 1-3 pages in length and should be a high-level
summary of the designers intent. The report should not include technical details, but should only
reference drawings and spreadsheets for the technical details. A copy of the EMI Site Electrical Load
Study should also be included in the report as an Appendix.
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5. Solar Design
5.1 Solar Sizing Concepts
When sizing solar panels for a system, one must first determine the total system energy needs (Et =
Watts x Time) per day. This energy must be harvested during the window of usable sunlight (about 7.5
hours at a latitude of less than +/-15 degrees). The Reference Document labeled ‘World Solar
Insolation Maps’ shows the equivalent sun hours on the surface of the earth. The system efficiency is
about 70%, so the solar panel wattage (P) is estimated as:
P = Et / (7.5 x 0.7)
Charge controllers must be sized to match the solar panel wattage, P. Inverters must be sized to
match the maximum power demand expected at any point during the day.
Batteries must be sized to store the total energy (Eb = watts x time) required outside the solar harvest
window. Since a battery efficiency of about 80% is typical, and since a deep cycle battery can be safely
cycled to about 50% depth of discharge (DOD) the battery bank W-h rating is estimated as:
W-h = Eb / (0.8 x 0.5)
A 100 A-h, 12V battery is a 1200 W-h battery.
5.2 Rough Cost for Solar Equipment
The following table is a rough estimate of the cost of the equipment needed in a typical solar system
(Year 2011 Values). These costs are for the USA, so 30% may need to be added in other countries.
These costs should be checked with a local distributor while in country. Also add about 20% of system
cost to cover solar panel mounts, battery racks, wiring and switch gear.
Item
Cost
Solar panels
3500 $/kW
Charge Controller
300 $/kW
Inverter
800 $/kW
Batteries
200 $/kW-h
Many Ministries would like to know how much a solar system would cost compared to the utility or
using a generator. The document called ‘EMI Solar vs Generator vs Utility Cost Comparison’ can be
used to calculate a rough estimate of the initial and on-going cost of each system. The cells
highlighted in yellow are the variables the designer must input for the specific project. The graph
shows the cost of each system over 25 years. The steps in the solar cost graph represent the purchase
of new batteries every 5 years.
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6. Hospital Electrical Design
6.1 Equipment List
A major part of hospital/clinic design deals with providing the correct voltage, phase, ampacity,
frequency and location for each piece of equipment. An equipment list and specifications from the
client is extremely important. This list usually requires some research, consulting and guessing by the
owner but it must be part of the design and documentation. The equipment list is also needed by the
other design team members for A/C requirements, plumbing requirements, architectural space needs,
structural considerations, etc.
Specialized equipment in hospitals and clinics is much more extensive than any other type of facility
design. In addition to the equipment, special room layouts, lighting and accessories will be required.
Equipment suppliers should be contacted for these special pieces of equipment and wiring layouts.
Examples of equipment in this category are: CAT Scans, X-Rays, MRI’s, .R. Exam Lights, O.R. special
equipment (ie. portable x-ray), Laboratory Equipment, and Intensive Care Suite special equipment (ie.
monitoring equipment).
6.2 Equipment Frequency Considerations
Equipment frequency (50Hz vs. 60Hz) must be clarified before design can proceed. Equipment is often
donated from the US with 60Hz requirements but at the same time the client will also want to use
local 50Hz equipment. If the utility service frequency is 50Hz, motor-driven 60Hz equipment will not
work unless a 50 to 60Hz converter is used. The equipment list should indicate where the equipment
is to be obtained to force a decision on frequency. In addition, equipment designed by the team must
specify the correct frequency depending on where it will be purchased/donated.
6.3 Air Conditioning and Heating
Air Conditioning and Heating are often the largest load requirement in a hospital or clinic, so it is
important to determine which areas specifically will be air conditioned, heated and ventilated and
what type of equipment will be used (window units, split systems, central systems, ceiling fans, etc.).
6.4 Code Requirements
NEC (NFPA 70), Article 517 – Health Care Facilities should be reviewed before the site visit. It may not
be possible, or desirable, to follow this code exactly, but it should be used as a basis of design. Any
downgrades from the code should be discussed with the client. For instance, providing only one or
two emergency branches instead of three may make sense for a small rural hospital, or the use of
fewer outlets per patient bed may make sense if minimal patient support equipment will be available
for plug-in.
Another standard that should be reviewed prior to the site visit is NFPA 110 – Standard for Emergency
and Standby Emergency Systems. When designing a generator for a site, this standard should be
followed as much as possible. In addition, a wealth of information is available on the internet from
generator manufactures regarding physical sizes, air supply requirement, clearances, heat dissipation,
EMI Electrical Design Guide
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etc. Caterpillar, Kohler and Cummins are all good sources. The generator voltage, phase and
frequency must match the system design parameters.
6.5 Transfer Switches
Transfer switches for a hospital should be of the automatic type in lieu of manual if the cost will allow.
Upon loss of power, which may be quite often in some locations, a generator can start and be on-line
within 10 seconds with an automatic transfer switch. This may be critical to some patients and
medical procedures. In some cases the generator will need to be used as “Base Power” and the utility
as backup due to totally unreliable utility power. In this case automatic switching will definitely be
required.
6.6 Other Systems
Several other systems may be requested by the client and will need to be addressed in some manner
by the engineer. These include: automatic or manual fire alarm system; nurse call systems; security
systems (usually cameras and door controls); data network and server systems; telecom systems;
satellite transmitting and receiving systems; electronic record-keeping systems; exit lighting; doctor’s
paging and others. Usually EMI Engineers do not have the time or, in some instances, the knowledge
to design these types of systems, but if the client requests any of the systems, they should be dealt
with in the project report in some manner. The most efficient way to handle these designs is to send
the floor plans to a manufacturer’s representative and ask for a design layout and cost to include in
the report (except possibly for the exit lighting which the engineer should be able to design). If a local
manufacture’s representative can be found for any of these systems, they should be given preference
to help and encouraged to be involved. Local service of these systems will be critical to their
operational longevity.
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Reference Documents
EMI Pre-Trip and During-Trip Electrical Engineer
Questions
Table of Contents
1. Before Trip .............................................................................................................................. 2
1.1. Power Requirements ........................................................................................................ 2
1.2. Solar Data......................................................................................................................... 2
1.3. Wind Data ........................................................................................................................ 2
1.4. Equipment to Bring .......................................................................................................... 2
2. During Trip.............................................................................................................................. 2
2.1. Sites with Existing Electric Infrastructure ....................................................................... 2
2.2. Sites to Add Local Electric Service ................................................................................. 4
2.3. Sites to Add a Generator .................................................................................................. 5
2.4. Planned Electrical Load Information ............................................................................... 5
3. Project Specific Information .................................................................................................. 7
4. Alternative Energy System Planning .................................................................................... 7
4.1. Solar Question List .......................................................................................................... 7
2
1. Before Trip
1.1. Power Requirements
Reference EMI Electrical Power Density and Load Demand Factors.doc as a guide for
estimating the value for the total electric service power requirement for your project.
1.2. Solar Data
Collect solar data for location (see World Solar Insolation Maps.pdf).
1.3. Wind Data
Collect wind data for location
1.4. Equipment to Bring
a)
b)
c)
d)
e)
Multi-meter (if possible with min, max, and avg. recording capabilities)
Amp-clamp
Calipers to measure the diameter of a wire
Multi-purpose tool (i.e. Leatherman)
Camera to document transformers, generators, panel locations, etc.
2. During Trip
Find out the cost of electricity per kW-hr. If you can get any costs per kW-hr for energy
supplied from the local utility, this information might be useful if there is any need to make
any kind of economic tradeoff comparison.
2.1. Sites with Existing Electric Infrastructure
If there is any existing electrical infrastructure, the tedious task of documentation is
necessary.
a) A rough sketch of existing buildings is needed - not architectural quality. Show
doors, but windows are not necessary. Only major room dimensions are needed to
about 5% accuracy. Somewhere in each room sketch, jot down the number of lights
with wattage, the number of outlets and the number of fans (if any). The locations
of these items are not needed.
b) If one of these buildings is a dining hall, document any electrical appliances in the
dining hall - especially any fridges, freezers, electric water heaters, or electric
stoves.
3
c) If there is an existing laundry area, document the number of electric washing
machines, electric dryers and electric irons in use.
d) If there are any air conditioning units, electric heating, bore-hole pumps or other
electrical motor loads, record name plate data and document locations on the site.
e) Indicate the locations of any power panels on the building sketches. Take a
photograph of these panels. If the breaker ratings do not show clearly on the panel
photos, record these values. Be sure to develop an identification scheme to
associate the panel photos with the located building.
f) Document the earthing (grounding) method for the main power panel. Earth rod?
Wire size? Check on any panels beyond the main power panel to document how
earthing is handled.
g) Although this may be a challenge, documentation of the electrical distribution
scheme for the existing buildings is needed. If an electrician familiar with the site
can be found, he would be an invaluable friend who could make this task simple. A
feed from the electric utility probably runs to a power panel in one of the buildings,
and then is distributed from that panel to the other existing buildings. A crude
sketch documenting the electrical feed entry point and its interconnection to
buildings is the goal.
h) Is the service drop overhead or underground?
i) Information on the incoming electrical feed is needed. It probably runs to a
transformer mounted in a pole along a road somewhere in the vicinity of the site. If
at all possible, determine the rating (kVA) of that transformer. Also, try to
determine the size of the electrical cable used for this feed. Make a reasonable
estimate of the length of this cable run from the transformer to the site connected
building.
j) Ask the ministry to give you copies or allow you to photograph any electrical
drawings that they have for the site. If you can obtain any such information, it
would be of great value.
k) If possible, a design goal should be to feed the existing electrical system from a
panel that is part of the new electrical system design.
l) If there is a generator, get complete nameplate data on it - voltage, kVA or kW
rating, power factor, three-phase or single-phase and primary or standby rating.
4
m) If there is an existing bore-hole pump, try to get name plate data.
2.2. Sites to Add Local Electric Service
If the site presently has no electrical service, but plans to request service, there are
several issues to explore.
a) Where is the closest utility power line?
b) Where will the electrical service enter the site?
c) Is a transformer already installed from which the service would be supplied? If it is
already installed, obtain Voltage and kVA rating on the transformer.
d) If there is no transformer, will the electric utility company pay for the new
transformer and to run the lines to the property?
i. If the ministry has to purchase the transformer, prices may range from $US
40-70 per kVA. (Year 2011 values).
e) Will the ministry quickly need any preliminary electrical plan to initiate the
application for electrical service? If so, determine the level of detail.
f) Does the local utility just offer service to certain customers for certain hours during
the day – in other words, rolling blackouts?
g) Is the local utility supplied service single-phase or three-phase? Determine the
voltage (see Electrical Voltages & Outlets Worldwide.pdf).
h) Find out if the local utility has rules, limits, or price breaks on levels of service per
service drop. It might be possible that multiple utility service drops are advisable.
i) Are there any national or local electrical codes to be satisfied? Are there any
government inspections to be made? If so on either count, find out all the
information available about the processes.
j) Is site electrical power distribution to be underground or overhead?
k) If underground distribution is to be used, ask if they use metallic shielded cable or
PVC conduit for direct burial.
l) Find out what standard circuit breaker sizes are readily available.
5
2.3. Sites to Add a Generator
a) Is there already a generator on the site? If so, record complete nameplate data and
photo document the generator unit and the associated generator house.
b) If a new generator is to be installed, identify a suitable spot for a generator house
(see EMI Diesel Generators Overview.doc). Ideally it needs to be 200 ft or less
from the most distant point of electric service to minimize voltage drop problems.
The building would need truck access to deliver diesel fuel. Noise emissions are
principally from one side of generator house, but it could be irritating to those on all
sides if sound-proofing is not used.
c) If the purpose of the generator is for backup power, will it be used for total site
backup or will it be used for certain loads deemed to be critical loads? If the latter,
get a clear definition of these critical loads.
d) The cost of an installed generation will probably be in the range of US$ 250-400
per kW plus an additional US$ 5000 -10000 for control panels. (Year 2011 values)
e) If any information on the cost of any recently delivered multi-kW diesel generator
set in the area can be found, this would be good information to know.
f) The fuel consumption for the diesel engine will be about 0.07 gallons per kW-hr.
Thus, a 50 kW load for 12 hrs per day with $5 per gallon diesel fuel costs $210 per
day. (Year 2011 values)
g) In addition to fuel, the engine will require an oil change (maybe 2-3 gal) and a filter
change each 100-150 hours of operation. A major engine overhaul will be required
every 25-30,000 hours of operation. There will be other expenses for operating an
engine – a mechanic on site would reduce these expenses.
h) Will there be a person on site with primary responsibility to keep the generator and
electric system properly functioning?
2.4. Planned Electrical Load Information
a) Obtain best estimates of walled square footages for the purpose of electrical load
planning.
b) Local practice on illumination power density needs to be determined and compared
to the EMI Electrical Power Density and Load Demand Factors.doc. Observe the
installed lighting wattage and roughly measure the floor area to determine the
W/sq-m illumination power density for some typical existing building in the site
neighborhood that has a living or dining area. Similarly, determine the illumination
power density for an office or library area.
6
c) What types of light bulbs will be used? Fluorescent tubes (length and wattage)?
Compact fluorescent lights (wattage)? Incandescent bulbs (wattage)?
d) Is there any air conditioning, electric heating (direct or furnace), or electric water
heating planned? If so, document specific locations. Get best description possible
of the power these devices consume.
e) Is a kitchen planned? If so, get all the information possible on the electric
appliances to be installed - quantities and sizes.
f) Will there be any pumping loads for fresh water or for sewage treatment facilities?
g) For a medical clinic, identify electrical medical equipment planned - especially such
items as X-ray machines and sterilization equipment.
h) If a water well is to be drilled on the site, find out the expected depth of the well,
the height of the storage tank above the well head, and the total daily water usage
anticipated for the purposes of sizing a pump. This information is needed to
determine the power requirement for the pump.
i) If laundry facilities are planned, document the number of any electric washing
machines, electric dryers, or electric irons anticipated?
j) If there are some administrative offices planned, identify anticipated types and
quantities of the electrical office equipment - PCs, printers, copiers, etc.
k) Determine the nature of desired security lighting around the site. Do they plan to
use street lights? Do they want motion activated lights around the entrance areas of
buildings?
l) If you are able to talk with an electrician or electrical contractor, ask if they wire
with Ring Circuits or with Radial Feeds in building wiring. Also, ask if they
specify their electrical wiring by the standard European sq mm sizes?
m) If possible, take some close-up photos of electrical plug receptacles (they may call
them outlets). It would be nice to know their particular plug pattern. Although that
information does not have to be specified on the wiring diagram, it is a clue as to
how close to they hold to the British standard (see Electrical Voltages & Outlets
Worldwide.pdf).
n) If possible, take some close-up photos of power panels in the area, both three-phase
and single-phase. Of special concern is the single-phase power panel. If there is
British influence, they may use what is called a Consumer Unit – breakers mounted
horizontally on a DIN rail. This information will allow use of the appropriate panel
template in the design work.
7
o) Assuming that there is to be indoor bath rooms in the project, check on a couple of
things that would be British practice related.
i. Are the plug receptacles inside the bathroom required to be special receptacles
called “Shaver Outlets” with transformer isolation?
ii. Are lights in the bathroom required to be either controlled by a switch located
outside the door or by an insulated pull-cord?
3. Project Specific Information
All eMi projects are different, thus a general question list will not address all the issues. For
example, there might be light manufacturing facilities, a hospital, or other operations that
have electrical service requirements beyond the scope covered by this document. In such
cases, the EE volunteer should do appropriate research in advance of the project trip to
prepare questions to properly gather information for the design phase.
4. Alternative Energy System Planning
Discussion might arise concerning the use of photovoltaic (PV) generation or wind
generation for backup electrical power since these two methods have low operating costs. PV
generation has a fairly prohibitive initial cost - say around US$ 6-7000 per KW (Year 2011
Values). Rarely will a site have the average wind speed to make wind generation feasible.
Unless the trees list at about 15 degrees from withstanding sustained winds, wind generation
probably will not be feasible. The annual average wind speed for the site should exceed 15
mph before wind generation should be considered.
Since PV generation is the more common alternate energy consideration for eMi projects, the
following planning guide may be found useful in explaining the costs associated with a solar
system. If the ministry definitely wants a solar system, then the items on the Solar Question
List should be addressed during the project trip.
4.1. Solar Question List
a) Get a clear definition of the loads to be operated during the solar harvest window
from about 8:30 am to 4 pm (the harvest window may be shorter for latitudes
greater +/- 15 degrees). This is a power-time profile – specific loads and time of day
for which each load exists (see World Solar Insolation Maps.pdf).
b) Get a clear definition of the loads to be operated outside of the solar harvest
window from about 4 pm to 8:30 am. This is a power-time profile – specific loads
and time of day for which each load exists.
c) Water pumps can be a challenge for operation on a solar system. The best approach
will be to use a small DC pump especially designed for solar power operation and
to operate the pump only during the solar harvest window. Otherwise, batteries will
8
have to be sized to handle the pump operation, thus significantly increasing the
capital outlay.
d) How would the ministry choose to handle cloudy days? If electrical service is to be
provided on cloudy days, then sufficient batteries would have to be installed to
provide the energy needs for the span of sunless days. Also, sufficient solar panels
would have to be installed to harvest the extra energy to be stored. Provision for
electric service for a single cloudy day could easily double the system cost; a twoconsecutive cloudy day contingency could easily triple the system costs, etc.
e) Batteries have approximately a 5 year life, thus this ongoing operational cost should
be understood. Also, battery terminals need to be cleaned about every 6 months.
Battery voltages need to be checked periodically – say once per month. Panel tilt
angles need to be seasonally adjusted for maximum efficiency.
f) A location for solar panels must be identified wherein there will be no blockage of
incident sunlight during the solar harvest window. Solar panels may need to be
washed down after dusty conditions. Keeping the solar arrays near the Power
Center is best as voltage drop in connection cabling can be a design issue.
Magellan's Adaptor Plugs:
Afghanistan
Albania
F
D
220/50 D
EA23MFG
EA351D
EA351D
EA23MFG
EA23MDG
EA23MDG
Algeria
220/50
Andorra
Angola
Antigua
EA23MFG
EA23MDG
EA23MDG
Argentina
220/50
220/50
230/60
110/60
220/50
Armenia
Australia
Austria
Azerbaijan
220/50
240/50
220/50
220/50
Bahamas
Bahrain
120/60
220/50
Bangladesh
220/50
Barbados
Belarus
Belgium
Belize
Benin
115/50
220/50
230/50
110/60
220/60
220/50
Bermuda
120/60
Bhutan
220/50
EA23MFG
EA351D
EA351D
EA351D
EA351C
EA351A
EA351E
EA351D
EA351D
EA351E
EA351D
EA351D
EA23MFG
EA351A
EA351C
EA23MFG
EA23MFG
EA351D
EA351C
EA351A
EA351A
EA351D
EA351D
EA351A
EA351C
EA23MFG
EA351D
EA351C
EA351A
EA23MFG
EA351C
EA351D
EA351A
EA351D
EA351D
EA351C
EA23MFG
EA351A
EA351D
EA351C
EA351D
EA351D
EA351C
EA351D
EA23MFG
EA351D
Bolivia
Bosnia/Herzegovina
Botswana
Brazil
220/50
110/50
220/50
220/50
220/50
Brunei
Bulgaria
Burkina Faso
Burma
110/60
220/60
240/50
220/50
220/50
220/50
Burundi
220/50
F
D
D
D
C
A
E
D
D
E
D
D
F
A
C
F
F
D
C
A
A
D
D
A
C
F
D
C
A
F
C
D
A
D
D
C
F
A
D
C
D
D
C
D
F
D
1
EA23MCG
EA23MAG
EA23MEG
EA23MDG
EA23MDG
EA23MEG
EA23MDG
EA23MDG
EA23MFG
EA23MAG
EA23MCG
EA23MFG
EA23MFG
EA23MDG
EA23MCG
EA23MAG
EA23MDG
EA23MDG
EA23MAG
EA23MCG
EA23MFG
EA23MDG
EA23MCG
EA23MAG
EA23MFG
EA23MCG
EA23MDG
EA23MAG
EA23MDG
EA23MCG
EA23MFG
EA23MAG
EA23MDG
EA23MCG
EA23MDG
EA23MDG
EA23MCG
EA23MDG
EA23MFG
EA23MDG
Guyana
120/50
240/50
Haiti
Honduras
Hong Kong
110/60
110/60
230/50
Hungary
Iceland
India
220/50
220/50
230/50
Indonesia
Iran
Iraq
220/50
110/50
220/50
220/50
Ireland, Northern
Ireland, Republic of
Israel
Italy
220/50
230/50
230/50
220/50
Ivory Coast
Jamaica
Japan
Okinawa Prefectorate
220/50
110/50
100/60
100/60
Jordan
220/50
Kampuchea
220/50
110/60
Kazakhstan
Kenya
220/50
220/50
Kiribati
220/50
110/60
220/50
110/60
110/60
220/60
240/50
1
1
1
1
1
Korea, Dem.
1
Korea, Rep.
Kuwait
1
Kyrgyz Rep.
Laos
220/50
220/50
Latvia
220/50
C
A
F
A
A
C
F
D
D
F
C
D
D
EA351C
EA351A
EA23MFG
EA351A
EA351A
EA351C
EA23MFG
EA351D
EA351D
EA23MFG
EA351C
EA351D
EA351D
D
C
D
F
C
C
D
D
EA351D
EA351C
EA351D
EA23MFG
EA351C
EA351C
EA351D
EA351D
D
A
A
A
E
C
D
F
D
A
C
D
C
F
E
A
D
A
A
D
C
D
F
D
A
D
D
EA351D
EA351A
EA351A
EA351A
EA351E
EA351C
EA351D
EA23MFG
EA351D
EA351A
EA351C
EA351D
EA351C
EA23MFG
EA351E
EA351A
EA351D
EA351A
EA351A
EA351D
EA351C
EA351D
EA23MFG
EA351D
EA351A
EA351D
EA351D
EA23MCG
EA23MAG
EA23MFG
EA23MAG
EA23MAG
EA23MCG
EA23MFG
EA23MDG
EA23MDG
EA23MFG
EA23MCG
1
EA23MDG
1
EA23MDG
EA23MCG
EA23MDG
EA23MFG
EA23MCG
EA23MCG
EA23MJG
EA23MIG
EA23MDG
EA23MDG
EA23MAG
EA23MAG
EA23MAG
EA23MEG
EA23MCG
EA23MDG
EA23MFG
EA23MDG
1
EA23MCG
EA23MDG
EA23MCG
EA23MFG
EA23MEG
EA23MAG
EA23MDG
EA23MAG
EA23MAG
EA23MDG
EA23MCG
EA23MDG
EA23MFG
EA23MDG
EA23MAG
EA23MDG
EA23MDG
1
Poland
Portugal
220/50
220/50
Puerto Rico
Qatar
120/60
240/50
Romania
Russia
Rwanda
St. Kitts-Nevis
220/50
220/50
220/50
220/60
St. Lucia
St. Maarten
St.Vincent/Grenadines
240/50
220/50
220/50
Samoa, American
120/60
220/50
Samoa, Western
San Marino
Sao Tome and Principe
Saudi Arabia
220/50
220/50
220/50
110/60
220/50
Scotland
Senegal
220/50
220/50
Serbia/Montenegro
Seychelles
220/50
220/50
Sierra Leone
220/50
Singapore
Slovak Republic
Slovenia
Solomon Islands
Somalia
South Africa, Republic of
230/50
220/50
220/50
220/50
220/50
220/50
Spain
Sri Lanka
220/50
110/50
230/50
Sudan
240/50
Surinam
Swaziland
120/60
220/50
Sweden
230/50
1
1
1
1
D
D
F
A
C
F
D
D
D
C
F
C
D
C
A
A
E
D
E
D
D
A
D
C
C
D
F
EA351D
EA351D
EA23MFG
EA351A
EA351C
EA23MFG
EA351D
EA351D
EA351D
EA351C
EA23MFG
EA351C
EA351D
EA351C
EA351A
EA351A
EA351E
EA351D
EA351E
EA351D
EA351D
EA351A
EA351D
EA351C
EA351C
EA351D
EA23MFG
D
C
F
C
F
C
D
D
E
D
H
C
D
EA351D
EA351C
EA23MFG
EA351C
EA23MFG
EA351C
EA351D
EA351D
EA351E
EA351D
EA23MHG
EA351C
EA351D
EA23MDG
EA23MDG
EA23MFG
EA23MAG
EA23MCG
EA23MFG
EA23MDG
EA23MDG
EA23MDG
EA23MCG
EA23MFG
EA23MCG
EA23MDG
EA23MCG
EA23MAG
EA23MAG
EA23MEG
EA23MDG
EA23MEG
EA23MIG
EA23MDG
EA23MAG
EA23MDG
EA23MCG
EA23MCG
EA23MDG
EA23MFG
EA23MKG
EA23MDG
EA23MCG
EA23MFG
EA23MCG
EA23MFG
EA23MCG
EA23MDG
EA23MDG
EA23MEG
EA23MDG
EA23MHG
EA23MCG
EA23MDG
F
D
C
D
D
H
D
D
EA23MFG
EA351D
EA351C
EA351D
EA351D
EA23MHG
EA351D
EA351D
EA23MFG
EA23MDG
EA23MCG
EA23MDG
EA23MDG
EA23MHG
EA23MDG
EA23MDG
ot
es
N
G
ro
u
A nd
da ed
pt
or
s
N
G onro
u
A nd
da ed
pt
or
s
Vo
lta
ge
/F
re
So
q
ck
et
C
ou
n
tr
y
N
G onro
u
A nd
da ed
pt
or
s
G
ro
un
A d
da ed
pt
or
s
N
ot
es
Vo
lta
ge
/F
re
So
q
ck
et
C
ou
n
tr
y
Vo
lta
ge
/F
So
re
q
ck
et
N
G onro
u
A nd
da ed
pt
or
s
G
ro
un
A d
da ed
pt
or
s
N
ot
es
C
ou
n
tr
y
Electrical Standards by Country:
1
1
1
1
1
1
1
1
1
1
Cambodia
220/50 D
110/60 A
C
Cameroon
220/50 D
Canada
110/60 A
Canary Islands
220/50 D
Cape Verde,Republic of 220/50 D
Cayman Islands
120/60 A
Central African Republic220/50 D
Chad
220/50 D
F
Chile
220/50 D
China
220/50 E
C
D
A
Hong Kong Region
230/50 C
F
Colombia
110/60 A
Comoros
220/50 D
Congo
220/50 D
Congo, Dem. Rep.
220/50 D
Cook Islands
240/50 E
Costa Rica
120/60 A
Croatia
220/50 D
EA351D
EA351A
EA351C
EA351D
EA351A
EA351D
EA351D
EA351A
EA351D
EA351D
EA23MFG
EA351D
EA351E
EA351C
EA351D
EA351A
EA351C
EA23MFG
EA351A
EA351D
EA351D
EA351D
EA351E
EA351A
EA351D
Cuba
A
D
C
D
D
D
C
F
A
A
D
A
D
C
D
D
D
D
F
E
D
D
D
D
A
D
C
D
D
C
D
F
C
D
D
D
EA351A
EA351D
EA351C
EA351D
EA351D
EA351D
EA351C
EA23MFG
EA351A
EA351A
EA351D
EA351A
EA351D
EA351C
EA351D
EA351D
EA351D
EA351D
EA23MFG
EA351E
EA351D
EA351D
EA351D
EA351D
EA351A
EA351D
EA351C
EA351D
EA351D
EA351C
EA351D
EA23MFG
EA351C
EA351D
EA351D
EA351D
EA351C
EA351D
EA23MFG
EA351D
EA351A
EA351A
EA351D
EA351D
Cyprus
Czech Rep.
Denmark
Djibouti
Dominica
110/60
220/60
220/50
220/50
230/50
220/50
230/50
Dominican Republic
Ecuador
Egypt
El Salvador
110/60
120/60
220/50
115/60
England
Equatorial Guinea
Eritrea
Estonia
Ethiopia
220/50
220/50
220/50
220/50
220/50
Fiji
Finland
France
French Guiana
French Polynesia
Gabon
Gambia
Georgia
Germany
Ghana
240/50
220/50
230/50
220/50
220/60
110/60
220/50
220/50
220/50
230/50
220/50
Gibraltar
240/50
Greece
Greenland
220/50
220/50
Grenada
220/50 C
D
F
220/50 D
110/60 A
120/60 A
220/50 D
220/50 D
Guadeloupe
Guam
Guatemala
Guinea
Guinea-Bissau
EA23MDG
EA23MCG
EA23MDG
EA23MAG
EA23MDG
EA23MDG
EA23MAG
EA23MDG
EA23MDG
EA23MFG
EA23MIG
EA23MEG
EA23MCG
EA23MDG
EA23MCG
EA23MFG
EA23MAG
EA23MDG
EA23MDG
EA23MDG
EA23MEG
EA23MAG
EA23MDG
EA23MAG
EA23MIG
EA23MCG
EA23MDG
EA23MKG
EA23MDG
EA23MCG
EA23MFG
EA23MAG
EA23MAG
EA23MDG
EA23MAG
EA23MDG
EA23MCG
EA23MDG
EA23MIG
EA23MDG
EA23MIG
EA23MFG
EA23MEG
EA23MDG
EA23MDG
EA23MDG
EA23MDG
EA23MAG
EA23MDG
EA23MCG
EA23MDG
EA23MDG
EA23MCG
EA23MDG
EA23MFG
EA23MCG
EA23MDG
EA23MDG
EA23MDG
EA23MKG
EA23MCG
EA23MDG
EA23MFG
EA23MDG
EA23MAG
EA23MAG
EA23MDG
EA23MDG
1
Lebanon
220/50
110/50
220/50
Lesotho
1
Liberia
Liechtenstein
Lithuania
Luxembourg
Macao
120/60
220/50
127/50
230/50
220/50
220/50
220/50
200/50
Macedonia
Madagascar
220/50
220/50
Madeira
220/50
Malawi
Malaysia
Maldives
230/50
240/50
220/50
Libya
1
1
1
1
Mali
Malta
Martinique
220/50
220/50
220/50
Mauritania
Mauritius
220/50
220/50
Mexico
Micronesia
Moldova
Monaco
120/60
120/60
220/50
220/50
Mongolia
Montserrat
Morocco
220/50
230/60
220/50
Mozambique
220/50
Myanmar
220/50
1
1
1
1
1
1
1
1
Namibia
220/50
Nauru
Nepal
220/50
220/50
Netherlands
Neth. Antilles
New Caledonia
New Zealand
Nicaragua
Niger
Nigeria
230/50
220/50
110/50
220/50
230/50
120/60
220/50
230/50
Norway
Oman
230/50
240/50
Pakistan
230/50
Panama
120/60
1
Papua New Guinea
Paraguay
Peru
1
Philippines
240/50
220/50
110/60
220/60
220/60
1
1
1
D
A
H
D
C
A
D
F
D
D
D
F
C
D
D
F
F
D
C
C
F
D
A
D
C
D
F
D
C
D
A
A
D
D
F
D
A
D
F
D
H
C
D
F
D
H
E
F
D
D
D
A
D
E
A
D
C
F
D
C
D
F
D
A
E
E
D
A
D
A
D
EA351D
EA351A
EA23MHG
EA351D
EA351C
EA351A
EA351D
EA23MFG
EA351D
EA351D
EA351D
EA23MFG
EA351C
EA351D
EA351D
EA23MFG
EA23MFG
EA351D
EA351C
EA351C
EA23MFG
EA351D
EA351A
EA351D
EA351C
EA351D
EA23MFG
EA351D
EA351C
EA351D
EA351A
EA351A
EA351D
EA351D
EA23MFG
EA351D
EA351A
EA351D
EA23MFG
EA351D
EA23MHG
EA351C
EA351D
EA23MFG
EA351D
EA23MHG
EA351E
EA23MFG
EA351D
EA351D
EA351D
EA351A
EA351D
EA351E
EA351A
EA351D
EA351C
EA23MFG
EA351D
EA351C
EA351D
EA23MFG
EA351D
EA351A
EA351E
EA351E
EA351D
EA351A
EA351D
EA351A
EA351D
EA23MDG
1
Switzerland
Syria
Taiwan
Tajikistan
Tanzania
230/50
220/50
110/60
220/50
230/50
Thailand
220/50
Tibet
220/50
Togo
Tonga
220/50
240/50
Trinidad & Tobago
110/60
220/50
Tunisia
Turkey
Turkmenistan
220/50
220/50
220/50
Turks & Caicos Islands
Tuvalu
Uganda
120/60
220/50
220/50
Ukraine
United Arab Emirates
220/50
220/50
USA
Uruguay
110/60
220/50
Uzbekistan
Vanuatu
220/50
220/50
1
1
Venezuela
Vietnam
120/60
220/50
110/60
1
Virgin Islands (British)
110/60
1
Virg. Isl.(US)
Wales
Yemen
110/60
220/50
220/50
Zambia
220/50
Zimbabwe
220/50
EA23MHG
EA23MDG
EA23MCG
EA23MDG
EA23MFG
EA23MSG
EA23MDG
EA23MDG
EA23MFG
EA23MCG
EA23MDG
EA23MDG
EA23MFG
EA23MFG
EA23MDG
EA23MCG
EA23MCG
EA23MFG
EA23MDG
EA23MDG
EA23MCG
EA23MDG
EA23MFG
EA23MDG
EA23MCG
EA23MDG
EA23MAG
EA23MAG
EA23MDG
EA23MDG
EA23MFG
EA23MDG
EA23MAG
EA23MDG
EA23MFG
EA23MDG
EA23MHG
EA23MCG
EA23MDG
EA23MFG
EA23MDG
EA23MHG
EA23MEG
EA23MFG
EA23MDG
EA23MDG
EA23MDG
EA23MAG
EA23MDG
EA23MEG
EA23MAG
EA23MDG
EA23MCG
EA23MFG
EA23MDG
EA23MCG
EA23MFG
EA23MDG
EA23MAG
EA23MEG
EA23MEG
EA23MDG
EA23MAG
EA23MAG
© 2008 Magellan's Travel Supplies. All Rights Reserved.
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EA23MFG
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EA351C
EA23MFG
EA23MSG
EA23MDG
EA23MAG
EA23MDG
EA23MCG
EA23MFG
EA23MDG
EA23MAG
EA23MDG
EA23MEG
EA23MDG
EA23MEG
EA23MFG
EA23MDG
EA23MAG
EA23MCG
EA23MFG
EA23MDG
EA23MDG
EA23MDG
EA23MAG
EA23MAG
EA23MEG
EA23MCG
EA23MFG
EA23MDG
EA23MCG
EA23MFG
EA23MAG
EA23MEG
EA23MIG
EA23MDG
EA23MEG
EA23MCG
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EA23MDG
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Notes:
In countries where multiple adaptors are listed, the most common
configuration is listed first. Wise travelers prepare for all possibilities.
(1) Not all electrical sockets in these countries provide grounding.
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Please Note: Electrical adaptor plugs do not change voltage (e.g. from 220 volts
to 110 volts for North American appliances). If your appliance is not designed to
operate on 220 volt systems found overseas, you will need a step-down transformer.
If your appliance has three pins we recommend that you use a grounded adaptor
plug. Grounding helps protect you from shock if your appliance is damaged and
an electrical short occurs. In areas where grounded sockets are not available
you may choose to bypass the grounding pin and use your appliance without the
protection of a grounded socket.
EMI Diesel Generators Overview
When considering a design where generators will be used a prime power for remote and small
operations (<1MW) there are several factors that need to be considered and known.
1. Terminology:
Technically “Generators” produce DC voltage and current, and “Alternators” produce AC
voltages and current, the same that we see from utility sources. While there are design
differences in the internal connections of the electrical side of things that make that
difference, it is common practice to call the entire system of engine driven alternators as
"generators", and we will use that term here. We will use the term “alternator” only to
describe design issues that impact the electrical portion of the overall generating system.
DC systems have current flowing in a single constant direction with typically steady voltages
and are commonly seen in battery powered systems. AC systems have current directional
flow alternating, typically many times a second; the voltage also varies in a sine wave
pattern, from zero to a positive peak then back down to zero and down to a negative peak
then rising back to zero in each cycle. Since the voltage is constantly varying, the output is
rated by an “RMS” (root mean square) voltage that is a mathematical calculation of the sine
wave that give the same power as a DC current at that same voltage would. Peak voltages
are higher than the RMS value by a factor of about 1.41 (the square root of 2). So a 120 volt
AC system will have peak voltages of about 170 volts, and 220 volt AC system peak voltages
of about 308 volts.
2. Ratings:
Generators are typically sold by KW capacity with a kVA rating also provided. Generator
sets (Gensets) are typically rated for Prime or continuous duty rating and at higher rating for
Standby or limited run hours. It is wise to buy the unit based on the lower kVA Prime or
continuous duty rating if it is to take to place of utility power and run all day or over 12-14
hours a day.
The KW capacity is controlled by available engine horsepower (work), while the alternator's
winding kVA rating (current) is limited due to temperature rise from windings resistance. At
higher altitude and hotter inlet air the engine will deliver less horsepower than at sea level
and standard temperature. Likewise hotter ambient air will also limit the acceptable
temperature of the windings in the alternator thus limiting kVA. Since almost all 3 phase
generators are rated with a 0.8 power factor, expect to see typical ratings like 80KW /
100kVA.
While power factor is more complicated than we will deal with here, it is the effect when the
current flow of an AC system doesn’t match exactly the voltage sine wave. Incandescent
lights and resistance heaters have a power factor of 1.0 and induction motors typically have
power factors closer to 0.8, lagging while capacitive loads such as UPS input filters tend to
have leading power factors. The voltage regulators in the alternators generally have
problems responding to leading power factor loads and loads with very low leading power
factors can result in loss of voltage stability. Using a generator to feed a normal mix of loads
this is not a problem but if you are feeding loads where a UPS kVA rating is over about 50%
of the load the generator will be carrying, special attention to getting an engineer’s review
would be wise.
At cooler temperatures and for short periods the genset can deliver slightly above its rating.
This allows for motor starting loads and brief load transitions. How well it will perform
during this overload varies with the ambient air temperature, amount of overload and
duration. You are at the edge or outside the envelope here so anything you get be grateful
for. Planning under normal conditions not to exceed 80% of the engines rating is wise.
3. Frequency:
The frequency of the output voltage is directly related to the engine speed. Thus with typical
4 pole armatures, a 50Hz machine will run at 1500 RPM and a 60 Hz machine will run at
1800 RPM. Engine speed is controlled by the governor. If you are having frequency and
engine speed problems that is where to look, not the alternator or voltage regulator.
So, yes some 60 hertz machines can be dialed back to run at the lower speed, but you will
lose some horsepower and torque, so it will not deliver full original KW/kVA ratings at the
lower speed. Likewise, some 50Hz machines could be adjusted upward in speed to provide
60Hz, where they would have more available engine horsepower but also might have
tendency for the engine to overheat if the radiator system was sized closely at the 50 Hz
rating, likewise fuel consumption will increase.
Other than motor loads, many loads such as lighting, resistance heaters (stove, ovens, toasters
etc), and many electronic devices are not frequency sensitive, they can work on either 50 or
60 hertz. Check the nameplate of the device to be sure.
4. Voltage:
The voltage regulator controls output voltage. Engine speed and operation would only
impact voltage if the engine is at the end of its performance range and can't hold any more
power OR if a large load is suddenly applied to the engine. This block loading (adding or
removing a large say >=25% fraction of the generator's rating) will briefly impact both speed
(frequency) and voltage output but in general the engine should recover within about 3-5
seconds.
Try to specify permanent magnet excited alternators, if they are available, other types can,
when out of service for some time, (maintenance issues) have to have the field windings
'flashed' to get the unit generating voltage again. While this is a fairly simple procedure, it is
easy for the procedure to be forgotten or trained personnel to leave before it is needed again.
Thus, getting written manufacturers troubleshooting and basic maintenance procedures
should be a part of the purchase if at all possible.
Some 277/480 VAC units could be dialed down at the voltage regulator to provide 230/416
or possibly 220/400 VAC power for overseas systems. If the voltage regulator won't adjust
that low possibly a replacement one can be obtained that will allow for the lower voltage.
3 Phase alternators are available in 6 lead and 12 lead winding arrangements, the leads are
typically marked T1- T12. The 12 lead machines can be connected to provide two or more
voltage levels across the three phases (120/208 or 277/480VAC). 6 lead machines have the
two ends of each of the three windings available to be connected as a delta or star (WYE)
arrangement. Be sure the connection is made as needed to match the electrical system design
you are working with. The delta arrangement has a single voltage between any two phase
connections and such will give only a single voltage, 120, 208, 240, 400, 480. While a star
or WYE connected arrangement ties one end of each phase winding to a common point and
then grounds them. This provides two voltage ranges, with the phase to ground voltage 120
in a 120/208 system, 220 in a 220/400 system and 277 in a 277/480 system. While the phase
to phase voltage gives the higher level in each of those pairings. If the machine is
reconnectable there will be a diagram in the owner’s manual and often a wiring diagram on
the alternator cover. Reconnecting to get a different voltage arrangement may require
changes in the sensing leads landed on the voltage regulator, watch closely if you have to
make a reconnection.
5. Single or 3 Phase:
A single phase unit can be connected to a 3 phase panel with each of 3 single phases wired
to each hot phase, but of course it will not support true 3 phase loads, still all those single
phase loads can be powered. The KW and kVA ratings will still apply since the three
connections each add load. It is possible to use a 3 phase unit and wire to a single phase
panel but the windings in the alternator will be heating unevenly and you need to reduce the
loading to 1/3 of kVA rating if you only connect 1 phase. If you connect 2 legs to a US
standard 120/240 panel you can use about 2/3 of the kVA rating of the unit.
6. Fuel choices:
Engine generators in smaller sizes are generally available in gasoline from under 1KW to
about 150KW, with natural gas (propane) and diesel units available in the whole range of 201000+ KW. In most majority world settings, diesel is the best choice for the following
reasons. Diesel is less flammable (listed as combustible) than gasoline. Liquid fuels are
categorized based on flash point, the temperature where the fuel gives off enough vapor to
ignite. Combustible fuels (kerosene, D-2, Jet A etc) have flashpoints above 100F, while
flammable fuels gasoline, alcohol have flashpoints under 100F (~37.7C). Thus combustible
fuels are safer to transport and store.Diesel fuel should not be stored or piped with galvanized
iron pipe. Black iron pipe is fine and the interior is preserved by the oily nature of the fuel.
Diesel tends to strip the zinc galvanizing off the pipe and it causes problems for the engine
injectors.
In general, diesel fuel stores pretty well, as least compared with gasoline, and so it is more
widely available in the more rural areas. Exceptions to this would be areas served by small
boats with gasoline outboard engines. Diesel engines are also generally considered longer
lived and to require less maintenance since they do not have points, spark plugs and electric
ignition systems.
While natural gas and propane are also scarce in the more rural areas due to transportation
issues, gaseous fueled engines also have slightly slower responses to varying loads, and
require spark ignition systems. There are some dual fueled engine that use some diesel fuel
as an ignition source and mix the intake air with gaseous fuel for the rest of the power
requirements but these are generally larger than the sizes reviewed here. So in general, diesel
is the preferred fuel for this application.
Many diesel engines are rated by their manufacturers to run on alternate fuels. Some fuels
have slighter lower energy per volume and so reduce the generator KW capacity, these rarely
require more than 5-10% derate. The key issue is often the fuel pump needing a certain level
of lubricity. Telephone companies in the US often operate diesel engine generators on K-1
kerosene and D-1 (lighter weight or winter diesel) since they are more stable in storage.
Most diesel engine vendors also have recommendations on use of so called bio-diesel fuels,
while long term storage of bio fuels is generally not recommended many engine vendors
have approved these fuels for operation with little if any KW derating. Always check with
the engine manufacturer for their recommendations. Likewise many diesel operators blend
used and filtered motor oil back into diesel fuel at ratios under 10% of used motor oil with
satisfactory results.
Bio fuels are not recommended for longer term storage (.>~45 days) since they tend to
degrade and or grow out microbial bugs. If bio fuels are to be used be sure there is no water
contamination as any water (even in standard diesel fuel) increases fuel microbial growth that
can lead to filter plugging and fuel deterioration. High storage temperatures are also very
bad for bio-diesel blends. Higher ratio blends of bio-diesel also can have greater than 12%
derate for horsepower and increased fuel quantity consumption values above 15%. If
biodiesel fuels are to be used, seriously consider use of fuel stabilizers. Biodiesel blends may
also tend to clean the tanks of any accumulations of sludge or other sediments and can result
in more frequent filter plugging than straight diesel.
If you are located in extremely cold climates be aware that diesel fuel has a paraffin point or
cloud point, a temperature where small crystals of waxy particulate condense out of the fuel.
To avoid plugging the fuel filter or even having the fuel gel in the tank, the fuel must be kept
above the paraffin point temperature. Your local fuel supplier should be able to provide you
info on the cloud point of their winter fuel. Be aware that fuel blends can change summer to
winter, so take that info account.
Underground storage is often recommended since it reduces the temperature swings of
aboveground tanks and so reduces moisture condensation that mixes into the fuel and tends
to promote microbial growth. A nearly full tank has less air space and so less moisture
condensation problems, but a large tank reduces fuel turnover so there is a greater change of
the fuel having some deterioration due to longer storage times. It is best to try to use the tank
down to very low level before refueling, as just mixing a little fresh fuel into a near full tank
gives a longer average life of the fuel being stored and so a higher risk of deterioration.
Environmental concerns recommend enclosing the diesel storage tank with a secondary
containment able to prevent release of the fuel into watercourses if the tank leaks or is
spilled. Since water is heavier than diesel fuel, be sure and pump any water or sediment laden
fuel off the bottom of the tank at least annually. You can use a rigid small diameter pipe to
get the water or fuel off the bottom of the tank, if there is no sump drain. For the same
reason, make sure the fuel pickup piping is installed at least a couple of inches (5cm) or so
off the bottom of the tank, so any water isn’t picked up and distributed to the fuel injectors as
they can be damaged by this. On larger tanks, the pickup point can be 4-6" off the bottom of
cylindrical tanks.
7. Fuel Consumption:
At least for planning and budgetary reasons, the designer needs to be aware of fuel
consumption requirements. Until a specific generator is selected and purchased, how do you
estimate fuel consumption and thus fuel storage requirements? Rule of thumb - For each
10KW of load being operated, a diesel generator will use about 1 GPH (~4 LPH) of diesel
fuel. This gets somewhat better with larger engines fully loaded and a little worse with
smaller engines or engines under small partial load, but gives you a starting point for
planning purposes.
Many larger capacity diesel engines have fuel return lines. Excess fuel is pumped by the fuel
pump to the injector pump and circulates in the fuel rail, cooling the injectors, the fuel that
isn't needed at the existing engine loading is returned via the fuel return line. Some
manufacturers have optional fuel coolers, small radiators for this fuel to pass thru before it is
returned to the fuel tank. For planning purposed only the fuel consumed by the engine per
hour is needed, but be aware that the fuel returned to the tank will tend to warm the fuel up
and thin it out somewhat.
8. Fuel Security:
Security of your fuel supply is a critical item. Loss by theft is all too common and a source of
unneeded expense. For critical applications (hospitals etc.) having a separate concealed
reserve can be helpful not only for emergencies requiring more fuel consumption than
normal but as a bridge to cover delays in fuel delivery, or in emergencies due to theft.
Locking and frequent inventory of fuel storage by principals to verify that (even otherwise
trusted) staff is faithfully managing the expensive fuel supply is a wise management control
item. While this seems harsh, such measures can also serve to reduce temptations to divert
what seems to be such a plentiful and valuable liquid commodity. Initial planning for fuel
storage should take these measures into consideration.
9. Radiator Cooled units:
The rule of thumb for radiator cooled units says you need at a clear open inlet area least 1 ½
to 2 times the area of the radiator. Since many units in majority world installations don't have
enclosed engine rooms or ducted air exhaust and inlet, this may not impact your design. But
it is wise to make arrangements so the air flow from the radiator is not easily recycled into
the inlet side of the radiator. The effect of such re-circulated air is to reduce engine cooling
capacity and if the hotter air is entrained into the diesel engine inlet filters, the reduced
density gives the effect of higher altitude operation and reduces available engine horsepower
and thus KW. Thus pay attention to prevailing wind directions, radiator discharge into
prevailing winds should be avoided or else use scoops or diverters to direct off radiator air
upwards or sideways to allow normal airflow to help dissipate radiator exhaust hot air plume.
If you have use for large quantities of hot water (hospitals) consider design of a heat
exchanger to use waste engine heat to provide domestic hot water.
10. Noise:
Remember the noise factor when designing placement of a diesel generator. Will it need to
run at nighttime? While voltage drop issues force the unit to be located close to higher amp
draw uses, look at orientation of the unit to minimize noise impact to sensitive areas.
Pointing the engine exhaust and radiator fan away from those areas is a basic starting point.
Scoops to divert radiator exhaust upwards can make significant noise reduction, as can
baffling of air inlets around the sides of the generator.
11. Operating an Engine genset at reduced loads:
While diesel engines can and do operate in wide range of loads, be aware that prolonged use
under about 30% of rated loading can result in "wet stacking" where the engine tends to ooze
a black tarry viscous liquid that is a mix of unburned diesel fuel, soot and carbon particles.
This can cause the engine problems over time and is cured by running the engine for several
hours at higher loads (50-75% of rating), before the problem gets too serious. Wet stacking
can reduce the ability of a generator to supply its full rated load and cause other maintenance
issues, so don't oversize a generator if the future load growth is several years off. Better to
buy a more closely right sized unit now and trade when the load exceeds 90% or so of rated
capacity. This problem is common with the older 2 cycle designs from Detroit diesel.
12. Operational Issues:
While operational costs will depend on the local staff skills of the facility, distance from a
service provider and cost of parts for that brand of unit in the country where it is located.
Preference should be given to using manufacturers with good support in the region or at least
the country. Importing the "finest" make in the world into an area where parts are simply
hard to get, or unobtainable will result in an out of service unit all too soon. Air freight and
import duties for specially imported parts will cost more than similar parts that are imported
in greater quantity due to wider use of that make and model of engine.Consider specifying a
fuel/water separator unit, and provide for spare fuel, oil and air filters. Try to get
manufacture’s training for the local service staff to at least be able to change oil and all
filters. The recommended service intervals will depend on how clean the air is at the
generator, wind blown dust and dirt will shorten service intervals and increase costs as air
filters will have to be replace more often and oil changes made more frequently. Labor costs
will of course vary so investigate those costs and make sure the owner is aware of them.
EMI Electrical Power Density and Load Demand Factors
For loads serviced by Electric Utility or Generator
Churches, Auditoriums, Dining Halls, Large Open Spaces
Illumination power density - 11 VA/m2 (1 VA/ft2)
General Outlet Loads - No additional load added for outlets
- AV and PA equipment are included in special
loads
Demand factor sizing - 50% for General loads when General loads are
over 3kVA. If less than 3kVA use 100%
- 100% for Special loads*
Dwellings, Offices, Schools, Dormitories, Small Clinics
Illumination power density - 11 VA/m2 (1 VA/ft2)
General Outlet loads - 6 VA/m2 (0.56 VA/ft2)
Demand factor sizing - 50% for General Loads when General loads are
over 3kVA. If less than 3kVA use 100%
- 100% for Special Loads*
Hospitals, Large Clinics
Illumination power density - 22 VA/m2 (2 VA/ft2) (Operating Rooms,
Delivery Rooms, Other rooms needing more
intense lighting)
- 11 VA/m2 (1VA/ft2) (All other rooms
needing normal lighting)
General Outlet Loads - 180 VA/outlet
Demand factor sizing - 75% for General Loads when General Loads are
over 3kVA. If less than 3kVA use 100%
- 100% for Special Loads*
* For certain special loads, demand factors allowed by NEC or IEE Regulations may be
appropriately applied.
Note: Alternate energy systems must be handled by a more carefully formed power-time profile.
EMI Electrical Report Example
1.1
Existing Electrical
The existing site presently has a 100 kW, 50 Hz, 380/220 VAC generator that is being used to run the
well pump. No utility electrical service comes onto the site; however, a three-phase distribution line does
exist across the road on the south side of the property. There will be line and transformer expenses
required to extend the electrical service onto the site.
1.2
Proposed Electrical System
The national electric utility grid will be the primary source of power for the Site. The government utility will
need to provide the site with high voltage power lines from the existing power lines across the street from
the property (see drawing ‘Site Electrical Plan’). The ‘EMI Electrical Load Study Example’ shows the
complete load planning for the site electrical grid – Phase 1 and Phase 2. A 150kVA transformer will be
needed for all phases of this project, but a 100kVA transformer would be sufficient for the first phase.
The 100kW generator will be used as a back-up for the site but it will not be able to power the whole site
when the future phases are added. Loads will have to be reduced or the backup loads separated when
the future phases are added. Air conditioners contribute to the majority of the electrical load on this site.
The new generator building will be located relatively close to the accommodations as they have the
largest power demands. The generator building is also centrally located on the site to minimize voltage
drop concerns if future buildings are added in the agriculture area. In addition to housing the generator,
the building will also contain the main distribution panel, and the manual transfer switch to select between
the utility as the primary power source, and the generator as the backup power source (see drawing
‘Generator Room Electrical Plans’).
The ‘Electrical One Line Diagram’ shows a drawing of the proposed site electrical system wherein cable
sizes are specified and electrical panels and switch gear are identified. Since some electrical cable runs
exceed 60 m in length, several cables have been sized larger than necessary based on ampacity to keep
voltage drop within the standard practice of 4% or less. Also, all panels, breakers and cables have been
sized to accommodate all future expansion on the conference facility, so that new cables and panels do
not have to be installed when the buildings are expanded.
The ‘Site Electrical Plan’ suggests a viable plan for buried distribution cable routing for the site. Electrical
power panels are also associated with each building on this drawing. Perimeter security lights are
activated by a switch in the generator room with power supplied from panel PPG.
1.2.1 Accommodations
Drawings ‘Wiring Diagram - Basement’ and ‘Wiring Diagram - Ground Floor’ show the wiring diagrams for
the accommodations. Electrical service to the building feeds through one main power panel located in
the worker’s room in the basement - PPA. Subpanels, fed from this main power panel, are distributed to
each floor to provide convenient access to breakers for isolation of building sectors. As floors are added
to the building a sub-panel for that floor can easily be connected in to the main panel in the basement.
The main panel has been sized to account for all the future floors of the accommodations building.
Calculations for the electrical loads serviced by each main power panel are shown below the respective
panel drawings.
EMI Site Electrical Load Study Example
PHASE 1
Load Description
Accommodations (2 levels)
Site Lighting
Soccer Field Lights
Qty
2
46
10
Area
(m2)
528
VA/m2
VA/m2
General
Special
Maximum
Phase
Lights Outlets Load (VA) Loads (VA) Demand (VA) Currents
11
6
17952
40780
58732
89
4600
4600
7
2000
2000
3
Phase 1 Max Demand (VA)
Demand Factor: 50% General Loads + 75% Special
40 hp Well Pump with 0.7 power factor(VA)
1 hp Filtration Pump (VA)
10 hp Booster Pump (VA)
Total Phase 1 Demand (kVA)
Area
VA/m2
Special Loads
*A/Cs (29), Washers(4) Dryers(4)
*Site Lights (46)
*Field Lights (10)
65332
44511
42629
1066
10657
99
PHASE 2
Load Description
Qty
2
Accommodations (2 levels)
2
(m )
528
VA/m2
General
Special
Maximum
Phase
Special Loads
Lights Outlets Load (VA) Loads (VA) Demand (VA) Current (A)
11
6
17952
36696
54648
Phase 2 Max Demand (VA)
Demand Factor: 50% General Load + 75% Special
Total Future Phases Demand (kVA)
*A/Cs (29)
54648
36498
36
SUMMARY
Property Loads
Qty
Phase 1
1
Phase 2
1
*Device Power Consumption
Device
Power
(VA)
Freezer
Microwave Oven
Washing Machine
Gas Dryer (motor)
Electric Dryer
Iron
Coffee Maker
PC
Printer
Copier
Field Lights
Site Lights
Air Conditioner (Small)
Air Conditioner (Medium)
Air Conditioner (Large)
Ceiling Fan
Data Projector
200
750
500
400
5000
1000
500
280
150
750
200
100
1232
1716
2310
150
600
Total (kVA)
98.86
36.50
Loads Total (kVA)
135.36
Xfmer Size (kVA)
150.00
Power Percentage Used
90.2%
EMI Solar vs. Generator vs. Utility Combined Equipment and Operation Cost Comparison
(NOTE: Pump loads not included in study, thus annual energy costs are larger than values below.)
Yellow-highlighted cells are input values
In table below, enter estimated hourly power demand values for the site in W.
Time of Day (am first row, pm second row)
12-1
1-2
2-3
3-4
4-5
5-6
6-7
7-8
8-9
(W)
500
5000
(W)
500
6000
(W)
500
6000
(W)
500
5000
(W)
500
5000
(W)
1500
3000
(W)
3000
3000
(W)
3000
1500
(W)
5000
1500
9-10
10-11
11-12
LOAD
Total Site Hourly (AM)
Power Demand (PM)
Solar System Assumptions:
Inverter efficiency (ηI )= 90%
Charge Controller efficiency (ηC) = 95%
Battery efficiency (ηB) = 80%
Daily sunlight =
(W)
(W)
(W)
5000 5000 5000
1000
500
500
Site Daily Energy Usage
System efficiency (ηS) = 70%
Depth of Battery Discharge (DOD) = 0.5
Battery replacement every 5 years
7
Generator Assumptions:
Fuel usage rate = 0.07 gal/kW-h
Diesel fuel price =
3.80 US$/gal
Utility Assumptions
Elect. Cost per kW-h
Distance to Site
Equipment costs:
Solar Panels
Charge Controller
Inverter
Batteries
Generator
Transformer
Cost for 3-phase to site
Generator replacement every 5 years
0.3 US$/kW-h
800 Meters
3500
300
800
200
300
US$/kW
Cost =
US$/kW
Cost =
US$/kW
Cost =
US$/kW-h
Cost =
US$/kVA
Cost =
Generator annual fuel cost =
35 US$/kVA
Cost =
39 US$/meter
Cost =
Utility electricity usage annual cost =
48571
3068
5333
13000
2000
6602
233
31200
7446
US$
US$
US$
US$
US$
US$
US$
US$
US$
ENERGY
(kW-h)
68.00
TOTAL CUMULATIVE COSTS of
SOLAR, GENERATOR & UTILITY
250,000
COSTS (US$)
200,000
150,000
100,000
50,000
0
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
YEARS
Solar
Generator
Utility
EMI Wire Chart
Adapted from NEC 2008 Table 310.16 & Ch 9 Table 8
Size
AWG/kcmil
Size
mm2
18
16
1.5
14
2.5
12
4
10
6
8
10
6
16
4
25
3
2
35
1
50
1/O
2/O
70
3/O
95
4/O
120
250
300
350
150
185
400
240
500
300
600
Copper(THHW) Aluminum(THHW)
Resistance
Ampacities
Ampacities
Factor (Copper) Diameter
(75 °C rating)
(75 °C rating)
ohm/km
in.
6
12
15
20
22
25
29
35
40
50
56
65
73
85
97
100
115
118
130
146
150
175
180
200
217
230
250
255
285
310
320
335
372
380
418
420
20
24
30
33
40
44
50
56
65
73
75
90
92
100
116
120
135
139
155
169
180
200
205
230
250
258
270
303
310
339
340
27.70
17.30
15.05
10.70
8.99
6.73
5.69
4.226
3.696
2.653
2.251
1.671
1.425
1.053
0.874
0.833
0.661
0.635
0.524
0.435
0.415
0.329
0.315
0.261
0.229
0.205
0.180
0.175
0.146
0.125
0.118
0.1080
0.0906
0.0870
0.0738
0.0732
Area
in2
0.046
0.058
0.002
0.003
0.073
0.004
0.092
0.006
0.116
0.011
0.146
0.017
0.184
0.027
0.232
0.042
0.26
0.292
0.053
0.067
0.332
0.087
0.372
0.418
0.109
0.137
0.47
0.173
0.528
0.219
0.575
0.63
0.681
0.26
0.312
0.364
0.728
0.416
0.813
0.519
0.893
0.626
Area
Diameter
cir. mil
mm
Area
mm2
1620
2580
2960
4110
4934
6530
7894
10380
11840
16510
19740
26240
31580
41740
49340
52620
66360
69070
83690
98680
105600
133100
138100
167800
187500
211600
237800
250000
300000
350000
365100
400000
473600
500000
592100
600000
1.16
1.46
1.6
1.84
2.06
2.32
2.59
2.93
3.21
3.7
4.12
4.66
5.18
5.88
6.48
6.61
7.42
7.62
8.43
9.27
9.45
10.62
10.9
11.94
12.8
13.41
14.4
14.61
16
17.3
17.8
18.49
20.3
20.65
22.6
22.68
1.06
1.67
2.01
2.66
3.33
4.23
5.27
6.74
8.09
10.75
13.33
17.06
21.07
27.15
32.98
34.32
43.24
45.60
55.81
67.49
70.14
88.58
93.31
111.97
128.68
141.24
162.86
167.64
201.06
235.06
248.85
268.51
323.65
334.91
401.15
403.99
Minimum Size Equipment Grounding Conductors for Grounding Raceway and Equipment
1
Size of Grounding Electrode Conductor ‐ Rating or Setting of Automatic Overcurrent Device in Circuit Ahead of AWG or kcmil(mm2)
Equipment, Conduit, etc., Not Exceeding Aluminum or ‐ (Amperes)
Copper
Copper‐Clad 15
20
30
40
60
100
200
300
400
500
600
800
1000
1200
1600
2000
2500
3000
4000
5000
6000
1
Referenced from NEC 2008 Table 250.122
14 (2.5)
12 (4)
10 (6)
10 (6)
10 (6)
8 (10)
6 (16)
4 (25)
3 (35)
2 (35)
1 (50)
1/0 (70)
2/0 (70)
3/0 (95)
4/0 (120)
250 (150)
350 (185)
400 (240)
500 (300)
700
800
12 (4)
10 (6)
8 (10)
8 (10)
8 (10)
6 (16)
4 (25)
2 (35)
1 (50)
1/0 (70)
2/0 (70)
3/0 (95)
4/0 (120)
250 (150)
350 (185)
400 (240)
600
600
800
1200
1200
Sun-Hour Map
World Design Insolation Map
Excel Sizing Form
Solarex’s World Design Insolation map plots design insolation—to the extent it has been reliably
recorded—on the surface of the earth. On this map, design insolation is expressed as the average value of
the total solar energy received each day on an optimally tilted surface during the month with the lowest
solar radiation. This worst-month data is commonly accepted as a valid solar energy index for designing
systems which must support a load 12 months per year, rather than seasonally. The unit of measurement
is kilowatt-hours/m²/day, often referred to as equivalent sun-hours, or ESH.
The map presents color-coded areas of essentially equal insolation (see key at bottom right) in addition to
point values recorded at selected monitoring stations. From the main map, you can access detailed
insolation maps of any area by clicking on that area. Consult the Adobe Acrobat Reader Help menu for
instructions on moving around on the map.
Select the site design insolation from the map, and enter it on line 9 of the Array Sizing Procedure form.
Particularly if the site is at a latitude higher than 45°, be aware that the ESH number represents average
daily insolation during the worst month of the year. It is not indicative of how much solar energy is
available during other months, which--particularly at high latitudes--may be substantial. Contact an
authorized Solarex representative for assistance in designing systems for such sites.
Reference Drawings