Kelda Water Services (Defence)
Section 15
LOW VOLTAGE
ELECTRICAL
INSTALLATION
Employers Specification Representative:
Tony Morgan
Engineering Specification V1
Asset Management
Version 1 – Approved December 2013
Kelda Water Engineering Specification
Section 15 - Low Voltage Electrical Installations
Record of Amendments
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Version 1 – Approved December 2013
Kelda Water Engineering Specification
Section 15 - Low Voltage Electrical Installation
CONTENTS
RECORD OF AMENDMENTS……………………………………………………………………….1
CONTENTS…….………………………………………………………………………………………2
15.1
SCOPE………………………………………………………...……………………………..3
15.2
ELECTRICAL SAFETY CODE OF PRACTICE………………………………………….3
15.3
CLARIFICATION ON WIMES 3.02………………………………………………………..3
15.3.1 General Requirements (WIMES 3.02 CLAUSES 1.0,2.0 & 3.0)
15.3.2 Installation Design Requirements (WIMES 3.02 CLAUSE 4.0)
15.3.2.1 Protection Studies and Cable Sizing
15.3.2.2 Obtaining External Earth Loop Impedance
15.3.2.3 Fault Protection
15.3.2.4 Harmonic Studies
15.3.3 Selection and Installation of Components and Equipment (WIMES 3.02 CLAUSE 5.0)
15.3.3.1 Distribution Boards (WIMES 3.02, CLAUSE 5.1,2)
15.3.3.2 Motor Isolation and Emergency Stops (WIMES 3.02 CLAUSES 5.1.3 & 5.2.5)
15.3.3.3 Local Isolation of Instrumentation (WIMES 3.02 CLAUSE 5.1.3)
15.3.3.4 Safety Isolation Transformer (WIMES 3.02 CLAUSE 5.1.6.1)
15.3.3.5 Hand Lamps
15.3.3.6 Electric Heating.
15.3.4 Cables (WIMES 3.02 CLAUSE 7.0)
15.3.4.1 Flexible Cables and Cords (WIMES 3.02 CLAUSE 7.3) Types of Cable
15.3.4.2 Installation of Cables (WIMES 3.02 CLAUSE 7.4)
15.3.4.3 Glanding and Identification of Cables (WIMES 3.02 CLAUSE 7.5)
15.3.5 Earthing and Protective Bonding (WIMES 3.02 CLAUSE 8.0)
15.3.6 Particular Types of Installations (WIMES 3.02 CLAUSE 9.0)
15.3.6.1 Hazardous Areas (WIMES 3.02 CLAUSE 9.1)
15.3.6.2 Lighting Installations (WIMES 3.02 CLAUSE 9.2)
15.3.6.3 Lightning Protection (WIMES 3.02 CLAUSE 9.3)
15.3.6.4 Fieldbus Networks (WIMES 3.02 CLAUSE 9.4)
15.3.6.5 Telecoms
15.3.6.6 Trace Heating.
15.3.7 Decommissioned and Disused Electrical Equipment.
15.3.8 Inspection and Testing (WIMES 3.02 CLAUSE 10)
15.3.9 O&M Manuals (WIMES 3.02 CLAUSE 11)
APPENDIX 1
ELECTRICAL CERTIFICATES AND TEST SHEETS……….29
APPENDIX 2
EXAMPLE PERIODIC INSPECTION NOTICE……………….30
APPENDIX 3
LOW VOLTAGE INSTALLATION SCHEDULE;……………..31
APPENDIX 4
MANAGING
THE
HARMONISED
CABLE
COLOURS………………………………………………………...32
APPENDIX 5
TYPICAL
EMERGENCY
STOP
RISK
ASSESSMENT…………………………………………………...36
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15.1
Section 15 - Low Voltage Electrical Installation
SCOPE
This Section of the Specification covers the design installation and testing of the Low
Voltage (<1000Vac or 1500Vdc) Electrical Installations.
Section 15 is to be read in accordance with THE WATER INDUSTRY MECHANICAL
AND ELECTRICAL SPECIFICATION (WIMES) 3.02 LOW VOLTAGE ELECTRICAL
INSTALLATIONS (ISSUE 3), the Particular Specification and, where appropriate,
Kelda Water’s LV Installation Schedules (Appendix 3).
15.2 ELECTRICAL SAFETY CODE OF PRACTICE
All installation work to be carried out shall adhere to the current Kelda Water Services
Code of Practice - Electrical Safety. All plant and equipment shall be installed and
constructed in such a manner to enable it to be operated and maintained in
compliance with the Code of Practice.
15.3
CLARIFICATIONS ON WIMES 3.02
Low Voltage installations shall comply with WIMES 3.02 Issue 3. The following sub
heading clause shall be read in conjunction with WIMES 3.02. The relevant
associated WIMES clause numbers are shown in brackets, adjacent the sub
headings.
The available Kelda Water clauses are listed in this specification but detailed
requirements are included with the Particular Specification
A number of sections are not covered within WIMES 3.02 but are included within this
specification.
15.3.1 GENERAL REQUIREMENTS (WIMES 3.02 CLAUSE 1.0, 2.0 & 3.0)
For the general requirements WIMES 3.02 Sections 1.0, 2.0 and 3.0 shall apply.
15.3.2 INSTALLATION DESIGN REQUIREMENTS (WIMES 3.02 CLAUSE 4.0)
The electrical installation and associated electrical equipment within it shall be
designed to be operated under the supervision of Instructed or Skilled Personnel and
to be maintained by Skilled Personnel, as defined in BS7671. The exception being
socket distribution systems within manned offices, facilities and commercial buildings
which shall be design to be operated by non-Instructed Personnel, but maintained by
Skilled Personnel, as defined in BS7671.
All relevant design information, as defined in WIMES 3.02 Clause 4.2, shall be
completed prior to commencing the electrical installation work and shall, where
requested, be made available to the Contractor.
Where the Power Distribution Transformer is part of Kelda Water’s Electrical System
then the system shall be design to be a TN-S System.
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Section 15 - Low Voltage Electrical Installation
15.3.2.1 Protection Studies and Cable Sizing
Cables shall be sized in accordance with BS7671.
Cables from distribution
transformers shall be sized and rated to the nominal rating of the Distribution
Transformer. All other cabling shall be sized in accordance with the selected rating of
the upstream protective device(s). Upstream protective device(s) to provide shortcircuit, earth fault and overload protection of the cable and any associated unprotected
downstream electrical equipment.
When considering the Whole Life Cost (WLC) of a cable installation the costs
associated with energy losses within the cable will, on occasion, outweigh the
additional CAPEX costs of installing a slightly larger cable. This is more prevalent on
larger loaded cables where BS7671 would call for a minimum cable size significantly
2
greater than 2.5mm . Further information on the “Economic Sizing of cabling” is
provided
on
the
Copper
Development
Association
website
http://www.cda.org.uk/frontend/pubs.htm.
The design of modifications and new electrical installations shall (unless defined in
BS7671 as a minor installation) be verified using AMTEC 2010 Pro-designer 17th
Edition or compatible design verification software to demonstrate compliance with the
requirements of BS7671. The resulting software model produced by the design
verification software shall be submitted in an electronic format at the end of the project
to the Employer’s Engineering Reliability Team.
Where the Site has an existing software model (store on the EDMS Corporate
Database), the model shall be obtained from Employer’s Engineering Reliability Team
(see above address), the alteration to the electrical installation added to the model and
the model returned to Engineering Reliability Team at the end of the project.
The following reports shall accompany the software model:
a)
Cable Sizing Calculations from the Design Verification Software
A detailed report of all power cable sizes, including protective devices, thermal
rating, etc. to show full compliance with BS7671.
b) Error report from the Design Verification Software
A detailed report outlining any errors generated by the Design Verification
Software during the final design verification of the Electrical System.
c)
Notes on Calculations
A report detailing any notes by the designer or inspector regarding various
discrepancy reports which may be generated by the Software due to its
limitation.
Reports are to be stored in electronic format with the software model. Reports to be
stored as plain text files (TXT), Word Files or CSV files.
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Section 15 - Low Voltage Electrical Installation
15.3.2.2 Obtaining External Earth Loop Impedance (Ze)
In order to carry out the Electrical Design, a value of Ze must be obtained for the
installation. A value for Ze at the metering point for the site or at each Power
Distribution Transformer can be obtained either:a)
b)
c)
By enquiry from the Distribution Network Operator (DNO); or
From the EaWR Records/AMTECH model; or
By direct measurement.
Where a value of Ze is not available (routes (a) and (b) above) and where, for
operational reasons, direct measurement is not possible then the following approach is
deemed acceptable by Kelda Water:Under BS7671, Ze is defined as “that part of the earth loop impedance which is
external to the installation”. The electrical installation is defined as “an assembly of
associated electrical equipment having co-ordinated characteristics to fulfil a specific
purpose”. Therefore, on large key operational sites where a value of Ze cannot be
obtained for the whole site a value of Earth Loop Impedance (ELI) for the part of the
site electrical installation for which the installation work is to take place on is
acceptable providing that the part of the site electrical installation meets the following
criteria:a)
It shall be part of a site electrical installation which carries out a specific
purpose or duty; and
It shall be supplied from a common origin; and
The point of measurement shall be as close to the origin of the electrical site
supply as is reasonably practicable.
b)
c)
It could therefore be a Pumping Station, Facilities Building, Control Room or Subprocess within a site. The recorded value of ELI will be that measured at the outgoing
side of the distribution board, fuseswitch or circuit breaker feeding the part of the site
electrical installation. Where this approach is taken, details of where the ELI has been
measured and the reasons for the not recording Ze at the metering point of the site
shall be recorded in the “Departures” section of the Electrical Installation Completion
Certificate.
15.3.2.3 Fault Protection
In compliance with BS7671, Section 4.11.3, fault protection shall comprise of the
following three components:a)
Protective Earthing.
b)
Protective Equipotential Bonding.
c)
Automatic Disconnection in case of fault.
The automatic disconnection times as detailed in BS7671 shall be achieved utilising
Fuses or Circuit Breakers in conjunction with suitably sized Circuit Protective
Conductors (CPC) and Line Conductor to ensure the maximum ELI value:a)
b)
Results in the particular protective device automatically disconnecting the fault in
the required time; and
Within the disconnection time, it does not exceed the maximum ELI value for the
particular protective device.
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Section 15 - Low Voltage Electrical Installation
Where it is not practicable to achieve the required disconnection time, then subject to
approval of the Employer and in accordance with Regulation 411.3.2.6 of BS7671,
extended disconnection times shall be allowable providing supplementary
equipotential bonding is provided in accordance with the requirements of Regulation
415.2 of BS7671. Consideration shall be given to the thermal effects of the fault
current on the cable and electrical equipment over the extended period.
The use of RCD or RCBO to meet the requirements of Fault Protection shall only be
used where there is no other means available. The use of RCD or RCBO on circuits
supplying process plants shall only be allowed subject to the approval of the
Employer.
15.3.2.4 Harmonic Studies
The requirements for Harmonic Studies, compliance and mitigation are as defined in
Section 13, Clause 13.2.4 of the Engineering Specification.
15.3.3 SELECTION AND INSTALLATION OF COMPONENTS AND EQUIPMENT (WIMES
3.02 CLAUSE 5.0)
Clause 5.0 of WIMES shall apply with the following clauses:
Access to electrical equipment within Substations and Switchrooms, shall be fully
compliant with BS7671 Section 729 with the exceptions that:a.
The gangway width shall be a minimum of 800mm between Barriers,
Enclosures, Switching Handles in the most onerous position, Circuit Breakers
in the most onerous positions, Walls and Obstacles.
b.
There shall be easy access and egress from all equipment.
c.
There shall be no equipment mounted within or obstructing gangways.
d.
For equipment mounted either side of gangways, even where the gangway is
less than 10m in length, there shall be two independent routes of access and
egress from all electrical equipment.
Electrical Equipment mounted near hand railing shall not be supported using or
obstructing the use of the top handrail. Such equipment shall not obstruct the
walkway adjacent to the handrail.
Where deemed necessary to support operation and maintenance the location of
sockets, tool transformers and hand lamps shall be agreed with the Employee’s
representative.
15.3.3.1 Distribution Boards (WIMES 3.02 CLAUSE 5.1.2)
The form and construction of distribution boards and their enclosures shall be suitable
for the environment and location for which they are to be installed, used and
maintained.
Where a distribution board is installed within an area which may be subject to wash
down, condensation or operational procedures resulting in spray, it shall be necessary
to improve the distribution board supplier’s standard IP rating. This shall be achieved
either by installing the distribution board within a separate GRP wall-mounted
enclosure with a rating of no less than IP54 or by utilising a heavy-duty distribution
with a rating no less than IP54. Where a distribution board is mounted inside a
separate GRP enclosure then cables shall be glanded on the outside of enclosure and
compression glands used on the entry into the Distribution Board.
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15.3.3.2 Motor Isolation and Emergency Stops (WIMES 3.02 CLAUSES 5.1.3 &
5.2.5)
Local isolators shall be of the Switch Disconnector type in accordance with WIMES 3.05.
Where necessary, an additional late-make, early-break auxiliary contact shall be
provided and interlocked into the starter protection circuit. The starter protection
interlock shall be fail-safe, stop and prevent the drive from running when operated and
allow the drive to restart once the interlock has been restored and a starter manual reset
instigated.
The position, location and function of local isolators and emergency stops shall be
assessed on a machine-by-machine basis. An assessment of the risk (in compliance
with PUWER regulations) and the operational requirements shall take place and as a
result a decision made on whether to use local isolators, and, if necessary, the location
of the local isolators. It may be appropriate to delete the need for field-mounted local
isolators for plant/equipment providing the installation itself and the procedures written
into the associated Operation & Maintenance Manual together constitute a “safe system
of work”. A similar assessment shall take place for local emergency stops and
emergency stop systems. Assessment of risks, as a minimum, shall take place during
design risk assessment and at the HAZOP stages.
An example where it may be inappropriate to delete the need for field-mounted isolators
and/or emergency stops are where a new installation is being retrofitted alongside an
existing installation already equipped with field-mounted isolators and/or emergency
stops.
The position, location and function of local isolators shall be the responsibility of the
Principal Contractor, however in general:a)
b)
c)
Where motors are provided with an individual means of isolation at the MCC or
Control Panel it is not always necessary to provide further local isolators
adjacent to the motor. Typical exceptions being where the motor is located a
significant distance from the MCC or Control Panel or where the normal
operation and maintenance will require a high frequency of isolation.
Where a package plant comprising of a single process stream, a single point of
isolation may be adequate without the need for individual local isolators for
each motor.
Where motorised valves are supplied via distribution boards, the individual
MCBs with individual locking facilities may be sufficient without requiring
specific local isolators adjacent to each valve. The MCB must comply with BS
EN 60898, BS EN 60947-2, BS EN 61009-1 and be suitably marked with the
symbol for isolation (ref. Table 43.2, BS7671).
A typical blank emergency stop risk assessment sheet is provided in Appendix 5.
15.3.3.3 Local Isolation of Instrumentation (WIMES 3.02 CLAUSE 5.1.3)
Where instrumentation is supplied at greater than ELV (i.e. >50Vac, >120Vdc) then it
shall be supplied by a local isolator of the Switch Disconnector Type in accordance
with WIMES 3.05, lockable in both the open and closed positions.
15.3.3.4 Safety Isolation Transformers (WIMES 3.02 CLAUSE 5.1.6.1)
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The transformer primary shall be 230V 50Hz; secondary windings shall be either or
both:
a)
b)
Centre tap earthed 110V (55V-0-55V); and/or
Unearthed 25V (SELV as defined in BS 7671).
Unless otherwise specified in the enquiry or order, the ratings of the secondary
windings shall be:
a)
b)
2 kVA for fixed power; and
100VA for hand lamps.
If the secondary voltages are not from separate windings, the common winding shall
be rated such that the rated outputs of both 110V and 25V loads may be used
simultaneously.
The transformer primary shall be protected only at circuit source.
Each pole of each secondary winding shall be fitted with a double-pole miniature
circuit breaker to BS EN 60898 Type C.
The circuit breakers shall have overload trip characteristics suitable for providing short
circuit and overload protection to the transformer windings, each pair being
mechanically ganged.
The circuit breakers shall be contained within the main enclosure but it shall be
possible to operate the circuit breakers without removing any main covers or other
covers, which shall expose live terminals.
15.3.3.4.1
Tool Transformer Enclosure
Shall be weatherproof, constructed either of metal or of a tough non-brittle
plastic/polycarbonate material.
Metal enclosures shall be of sheet steel or cast construction of not less than 1.5mm
thickness. After shot blasting or other approved preparation, the enclosure shall be
electroplated with zinc to BS EN 12329 and BS EN 12330 Class A.
External wall mounting lugs shall be fitted.
15.3.3.5 Hand lamps
Hand lamps shall comply with BS4533: Part 102 Class III, and be suitable for 25V
operation. Hand lamps shall be complete with specified length of TRS flexible cable,
lamp and guard. Unless otherwise specified, the cable shall be terminated in a plug
complying with BS EN 60309-2.
When used with a portable supply transformer the cable may be permanently
connected to the output terminals via a suitable compression gland.
Hand lamps shall be complete with a reeling drum or wall brackets or both for the neat
storage of the cable when not in use.
15.3.3.6 Electric Heating
Where specified, electric heating shall be suitable for the environment. The
preference shall be to install Convection Heating over Fan Heaters. Radiant heating
shall only be installed subject to approval by the Employer.
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Section 15 - Low Voltage Electrical Installation
All heating shall be installed with thermal cut outs.
Unless agreed otherwise with the employer, the use of Fan Heaters within corrosive
environment is prohibited.
15.3.3.6.1
Fan Heaters (WIMES 3.02 CLAUSE 5.1.6.4)
Heaters rated up to 2kW shall be single-phase. Heaters rated at or more than 2kW
shall be three-phase.
An integral thermostat shall be provided with means for locking or concealing the
setting adjustment to prevent unauthorised operation. The control unit shall be
located directly below its associated heater. For low occupancy buildings, frost-stats
shall be used instead of thermostats.
15.3.3.6.2
Convection Heaters
Convection heaters shall be of the tubular pattern, electric oil filled radiator or totally
enclosed panel type, as specified.
Tubular heaters shall be rated at 60W per linear foot and shall be suitable for wall
mounting.
Thermostats controlling a separate heater or group of heaters shall have an adjustable
temperature setting complete with means for locking or concealing the setting
adjustment to prevent unauthorised operation. For low occupancy buildings, froststats shall be used instead of thermostats.
The provision of the open element convection heater is prohibited.
15.3.3.6.3
Room Thermostats (WIMES 3.02 CLAUSE 5.1.6.5)
Thermostats shall have an adjustable temperature setting, typically of the range of
10°C to 30°C, and a provision to permit manual overriding of the thermal switching
action.
Each heater or group of heaters controlled from a single thermostat shall be provided
with a supply-isolating switch. The isolating switch shall be wall mounted in a
prominent position and be fitted with an appropriate label. The isolating switch shall
be connected on the supply side of the thermostat.
For low occupancy buildings, frost-stats (i.e. typical range of 3° to 20°C) shall be used
instead of thermostats.
15.3.4 CABLES (WIMES 3.02 CLAUSE 7.0)
Clause 7.0 of WIMES shall apply with the following clauses.
Where existing equipment on site contains control cabling colours not in compliance
with the current engineering specification (see section 14 of the Engineering
Specification) or the installation contains non harmonised cable colour (to BS7671)
then the selection of cable colours and application of Caution Notices on site shall be
as detailed in Appendix 4 (Guidance in Managing the Harmonised Cable Colours).
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Section 15 - Low Voltage Electrical Installation
Any damage to any of the cables, or the outer sheaths, during installation shall not be
accepted.
The provision of motor power and motor heater cables within the same motor supply
cable is acceptable.
Aluminium conductor cables may be used subject to the written permission of the
Employer.
15.3.4.1 Types of Cables (WIMES 3.02 CLAUSE 7.3)
Unless specifically specified otherwise by the equipment supplier associated with the
cables application, cabling shall comply with:a)
b)
c)
Domestic/Commercial Power Cabling shall comply with BS 6004 (Table 5).
Industrial/Non Commercial Power Cabling shall comply with BS5467 or
BS6346 (PVC/SWA/PVC).
Instrumentation Cabling shall comply with BS5308 (Type 2).
Where a non-rigid power and control cabling installation is necessary, the cabling shall
have multi-stranded copper conductors, be kept to a minimum length taking due
consideration of the application and be selected from the following: a)
Unarmoured cable to be used for final connections to low power equipment
operating at 230V and below and for flex outlet wiring accessories.
b)
Braided armour cable to be used for final power connections to moving plant,
where total flexibility and significant abrasion resistance are required e.g.
submersible pumps. Core insulation shall be EPR, with a braided or pliable
wire armour and a CSP outer sheath.
Cabling between the controller and the sensor or detector on Fire Alarm or Fixed Gas
Detection Systems may be carried out using Fire Retardant LSOH cabling to BS76291. Where cabling is to be used for Fixed Gas Detection Systems the out sheath shall
be coloured White.
15.3.4.2 Installation of Cables (WIMES 3.02 CLAUSE 7.4)
15.3.4.2.1
Cable Installation - Inside Buildings
All cables shall be neatly run vertically or parallel to adjacent walls, beams or other
structural members.
Cables are to be adequately supported so as to prevent sagging.
Fixing of cables direct to structures via cable cleats shall be prohibited on cable routes
containing more than two cables.
No direct fixing shall be made onto any pipe, vessel or item of equipment.
The use of connector strips within junction boxes, panels or freestanding as a means
of cable jointing is prohibited.
15.3.4.2.2
Cable Installation - Outside Buildings and Below Ground
Any damage to the cable, or the outer sheath, during installation shall not be
accepted.
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Section 15 - Low Voltage Electrical Installation
Cables shall not be installed when the temperature is at or below 0ºC, unless
appropriate precautions are taken. The precautions shall be agreed with the Employer’s
agent and shall include the provision of a heated storage room in which the cable is
stored for not less than 24 hours immediately prior to installation.
All cables shall be installed in continuous lengths without through joints or tees. Joints
shall be installed where approved by the Employer and then joints shall be to BS6910
and recorded on the drawings. Joints shall not be permitted under roads or other
inaccessible places.
15.3.4.2.2.1
Installation Direct in the Ground (WIMES 3.02 CLAUSE 7.4.4.2)
Cables shall have a minimum of 500mm of cover in soft ground and 1000mm of cover
in agricultural land.
Cables laid direct in the ground shall be laid, as a minimum, on a bed of 150mm of
sand and covered by a further 150mm of sand. Selected backfill shall be used above
the sand bed and surround. Cable identification tape shall be laid on top of the final
sand cover before backfill.
15.3.4.2.2.2
Installation in Underground Ducts (WIMES 3.02 CLAUSE 7.4.4.4)
As detailed in Section 29 of the Engineering Specification draw pits access covers
shall be appropriately secured as dictated by the outcome of a Security Risk
Assessment. Draw pit access seals shall be renewed as necessary, if rendered
ineffective following removal.
Unless agreed otherwise with the Employer, to minimise damage from rodents, only
armoured cables shall be installed within underground cable ducts.
Cable identification tape shall be laid 200mm above the top of the cable duct.
15.3.4.2.2.3
Marking of Underground Cables
The location of all underground cables shall be identified by marker plates fixed to the
exterior surface of all walls of buildings 300mm above ground level and directly above
the point where cables pass through the wall.
15.3.4.2.3
Cable and Wiring Support Systems (WIMES 3.02 CLAUSE 7.4.5)
Cable support system located within high corrosion areas (e.g. near sodium
hypochlorite plants) shall be heavy-duty plastic or stainless steel.
15.3.4.2.3.1
Installation using Cleats
Cables erected on walls or steelwork shall be supported such that flexing cannot
occur. Cables shall be supported by cleats to prevent longitudinal movement.
Cleats shall be provided in all vertical runs of cables at intervals of not more than one
metre and on horizontal runs at intervals of not more than 500mm.
Only one cable shall be fitted into a single cable cleat, and the cleat shall fit the cable
correctly.
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15.3.4.2.3.2
Section 15 - Low Voltage Electrical Installation
Installation using Tray and Ladder
Cable Tray, Ladder and support systems shall be Post Hot-Dipped Galvanised to BS
EN ISO 1461.
Where installed outside of an enclosed building, Cable Trays and Ladders shall be
hidden or obscured from view. Where this is not practical, as detailed in Section 29 of
the Engineering Specification, cable trays and ladders shall be appropriately
covered/protected as dictated by the outcome of a Security Risk Assessment.
Cables, cable trays and ladders shall be neatly fixed plumb and square to the lines of
the structure. The cables, cable trays and ladders shall be properly secured and shall
present a neat and workmanlike appearance. Tray and ladder shall be free from any
deformation after installation of the cables.
Proprietary standard non-site fabricated tray, ladder and accessories shall always be
used unless it can be demonstrated that the use of such components will result in:a)
OR
b)
Gaps, spaces or extensive runs of unsupported cables within cable tray runs;
Complex sequences of bends.
Under these conditions, site fabricated accessories may be used but must be of the
same level of construction (i.e. same materials, thickness and finish) as non-site
fabricated accessories.
Holes cut in cable tray for the passage of cables shall be provided with grommets.
Alternatively, they shall be bushed or lined with an approved material.
Not more than one side of any tray or ladder may be used for the support or fixing of
cables.
15.3.4.2.3.3
Installation using Steel Wire Cable Trays.
Steel Wire Cable tray shall be installed and cables mounted on the tray in compliance
with clause 15.3.5.2.3.2 and WIMES Clauses 7.3 and 7.5
Where installed outside of an enclosed building, Steel Wire Cable Trays shall be
hidden or obscured from view. Where this is not practical, as detailed in Section 29 of
the Engineering Specification, Steel Wire Cable Trays shall be appropriately
covered/protected as dictated by the outcome of a Security Risk Assessment.
Wire Cable tray shall be manufactured from a minimum 4mm diameter steel wires,
welded together and bent into final shape. The tray shall be manufactured with a
longitudinal ‘T-welded’ safety edge to prevent damage to cabling.
Steel Wire Cable tray shall be Post Hot-Dipped Galvanised to BS EN ISO 1461.
All trays shall be arranged and positioned on the site in accordance with the
manufacturer’s instructions. The deflection of the wire cable tray shall be no more
than 1/200th of the distance between two supports and tested in accordance with IEC
61537.
Wire cable trays shall be designed with an optimum span of 2m, taking into account
the maximum carry capacity authorised by the manufacturer.
Accessories for wire cable tray to form bends, risers and tees shall be constructed in
accordance with the manufacture’s instructions. Cuts and bends to treated steel shall
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Section 15 - Low Voltage Electrical Installation
be treated to prevent corrosion (i.e. cuts in Hot Dip galvanised tray shall be treated
with galvanising paints).
Only supports, brackets or hangers designed, mechanically tested and supplied by the
wire cable tray manufacturer shall be used. The loading capacities of the brackets
and the hanger torques shall be tested in accordance with IEC 61537.
Earthing and earth continuity shall be carried out by components in compliance with or
as supplied by the wire cable tray manufacturer.
15.3.4.2.3.4
Installation in Cable Trunking
Cable trunking shall not be used on any outdoor installation unless approved by the
Employer.
The Contractor shall ensure a minimum usable 25% spare capacity within all cable
trunking systems following completion of the cable installation.
Where trunking passes through a floor, wall or ceiling, the lid shall be solidly fixed for a
distance of 100mm either side.
Where connection is made between trunking and a distribution board, the cable entry
or entries shall be sized to accept all cables from all used and "spare" ways.
15.3.4.2.3.5
Cable Installation in Conduit
Conduits and fittings shall be either heavy-duty PVC type or galvanised heavy-gauge
screwed type as specified in the Particular Specification.
A separate CPC shall be installed in all conduit systems, whether these are rigid,
flexible, plastic or steel.
Cables for AC circuits shall always be grouped such that all phases and any neutrals
conductors are contained within the same enclosure.
The whole of the installation shall be arranged for a loop-in type of system, with joints
only being carried out at switches, isolators or appliance fittings.
Ends of conduits, liable to be left open for any length of time during building
operations, shall be plugged to prevent the ingress of dirt. Covers shall be fitted on all
boxes.
15.3.4.2.3.6
PVC Conduit
Joints between conduits, fittings and accessory boxes may be by ‘push-fit’
compression, mechanical locking or socket end sealed with a PVC adhesive. Where
weatherproof or watertight protection is required, ‘push-fit’ compression arrangement
alone shall not be acceptable.
Expansion couplers shall be fitted in straight surface runs every 12m. The free end
shall be sealed with non-setting mastic to form a waterproof seal.
Purpose-made bends may be used providing that the appropriate cable bending
radius is maintained. Cracked or crinkled conduit shall be rejected.
Adaptable boxes and accessories shall be made from heat-resistant insulating
material. The minimum wall thickness of boxes having a nominal internal depth of
16mm or less shall be 1.5mm. For deeper boxes, the minimum wall thickness shall be
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2mm. All boxes intended to support luminaries or other heat sources shall have either
external fixing lugs riveted to the metal fixing inserts or utilise steel insert clips. All
accessories shall be fitted with earthing terminals.
15.3.4.2.3.7
Flexible Conduits
Flexible conduit shall only be used as means of spanning conduit between two points
which may be subjected to vibration, expansion or movement or where appropriate for
final connections to rotating machines.
The use of flexible conduit shall be kept to a minimum and, where used, shall only be
used at the point(s) along the length of the cable run under which the cabling shall be
subjected to vibration, expansion or movement. Under all other circumstances the
use of flexible conduit is prohibited.
Where conversion from rigid conduit to flexible metallic conduit is to be made, the rigid
conduit shall terminate in a through-type box. The flexible conduit shall extend from
this box to the equipment. The earth continuity cable shall be secured to the box and
to the piece of equipment.
15.3.4.3 Glanding and Identification of Cables (WIMES 3.02 CLAUSE 7.5)
Cable glands shall be of the heavy-duty types and be appropriate for the type of cable
used and the environment. Cable glands shall comply with Clause 7.5 of WIMES.
Each cable shall carry, for that site, a unique cable number. Where possible, the
cable numbers shall following an existing cable numbering system for that site. Where
this is not practical, then it is suggested that cables on existing sites shall be labelled:a)
b)
c)
d)
Power cabling: <YW Project Number>P<Unique Ref.> (e.g. A7043P001).
Control cabling: <YW Project Number>C<Unique Ref..> (e.g. A7043C001).
Instrument cabling: <YW Project Number>I<Unique Ref..> (e.g. A7043I001).
Earthing cabling: <YW Project Number>E<Unique Ref.> (e.g. A7043E001).
Cable core labelling shall be consistent with the labelling used within the MCC, Control
Panel, Control System or other Electrical Equipment terminated to the cable.
15.3.5 EARTHING AND PROTECTIVE BONDING (WIMES 3.02 CLAUSE 8.0)
Clause 8.0 of WIMES shall apply with the following clauses.
Refer also to Section 18 of the Engineering Specification with respect to earthing in
substations.
The Contractor shall obtain Earthing Declaration forms, where required, from the DNO
and shall be responsible for their completion and submission to the DNO when the
installation is complete and ready for bonding to the earth terminal. A copy of this
form or any other documents pertaining to earthing shall be sent to the Employer.
Circuit and main earthing and equipotential bonding conductors shall be highconductivity copper tape (which is tinned where there is a likelihood of corrosion) or
1000V grade PVC insulated multi-stranded cable.
Inspection pits shall be provided to mark the position of the electrodes and buried
connections.
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Within each installation, protective (main) equipotential bonding conductors complying
with Chapter 54 of BS7671 shall connect to the main earthing terminal extraneousconductive-parts (i.e. a conductive part liable to introduce a potential, generally Earth
potential, and not forming part of the electrical installation) which shall include, but are
not limited to:a)
Water installation pipes.
b)
Gas installation pipes.
c)
Other installation pipework and ducting.
d)
Heating and air conditioning systems.
e)
Exposed metallic structural parts of the building.
Where there is a risk of live parts or flexible cables making contact with support
steelwork, lifting equipment, or major parts of process plant then these should be
considered as main equipotential bonds to provide a safety earth. This would include
but is not restricted to :a)
Pump guide rails/support steelwork/cover plates (on New Installations).
b)
Lifting beams (whether or not there is fixed electrical lifting equipment).
c)
Lifting Davit Sockets
d)
Borehole pump rising mains and head plates.
Where electrical equipment is located in isolation to the remainder of the electrical
system and the equipment, along with all adjacent electrical services, is supplied off a
single feeder cable, then the main equipotential bonding conductors may be sized on
the size of the common feeder cable to the electrical equipment rather than the site
incoming supply cable.
The protective equipotential bonding conductor shall be not less than 16mm2. All
connections shall be made using compression-type cable lugs. The surface to which
earthing bonds are fixed shall be thoroughly cleaned, free from paint and other nonconducting material. The connection shall be coated in petroleum jelly to prevent
corrosion.
Supplementary equipotential bonding conductors shall be provided as means of
additional protection for Fault Protection (as detailed in Regulation 415.2 of BS 7671).
As a minimum, it shall be provided where there is an increased risk of electric shock
either within special installations or locations (e.g. locations as defined by BS7671,
Part 7 or special locations covered by other standards, such as hazardous areas, or
manufacturers recommendations) or, with the agreement of Employer, where
automatic disconnection times cannot be achieved.
Supplementary equipotential bonding may be required either within or external to the
installation. An assessment shall be made in accordance with Regulation 415.2 of BS
7671 to establish the requirement for, and the size of, conductors to connect
extraneous-conductive parts and exposed-conductive-parts.
Metal cable support systems (e.g. conduit, trunking, ducting, channelling and trays) do
not require earthing via supplementary equipotential bonding where the live
conductors are separated from the support systems by:a)
Basic insulation plus an earth screen, sheath or armour of current carrying
capacity equal to the live conductors; or
b)
Basic insulation plus supplementary insulation.
An example of such
supplementary insulation would be plastic conduit but not sheathing.
Under all other conditions, even if the support systems are not used as the protective
conductors, metal cable support systems require earthing.
Where it has been judged that supplementary equipotential bonding is required the
effectiveness of the bonding shall be verified in accordance with Regulation 415.2.2 of
BS7671.
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Where appropriate and where available space is limited, a MET comprising of a
minimum of 25mm x 6mm may be installed, as opposed to the dimensions detailed in
WIMES 3.01 Clause 8.3.
15.3.6 PARTICULAR TYPES OF INSTALLATION (WIMES 3.02 CLAUSE 9.0)
Clause 9.0 of WIMES shall apply with the following clauses and additional sections.
15.3.6.1 HAZARDOUS AREAS (WIMES 3.02 CLAUSE 9.1)
Attention is drawn to Kelda Water’s Flammable Atmospheres Guidance on
Identification and Design and Related Issues.
Persons designing, installing, commissioning and inspecting circuits on or within
Hazardous Areas should have adequate training on the installation, examination and
testing of Explosion-proof and Intrinsically Safe electrical equipment.
Unless
otherwise agreed with the Company Electrical Engineer (as defined in Kelda Water
Safety Code of Practice), the inspector and installation supervisor must have a valid
COMPEX certificate of competency in the applicable units (EX01-EX10) for the area
where equipment is to be installed or testing is to be performed. Where the hazard is
a gas, the installation supervisor and inspector shall have attended EX01-EX04, and
where the hazard is a dust the installation supervisor and inspector shall have
attended EX05-EX06.
Electrical supplies within a Hazardous Area shall not be TN-C or TN-C-S (i.e. the
neutral and the protective conductor shall not be connected together or combined
within the hazardous area). For TN-C-S systems, at any point of transition between a
TN-C and TN-S system, the protective conductor shall be connected to the
equipotential bonding in the non-hazardous area and the TN-S system used within the
Hazardous Area.
All intrinsically safe cabling shall have a light blue outer sheath. All intrinsically safe
cabling run underground shall be installed within ducts to differentiate from water
pipes.
In designing the installation, the Contractor shall take into consideration the stored
energy where long cable runs are part of an intrinsically safe system.
Where cables pass through hazardous area boundaries, precautions shall be taken to
prevent the passage of flammable gasses, vapours or liquids across the boundary.
This shall be achieved as detailed in WIMES 3.02, Clause 7.4.3 or via a proprietary
gas-tight seal system.
The method of sealing hazardous area boundaries shall take due consideration of
operational and maintenance requirements. Where the sealing on a hazardous area
boundary is likely to be modified on a regular basis, the selected method of sealing the
boundary shall be suitable for regular modification whilst retaining a gas-tight seal.
Cables entering and leaving gas-tight transits shall be labelled making it clear that the
cable transit is gas tight.
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Where areas have been classified as hazardous (under BS EN 60079), the Contractor
shall carry out inspecting and testing in accordance with both BS7671 and BS EN
60079. The outcome of the inspection and testing shall be submitted within the O&M
manuals, along with:a)
b)
c)
d)
e)
f)
g)
h)
Certification to confirm that those parts of the electrical installation within or
affected by the Hazardous Area are fully compliant with the requirements laid
out within BS EN 60079 and DSEAR (Dangerous Substances and Explosive
Atmospheres Regulations).
A Zoning Plan of the Works Outlining the Limits of the Hazardous Area.
A Risk Assessment, where the zoning differs from the rule-based zoning
approach detailed within “Kelda Water’s Flammable Atmospheres Guidance on
Identification and Design and Related Issues” Document
Test sheets confirming the outcome of a Detailed, Close and Visual Inspections
and Tests of the installation.
All manufacturers' supplied documentation on the apparatus.
EX test Certificates.
For IS Circuits, calculations to demonstrate the issues associated with stored
energy within cables have been considered.
Records sufficient to enable the explosive protection equipment to be
maintained in accordance with its type of protection (i.e. list and location of
apparatus, technical information, manufacturer’s instructions, Type, Serial
Number, Ex Rating, for ‘X’ rated equipment special requirements etc.).
15.3.6.2 LIGHTING INSTALLATIONS (WIMES 3.02 CLAUSE 9.2)
15.3.6.2.1
Standards of Lighting
All lighting shall comply with the Clause 9.2 of WIMES. Additional lighting required for
operational and maintenance reasons (e.g. local floodlights for monitoring a wet well)
shall be specified in the Particular Specification.
Where lighting is required to provide enhanced site security or support to security
systems (e.g. Lighting for Security Cameras) then reference shall also be made
Section 29 of the Engineering Specification.
15.3.6.2.2
Energy Efficiency
Lighting systems shall be designed to ensure maximum energy efficiency. Not only
should consideration be made to the type of lamps used but also how they can be
controlled. There should be easy means of switching lighting off, particularly for inside
lighting. Outside lighting shall be suitable for the way the site is to be operated.
Unless agreed otherwise with the Employer :a) Non walk in Kiosk general Lighting to be operated off a switch.
b) General Lighting on large sites to be switched on/off at a central place with a
photo cell to switch the lights off at daybreak following the lights being left on
overnight.
c) General Lighting on small sites to be switched on/off at a central place.
d) Road Lighting to be switched on/off at each road entrance to the site with a
photo cell to switch the lights off at daybreak following the lights being left on
overnight. Each Road Light switch shall be illuminated by a single lamp
(generally a street light) operated off a Photo Electric Cell.
The location of the on/off switch outline in b) and c) above shall be in an area
illuminated by the road lighting outlined in d) above.
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Discharge lighting shall not be controlled off an infra red sensor.
Fluorescent luminaires shall be of the energy-efficient triphosphor high-frequency
type, unless otherwise specified. Energy-saving fluorescent lamps used instead of
tungsten filament lamps shall have integral control gear and a minimum useful life of
8,000 hours.
Energy-efficient, long life high-intensity discharge or fluorescent lamps shall be used in
place of tungsten-filament lamps.
LED luminaires shall be used where it can be demonstrated that they have a lesser
whole life cost than other equivalent types of luminaires. Whole life costs to consider
the cost of installation, energy used by, expected asset life of and replace of
luminaires.
Wherever possible, Lighting Systems (i.e. Luminaires and Lighting Control Systems)
shall meet the criteria detailed within the “Energy Technology Criteria List” set by the
Carbon Trust (See Website www.eca.gov.uk for more details). Where lighting
systems meet these criteria the Employer shall be notified.
15.3.6.2.3
Luminaires
General-purpose fluorescent luminaires shall be manufactured from zinc-coated sheet
steel of minimum thickness 0.7mm with white epoxy polyester powder or equivalent.
Luminaires shall be fitted with a trough reflector or prismatic diffuser as specified.
Luminaires for installation in clean and dry areas shall have a minimum degree of
protection IP20 (without a diffuser) and IP40 (with a diffuser) to BS EN 60529.
Luminaires for use in a corrosive environment shall have a glass-reinforced plastic
body with a prismatic acrylic or polycarbonate diffuser. The degree of protection shall
be IP65 to BS EN 60529.
Bulkhead luminaires shall be of the heavy-duty type and shall have a die-cast
corrosion-resistant aluminium body and front frame with epoxy polyester powder or
equivalent finish, and prismatic cover. Covers fitted to luminaires located outdoors
shall be impact-resistant polycarbonate. The cover shall be sealed to the body with a
silicon rubber gasket and shall be secured using stainless steel captive screws.
Retaining hinges shall be stainless steel.
Bulkhead luminaires for indoor location shall have a minimum degree of protection
IP54 and for outdoor location IP65 to BS EN 60529.
Floodlighting luminaires shall be of similar construction to the bulkhead luminaires
except they shall be fitted with a clear toughened glass panel. Floodlighting luminaires
shall be complete with high-purity anodised aluminium reflector and galvanised steel
mounting brackets. Reflector characteristics shall be selected to suit the floodlight
application.
15.3.6.2.4
Lamps
The use of tungsten-filament lamps is prohibited.
Unless agreed otherwise with the Employer, All lamps for installation in industrial
areas shall have a correlated colour temperature of 3,500K (white appearance) and
for other areas shall have a correlated colour temperature of 3,000K (cool white
appearance) unless otherwise specified. The minimum rated useful lamp life shall be
3,000 hours.
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The lamps shall be rated for an applied voltage of 230V 50Hz.
15.3.6.2.5
Mechanical Installation
Due regard shall be paid to the accessibility of all luminaires for lamp changing,
maintenance and environment both outside and inside the buildings.
The location, position and access to luminaires, either located inside or outside, shall
be selected on the basis of lowest whole life costs. Consideration on whole life costs
shall include:a) The asset life of the structure used to support the luminaire (e.g. 30 years for a
lighting column).
b) The number of luminaires on site.
c) The lamp replacement interval (based on the service life of the lamps).
d) The cost for hire or supply and maintenance of specialist tools or equipment to
facilitate lamp replacement (i.e. Scaffolding, “Cherry Pickers”, “Hydraulic
Counterbalances”, Winches) and their ease of use on site (i.e. vehicular access
for a “Cherry Pickers” or suitable ground to construct scaffolding).
e) Maintenance Costs associated with Winches and Hoists within the lighting mast
(as recommended by the column manufacturer).
Luminaires shall be mounted on existing structures wherever practicable.
Where a conduit box or trunking supports the weight of the luminaries, the fixings shall
be adequate for the purpose.
Luminaires having metal back plates shall not be fixed directly to a conduit box in
which a thermoplastic material is the principal load bearing member.
Where luminaires are supported from the structure other than by the conduit or
trunking system, they shall be fixed by approved purpose-made clamps, bolts,
washers and nuts, expanding anchors or proprietary wall plugs and non-ferrous
screws as appropriate.
15.3.6.2.6
Electrical Installation
Where a fluorescent tube luminaire is fixed directly to circular conduit boxes, the final
circuit wiring may be terminated within the luminaire. The wiring shall enter each
luminaire at the conduit entry nearest to the terminal block. Where a loop-in wiring
system is used, the wiring shall leave by the same entry. Wiring shall not pass
through the luminaire.
15.3.6.2.7
Outdoor Lighting Installation
In general, lighting levels on site shall be maintained at a background level as defined
within the table located in WIMES Clause 9.2.2.1. At specific locations where a
frequent proactive or reactive maintenance/operational task is likely to take place
during periods of poor light (i.e. evening and night) or in a dark or poorly lit location,
then additional task lighting shall be installed. Typical examples of locations which
may require task lighting include, but are not limited to:a)
b)
c)
d)
e)
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Control Panels.
Plant that needs to be operated out of hours (e.g. Screening Plant).
Tanker loading areas.
Kiosks.
Compliance-critical Process Plant.
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The location of Outdoor Task Lighting shall be agreed with the Employer.
As dictated by Operational requirement, individual task lighting may be switched on/off
by a separate switch to the rest of the general site lighting.
Due regard shall be paid to the re-striking time of certain types of luminaries, such that
at places where there is danger from moving traffic and vehicles, additional and
suitable luminaires shall be installed.
Control gear, when sited outdoors, shall be housed in weatherproof enclosures, and
warning notices shall be affixed to such enclosures, stating:
"Isolate elsewhere before opening or remove this cover".
15.3.6.2.8
Lighting Columns, Masts and Towers
The scope of supply for each lighting column, mast or tower shall include the
following:
a)
b)
c)
d)
The lighting column, mast or tower itself, including all necessary fixtures and
fixings for attaching the luminaire to the support;
The excavation of the support foundations;
The supply and installation of the concrete base; and
The erection of the column, mast or tower.
Lighting columns, masts or towers shall be earthed at the base of the support and
shall contain a switched isolator (lockable in the ‘OFF’ position) in a weatherproof
enclosure.
Lighting columns shall comply with BS 5649-5 and BS EN 40 (all relevant parts).
Lighting towers shall be of galvanised and painted tubular steel construction complete
with, where necessary, railed platform, ladders and safety cage.
15.3.6.2.9
Emergency Lighting
Emergency lighting shall be installed as dictated by the outcome of a risk assessment
under the Workplace (Health, Safety and Welfare) Regulation 1992. The risk
assessment shall not only consider the issues highlighted by those regulations but
also the likelihood of people being on site and anticipated response time of any
personnel likely to be required to respond to an emergency situation.
Emergency Lighting to enable the safe egress from a building/structure shall generally
be provided where the outcome from the Site Fire Risk Assessment (as detailed in
Kelda Water Safety COP 27 Appendix 3, as defined in the Site Fire Standards COP
27 Appendix 4 and provided in Section 26 of the Engineering Specification) categories
the building/structure as a Type 1, Type 2 or Type 3.
An Emergency Lighting System shall comprise of either individual self-contained
Emergency Lighting fittings or Emergency Lighting fittings supplied off a central
Battery Charging Unit.
Emergency Lighting fitting shall be designed to carry out Automatic Self-testing
generating a visual and, where not a nuisance to the general public, audio alarm when
urgent repair work is required. The automatic self-test shall as a minimum carry out
the monthly tests and yearly discharge tests as defined in BS5266 and BS EN 50172.
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On Emergency Lighting fittings, the timing of automatic annual discharge testing shall
be such that it ensures that an adequate level and duration of emergency lighting is
available throughout the building at all times. This shall generally be achieved by
staggering the automatic discharge testing over the various light fittings within each
specific area.
When choosing between self-contained Emergency Lighting Fittings and Emergency
Lighting supplied off a central Battery Charging Unit, due consideration shall be taken
to the Whole Life Costs associated with installing, maintaining and testing emergency
light fittings. In general, emergency lights supplied off a Central Battery Charging Unit
shall be preferred on permanently manned sites (e.g. Facilities Buildings, Office
Blocks and Data Centres).
The rated duration of emergency lighting luminaires shall be a minimum of 3 hours.
15.3.6.3 LIGHTNING PROTECTION (WIMES 3.02 CLAUSE 9.3)
15.3.6.3.1
Scope
This specification gives the requirements for the provision of lightning protection of
buildings and for the protection of instrumentation systems and radio aerials from the
effects of lightning.
The requirements for the provision of lightning protection systems shall be in
accordance with BS EN 62305 (Code of practice for protection of structures against
lightning).
High risk and/or exposed structures shall be protected against lightning. In general
the following shall be protected: Reservoir Valve Towers
 OSEC Plants
 Water Towers
 Oxygen Vessels
 Digesters
 Gas Holders
 Computer Centres
 Facilities Buildings
 Wind Turbines; AND
 Any other exposed buildings.
15.3.6.3.2
Competency of the Contractor
An electrical contractor who specialises in the type of work shall carry out lightning
protection.
15.3.6.3.3
Information to be provided by the Contractor
The Contractor shall submit details of his proposed lightning protection installations
prior to the installation commencing.
The details shall include:
 Locations and connecting points for lightning air terminals, conductors and earth
mats.
 The location of every lightning protection units (LPU) and associated wiring and
connections.
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 Specification for all proposed materials and fittings including manufacturers’
details and literature.
15.3.6.3.4
Lightning Protection of Buildings and Structures
The down conductors shall be made of hard-drawn high-conductivity copper tape of
minimum 25mm × 3mm section, or an equivalent aluminium conductor current
carrying capacity.
The tape shall be fixed to the outside of the structure using "stand off" saddles.
Where possible the down conductors shall be obscured from general view.
The installation shall be protected against corrosion or other adverse effects of the
environment.
The overall resistance of the earth termination system shall not exceed 10 ohms.
The route and material used for the lighting protection system shall take due
consideration of site security risk (see Section 29 of the Engineering Specification).
15.3.6.3.5
MCCs, SCADA, PLCs & Instrumentation
For protection of SCADA, PLCs & Instrumentation see Engineering Specification
Section 20. For details on the application of surge and lighting protection within
switchboard see Section 14 of the Engineering Specification.
15.3.6.4 Fieldbus Networks (WIMES 3.02 CLAUSE 9.4)
The design of PROFIBUS communication cabling topology shall be in accordance with
specifically Section 20 but also Section 21 to 23 of Kelda Water’s Engineering
Specification and WIMES 3.02(A) PROFIBUS and Optical Fibre Network Design. The
network topology shall be approved by the Employer before commencing installation
work.
The system shall be designed such that a device can be disconnected and removed
without disrupting the bus.
The design, configuration, close supervision of installation, testing and commissioning
of PROFIBUS systems shall be carried out by competent persons who have been
properly trained, and independently certified by a registered PROFIBUS competency
centre. Components used in PROFIBUS installation systems shall be appropriately
certified.
15.3.6.4.1
PROFIBUS DP Networks (WIMES 3.02 CLAUSE 9.4.2)
PROFIBUS DP shall comprise of balanced two-wire data transmission using armoured
and shielded, twisted two-pair wire. There shall be no more than 32 stations per
segment including the scanner, repeater and secondary master when connected.
PROFIBUS DP networks shall be set to operate at 93.75 kbit/s for field-mounted
networks, but, to make the system robust, designed and installed to be capable of
operating at 187.5 Kbit/s. Repeaters shall be installed to create multiple segments for
longer bus lengths. There shall be a maximum of 3 repeaters on any PROFIBUS DP
network.
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The PROFIBUS DP site cabling shall be IEC 61158-2, Type A, twisted-pair (equivalent
to Belden 3079), shielded and armoured with a purple outersheath. Conductor size
shall be AWG 22/1, 0.64mm2.
PROFIBUS DP Connections within panels and enclosures shall be made using 9-pin
Sub D Connections. Field-mounted devices shall be connected to PROFIBUS via a
proprietary “T” type connection located within an adjacent junction box and connected
to the device by a spur. The total length of the spur shall be kept to a minimum but
not less than 1 metre in length however the total length of all spurs on a segment shall
not exceed 33 metres. Where available and subject to approval of the Employer a
proprietary disconnectable loop in loop out terminal box/plug may be used instead of
the “T” type connection.
In addition to the requirement stated in WIMES 3.02 Clause 9.4.2.1 with respect to the
location of piggyback connectors, piggyback connector shall be fitted on:a) each master socket on the PLC; and
b) on the first, central and last socket within each segment.
The operation of the termination resistor enable/disable switch on all 9-pin Sub-D
connectors within an installation shall be consistent (e.g. Up is always enabled). The
9 pin Sub-D connector shall have a form of construction suitable for the environment.
The Bus shall be terminated on the connector and not on the device such that the
termination point is evident. Active terminations shall be carried out in the ICA section
of the MCCs. Active terminations may be located in other locations subject to the
approval of the Employer.
15.3.6.4.2
PROFIBUS PA Networks (WIMES 3.02 CLAUSE 9.4.3)
PROFIBUS PA shall comprise of a power supply and data transmission over single
armoured and shielded twisted-pair cable. Current and voltage drop shall be
calculated and demonstrated to be acceptable. There shall be no more than 32
stations per segment.
The PROFIBUS PA cabling shall be IEC 61158-2, Type A, twisted pair (equivalent to
Belden 3076), shielded and armoured with an Orange outersheath. Conductor size
shall be AWG18/7, 0.88mm2.
Where PROFIBUS PA cabling is to be used on Hazardous Area equipment then the
outer sheath of the cables shall be coloured blue and the cable shall be treated as an
Intrinsically Safe cable (as defined within this document).
15.3.6.4.3
Optical Fibre Networks (WIMES 3.02 CLAUSE 9.4.4)
The design, configuration, supervision of installation, testing and commissioning of
Optical Fibre Networks systems shall only be carried out by competent persons who
have been suitably trained and work for a contractor who specialise in Optical Fibre
Network installation.
Unless agreed otherwise with the Employer, fibre optic cable shall always be of the
Multimode glass, OM3 50/125 type. The number of fibres within a fibre optic cable
shall be as defined in Section 20. Fibre optic cables shall be steel wire armoured,
unless otherwise agreed, to protect them from vermin attack. If non-armoured cable is
accepted by the Employer, it shall be installed within an appropriately sized PVC duct
throughout its length.
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Where installed outside of buildings, the route shall be clearly identified and shall be
installed in PVC or earthenware ducts. Wherever non-armoured cables are installed
an additional copper tracer wire shall be installed within the same duct to facilitate
future cable location.
The PVC or earthenware ducts provided shall not be protected by concrete unless
there is a reasonable risk to the integrity of the ductwork through traffic, etc.
15.3.6.4.4
Network Design Verification and Testing (WIMES 3.02 CLAUSE
9.4.5)
15.3.6.4.4.1 Pre-Commissioning - Visual Inspection
The PROFIBUS installation shall be visually inspected before other tests are started to
confirm correct installation in accordance with the following:
a)
b)
c)
d)
e)
f)
g)
h)
i)
j)
Installation in accordance with design.
Compliance with minimum spacing between cabling categories, or metal
partitions inserted.
No damage to PROFIBUS cabling.
Bending radii specification observed.
Cables crossing at right angles.
Sharp edges removed/covered.
Protected against mechanical damage.
Main Equipotential bonding installed.
Cable Screens earthed on the entrance to enclosures, MCCs, control panels,
etc.
Ex certified devices used as appropriate in hazardous areas.
15.3.6.4.4.2 Pre-Commissioning - Acceptance Measurements.
The electrical function of the PROFIBUS installation shall be checked by the following
acceptance checks and measurements. The results shall be recorded and
documented in the O&M Manuals.
A handheld bus test device shall be used for these checks and measurements:
a)
b)
c)
d)
e)
f)
g)
h)
i)
j)
k)
l)
Detection of open circuits in data cores.
Detection of open circuits in shielding.
Detection of short circuit between data cores.
Detection of short circuit between data cores and shielding.
Data cores not reversed.
Terminator resistor settings.
Transmission speed and PROFIBUS addresses properly set.
Voltage present for terminators on all interfaces.
RS485 signal strength sufficient on all stations.
CNTR signal present on the Master.
Check Slave addressing (bus scan)
Segment length measurements.
15.3.6.4.4.3 Commissioning
Once testing has been satisfactorily completed, the PROFIBUS system shall be
commissioned in the following sequence:
a)
b)
c)
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A Reflection test.
Voltage Level at each device.
System Configuration.
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d)
e)
f)
g)
Section 15 - Low Voltage Electrical Installation
(A software configuration tool shall be used to set up and check:
I.
Data rate.
II.
Device description files (‘GSD’ files).
III.
Addressing.
IV.
Bus parameters.
The system configuration shall be saved on CD and copies issued with the
O&M Documents.)
Verifying PROFIBUS Station Addresses.
Commissioning the PROFIBUS Stations.
Testing the signal inputs.
Testing the signal outputs.
The above tests shall be repeated during performance testing of the works to ensure
no interference occurs between the PROFIBUS Network and working equipment. A
commissioning checklist shall be completed and included within the O&M Manuals.
15.3.6.5 TELECOMMS
Telephone Cord Outlets
Telephone cord-outlets shall be of a type approved by British Telecom. Refer to
Section 22 with respect to the procurement and specification of PSTN and Private
Wire networks.
15.3.6.6 TRACE HEATING
15.3.6.6.1 Selection
Trace heating, sometimes referred to as surface heating, shall comprise of either:a) Trace heating tapes beneath fixed/removable insulation and cladding; OR
b) Electrically-heated jackets; OR
c) Heated pads beneath fixed/removable insulation and cladding.
The selection of the appropriate type of installation shall be made based on whole life
costs, taking into account:a) Capital installation costs of the trace heating plus the costs of the associated
lagging.
b) Energy usage over the design life of the installation.
c) Maintenance costs associated with retaining the integrity of the installation after
mechanical maintenance of the item being trace heated. In the case of trace
heating tape, the tape and thermostat shall be assumed to require replacement
each time the lagging is removed.
15.3.6.6.2 General Installation Requirements
The design and selection of suitable trace heating and its installation shall be carried out
by a competent trace heating specialist.
The trace heating shall be installed with the lowest practical voltage:a) Preferably SELV (as defined in BS7671:2008);
b) Where this is not practicable, 110V centre-tapped.
c) Where the above two are not practicable and subject to permission of the
Employer, 230V Live & Neutral with earth leakage protection fitted.
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Trace heating shall be installed on separate circuits for ease of dismantling the item
being protected.
Any lagging associated with trace heating shall be fitted with suitable warning notices.
Care shall be taken to avoid localised over or under heating of the pipework.
15.3.6.6.3 Traceheating Tape
Trace heating shall by of the self-regulating, parallel type.
Thermostat sensing bulbs shall be in direct contact with the surface of the item being
protected.
A thermostat shall be fitted with indication of when the trace heating tape is running, and
an override facility. The thermostat temperature should be manually selected but shall
be tamper proof.
When tapes are to be spirally wound onto pipes, then care shall be taken to avoid
bunching. Windings shall be widely separated and spaced as uniformly as possible.
Thermoplastic pipes and equipment shall be wrapped in aluminium foil prior to applying
the heating tapes. The rating of such tapes shall not exceed 12 watts/metre. Heating
tapes with silicone rubber, woven wire or woven polyester outer sheaths shall be used
on thermoplastic pipes and equipment. The use of heating tapes sheathed in plasticised
PVC is prohibited on such equipment. Any adhesives, tapes or other material containing
plasticisers shall not be used to secure heating tapes on to thermoplastic pipes and
equipment.
The trace heating tape shall be tested and inspected before any installation of insulation
is undertaken.
15.3.6.6.4 Electrically Heated Jackets or Pads
Trace heating systems comprising of heated jackets or pads shall consist of a
uniformly electrically heated flexible membrane encapsulated within either an insulated
jacket or uninsulated pad.
Heated jackets shall be designed for ease of maintenance to be easily removed and
reinstated without the need for modification. Where appropriate, they can replace the
need for separate lagging.
The temperature within the heated jackets or pads shall be controlled via a local
thermostat within each jacket or pad. Local indication shall be provided for each
heated jacket or pad circuit indicating when the electrical circuit supplying the jacket or
pad or system of jackets or pads is energised.
15.3.7 DECOMMISSIONED ELECTRICAL EQUIPMENT.
Decommissioned Electrical Equipment (i.e. where there is no expectation the electrical
equipment will be reused at a later date) resulting from the Contract shall be left in a
state where inadvertent use or reconnection can be prevented.
Where practicable all Electrical Equipment (including cabling) made redundant by the
Contract shall be disconnected and removed from site.
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As a minimum, unless agreed otherwise with the Employer, this shall comprise of:a)
All cables made redundant by the Contract entering and leaving free standing
Control Panels, Junction Boxes, Instruments or other items of free standing
Electrical Equipment should be removed at the gland plate and pulled back as
far as reasonably practical.
b)
All Junction boxes, distribution boards, control panels, Instruments and other
items of electrical equipment which are no longer energised following the work
carried out under the Contract shall be removed.
c)
Fuses shall be removed from within all decommissioned MCC cubicles and
Distribution Board fuse ways. All outgoing and incoming cables shall be
removed at the gland plate and pulled back as far as reasonably practical.
Labels on decommissioned MCC cubicles, distribution board fuse ways and
distribution board Circuit Breaker ways shall be removed and replaced either
with a “SPARE” label or “DECOMMISSIONED” label as deemed appropriate.
d)
Decommissioned cables shall be pulled back as far as reasonable practical.
Cables, or parts of cables, support by cleats, laid in groups of 3 or less cables or
run freely through ducts shall be removed.
e)
Underground disused cables shall be clearly marked on the underground
services drawings. Cores of cables shall be connected together, earthed and
capped.
15.3.8 INSPECTION AND TESTING (WIMES 3.02 CLAUSE 10)
Clause 10 of WIMES 3.02 shall apply for the electrical inspection and testing with the
following clauses.
Other than minor electrical installations (as defined by BS7671) for which the BS7671
Minor Completion Certificate shall be used, all cable schedules and Test & Inspection
records shall be prepared using the standard Kelda Water Electrical Test & Inspection
documents. These documents have been produced as a Microsoft Excel Workbook
“Kelda Water Test Documents.XLS” and are provided in Appendix 1.
To ensure that the installation has been constructed in accordance with the design
and to record that safety features have been checked and tested, copies of the Test &
Inspection sheets shall be completed during actual site testing. Any hand written
information shall be transferred to the electronic Excel Workbook as soon as possible
after carrying out the site inspection and testing work.
The original signed and completed Electrical Inspection Certificate (Appendix 1) or
where applicable: Minor Electrical Installation Certificate shall be submitted to the
Employer’s Engineering Reliability Team (see address in Section 15.3.2.1), and copies
of each, as appropriate, shall form part of the O&M Manuals.
The standard Kelda Water Electrical Test & Inspection workbook does not constitute a
complete list of electrical tests and inspections. Additional tests and inspections will
need to be undertaken and recorded as necessary.
The standard Certificate and Test & Inspection Sheets must not be modified or
revised.
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The following information shall be provided and located on a suitable wall or structure
adjacent to either the Point of Common Coupling (PCC) (for sites supplied at Low
Voltage) or the first Low Voltage switchboard supplied off each distribution transformer
(for sites supplied at High Voltage):
a)
Single Distribution Drawing
A single line drawing of the Low Voltage Electrical Systems either from the
PCC (for sites supplied at Low Voltage) or from the relevant distribution
transformer (for sites supplied at High Voltage).
b)
Earthing Drawing
Schematic drawings(s) showings the sites earthing and bonding connections.
c)
Periodic Inspection Notice
Where an entire Electrical Installation being supplied from a single PCC or
distribution transformer has been subjected to an initial Inspection and Test,
then a Periodic Inspection Notice (as given in Appendix 2) shall be provided
and dated.
Where existing drawings are unavailable and the modification(s) or addition(s) to the LV
Electrical System affect less than 20% of the entire LV System then a Single Line
Drawing and Earthing Schematic of the modified and/or additional electrical circuits
making reference to their connectivity with the PCC (for Sites supplied at LV) or
Distribution Transformer (for Sites supplied at HV) is acceptable.
15.3.9 O & M MANUALS (WIMES 3.02 CLAUSE 11)
The Contractor shall use Kelda Water Engineering Specification, Section 27 for O&M
Manuals.
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APPENDIX 1 – Electrical Certificates and Test Sheets
YW Test DOCS V1.08 I1.xls
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APPENDIX 2 – EXAMPLE PERIODIC INSPECTION NOTICE
This installation should be periodically inspected and tested
and a report on its condition obtained, as prescribed in BS7671
(formerly the IEE Wiring Regulations for Electrical
Installations) published by the Institution of Engineering
Technology.
Date of last Inspection
…………………………..
Recommended date of next Inspection
Refer to COP 16A
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APPENDIX 3 – Low Voltage Installation Schedules
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APPENDIX 4 – Managing the Harmonised Cable Colours.
A4.1. REASON FOR THE CHANGE.
As from the 31st March 2004 the IEE published Amendment No.2 to BS7671 (the IEE
Wiring Regulations) which specified a change in cable colours for all new fixed wiring in
electrical installations in the UK. These colours (sometimes referred to as “harmonised”
colours) had been introduced to bring the UK in line with practice on mainland Europe.
In response to this change and to drive in cost savings (resulting from standardisation
across the industry) the Pump Centre, authors of the WIMES (Water Industry
Mechanical & Electrical Specifications) documents agreed a set of control and power
cables colours with all the water companies. As from late 2003, starting with WIMES
3.04 issue 2, all new WIMES specifications had and continue to specify the new set of
cable colours.
The following appendix outlines the changes in control and power cable colours which
occurred in 2004 and how the interface between existing and current cable colours shall
be managed.
A4.2. CHANGES IN CABLE COLOURS.
A4.2.1 Single Phase.
The fixed installation colours of red phase and black neutral were replaced by brown
and blue respectively (the colours used in appliance flexible cables for many years).
The Protective conduct continued to be identified by the colour combination of green
and yellow.
Application
Old Colours
New Colours
Live
RED
BROWN
Neutral
BLACK
BLUE
Earth
GREEN/YELLO
GREEN/YELLOW
W
A4.2.2 Three Phase.
For three-phase cables the phase colours were replaced by brown, black, grey instead
of red, yellow and blue respectively, and the neutral colour were replaced by blue as
opposed to black. An alternative colour of brown for all phase colours with phases
marked L1, L2 and L3 will also be acceptable. Again the protective conductor
continued to be identified by the colour combination green and yellow.
Application
Old Colours
New Colours
L1
Live 1
RED
BROWN
BROWN
L2
Live 2
YELLOW
BLACK
BROWN
L3
Live 3
BLUE
GREY
BROWN
OR
Neutral
BLACK
BLUE
BLUE
Earth
GREEN/YELLO
GREEN/YELLO
GREEN/YELLO
W
W
W
A4.2.3 Control Cabling.
Prior to 2004 all water companies used a different set of control cable colours. In order
to harmonise control cable colours across the industry it was agreed that control cabling
were simplified to ELV (Extra Low Voltage i.e. <120Vdc, <50Vac and Analogues) to be
Yellow, LV (Low Voltage i.e. 110Vac) to be Red, Intrinsically Safe Cabling to remain
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Light Blue and Telemetry to remain Pink. In addition Analogue cable numbers would
be prefixed with a letter “A” to distinguish them from other ELV circuits.
Application
Old Kelda
New Colours
Water Colours
110Vac
BLACK
RED
110Vdc
GREY
YELLOW
24Vac
ORANGE
YELLOW
24Vdc
WHITE
YELLOW
Volt free
PINK
Coloured in line with application/voltage.
Telemetry (12Vdc)
PINK
PINK
Control Neutrals
BLUE
Analogues (Singles) WHITE
YELLOW
Intrinsically Safe
LIGHT BLUE
LIGHT BLUE
For practical reasons, White with Grey over sheath multi-cores and Blue/White with
Grey over-sheath twisted paired cables can be adopted for inter-compartment and
analogue screened cables respectively.
New Colours
Sheath
Cores
Blue
Analogues
(Twisted
Grey
Pair)
White
Inter-compartment
Grey
White
Application
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A4.3. MANAGING THE CHANGE TO NEW COLOURS.
Figure A4.1 – Selecting Appropriate Cable Colour Convention.
For safety reasons and ease of management it is essential that the interface between
new (current) and existing (non current) site cable colouring standards shall be kept to
an absolute minimum. To this end it is recommended (See figure A4.1) that:a)
Where modifications are to be carried out to installations/panels wired to an old
cable colour convention, then the modifications should be carried out as far as
practical using the existing cable colour system on site. It is anticipated that in the
near future it will be impractical, not cost effective and, in the case of power cables,
non compliant to supply field power cable to the old colour code. In this case power
cables to the new colour code shall be used and the enclosures shall be labelled
appropriately (see section A4.4).
b)
Where modifications are to be carried out to installations/panels wired to a mixture
of old and new cable conventions, then the modifications should be carried out to
the predominant cable colouring convention used within the installation/panel. At
the interfaces between the old and new cable colours conventions, the enclosure
shall be labelled appropriately (see section A4.4)
c)
Where extensions (e.g. new MCC Tiers) or new equipment (e.g. New Panels) are
to be installed on an installation wired either to the new or old colour conventions,
then this equipment shall be wired to the new cable conventions. At the interfaces
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between the old and new cable colours conventions, the enclosures shall be
labelled appropriately (see section A4.4)
d)
Where new equipment is to be supplied then this shall be wired to the new cable
colour convention. At the interfaces between the old and new cable colours
conventions, the enclosure shall be labelled appropriately (see section A4.4)
e)
Where an extension or modification is to take place on a site where there is no
clear and coherent cable colour convention then the new cable colouring
convention shall be used and labels as detailed in section A4.4 attached at the
extents of the extension or modification
A4.4. MANAGING THE INTERFACE BETWEEN NEW AND EXISTING CABLE COLOUR
SYSTEMS.
4.1 Single Phase Power Cabling.
Where only the single phase cable colours have been used then there is no
requirement at the interface between old and new cabling to label the cores providing
that they are correctly coloured. However the following caution notice (Figure A4.2)
must be fixed at the distribution board or consumer unit supplying the equipment.
Figure A4.2 Example Installation Caution
Notice.
Figure A4.3 Example Power Cable
Interface Notice
4.2 Three Phase Power Cabling.
Where three phase cable colours or a mixture of three phase and single phase colours
have been used then all cabling to the new colours and cabling at the interface to the
old colours shall (via ferrules) be labelled L1, L2, L3 for the phases and N for the
Neutral. The aforementioned caution notice (figure A4.2) must again be fixed at the
distribution board or consumer unit. A separate label (Figure A4.3) shall be mounted on
the enclosure containing the interface between new and old cable colouring systems.
4.3 Control Cabling.
On installations containing a mixture of control cabling to the new and old cable colours
the following caution notice (Figure A4.4) shall be fixed to all enclosures containing an
interface between cabling in the new and the old control cable colour standards. All
control cabling shall contain an appropriate ferrule referenced back to the schematic
drawings.
CAUTION
CAUTION
This wiring installation has control wiring
colours to two versions of Yorkshire Water
Engineering Specification.
Great care should be taken before undertaking
extensions alterations or repair that all
conductors are correctly identified.
This wiring installation has
control and power cabling
colours to the European and
Water Industry harmonised
colours.
Figure A4.4 Example Control Cable
Interface Notice
Figure A4.5 Example New Wiring Colour
Notice.
4.4 New Equipment.
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It is advised that new panels/enclosures wired to the new cable convention installed on
site containing a mixture of cable colouring conventions shall be suitably identified (e.g.
via Caution Label, as Figure A4.5, and/or being of a different coloured (e.g. blue to
BS4800, code 18E51 as for new MCCs)) drawing attention to the fact that they are
wired to the new wiring convention.
A4.5. PROGRAMME FOR ADOPTION.
The procedures detailed in this appendix came into force on 1st September 2004 and
shall be applied to all applicable sites.
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APPENDIX 5 – Typical Emergency Stop Risk Assessment.
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