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Railway Group Standard
GL/RT1255
Issue One
Date February 2009
Low Voltage Power
Supplies in Electrified
Areas
Synopsis
This document mandates requirements
for control of return and stray currents
and the management of earthing for low
voltage power supplies in electrified
areas.
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Published by:
Plant Standards Committee on 16 October 2008
Authorised by RSSB on 20 November 2008
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© Copyright 2009
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Railway Group Standard
GL/RT1255
Issue One
Date February 2009
Low Voltage Power Supplies in
Electrified Areas
Issue record
Issue
Date
Comments
One
February 2009
Original document
Supersedes GI/RT7007
The three new requirements have been marked by a vertical black line.
Superseded documents
The following Railway Group documents are superseded, either in whole or in part as
indicated:
Superseded documents
Sections
superseded
Date when
sections are
superseded
GI/RT7007, issue 1, June 2002
Low Voltage Electical Installations
All
04 April 2009
GI/GN7607, issue 1, June 2002
Guidance for Low Voltage Electrical Installations
All
04 April 2009
Supply
Controlled and uncontrolled copies of this Railway Group Standard may be obtained from
the Corporate Communications Department, Rail Safety and Standards Board, Evergreen
House, 160 Euston Road, London NW1 2DX, telephone 020 7904 7518 or e-mail
[email protected]. Railway Group Standards and associated documents can also be
viewed at www.rgsonline.co.uk.
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Low Voltage Power Supplies in
Electrified Areas
Railway Group Standard
GL/RT1255
Issue One
Date February 2009
Contents
Section
Description
Part 1
1.1
1.2
Purpose and Introduction
Purpose
Introduction
4
4
4
Part 2
2.1
2.2
5
5
2.5
Earthing Requirements
General earthing requirements
Earthing requirements for LV electrical installations in ac electrified lines
areas
Earthing requirements for LV electrical installations in dc electrified lines
areas
Residual current devices providing additional protection against direct
contact in dc electrified lines areas
Guidance for Part 2
6
6
Part 3
3.1
3.2
3.3
3.4
Other Requirements
Segregation
Interlocking of power supplies
Consultation with affected parties
Guidance for Part 3
7
7
7
7
7
Part 4
4.1
Temporary LV Electrical Installations
Temporary installations
8
8
Part 5
5.1
5.2
5.3
Application of this document
Application – infrastructure managers
Application – railway undertakings
Health and safety responsibilities
9
9
9
9
Appendices
Appendix A
Appendix B
Guidance for Part 2 of this standard
Guidance for Part 3 of this standard
2.3
2.4
Page
5
5
10
10
16
Definitions
17
References
18
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Railway Group Standard
GL/RT1255
Issue One
Date February 2009
Part 1
1.1
1.2
Low Voltage Power Supplies in
Electrified Areas
Purpose
Purpose
1.1.1
This document mandates requirements for the management of earthing to avoid
hazardous potentials, and for the management of segregation to control stray
currents and minimise current transfer between different electrical power supply
systems.
1.1.2
These requirements are additional to those normally required for low voltage (LV)
power supplies (for example. compliance with BS 7671) and are needed to avoid
hazardous touch potentials arising from differences in two independent power
supply systems (LV power supplies and traction power supplies) while ensuring
fault and stray currents are effectively controlled.
1.1.3
This document excludes power supplies to signalling and telecommunications
(S&T) equipment, for which specific earthing arrangements are made.
1.1.4
This document excludes installations which do not form part of the main line
railway, such as traction substations and depots.
Introduction
1.2.1
Page 4 of 18
Infrastructure managers need to co-operate to design, install and maintain LV
electrical installations such that the earthing and segregation arrangements are
not compromised.
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Low Voltage Power Supplies in
Electrified Areas
Part 2
Railway Group Standard
GL/RT1255
Issue One
Date February 2009
Earthing Requirements
2.1
General earthing requirements
2.1.1
Touch potentials
2.1.1.1 Where it is possible for a person to simultaneously touch exposed conductive
parts that are connected to the equipotential bonding system of a LV electrical
installation and the exposed conductive parts of the equipotential bonding system
of another electrical system or rail mounted vehicle, the LV electrical installation
shall be designed to ensure the touch voltage values do not exceed those
specified in BS EN 50122-1.
2.1.2
Circuit protective conductor
2.1.2.1 Metallic conduit, trunking and cable trays shall not be used as a circuit protective
conductor where high currents associated with other electrical systems could
affect the integrity of the circuit protective conductor.
2.2
Earthing requirements for LV electrical installations in ac electrified
lines areas
2.2.1
LV electrical equipment directly bonded to the traction return circuit
2.2.1.1 Where LV electrical equipment is either a) in contact with a conductive structure
directly bonded to the traction return circuit, or b) is directly bonded to the traction
return circuit, then the LV electrical equipment circuit protective conductor and
any other earthed metallic conductor (for example screen wire or armouring) shall
not be connected to the LV electrical equipment.
2.2.1.2
2.2.2
Guidance for 2.2.1 is set out in A.1.2 and Figure A.1.
LV electrical equipment indirectly bonded to the traction return circuit
2.2.2.1 Where LV electrical equipment is not directly bonded to traction return circuit as
set out in 2.2.1, then the LV electrical equipment circuit protective conductor shall
be connected to the LV electrical equipment.
2.2.2.2
The LV electrical equipment and circuit protective conductor shall be rated to
carry the prospective traction fault current, unless the equipment is not at risk of
carrying this current under fault conditions.
2.2.2.3
Where indirect bonding is used, a bond between the LV electrical installation
supply main earth and the traction return circuit shall be provided.
2.2.2.4
Guidance for 2.2.2 is set out in A.1.3 and Figure A.2.
2.2.3
Utility services and LV electrical installation bonding
2.2.3.1 Where the LV electrical installation is bonded to another electrical system, the
bonding and segregation arrangement of the utility services (for example gas,
water etc) shall avoid hazards arising from touch voltages and the transfer of
current between the systems and the utility services under operating and fault
conditions.
2.3
Earthing requirements for LV electrical installations in dc electrified
lines areas
2.3.1
Protection against dc leakage
2.3.1.1 Where a socket outlet is located such that an electrical appliance could be used
on or near an object in contact with the running rail or other exposed conductive
parts of the traction return circuit, then the design of the LV electrical installation
shall prevent the adverse effects of dc leakage in the earth wire.
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GL/RT1255
Issue One
Date February 2009
2.3.1.2
Low Voltage Power Supplies in
Electrified Areas
The design of the LV electrical installation shall prevent adverse effects from dc
leakage entering the neutral conductor of any other equipment or electrical
distribution system because of earth faults between the earth conductor and
neutral conductor.
2.3.1.3. The detection system of earth monitoring or earth proving devices shall be
protected against the effects of dc leakage.
2.3.1.4
2.4
Residual current devices providing additional protection against direct
contact in dc electrified lines areas
2.4.1
2.5
Guidance for 2.3.1 is set out in A.2.2.
In dc electrified lines areas dc leakage can affect the operation of the residual
current devices (RCD) used to provide additional protection against direct
contact. Therefore, Network Rail shall produce and maintain a list of approved
RCDs that are immune up to declared levels of dc leakage and shall make this
list available to others on request.
Guidance for Part 2
2.5.1
Page 6 of 18
Guidance for Part 2 is set out in Appendix A.
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Low Voltage Power Supplies in
Electrified Areas
Part 3
3.1
Other Requirements
Segregation
3.1.1
3.2
Interlocking of power supplies shall be provided where it is necessary to prevent
paralleling of independent LV electrical power sources.
Consultation with affected parties
3.3.1
3.4
High voltage (HV) and traction systems shall be segregated from LV earth
systems in order to avoid extraneous connections.
Interlocking of power supplies
3.2.1
3.3
Railway Group Standard
GL/RT1255
Issue One
Date February 2009
Before making any change to a LV electrical installation the infrastructure
manager shall consult with any other infrastructure manager that could be
affected to ensure that the design, installation, testing and maintenance of the LV
electrical installation maintains the separation and ensure the values of touch
voltages specified in BS EN 50122-1 are not exceeded.
Guidance for Part 3
3.4.1
Guidance for Part 3 is set out in Appendix B.
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Date February 2009
Part 4
4.1
Low Voltage Power Supplies in
Electrified Areas
Temporary LV Electrical Installations
Temporary installations
4.1.1
Temporary LV electrical installations shall comply with the arrangements set out
in Part 2.
4.1.2
Temporary LV electrical installations shall not affect existing permanent earthing
arrangements or segregation arrangements.
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Low Voltage Power Supplies in
Electrified Areas
Part 5
Railway Group Standard
GL/RT1255
Issue One
Date February 2009
Application of this document
5.1
Application – infrastructure managers
5.1.1
Scope
5.1.1.1
5.1.1.2
5.1.1.3
The requirements of this document apply to all new and existing LV electrical
installations, including all cabling and equipment from the main incoming power
supply, through distribution and sub-distribution boards to ring mains, and
discrete power supplies to fixed and portable equipment.
Where it is known, or becomes known, that existing LV power supplies do not
comply with the requirements of this document, action to bring them into
compliance is required as follows:
a)
When a LV power supply is modified
b)
When a LV power supply is renewed as a whole
c)
When any major component of a LV power supply is replaced.
The requirements of this document apply to all work that affects LV power
supplies, whether new or altered.
5.1.2
Exclusions from scope
5.1.2.1 There are no exclusions from the scope specified in 5.1.1 for infrastructure
managers.
5.1.3
General compliance date for infrastructure managers
5.1.3.1 This Railway Group Standard comes into force and is to be complied with from
04 April 2009.
5.1.3.2
5.2
Application – railway undertakings
5.2.1
5.3
After the compliance dates or the date by which compliance is achieved if earlier,
infrastructure managers are to maintain compliance with the requirements set out
in this Railway Group Standard. Where it is considered not reasonably
practicable to comply with the requirements, authorisation not to comply should
be sought in accordance with the Railway Group Standards Code.
There are no requirements applicable to railway undertakings.
Health and safety responsibilities
5.3.1
Users of documents published by Rail Safety and Standards Board (RSSB) are
reminded of the need to consider their own responsibilities to ensure health and
safety at work and their own duties under health and safety legislation. RSSB
does not warrant that compliance with all or any documents published by RSSB
is sufficient in itself to ensure safe systems of work or operation or to satisfy such
responsibilities or duties.
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Railway Group Standard
GL/RT1255
Issue One
Date February 2009
Low Voltage Power Supplies in
Electrified Areas
Appendix A Guidance for Part 2 of this standard
The content of this appendix is not mandatory and is provided for guidance only.
In addition to the guidance below reference can also be made to BS EN 50122-1:1997.
Clause 6.2 of BS EN 50122-1:1997 gives some information relating to protective provisions
for electrical equipment in ac and dc electrified areas, and illustrates some techniques
which may be employed in addressing voltage and current transfer. It should be noted that
BS EN 50122-1:1997 is being updated and the corresponding provisions are set out in
clause 7 of prEN 50122-1:2008. Consideration of these proposed provisions may also be
helpful pending publication of the final version.
When considering the guidance below it is necessary to consider the distribution network
operator (DNO) supply earthing arrangements (existing or proposed), and if direct
connection of the DNO and railway systems is to be undertaken or avoided. The transfer
of potentials and currents between the DNO and railway systems is influenced by the
arrangements employed by both parties. The arrangements employed on the railway
should not result in a risk to the DNO installation. Early dialogue with the DNO is strongly
recommended.
A.1
Earthing requirements for LV electrical installations in ac electrified
lines areas (2.2 of this standard)
A.1.1
General
A.1.1.1 The overhead contact wire is energised at a nominal voltage of 25 kV. Electric
trains draw power from the overhead wire with current returning to the feeder
station via the running rails, return conductors or aerial earth wire depending
upon the specific location design. Each overhead line equipment (OLE) support
mast is bonded to the traction return circuit and provides an earth path through
the mast foundation.
A.1.2
A.1.1.2
Where there is a risk of an exposed conductive part (for example trackside LV
equipment enclosure, station platform awning, etc) becoming electrically
connected to live OLE (by flashover, breakage of conductors, etc) exposed
conductive parts and services are bonded to the traction return circuit to ensure
rapid disconnection of the traction power supply in the event of a fault on the
traction supply system.
A.1.1.3
Additionally, equipotential bonding is required where it is possible simultaneously
to touch exposed conductive parts and the running rails, trains or other
conductive objects connected to the traction return circuit. This is necessary to
limit touch voltage to values not exceeding those specified in BS EN 50122-1.
A.1.1.4
The final choice of whether to bond directly or indirectly depends on several
factors, including the cost of providing a reinforced circuit protective conductor for
indirect bond compared to the cost of direct bonding and the practicality of
segregating the systems at the LV electrical equipment or elsewhere.
LV electrical equipment within the LV electrical installations directly bonded to the
traction return circuit
A.1.2.1 Parallel paths for traction current can be avoided by not connecting the LV
electrical installation supply circuit protective conductor, cable armouring and
other earthed metallic conductors to the LV electrical equipment (see Figure A.1
for a typical arrangement) when the LV electrical equipment is either directly
bonded to the traction return circuit, or is in contact with a conductive structure
having a direct bond to the traction return circuit.
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Issue One
Date February 2009
Low Voltage Power Supplies in
Electrified Areas
Conductive
structure
connected to
traction return
circuit
LV electrical installation
LV
supply
LV
electrical
equipment
2.2.1.1 - in contact
with traction return
circuit
L
L
L
N
N
N
E (cpc)
E (cpc)
E
Armour / metallic screen
A.1.2.1 and A.1.2.2 cpc and where
applicable cable
armour / metallic
screen etc not to be
connected
Traction
return
circuit
2.2.1.1 - directly
bonded to traction
return circuit
A.1.2.5 - possible
bond by agreement
with DNO
LV
supply
main
earth
Traction
Supply
Traction return circuit
Traction
return
circuit
distributed
earthing
Traction
return current
bus-bar
Traction
supply main
earth (Feeder
Stations only)
Figure A.1 LV electrical equipment within the LV electrical installations directly bonded to
the ac traction return circuit
A.1.2.2
Separation is achieved by ‘gapping’ the supply cable armouring, by either:
a)
The use of an insulated gland
Or
b)
Cutting back the cable armouring to a maximum distance of 300 mm from
the equipment entry point
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Date February 2009
Low Voltage Power Supplies in
Electrified Areas
A.1.2.3
In both cases apply heavy-duty heat-shrink sleeving, or equivalent, to cover the
gland or the cut back section and 150 mm of the cable outer sheath, and
terminate any other earthed metallic conductor and additional circuit protective
conductor before it reaches the equipment.
A.1.2.4
A suitable permanent warning label should be installed (securely attached to the
cable at the gapping location) which identifies that the cable has been ‘gapped’
and should not be bridged. The preferred warning label wording (black text on
yellow background) is as follows:
“Caution – cable gapped (see Railway Group
Standard GL/RT1255). Do not bridge this gap”
A.1.3
A.1.2.5
A bond may be required between the traction return circuit and the LV electrical
installation supply main earth to provide earth fault protection for the equipment
and / or minimise touch voltages. This bond between the traction return circuit
and the LV electrical installation should not be fitted at feeder stations because of
the high level of traction currents which could flow via the bond into the LV supply
network. The type and rating of this bond should be agreed with the
infrastructure manager responsible for the traction system and the DNO –
formerly known as the regional electricity company.
A.1.2.6
The LV protection arrangement for gapped circuits needs to be carefully
considered because of the discontinuity of the circuit protective conductor. The
characteristics of the traction system return circuit and its earthing arrangements
can allow conduction of the LV fault current via the traction return system. In
some cases use of this path is adequate for protection even if a bond in
accordance with A.1.2.5 is not fitted (subject to the requisite earth loop
impedance being achieved). Consideration should be given to provision of
appropriate RCD protection.
LV electrical equipment within the LV electrical installations indirectly bonded to the
traction return circuit
A.1.3.1 When the LV electrical equipment requires to be bonded to ensure safety during
traction fault conditions (for example flashover or conductor breakage) or to
control touch potentials, but is not in contact with any metalwork which itself is
connected to the traction return circuit, an alternative to direct bonding of the
equipment is required (see Figure 2 for a typical arrangement).
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Low Voltage Power Supplies in
Electrified Areas
Conductive
structure
connected to
traction return
circuit
LV electrical installation
LV
electrical
equipment
A.1.3.2 – armour / metallic
screen connected subject to
consideration of traction
fault current conduction
LV
supply
Armour / metallic screen
L
L
L
N
N
N
E
E (cpc)
E (cpc)
2.2.2.1 and 2.2.2.2 cpc connected and
where applicable rated
for traction fault
current
2.2.2 – electrical
equipment indirectly
bonded to traction
return circuit
Traction
return
circuit
Traction
Supply
LV
supply
main
earth
2.2.2.3 and A.1.3.2 –
bond between LV
main earth and
traction return return
circuit
Traction return circuit
Traction
return
circuit
distributed
earthing
Traction
return current
bus-bar
Traction
supply main
earth (Feeder
Stations only)
Figure A.2 LV electrical equipment within the LV electrical installations indirectly bonded
to the ac traction return circuit
A.1.3.2
Where the LV electrical equipment is at risk from traction system faults (for
example flashover) the LV circuit protective conductor provides a fault path which
is completed by a bond between the LV electrical installation supply main earth
and the traction return circuit. When assessing the risk to LV electrical equipment
resulting from OLE conductor breakage or current collector failure, the LV
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Low Voltage Power Supplies in
Electrified Areas
equipment’s location in relation to the overhead line zone and pantograph zone
as set out in BS EN 50122-1 should be considered. Where the LV equipment is
not directly at risk from traction system faults, the bond is used to control touch
potentials between the LV equipment and exposed conductive parts connected to
the traction return system. The type and rating of this bond should be agreed
with the infrastructure manager responsible for the traction system. Care should
also be taken when considering cable termination arrangements on LV
equipment at risk from traction system faults where armour / metallic screens are
present.
A.1.3.3
A suitable permanent warning label should be securely attached to the bond
identifying that the traction return circuit is connected to the LV supply main earth
and that care needs to be taken when disconnection is required.
A.1.4
Non-electrified sidings in an electrified area
A.1.4.1 Non-electrified sidings in an electrified area should be treated as electrified lines
unless fitted with insulated rail joints.
A.2
Earthing requirements for LV electrical installations in dc electrified
lines areas (see 2.3 of this standard)
A.2.1
General
A.2.1.1 The conductor rail is energised at a nominal voltage of 750 V dc. Electric trains
draw power from the conductor rail with current returning to the substation via the
running rails. The running rails are not deliberately earthed but allowed to ‘float’
electrically about true earth.
A.2.1.2
A.2.2
As a result of the high-traction current levels and corresponding volt-drop, the
running rails may rise to some tens of volts above true earth. Also, because the
running rails are not electrically insulated from the ground, the track ballast,
surrounding area and the conductive framework of buildings nearby takes up a dc
voltage between true earth and the running rail potential.
Protection against dc leakage – supplies from socket outlets
A.2.2.1 When an earthed electrical appliance makes contact with a running rail or
conductive object at running rail potential dc current may flow dependent upon
the actual voltage and circuit parameters. In the case of an earthed electrical
appliance, this current flows in the earth lead. An arc may be produced when
contact between the electrical appliance and the running rail, or conductive object
at running rail potential occurs. Overheating is possible in the earth lead and
possibly the circuit protective conductor of the electrical distribution system. Also,
uncontrolled dc can cause corrosion in adjacent metalwork.
A.2.2.2
Special precautions are required where any socket outlet, within 30 m of a
running rail at traction potential, may provide power to an electrical appliance to
be used on or about an object in contact with the running rail. Because earthed
portable appliances can come into contact with the running rail or conductive
object in connection at running rail potential, precautions are required to ensure
the current flow is prevented, or reduced so as not to impair the effectiveness of
the appliance conductors or supply conductors. Techniques to achieve this
depends upon the specifics of the application, but might include one or more of
the following:
a) Ensure the earthing path has a sufficiently high value (for example provide
additional resistance but without prejudicing disconnection times) to ensure the
dc current flow is not significant
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Low Voltage Power Supplies in
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Railway Group Standard
GL/RT1255
Issue One
Date February 2009
b) Block dc current flow by inserting a suitable device such as a capacitor (with a
discharge resistor in parallel) within the earth path of the supply but ensuring
that the protection for ac faults remains effective
c) Use of RCDs and multi-pole protection to detect and disconnect the appliance
(phase and neutral circuits) if inadmissible currents flow.
A.3
A.4
A.2.2.3
Special precautions are required as the neutral conductor is earthed at the supply
point, and neutral to earth faults can remain undetected and if unchecked, cause
unacceptably high stray traction current to flow through the neutral conductor
system. Techniques to achieve this will be dependent upon the specifics of the
application, but might include the use of RCDs and multi-pole protection to detect
and disconnect the appliance (phase and neutral circuits) if inadmissible currents
flow.
A.2.2.4
For a supply with a nominal voltage of 400 V 3 phase there should be no neutral
connection at the socket outlet. Any neutral necessary for control circuits should
be derived from an isolating transformer mounted on the appliance.
A.2.2.5
For a supply with a nominal voltage of 110 V or 230 V, the supply should be
derived from an isolating transformer, centre tapped to earth.
Earth monitoring or earth proving device
A.3.1
An earth monitoring system provides a pilot conductor to the device, usually in
the form of a cable braid, which forms a loop with the circuit protective conductor.
The continuity of the earth path is proven by passing a small electrical current
through the loop. If the earth path is not continuous, or if it has a resistance
higher or lower than set values, the power supply is not energised.
A.3.2
Currents flowing through the body under fault conditions produces a momentary
electric shock. Where appliances are used in hazardous situations, for example,
where there is an increased risk of falling as a result of an electric shock or where
there is an increased risk due to using water, then the use of an earth monitoring
device, in addition to an RCD, should be considered.
A.3.3
Guidance on methods of protection for areas where high pressure water jets are
used is set out in HSE Guidance Note PM29 ‘Electrical hazards from steam /
water pressure cleaners etc’.
LV electrical equipment attached to a running rail
A.4.1
All electrical equipment powered from a LV power supply and attached to a
running rail should be energised from an earth-free, isolated power supply,
operated at a nominal voltage not exceeding 110 V.
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Document superseded by RIS-1855-ENE Iss 1 with effect from 04/03/2017 and ceases to be in force on 03/06/2017
Railway Group Standard
GL/RT1255
Issue One
Date February 2009
Low Voltage Power Supplies in
Electrified Areas
Appendix B Guidance for Part 3 of this standard
The content of this appendix is not mandatory and is provided for guidance only.
B.1
B.2
Fuses
B.1.1
Cartridge fuses should be used for short circuit and / or overcurrent protection.
B.1.2
Rewirable fuses should not be used.
Miniature circuit breakers
B.2.1
Miniature circuit breakers (MCB), complying with BS EN 60898 series, may be
used to protect final circuits. The selection of the correct type and rating of MCB
to match the circuit duty depends on the methods used by manufacturers to
determine device ratings.
B.2.2
MCBs have a relatively low maximum fault current rating, and back-up fuse
protection may be necessary.
B.2.3
Miniature circuit breakers should not be installed where they may be used as a
switch, for example as a light switch. The careful selection of location of MCBs
during the installation design process can inhibit the use of the MCBs as
switches.
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Document superseded by RIS-1855-ENE Iss 1 with effect from 04/03/2017 and ceases to be in force on 03/06/2017
Low Voltage Power Supplies in
Electrified Areas
Railway Group Standard
GL/RT1255
Issue One
Date February 2009
Definitions
Circuit protective conductor (cpc) (BS 7671)
A circuit protective conductor is a protective conductor connecting exposed-conductiveparts of equipment to the main earth terminal.
Electrical installation (BS 7671)
An assembly of associated electrical equipment supplied from a common origin to fulfil a
specific purpose and having certain co-ordinated characteristics.
High voltage
High voltage (HV) is normally exceeding low voltage.
Low voltage
Normally not exceeding 1000 V ac or 1500 V dc between conductors, or 600 V ac or
900 V dc between conductors and earth.
Nominal voltage (BS EN 50122-1)
Voltage by which an installation or part of an installation is designated.
Temporary installation
An installation that is not intended to become a fixed installation, regardless of the length of
time.
Touch voltage (BS EN 50122-1)
Voltage between parts when touched simultaneously1.
Traction equipment
The term traction equipment is used to mean the electrical equipment and conductors
necessary to power the trains on an electrified railway. It includes the incoming supply
feeders, switchgear and transformers which control and provide the electrical current at the
traction system’s line voltage, the distribution network and overhead contact wire or
conductor rail system including the traction return circuit.
Traction return circuit
The path by which the traction current returns from the traction unit to the feeder station, or
substation, incorporating the traction return rails, bonding connections, return conductors
and booster transformers as appropriate.
1
The definition of touch voltage used in BS EN50122-1:1997 differs from those proposed in
prEN50122-1:2008.
RAIL SAFETY AND STANDARDS BOARD
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Uncontrolled When Printed
Document superseded by RIS-1855-ENE Iss 1 with effect from 04/03/2017 and ceases to be in force on 03/06/2017
Railway Group Standard
GL/RT1255
Issue One
Date February 2009
Low Voltage Power Supplies in
Electrified Areas
References
The Catalogue of Railway Group Standards and the Railway Group Standards CD-ROM
give the current issue number and status of documents published by RSSB. This
information is also available from www.rgsonline.co.uk.
Documents referenced in the text
RGSC 01
Other references
BS 7671
BS EN 50122-1
BS EN 60898
PM29
The Railway Group Standards Code
Requirements for electrical installations. IEE Wiring Regulations.
Seventeenth edition
Railway applications. Fixed installations. Protective provisions relating
to electrical safety and earthing
Electrical accessories. Circuit-breakers for overcurrent protection for
household and similar installations.
HSE Guidance Note Electrical hazards from steam / water pressure
cleaners etc
Other relevant documents
Other references
SI 1999/3242
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Management of Health and Safety at Work Regulations: 1999
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