Document Number: EDS 07-0020
Date: 26/03/2015
ENGINEERING DESIGN STANDARD
EDS 07-0020
CIVIL REQUIREMENTS FOR NEW CUSTOMER SUPPLIES AND
GENERATION CONNECTIONS
Network(s):
EPN, LPN, SPN
Summary:
This standard provides guidance on the Civil and Building services requirements
for substations and switchrooms constructed by customers and developers to
accommodate equipment to be installed or adopted by UK Power Networks.
Owner:
Mark Dunk
Date:
26/03/2015
Approved By:
Steve Mockford
Approved Date:
31/03/2015
This document forms part of the Company’s Integrated Business System and its requirements are mandatory throughout UK
Power Networks. Departure from these requirements may only be taken with the written approval of the Director of Asset
Management. If you have any queries about this document please contact the author or owner of the current issue.
Applicable To
UK Power Networks
External
All UK Power Networks
G81 Website
Asset Management
Contractors
Capital Programme
ICPs/IDNOs
Connections
Meter Operators
HSS&TT
Network Operations
UK Power Networks Services
Other
THIS IS AN UNCONTROLLED DOCUMENT, THE READER MUST CONFIRM ITS VALIDITY BEFORE USE
Version: 3.0
Civil Requirements for new Customer Supplies and
Generation Connections
Document Number: EDS 07-0020
Version: 3.0
Date: 26/03/2015
Revision Record
Version
3.0
Review Date
11/07/2016
Date
02/02/2015
Author
Mark Dunk
Why has the document been updated – Update and clarification of information
What has changed - Section 1 - Introduction updated to provide greater clarity of the use and
application of this document. Section 4 updated to clarify requirement for separate rooms for
Customer and UKPN equipment. Section 5.7.1 updated to clarify security rating and heavy duty doors
stay requirements.
Document title amended.
Version
2.0
Review Date
11/07/2016
Date
26/02/2015
Author
Mark Dunk
Why has the document been updated: Updated to include drawing EDS 07-0020-04
What has changed: Addition of drawing EDS 07-0020-04 and references updated in document.
Version
1.0
Review Date
11/07/2016
Date
19/06/2013
Author
Mark Dunk
© UK Power Networks 2015 All rights reserved
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Document Number: EDS 07-0020
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Contents
1
Introduction ............................................................................................................. 4
2
Scope ....................................................................................................................... 4
3
Glossary and Abbreviations ................................................................................... 5
4
General Requirements ............................................................................................ 5
5
Technical Requirements ......................................................................................... 6
5.1
Building Construction................................................................................................. 6
5.2
Switchgear Base Construction ................................................................................... 6
5.3
Flood Risk ................................................................................................................. 7
5.4
Fire Risk .................................................................................................................... 7
5.5
Environment .............................................................................................................. 7
5.5.1
Facilities Required for Indoor Extensible Switchgear ................................................. 8
5.5.2
Facilities required for Ring Main Unit switchgear ....................................................... 8
5.5.3
Building Services ....................................................................................................... 8
5.6
Access....................................................................................................................... 9
5.7
Security ..................................................................................................................... 9
5.7.1
Doors ........................................................................................................................ 9
5.7.2
Locks ....................................................................................................................... 10
6
Drawings ................................................................................................................ 10
7
Earthing.................................................................................................................. 11
8
References ............................................................................................................. 11
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Document Number: EDS 07-0020
Version: 3.0
Date: 26/03/2015
1
Introduction
The purpose of this Engineering Design Standard and the associated drawings is to provide
guidance for civil and building services requirements to internal and external designers,
ICPs, customers and contractors who need to provide accommodation for UK Power
Networks incoming supply and related auxiliary equipment for customer electrical supplies at
voltages from 6.6kV to 33kV.
This Design Standard is only applicable to structures provided by customers to
accommodate UK Power Networks’ owned or adopted equipment installed to afford an
electricity connection to a customer. It is anticipated that the building or housing will remain
in the ownership of the customer, who shall maintain it in good condition and ensure that it is
fit for its intended purpose.
Where it is specified in the connection agreement that UK Power Networks are to adopt
and/or are responsible for the maintenance and repair of the building and structural assets,
all building and structural works shall be designed, specified and constructed in accordance
with EDS 07-0105 Grid and Primary Substation Civil Standards.
2
Scope
This document is intended to provide general guidance for the construction of buildings or
housings suitable to accommodate all of the supply-side equipment required for customer
demand or generator connections at voltages between 6.6kV and 33kV to networks owned
by UK Power Networks. It is not intended that any customer owned equipment shall be
installed in the chamber used to accommodate equipment owned by, or to be adopted by,
UK Power Networks with the exception of the cables connecting to the customer’s
installation.The equipment footprint and any support designs shown in the associated
drawings have been produced for use with specific equipment types. It is intended that the
designs may be modified or adapted where necessary to suit switchgear of other types and
manufacturer, provided that the switchgear to be installed is of a type approved for use by
UK Power Networks and the general clearance and access principals are met. All works
designed for adoption by UK Power Networks, under the provisions of ENA ER G81
‘Framework for Competition in Connections’, will need to have written approval from UK
Power Networks design staff prior to commencement of construction.
The external appearance of the building and the type of construction used shall be designed
and constructed by the customer, or their appointed contractors, and will need to comply
with any local authority planning and construction regulations; all planning and building
consents are to be obtained by the customer.
Approval from UK Power Networks for the switchroom building design team or Lead
Designer should be obtained before the final planning application is made.
© UK Power Networks 2015 All rights reserved
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Document Number: EDS 07-0020
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3
Glossary and Abbreviations
Term
Definition
BSEN
British Standard incorporating European Standard
GRP
Glass Reinforced Plastic
RTU
Remote Terminal Unit
SCADA
Supervisory Control And Data Acquisition
U Value
Measure of Thermal Conductivity
UK Power Networks
UK Power Networks (Operations) Ltd consists of three electricity
distribution networks:
(UKPN)
4

Eastern Power Networks plc (EPN).

London Power Network plc (LPN).

South Eastern Power Networks plc (SPN).
General Requirements
The building or housing for UK Power Networks owned or adopted equipment, wherever
possible, shall be a free-standing structure constructed at a boundary location. The
switchroom shall be accessible to UK Power Networks staff at all times from the public
highway and be fitted with UK Power Networks standard locks or approved security system.
Semi-detached buildings attached to a main structure or customer’s switchroom, but not
integrated into the main building, may also be acceptable provided that access is not
restricted. If no other alternative is available, e.g. due to space or planning restrictions, a
switchroom at ground level, which is integrated into the larger building, may possibly be used
provided that there is adequate and unrestricted access and is subject to agreement by the
UK Power Networks Regional Design Manager. Locations above or below ground level shall
not normally be considered, regardless of building configuration, for reasons of maintaining
safety and control over operation UK Power Networks and Customer/Developer equipment
must be located in separate rooms with their own separate access
The Civil Designer shall consider all future maintenance requirements to ensure that future
building maintenance will be minimal. Access restrictions and future risk to operational
engineers is also to be considered. In accordance with the latest version of Construction
(Design and Management) Regulations, the Designer shall consider the safe construction,
access, maintenance, operation and demolition of the structure in addition to the installation
and removal/replacement of all plant.
© UK Power Networks 2015 All rights reserved
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5
Technical Requirements
5.1
Building Construction
All UK Power Network’s switchroom buildings or housings shall provide a robust, windowless, vandal-resistant and stable environment for the switchgear and ensure that equipment
is not damaged by any environmental cause such as condensation, dust or other pollutants.
There must be sufficient space for operator safety and all necessary auxiliary and
operational equipment, including steps, where these are required to access operational
equipment.
The building or housing may be of traditional brick built, steel frame, or any other suitable
construction type, and may include pre-fabricated GRP housings provided that the correct
environment is established to ensure that the equipment installed is not damaged or put at
risk in any way by environmental conditions.
For all installations at 20kV and above and for 6.6/11kV installations where indoor extensible
switchgear is used, the switchroom must provide a regulated indoor environment. The
external walls of the building shall achieve a U value of 0.43W/m2K and, where practicable,
all walls must be suitable to allow the secure fixing of wall mounted equipment and
associated cabling. The details of roof construction are to be designed by a Structural
Engineer employed by the customer, and may be subject to approval by the local planning
authority and/or building control. The roof construction is to achieve a U value of 0.25
W/m2K.
All designs will need to take account of the switchgear manufacturer’s requirements for
overpressure venting and have a minimum floor to ceiling height of 3150mm, this may need
to be increased depending upon the switchgear manufacturer’s requirements.
5.2
Switchgear Base Construction
The concrete base, floor slab and walls are to be constructed to the customer’s design and
will be subject to UK Power Networks approval.
All concrete is to be grade C32/40 with a minimum content of 300kg/m 3 of Sulphate
Resisting Cement to BS12, and maximum water/cement ratio of 0.6. The maximum
aggregate size is not to exceed 20mm. A Visqueen 1200 gauge membrane (or equivalent) is
to be provided beneath the floor slab, laid on 25mm of sand blinding, on a minimum 150mm
thick, well compacted, sub-base.
Reinforcement bar layouts are to be designed by the Structural Engineer employed by the
customer. Reinforcing bars are to be fitted with two 70mm2 copper earth bond connections
on diametrically opposite sides of the building with connections in the cable pit to enable
connection to be made to the switchroom main earth bar. Reinforcing bars are to be
electrically continuous across the building. Earth bonding joints to the reinforcing bar shall
use the approved connection arrangements, as shown in UK Power Networks document
EAS 06-0011, may be welded or may be sil-fos brazed. The reinforcement mesh is to be
supported with proprietary chairs with a minimum cover of 50mm. The mesh is not to be
trodden into the concrete surface.
The straightness tolerance of the Unistrut foundation channels, which are provided by the
customer, will be in the range of 1mm over a metre of channel length. The switchgear
manufacturer’s installation instructions shall be consulted to confirm the required accuracy
tolerance for fixing the switchgear.
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5.3
Flood Risk
All switchrooms and substation sites shall be adequately drained for the anticipated normal
environment with precautions to prevent ingress of moisture. External ground/access road
levels shall be designed such that there is no detrimental build-up of surface water in the
proximity of the enclosure. The floor level of the switchroom should be constructed at a level
of 300mm above the 1 in 100 river flood level or the 1 in 200 year tidal flood level, whichever
is higher. A flood risk assessment shall be carried out, and switchrooms and substations
should not normally be constructed in areas which may be subject to flooding with a greater
risk than 1 in 100 year river flood level or 1 in 200 year tidal flood level. Information about
flood risks is available on a postcode basis from the Environment Agency website.
All duct and cable entries to the switchroom shall be sealed after cable installation using
Tyco Rayflate duct sealing system (or equivalent) to prevent water or gas ingress into the
building.
Where there is no other option but to construct in an area known to have a higher flood risk
than that quoted above, the guidelines in UK Power Networks document EDS 07-0106,
which deals with flood precautions, shall be followed.
It is not always possible to seal cable entry ducts such that they are 100% water-tight and
seepage can cause pooling or standing water which can contribute to the corrosion of
contacts within the switchgear leading to operational malfunction. In areas where a high
water table has been identified it will be necessary to install a pump with which to remove
water from the cable trench, the 230v pump should be constructed from stainless steel, float
switch activated and able to discharge 110litres per minute at 2-3metre head.
5.4
Fire Risk
The switchroom shall be included in the fire risk-assessment for the site and have a
minimum fire resistance of one hour. Fixed or portable fire-extinguishing equipment shall not
normally be fitted in UK Power Networks switchrooms.
In the event that the local fire authority requires the fitting of an automatic fire suppression
system to a building, if the system is fitted in the UK Power Networks switchroom, it shall be:




5.5
Suitable for high voltage electrical hazards;
Fitted with external lockable isolation adjacent to the switchroom entry door;
Designed by a fire suppression system specialist employed by the customer;
Approved by the UK Power Networks designer.
Environment
Switchrooms designed for the installation of indoor extensible switchgear at 33kV, 20kV,
11kV, or 6.6kV or its controlling equipment, must have a controlled environment designed to
prevent condensation forming in or around the equipment. In practice this will require the
installation of heating and de-humidification with automatic control systems and alarm
systems to be linked to the UK Power Networks SCADA system. Where there is a likelihood
of other possibly harmful pollutants entering the switchroom, appropriate preventative
sealing methods will be required. Switchrooms or housings used for outdoor ring main unit
type equipment will not require heating or de-humidification equipment. It should be noted
that UK Power Networks no longer installs and will not adopt metal clad 6.6kV to 33kV
distribution substation equipment installed in an outdoor environment.
© UK Power Networks 2015 All rights reserved
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In addition to the HV/EHV Switchgear the following equipment as detailed in Sections 5.5.1
and 5.5.2 may be required, and the necessary wall/floor space is to be provided or allowed
for as specified by UK Power Networks or by the switchgear manufacturer.
5.5.1







Lockable box or cupboard fixed to the wall for test bushings, test attachments, test
devices and operational tools or handles as recommended by the equipment
manufacturer.
Sufficient wall or floor space to allow the fitting of: Tripping Battery, SCADA RTU,
SCADA Battery (this may be integrated with the RTU) and pilot interface wall boxes for
incoming and customer interface pilot terminations.
External wall space may be required to fit a satellite dish aerial (this may require
planning permission).
Fixed platform steps to UK Power Networks specification where access is required to
high level operational equipment such as relays. Note: operational equipment should not
normally be fitted more than 1.5m above floor level where this can be avoided.
Adequate lighting with a minimum of 500 lux maintained luminance with a uniform factor
of 0.8 across the front and rear elevation for the whole the switchgear.
Reliable Power Supplies for equipment and battery charging.
SCADA equipment will be provided and installed by UK Power Networks where needed.
5.5.2






Facilities Required for Indoor Extensible Switchgear
Facilities required for Ring Main Unit switchgear
Lockable cabinet fixed to the wall or floor for Test Bushings, test attachments and
operational tools, if not integral to the switchgear, as recommended by the equipment
manufacturer.
Sufficient space to allow the fitting of: Tripping Battery, SCADA RTU, SCADA Battery
(this may be integrated with the RTU in some cases), and pilot interface wall boxes for
incoming and customer interface pilot terminations.
External wall space may be required to fit a satellite dish aerial (this may require
planning permission).
Lighting for access.
Reliable Power Supplies for equipment and battery charging.
SCADA equipment will be provided and installed by UK Power Networks where needed.
5.5.3
Building Services
In all cases a secure LV AC electricity supply shall be provided by the customer for battery
charging and other building services functions, (refer to EDS 08-0051 for the detailed
requirements). The consumer unit for this supply shall be fitted in the UK Power Networks
switchroom and all wiring shall comply with BS 7671. Cables, pipes or other services that
are not required for connection in the switchroom shall not enter or pass though the building
structure. The general requirements for the electrical installation are shown in the associated
drawings EDS 07-0020-01 to EDS 07-0020-04. UK Power Networks drawing Number EDS
07-0102-16 shows the basic requirements for a GRP housing suitable for a Ring Main Unit
with metering transformers. It should be noted that provision of lighting and power, and
accommodation for control cable terminations will also be required. Suitable external
provisions to house metering equipment adjacent to the GRP (no more than 5m distant) will
also need to be added if this layout is adopted.
© UK Power Networks 2015 All rights reserved
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5.6
Access
Once commissioned, the supply chamber shall only be accessible to persons who hold the
necessary Authorisation under UK Power Networks Distribution Safety Rules. This will not
normally include the customer’s staff.
It is essential that all designs allow unrestricted access for equipment and UK Power
Networks’ or their agents’ personnel. Designs shall cater for equipment delivery using a
Large Goods Vehicle with a lorry mounted crane, and have a minimum width of 3.5m and
height of 4m with an unloading area directly outside the switchroom doors. The access shall
be designed to accept a minimum axle weight of 11 tonnes and an adequate turning bay if
access is possible from one direction only. Access to replace faulty equipment, should the
need arise, must be maintained at all times.
5.7
Security
5.7.1
Doors
All doors are to be certified to minimum grade of SR2 in accordance with the latest issue of
the Loss Prevention Board LPS 1175 specification, subject to site security conditions and
location it may be necessary for SR4 rated doors to be installed.
Standard security door cores are to be a minimum of 45mm thick flush double pan
construction formed from 1.2mm nominal thickness zinc coated steel sheet to BSEN 10152
(BS 6687). Resin impregnated core material, or mineral wool core material is to be provided,
and the whole construction is to be riveted, glued and welded, as required, to give adequate
rigidity and performance. Doors are to be polyester powder coated generally in BS colour
14C39 green or as required for the local colour scheme which may be required by planning
regulations.
Each door leaf is to be hung on a minimum of three heavy-duty stainless steel hinges.
Hinges are to incorporate 'dog bolt' protection or alternatively, three separate dog bolts are
to be provided to protect the hinges. Adequate and suitable door restraints capable of
holding the doors open at 90 degrees are to be fitted at the head of each door leaf, for doors
taller than the standard 2240mm or doors of heavy duty construction will require heavier duty
door stays. A security strip is to be provided to the leading edge of the doors to mask the
gap between the doors or between the door and frame. External door sets shall be fitted with
a suitable weather seal strip.
The double door to the switchroom is to be fitted with a double panic bar with top and bottom
shoot bolts and locking handle to suit UK Power Networks Europrofile lock barrel. The
double door must achieve a minimum clear opening height of 3000mm to conform to
switchgear manufacturer’s requirements. The necessary door height may vary according to
the requirements of different manufacturers and a transom is to be allowed for where the
delivery height exceeds that of the 3000mm door clear opening. Three metres height should
be suitable for most equipment types but will need to be confirmed prior to construction.
The single door to the rear of the switchroom is to be fitted with a panic bar with top and
bottom shoot bolts and should not be fitted with an external handle or lock barrel.
The single door to the metering room is to be fitted with a mortice sashlock, with round
section external lever handle and escutcheon, and Europrofile cylinder with internal thumbturn to suit metering operator lock barrel.
© UK Power Networks 2015 All rights reserved
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Civil Requirements for new Customer Supplies and
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Document Number: EDS 07-0020
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All doors must have a minimum clear opening width of 750mm to facilitate emergency
egress.
Doors fitted to GRP enclosures will require UK Power Networks approval and must conform
to the specification detailed above.
5.7.2
Locks
The switchroom chamber is to be fitted with UK Power Networks standard locking, which will
be supplied and installed by UK Power Networks, when the supply is energised. Where the
switchroom is accessed via a gate in an external boundary, a dual locking system shall be
installed to allow access to UK Power Networks staff by fitting a UK Power Networks
standard security padlock.
6
Drawings
Drawing Number
Subject
EDS 07-0020-01
33kV Metering Switch-house Using Siemens NXPLUS – Single Circuit
EDS 07-0020-02
33kV Metering Switch-house Using Siemens NXPLUS – 3 Panel Loop
EDS 07-0020-03
11kV Metering Switch-house Using Schneider Genie Evo – 3 Panel Loop
EDS 07-0020-04
Standard Brick Enclosure for Customer RMU with Metering Panel
EDS 07-0102-16
GRP Enclosure & Plinth Design for Metered RMU
A number of generic footprint drawings have been produced to assist customers and ICPs
with the design of switchroom chambers. The drawings numbered EDS 07-0020-01 to EDS
07-0020-04 have been produced for the indicative layout of specific types of switchgear, as
shown on the drawings, and will need to be modified, or otherwise adapted, to accommodate
other manufacturers and types, particularly with regard to fixings, supports, and switchgear
main and auxiliary cable entry arrangements. UK Power Networks drawing Number EDS 070102-16 may be used as the basis for housing a ring main unit at 6.6 or 11kV, with the
addition of 230 Volt electrical supplies, control cables and metering. The external design and
appearance of the building will be decided by the customer but will need to comply with the
local authority planning and building control regulations.
Designers shall ensure that switchgear cable entry arrangements for main and auxiliary
cables are adequate to permit safe and practicable termination of all cables. The requirement
for external duct entries into the switchroom shall ensure that adequate provision is made for
all incoming and outgoing circuits including control and communications cables and earth
connections. The cable access arrangements shall allow a minimum bending radius of 1m for
all 6.6, 11 & 33kV cables.
All ICP or customer’s drawings will need to be approved in writing by the UK Power
Networks designer before any construction work is commenced.
© UK Power Networks 2015 All rights reserved
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Civil Requirements for new Customer Supplies and
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Document Number: EDS 07-0020
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Date: 26/03/2015
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Earthing
During the construction phase for the switchroom the customer shall install earthing
connections for the incoming UK Power networks supply. In most cases this will require a
copper earth conductor, with a minimum equivalent size of 70mm2 copper, but the conductor
is to be appropriately sized for the prospective earth fault current related to the incoming
supply, which may require larger sized conductors, particularly at 33kV. The earthing
conductor should be installed around the outer perimeter of the switchroom with earth rod
connections as near as practicable to each of the four corners. Materials used for earthing
shall comply with UK Power Networks document EAS 06-0011 ‘Earthing Materials’. During
the construction phase effective bonding of all metallic support work, cladding or other
structural metal parts, including doors, is required using a minimum equivalent of 50mm2
copper conductor.
The earthing shall be installed and tested by a specialist contractor and comply with EDS 060013 ‘Primary Substation Earthing Design’, EDS 06-0014 ‘Secondary Substation Earthing
Design’ and EDS 06-0017 ‘Customer Installation Earthing Design’ as appropriate. The
customer’s earthing survey report shall be used as the basis for the earthing installation.
8
References
UK Power Networks documents
EDS 06-0014
Secondary Substation Earthing Design
EDS 06-0017
Customer Installation Earthing Design
EAS 06-0011
Earthing Materials
EDS 07-0105
Grid and Primary Standard Civil Designs
EDS 07-0106
Substation Flood Protection
EDS 08-0109
11/6.6kV Distribution Network Design
EDS 08-0113
Guidance for the Application of ENA Engineering Recommendation G88 and
G81 Inset Networks (IDNOs and other Licensed DNOs)
EDS 08-0141
Customer HV Supplies
EDS 08-0145
EHV Design
EDS 08-0051
Customer Supplies between 6.6 & 33kV – Notes of Guidance for New Demand
& Generation Connections
EDS 08-0142
Planning Requirements for Secondary Substations
External Documents
ENA ER G81
Framework documents in 7 parts for competition in connection
ENA E Rep2
Guidance on Security of Substations
CDM 2007
The Construction (Design and Management) Regulations 2007
© UK Power Networks 2015 All rights reserved
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