Engineering Recommendation G81 - Part 6 - Energy Networks ...

ENA Engineering Recommendation G81 Pt6 Issue 1
Amendment 1: January 2008
Page 12 of 16
d. Communal LV meter / service enclosures shall not be used for other purposes
posing increased risk to equipment, risk of fire or risks to operatives. The size of
the LV enclosure is dictated by the equipment installed and the need for adequate
working space. There shall be a minimum of 300mm separation to any gas meter
or gas pipe joints. The average temperature shall not exceed 30C.
e. Where the building entrance is closed for security reasons or there is no
alternative means of escape, the LV enclosure should be sited adjacent to an
external wall and be accessible from outdoors. HV substations shall be arranged
to be in a separate building or on an outside wall unless otherwise agreed with
the Host DLH. Outside doors shall be lockable, weatherproof and vandal resistant.
See Appendix B for Host DLH requirements on locks.
f. Lateral connections:
The developer is responsible for the design, construction and installation of the
service cable routes within the building. The design route / cable length used to
calculate voltage drop shall not be exceeded.
g. Service cables must not be routed through individual (non common space)
premises other than the one being served. Mains shall not be routed through
premises. The routes selected within the building must ensure that after
installation cables are accessible for withdrawal / replacement without damage to
the building.
h. Mains and service cables must not be in the same duct as non electrical services.
Where not ducted it must be clipped to cable tray. Where a multi-service shaft is
provided, the electrical installation must be compartmented to provide a fire
barrier from the other services. Every vertical duct, shaft or trunk must have
internal barriers to prevent excessive heat rise at the top. The maximum
separation between barriers is 1 floor or 5 metres, whichever is less. After
installation of cabling the developer shall carry out fire stopping using materials
such as cement mortar, gypsum based plaster, cement or gypsum based
vermiculite / perlite mixes, intumescent mastics, proprietary sealing systems,
rockwool or as specified differently by the Host DLH in Appendix B. The method of
ducting should be agreed with the Host DLH taking account of the derating factor
of the current carrying capacity of the cables.
i. If service or mains cables pass through a part of the building required to have a
minimum fire resistance period, the installation must maintain the integrity of the
fire resistance. Minimum fire resistance periods are listed in the Building
Regulations, to which reference must be made.
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