Code of Practice for the Electricity (Wiring) Regulations - 2009 Edition

exterior installation and a temporary installation in a permanent
building used for exhibitions is considered as an interior installation
and not an exterior installation.
(f ) for interior installations, be near the main entrance to the building or
alternatively in a position to be agreed with the electricity supplier
and the Fire Services Department.
(4) Installation
(a) The luminous discharge tubes should be substantially supported at a
sufficient distance from the sign face to ensure no arcing from the
tube to any other portion of the sign could occur under normal
condition, and be so installed as to be free from contact with
inflammable material except that rubber glands are permitted where
a weather proof construction is desirable.
(b) Tubes should not be unduly exposed to mechanical damage.
(c) Ancillary equipment for high voltage installations including
inductors, capacitors, resistors and transformers should either be
totally enclosed in a rigid and effectively earthed metal container
(which may form part of the luminaires), or alternatively should be
placed in a suitably ventilated enclosure of incombustible material or
of fire resisting construction.
(d ) High voltage cables and conductors should be supported at intervals
not exceeding the appropriate values stated in the following table.
Support for insulated-and-braided cables and for bare conductors
should be of non-ignitable, non-hygroscopic insulating material, e.g.
glass or glazed porcelain.
Type of Cable or Conductor
Spacing of Supports
Horizontal
(mm)
Vertical
(mm)
Bare conductor 1 500 1 500
Insulated-and-braided cables 1 500 1 800
Metal sheathed, non-armoured cables 1 800 1 250
Armoured cables 1 000 1 500
(e) Every inductor and high reactance transformer should be installed as
near as practicable to its associated electric discharge tube.
(f ) The transformer, discharge tube and other parts of high voltage
circuits should be located out of reach.
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