7.14.2 - Garden installations
Increasing use is being made of electrical
supplies in the garden, for pond pumping systems, lighting,
power tools and so on. The following points apply:
1. - Socket outlets installed indoors
but intended to provide outdoor supplies must be protected
by an RCD with a maximum operating current of 30 mA. Any
portable equipment not fed from a socket outlet must also
be protected by an RCD with a 30 mA operating current. Outdoor
sockets also require the same RCD protection and must also
satisfy IP44 requirements (see
{2.4.3}).
2. - Garden lighting, pond pumps
and so on should preferably be of Class Ill construction,
supplied from a SELV system and having a safety isolating
transformer supply. Where 240 V equipment must be used,
it should be Class II double insulated (no earth) and should
be suitably protected against the ingress of dust or water.
If accessible Class I equipment is used its supply system
must have an earth fault loop impedance low enough to allow
disconnection within 0.4 s in the event of an earth fault.
3. - Earthing must be given special
attention. All buildings must be provided with 30
mA RCD protection, but the Electricity Supply Company should
be consulted to ascertain their special requirements if
the supply system uses the PME (TN-C-S) system. Where the
supplier does not provide an earth terminal, each outbuilding
must be provided with an adjacent earth electrode.
4. - Outbuildings are often of light
construction and therefore are subject to extremes as far
as temperature swings are concerned. It is therefore important
to bear this in mind when selecting equipment and components.
5. - Extraneous conductive parts
of an outbuilding which may become live due to a fault should
be bonded to the incoming protective conductor.
6. - Every outbuilding with an electrical
supply should be provided with a means of isolation to disconnect
all live conductors including the neutral.
7. - All outbuildings where protection
against direct contact is by earthed equipotential bonding
and automatic disconnection of the supply should have a
disconnection time in the event of an earth fault which
does not exceed 0.4 s.
8. - Cables which are not buried
must be shielded from direct sunlight, whose ultraviolet
content will affect plastics. Cables with ultra-violet protected
sheaths may be used; the preferred colour for such cables
is black.
9. - Large garden ponds present
a particular problem because of the probability that sooner
or later people will fall into them. In such a case, the
Regulations applying to swimming pools (see
{7.3}) should be applied. Pumps and lighting should
be SELV with the safety source at least 3.5 m outside the
edge of the pond. All cables in the pond must be in ducts
or conduits which are built into it and not be allowed to
lie loose. All pond equipment must be protected to IP55
(see
{2.4.3}) or better.