9
ENGLISH
The current rating will be reduced if the
cabling is bunched with others, surrounded
by thermal loft or wall insulation or placed in
areas where the ambient temperature is
above 30°C. Under these conditions, derating
factors apply and it is necessary to select a
larger cable size.
In the majority of installations, the cable will
unavoidably be placed in one or more of the
above conditions. If so, it is strongly
recommended to use a minimum of 10mm
cabling throughout the shower installation.
In any event, it is essential that individual site
conditions are assessed by a competent
electrician in order to determine the correct
cable size and permissible circuit length.
Circuit Protection table.
Where shower cubicles are located in any
rooms other than bathrooms, all socket
outlets in those rooms must be protected by
a 30mA RCD.
The current carrying capacity of the cable
must be at least that of the shower circuit
protection (see Cable current carrying
capacity table).
To obtain full advantage of the power
provided by the shower, use the shortest
cable route possible from the consumer unit
to the shower.
The shower circuit should be separated from
other circuits by at least twice the diameter of
the cable or conduit.
Unit Rating
(240V)
Circuit Protection Device
MCB
Cartridge Fuse
8.5kW
9.5kW
10.5kW
40A
45A
40/45A
45A
45A
45A
Cable current carrying capacity table (for twin and earth PVC insulated cable)
Current carrying capacity
In an insulated wall
In conduit or trunking
Clipped direct or buried
in a non insulated wall
A
6
4
²
m
m
6
A
8
3
²
m
m
6
A
2
3
²
m
m
6
10mm² 43A
10mm² 52A
10mm² 63A
Note: Cable selection is dependant on derating factors
For close circuit protection DO NOT use a
rewireable fuse. Instead use a suitably rated
Miniature Circuit Breaker (MCB) or cartridge
fuse (see Circuit protection table).
A 30mA residual current device (RCD) must
be installed in all UK electric and pumped
shower circuits. This may be part of the
consumer unit or a separate unit.
A 45 amp double pole isolating switch with a
minimum contact gap of 3 mm in both poles
must be incorporated in the circuit.
It must have a mechanical indicator showing
when the switch is in the OFF position, and
the wiring must be connected to the switch
without the use of a plug or socket outlet.
The switch must be accessible and clearly
identifiable, but out of reach of a person
using a fixed bath or shower, except for the
cord of a cord operated switch, and should
be placed so that it is not possible to touch
the switch body while standing in a bath or
shower cubicle. It should be readily
accessible to switch off after using the
shower.
