13
INSTALLATION REQUIREMENTS
10. A 45 amp double pole isolating switch with a minimum contact gap of 3mm 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.
11. 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.
12. Where shower cubicles are located in any rooms other than bathrooms, all socket outlets in those
rooms must be protected by a 30mA RCD.
13. The current carrying capacity of the cable must be at least that of the shower circuit protection
(
Fig.2
). To obtain full advantage of the power provided by the shower, use the shortest cable
route possible from the consumer unit to the shower.
14. The shower circuit should be separated from other circuits by at least twice the diameter of the
cable or conduit. The current rating will be reduced if the cabling is bunched with others, sur-
rounded 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 (
Fig.2
), the cable will unavoidably be placed in one or
more of the above conditions. This being 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.
Isolating
stop
valve
Mains
water
supply
Switch may
be wall
mounted
in accordance
with IEE wiring
regulations
Mains electric supply (via double pole switch)
Double
pole
isolating
switch
Separate permanently
connected supply
from consumer unit
Shower
unit
Diagrammatic view (not to scale)
Fig.4
L
N
E
1.
Terminal block
2.
Earth post
3.
Start/Stop PCB
4.
Control PCB
5.
Solenoid
6.
6-way ribbon cable
7.
Thermal cut-out
8.
PCB live
9.
PCB neutral
10 & 11.
Relay
12.
Power PCB
13.
5.25kW
14.
Triac
15.
3.25kW/4.25kW
16.
Outlet thermistor
17.
Flow sensor
Fig.5 Shower Wiring Diagram