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Limitations on electrical supply
Where there is an electric shower and an electric boiler installed, the electrical supply may be
overloaded if both units are operating at the same time. To prevent this condition a simple switch
over relay box must be added.
Connections: - The coil of the relay is connected across the switched supply to the electric shower.
The ‘normally closed’ contact of the relay is connected into the control line of the electric boiler.
The relay does not switch the high current to the boiler, only the control signals.
Operation: - When the shower is switched on, the relay is activated breaking the control signal to the
boiler, and hence shutting it down in a controlled manner, thereby preventing overload on the mains
electrical supply. After showering the boiler will restart.
Electric showers are normally run for short periods at a time, and therefore shutting down the heating
during these times should not cause any discomfort.
Note, this is only required if there is doubt with regard to supply limitations, and an electric shower
that heats the water at the same time as the electric boiler is used. It is not required with power
showers, which only pump the water.
A suitable relay unit is available from POTTERTON GOLD. Part number 94970056. This relay unit is
also suitable for other applications where there is a high load demand to be shared with the boiler.
Other relay units containing 2 or 3 relays are also available from POTTERTON GOLD.
SHOWER - RELAY CONTROL FOR POTTERTON GOLD
ELECTRIC BOILERS
FIGURE TWENTY SIX: SHOWER RELAY CONTROL
-
N R N L
PULL SWITCH
2 AMP FUSE
SHOWER OR OTHER
HIGH LOAD
DEVICE
POTTERTON GOLD
PART NUMBER
94970056
ELECTRIC BOILER
SUPPLY
BOILER CONTROL
SIGNAL
NORMALLY CLOSED
CONTACT (240V)
COIL
240V
50/60HZ
A1
A2
11
12
14
N L