Some while back I posed a question on the forum. How to install a second instant electric shower in a house when the supply was not capable of providing sufficient current to allow both to run together? At the time, though some people did make some suggestions, I did not get what I regarded as a workable solution. I did some further looking and this is the solution I came up with. It is based on parts manufactured by Doepke. They appear to be a German company but have a UK subsidiary Doepke UK Ltd in Maidenhead Berks.
The solution is sold in Ireland as a “Priority Unit” It consists of two of their LM3 units Two MCBs, one rated for the shower the other a 5 amp one for the control circuit [LM3s]. These are linked together to result in both tripping if either has a fault. There is also a 30mA RCD and two contactors. Power to each shower is fed through an LM3 sensor. When current is flowing, it is detected and used to close a contact in the LM3. The power, from the 5 amp MCB is switched by this and in turn is used to put power onto the coil of the contactor supplying the second shower. Wiring to the shower through the contactor is via the normally closed contacts, so energising the coil opens these and this turns off power to the second shower.
It is fully automatic. When a shower is switched on there is an indication at the second shower that it is not available as the mains on indicator lamp on the local isolation switch goes out. Once you start a shower someone trying to use the second unit will not interrupt it. In its idle state power is available at each showers and all coils are deenergised. All the parts mount on standard DIN rail.
Hope this is of help to anyone else facing the same project. It does cost a few Euro / Pounds but you have a good solution in place
The solution is sold in Ireland as a “Priority Unit” It consists of two of their LM3 units Two MCBs, one rated for the shower the other a 5 amp one for the control circuit [LM3s]. These are linked together to result in both tripping if either has a fault. There is also a 30mA RCD and two contactors. Power to each shower is fed through an LM3 sensor. When current is flowing, it is detected and used to close a contact in the LM3. The power, from the 5 amp MCB is switched by this and in turn is used to put power onto the coil of the contactor supplying the second shower. Wiring to the shower through the contactor is via the normally closed contacts, so energising the coil opens these and this turns off power to the second shower.
It is fully automatic. When a shower is switched on there is an indication at the second shower that it is not available as the mains on indicator lamp on the local isolation switch goes out. Once you start a shower someone trying to use the second unit will not interrupt it. In its idle state power is available at each showers and all coils are deenergised. All the parts mount on standard DIN rail.
Hope this is of help to anyone else facing the same project. It does cost a few Euro / Pounds but you have a good solution in place
