Immersion heater circuits with additional connections

[Octopus]

All,

About 50% of the houses I've been in recently have had additional connections added to the immersion heater circuits. The most common is a socket or FCU for a shower pump.

In my mind BS 7671 says that water heaters should be on their own circuits.

Bearing in mind that the vast majority of people only use an immersion heaters as a back up, are there any occassions that such additions are permissable??

 

[malcolmsanford]

Murdoch appendix 15 advises that an immersion heater should not be fed via a ring main 1 (i), but falls short of saying that it should be on it's own radial, the appendix leaves that to (ii) where it names cookers, ovens and hobs with a rated power exceeding 2kw should be on a dedicated radial.

Now why in the IET infinite wisdom they decided to omit an immersion heater from equipment exceeding 2kw which is does in most cases from the dedicated radial design only they maybe able to tell us.

Personally if the immersion is on a 16amp protection device and is a 3kw unit I can see no problem if someone wanted to fit say a 700w power pump via a FCU.

Bottom line for me would be as long as the manufacturers did not ask for a dedicated circuit for the immersion, the pump would get put on with it and note up at the CU.

 

[Octopus]

Malcolm, thanks for your thoughts, and you effectively "echo" my thoughts whereby the load on the circuit is the deciding factor!

 

[MarkieSparkie]

OSG, 8.5; EGBR 4.5 and GN1, C4 advise "Water heaters fitted to storage vessels >15 litres ... should be supplied by their own separate circuit."