This discussion is locked.
You cannot post a reply to this discussion. If you have a question start a new discussion

Adding spurs to immersion heater circuit

About 25 years ago we had a shower fitted and the plumber added a fused spur to the immersion heater circuit for the pump.

I want to upgrade our heating system by fitting an ebus controller in the airing cupboard. This needs a mains supply and there is no accessible ring circuit. Is it permissible to add another fused spur to the immersion circuit?

Mike

Parents
  • Regs wise an immersion heater circuit is nothing special, just another  radial circuit for a fixed load, and as such it may as well be extended for fans, pumps,timers lights etc. I would be a little wary of adding a 13a socket as there is a temptation for excessively large  loads like  a heater to be added, but even if that happened, assuming the breaker and cable protected by it are suitably co-ordinated, all that happens is the breaker trips first. Cold bathwater is a nuisance, not a serious danger.

    What you propose is fine, just label it up clearly so any future user knows which breaker isolates what items. If you were putting it in today it  would need RCD protection, but if it is already there and hasn't  I'd not lose too much sleep so long as it is all done in a way that it stays dry and is positioned so it is unlikely  that a wet handed person would have hold if it and something else to complete a fault path at the same time.

    Mike

Reply
  • Regs wise an immersion heater circuit is nothing special, just another  radial circuit for a fixed load, and as such it may as well be extended for fans, pumps,timers lights etc. I would be a little wary of adding a 13a socket as there is a temptation for excessively large  loads like  a heater to be added, but even if that happened, assuming the breaker and cable protected by it are suitably co-ordinated, all that happens is the breaker trips first. Cold bathwater is a nuisance, not a serious danger.

    What you propose is fine, just label it up clearly so any future user knows which breaker isolates what items. If you were putting it in today it  would need RCD protection, but if it is already there and hasn't  I'd not lose too much sleep so long as it is all done in a way that it stays dry and is positioned so it is unlikely  that a wet handed person would have hold if it and something else to complete a fault path at the same time.

    Mike

Children
  • Thank you Mike. I did consult the OSG but was none the wiser which is why I appreciate the advice this forum provides. It will be a 3A fused "spur" not a 13A socket and will be clearly labelled (as all my switches are). The CU has RCD protection.

    Mike

  • Bear in mind that the 3A fuse will make that circuit , by definition, a new circuit therefore Part P notification applies (I do not think anyone would worry about that though in the real world).

    By technical means I do not think your circuit should cause any problems

  • Not sure I agree because adding a spur to an existing circuit is not notifiable, although as David Stone pointed out above it's not technically a spur ...

    Mike

  • A spur being likened to the spur on a railway track, whether the spur is off a radial or a ring final circuit is not, in itself, notifiable because it is merely an addition to the circuit.

    However, Mike said "Spur" which I suspected he really meant a switched (or unswitched) fused connection unit, they are often, incorrectly, called spurs and if such a thing contained a fuse then by definition in BS7671 it is a circuit. 

    Take the standard Ring Final Circuit, as the name says it is a "final" circuit, however if it contains some fused connection units (say 3A example) then pedantically,the circuit (sub-circuit if you like) is actually a circuit in its own right and therefore the "Ring Final Circuit" is actually a distribution circuit insofar as the fused connection units are concerned.

    As I mentioned I doubt anyone but a pedantic building officer or a heinous electrician would try take you to task on it. But they could do. Most of us would reply "Oh Get Lost!" or something

  • Understood, thanks.

    Mike