HelloI've had my underfloor heating installed but not wired in yet. I planto wire it in where I have removed a double socket, so on the ringmain. Do I just wire in a FCU to the old socket cables and then thethermostat from that? I read in some posts that permanently fixedheating devices shouldn't be wired directly to the ring main and ifthis is true what is the correct way to do this using my existing ringmain cables, do I need to use a junction box and spur from this? notsure how this is different though. Help and explanantions appreciated.TIACheersRichard

The basic principle you mention is right: fixed heating appliances ought to have their own dedicated circuit from the CU. The reason is that when they're on (autumn/winter/spring) they're drawing a fairly substantial proportion of the total design current for the ring. So if you draw the previously-anticipated full load from the ring at the other appliances, you'll be in overload territory. Contrary to what you may imagine, the fuse or MCB in the CU will *not* do all that good a job of protecting the ring wiring from a "small" sustained overload - a 32A MCB will pass a current of say 40A more or less indefinitely, but the wiring will at that load - especially if much of it occurs close to one end of the ring - be getting hotter than it should, over time pushing its way through the insulation at any bends and so on. Not good.That said, we'd need to know what else is on the ring and (most of all) how much power your UFH will draw. At one end of the scale, if it's 1kW or less to keep a...

FCU Wired to Ring Main?

Jan 09, 2005 21 Replies

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r.rain 21 years ago

On looking at the post again you DIDN'T in fact state that, so my profuse apologies. Having problems telling who said what must do better!

Anyway thanks for all the great information you have provided me. In this case I will put it on the ring main but only due to the fact of the MAJOR hassle it would be to put it on a sep circuit, so dont think I'm just ignoring your advice and not answer my future questions ;) I have learn't a hell of a lot just from this thread.

I will however plan to do this for the future when we renovate the upstairs. I really didn't need the extra stress of trying to sort wiring out as well as all my other jobs I have on at the moment. I'm in stress city at the moment, I dont think I'll ever buy an old house in need of renovation again. Nearly done downstairs now though and looking sweet............

Thanks again

Cheers

Richard

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r.rain 21 years ago

:) Well as usual I would just like to thank everyone for all their contributions, you have all been a great help. See response to Stefeks last posting

Cheers!

Richard

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