Spur for boiler needed - Via junction box or socket?

[lavenders19]

I am to install central heating in my house and need a single socket for the boiler to be close to it.

Can anyone advise which is the better option -

1) To take a spur from an existing socket on a ring to this additional socket or

2) To take a spur from a junction box intercepting the ring main. I understand from this that I need to remove the sheathing on the cable and strip away some casing to leave about 1/2" of the neutral and live exposed and connect this without cutting the 2 wires. The only wire that needs to be cut in 2 is the earth wire and then linked to the spur.

I think the junction box would be the easier option as I could take a feed from the cable in the ceiling as the socket is needed half way up a wall. The socket spur would involve a wire going down from an existing socket into the cellar, along then up the wall.

Any advice would be greatly appreciated and many thanks in advance.

[Dave Plowman (News)]

The normal way is to use an FCU to feed the CH electrics. And it's probably better to run the feed to this direct off the CU on the none RCD side.

[Andrew Gabriel]

There's no requirement to avoid cutting any of the 3 wires. (Having said that, I do try to avoid cutting conductors that are to be connected anyway, but it's not worth jumping through hoops to do it.)

Do whichever is easiest. Incidently, if you fit a socket for the boiler, it should be an unswitched socket. Alternatively, install a switched fused connection unit (which will be double pole switching).

[OldBill]

You can do it either way. My preference is to to take the spur from an existing ring socket. Then the junction can be always examined in case of problems. If you do use a junc box it must be kept accessible.

[Martin Angove]

Presumably then a DP switched socket would be just as good?

Hwyl!

M.

[Andrew Gabriel]

In theory yes. In practice no, as the CORGI installer probably won't understand why the rule is there, nor be able to tell if the socket is DP switched.

[Martin Angove]

Ooh good. I'm looking forward to that argument then :-)

Hwyl!

M.

[John]

I can just visualise the sudden leap in Dymo tape sales for all the "This socket is double pole switched" labels that are going to be "required"

[Andy Wade]

Bear in mind though that there's no requirement in BS 7671 for any 'means of isolation' to interrupt the neutral conductor, *except* (a) for the main switch in a household installation, and (b) for any isolator in a TT-earthed installation. (If the main switch doesn't isolate the neutral there should be a removable neutral link, and this is common practice in industrial 3-ph installations.) [OSG sect. 5.1, p.34]

I doubt that the switch on /any/ 13A socket, whether SP or DP, could be classed as an isolator, due to its not meeting the requirements for "the position of the contacts to be externally visible or be clearly, positively and reliably indicated." [476-02-02]

[Martin Angove]

[re. isolation of a central heating system]

Why not? What does the rocker switch do (a modern one with red splash) if not "clearly, positively and reliably" indicate the state of the switch?

These switches are also designed to interrupt the full load current of the socket, which implies that their contact gaps must be the same as for SFUs which are usually classed as isolators I think, and are certainly allowed for isolating central heating systems AIUI.

Hwyl!

M.

[Bill H]

One advantage of a socket is that you have the capability to run the CH system during a power blackout if you are in a rural area.

Aldi sell small petrol generators occasionally for about £75. Can also get invertor units which run off a 12v battery. Bill H Derby x-no-archive: yes