Can I do this?

[Guitarguy]

I was wondering if this is allowed or not. Basically I have just had a shower pump fitted in the airing cupboard and in there already is:

The immersion heater switch (fed from the cu on it's own mcb)
A Fuse spur for the CH control unit. It's already a spur off the socket ring.

What I was wondering is can i spur off an additional single socket from the spur to be used for the shower pump (pump has a molded plug and is rated at about 3A) off this or is it a no no?

Other option is pulling up the floorboards and installing a spur for this socket which would mean carefully using a circular saw to make the floorboards removable in that area as everything is built on top of them (banisters, stud walls etc).

If I have to do this then fair enough but I was just wondering if i could do the former?

 

[securespark]

What is the rating of your immersion?

What size cable feeds it?

What size and Type of CPD is it?

Has that circuit got RCD protection?

Has the RF circuit got RCD protection?

 

[skenk]

You could add another fused spur fed from the first one (on the load side) and wire it to this directly (you would need to cut the plug off) or use a single socket (no need to cut plug off but do not do it if airing cupboard is inside bathroom....).

Better would be to have 2 new FCU's fed from the load side of the existing FCU so CH timer and pump would have separate switches. 13A fuse in FCU1 and 3A (or whatever is appropriate) in the other two.

I assume the existing spur is the only one from that point on the ring (ie correctly installed in the first place)

Best to leave the immersion circuit alone, esp. if it not a backup.

Someone else may be able to explain better if that sounds a bit convoluted - basically you can have as many outlets as you like on a spur as long as it protected by a 13A fuse.

EDIT: as secure says you'll be wanting RCD protection for the pump

 

[holmslaw]

..

 

[holmslaw]

..

 

[Guitarguy]

Right, I've drawn a diagram of what im thinking

I agree, I would prefer to hardwire the pump in. Both the up and downstairs socket circuits are on the RCD Protected side of the CU. The immersion is not but i wasn't planning on trying to spur off that anyway. Hope the diagram helps as i suck at trying to explain things!

 

[skenk]

Yeah that looks fine as long as they both take a 3A fuse and used together aren't more than 3A and the socket is on the LOAD side of the FCU.

It might breach some reg re not being able to isolate the CH without cutting off the pump but IMO not a problem in this case.

 

[securespark]

You cannot do that.

The fuse in the CH spur must not be larger than 3A. But if you feed a shower pump off the load terminals of the CH spur, it'll blow unless you increase the size of the fuse in the CH spur. If you keep them both at 3A, you'll have diversity issues and the pump will not be independent of the CH. Best idea, seeing as the RF is RCD protected....

Remove the CH spur. Replace it with a 13A spur feeding the CH spur. Then run a feed from the incoming terminals of the CH spur to the shower pump spur. Put the relevant fuses in the CH and shower spurs. This way, everything is independently switched and everything is appropriately fused down.

 

[skenk]

If the pump and timer are rated together at less than 3A, your only issue would be discrimination, not a major issue IMO. Although your best bet is still the 3x FCU (or 2 + socket).