Extending Mains Power into my loft

[sunshine34]

I want to add a couple of power sockets into my loft space to power one or two appliances (TV, Xbox etc) but the mains ring obviously does not go up there. The lighting ring for the first floor of the house does extend into the loft and there are even some dead spurs that the previous owner has capped off, but I'm assuming that I can't run mains power from the lighting ring.

The other option I have is to that we have a powered shower unit which has its own dedicated 32amp fuse on the mains unit and that cable does already run into the loft space. Can I ran a spur from this cable to add one or two mains sockets in the loft ? I understand that the shower is a high power unit and that it could potentially 'hog' a chunk of the 32amps, but actually we rarely use the shower so I don't see this as being an issue(no, we are not smelly, we just prefer to have baths ). I really can't see why this wouldn't work, but wanted to see if there were any experts out there that can tell me for sure.

 

[Chri5]

It all depends on your honest appraisal of what will be used in the loft.

If the load is limited to 400 or 500w then there a good chance a lighting circuit spur with a 3a fuse (about 700w) would be ok.

Check the total wattage count of all your 1st floor lights divide that by 230v = load amps on circuit.

Then check the fuse size at the main cu / fuse board. The difference between the fuse size and the lighting load will give you a figure. That figure is the amps of load that you have 'spare'. That spare when x 230v gives you watts.
This figure would need to be used by the appliances / electrical goods you intend to run AND the loft lights.


Best will be full extension of the 1st floor ring / socket circuit.

Second best is a 13a fused spur based on 1 x 2.5mm cable from a 1st floor socket.

Last, and least liked is the 3a fuse spur from a lighting circuit.


The reason for this is that a loft room becomes a play room with hifi, tv, games boxes, further lighting load and the someone wants heating, hair driers and other high load requirements that the lighting circuit simply was never designed for.

If you have anything built in such as a airing cupboard or floor to ceiling wardrobes, then getting a spur from the 1st floor sockets shouldn't be impossible.

Under NO circumstances take a feed from the shower !

 

[kevindgas]

would agree with chris on this, except i would never use a lighting circuit for powerpoints under any circumstances. can you not get a seperate radial circuit from the CU?

 

[sunshine34]

Chri5,

Thanks for the quick and detailed response. I don't expect to use a great deal of power in the loft, it's going to be a little occasional play area for my kids, so will have a TV, DVD, games console and maybe a Scaletrix running every now and then, no heating or hairdryers or anything, but will require permanent lighting as there are no windows, so I'd already pretty much decided that using the lighting ring was not the way to go anyway.

Just for my knowledge (not questioning your advise in any way) why is not a good idea to use the shower circuit (other than the showers power requirement) ? Is the cable or fuse different in some way to a normal mains ring ?

Would this be viable if I was to disconnect the shower and just use the existing fuse / cable as a dedicated mains feed to the loft (effectively a third mains ring) as like I said, we never actually use it ?

 

[Chri5]

If you wish to convert the shower circuit and do away with the shower then fine, but you mustn't have shower + spur.

The shower fuse is rated at 30 /32a ?

If so then a radial in 4mm TE will cover all sockets (including heaters !) in a loft area.

If you intend to run 2.5mm TE then the CU fuse will need to be restricted to 20a.

The reason you shouldn't have spur off the shower is simply because it's a dedicated circuit and was designed purely for the shower without any head room (or spare load).