Domestic electrical wiring

Participant · 26 May 2013 at 15:21

I have a few electrical jobs that I need to do and although I'm not practiced in domestic electricity, I've done a lot of other DIY, have a basic knowledge of circuits, and have read a lot and am confident that I can tackle it.

Please could a kind person let me know which of the following am I allowed to do myself?

Add new power outlet in main bedroom

...by spurring off a power outlet already in the main bedroom. Plan is to run 2.5mm2 cable under the floorboards to the other side of the bedroom.
Install 2 x LED spotlights in bedroom ceiling

...above location for fitted wardrobe. Haven't found a suitable rose yet, but again the plan is to spur off the current upstairs lighting circuit. Switch-wise, it's going to be a pressure switch that switches the lights on when the door is open.
Install extractor fan in main bathroom

...in place of a current spot light. I would have just had the fan coming on with the spotlights (which would presumably have made things simpler?) were it not for the fact that there's a spare power cable for the old electric shower hanging around not being used.

My thoughts are to wire the fan to the shower circuit as was (which has a di-pole isolated switch thing and its own circuit back to the RCD etc.) so that I can control the fan independently of the bathroom lights. The RCD has a 40A fuse on this ring...so presumably I'd need to swap that for something lower? And if so, what?

Many thanks! Oh and if anyone has any good links for explanations of domestic wiring, I'd be grateful

. I've been reading about junction boxes but I'd find it easier to wire from existing roses, because there's a lot of insulation in our roof.

Participant · 26 May 2013 at 19:49

Thank you guys. I'll read this properly later, as I've got some meat on the BBQ...! (Like 99% of the rest of the UK)

Participant · 26 May 2013 at 22:08

Nightglow said:
or a seperate pull switch in bathroom, it's ok to come off the lighting circuit or a spur off a ring main.

So I could use the existing pull switch that was once used for the electric shower, disconnect the 40A fused feed from the RCD, then re-connect it to a spur from the bathroom downlighters?

Nightglow said:
EDIT: Robbie, Haven't found a suitable rose yet, do mean junction box?

I meant rose, 'cause I wanted to take a feed off a rose as I'd heard it was easier than using a junction box. However if I can't find the last rose in the circuit, then it'd be quicker and easier to split the circuit somewhere in the attic and fit a junction box.

Anyway thanks for all the tips guys. Going to get back in the attic tomorrow and start clearing that insulation out the way! *weeeeze*

Participant · 27 May 2013 at 07:55

Thank you hardwaregeek. I'll swap the shower iso for a pull switch, then I can just use the existing holes in the ceiling. Might leave the old cable hanging around (taped and isolated of course!), in case we ever upgrade to an aqualisa digital or something.

The ideal extractor fan configuration for us is that the fan operates independently of the lights. This is because our main bathroom is very bright and we don't always need the lights on when showering. However it'll be a bit of a faff to switch both on separately over the winter etc. so on balance I think we'll wire it with the lights and on the timer, but having the ability to knock it off if required.

Participant · 28 May 2013 at 18:03

Thank you guys for your help.

Today I installed a power socket and coaxial lead to the main bedroom. By far the hardest part was routing the cable through the joists and under the boards, despite having a (fantastic) cable access kit.

So first I sawed through these old tile supports from the old roof, so I could get to the access rods down past the insulation right down in the corner of the roof (saw some ******* big spiders!):

Then I lifted a board in the landing and identified what I hoped was 2.5mm2 ring main (the one nearest the blue access rod):

Then I routed the power cable under the floor and the co-ax through the roof, cut out the holes for the coax wall plate, dry wall box and 2 gang outlet, switched the power off and connected it all up. I spurred off the ring main via a 30A junction box (accessible via an access hatch I created in the floorboard).

The power cable goes left to right under the boards and through the old exterior wall from the old part of the house. The co-ax goes vertically down the angled drywall. This was a bit weird as rather than stud work, there seemed to be two layers of very thick foam insulation. Well I couldn't find any stud work at least!

Needs some touching up as the plasterboard saw chipped away some paint. Also managed to scratch the paint with the cable access rods somewhat, but dead happy with the job.

Those drywall boxes that clamp up when you screw the switch in are flipping marvelous. Only a few quid from Screwfix.

A lot of effort to go to just to get a TV in the bedroom, but the wife is pleased! Left a free connector in the attic too in case I need to stick on in another bedroom at some point.

Now to start thinking about the downlights, as our wardrobe is being installed in a few weeks.

Participant · 28 May 2013 at 20:05

Scoring with a Stanley Knife sounds so obvious now. Thanks for that! No a problem this time as we're redecorating soon and it's now hidden by a chest. Handy tip for next time though.