Domestic electrical wiring

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Caporegime
Joined
13 May 2003
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Location
Warwickshire
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 :p. 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.
 
Robbie G said:
Please could a kind person let me know which of the following am I allowed to do myself?
Click to expand...

In theory you can do anything yourself if your 'competent' although your supposed to notify building control and get it inspected if your not qualified to sign the work off yourself, most people don't bother, lots of DIY work gets done, even really poor stuff, nothing ever gets said, pretty much not policed.

Ps. By regs before any additions or alterations the rest of the installation should be up to current standards like bonding to gas and water and RCD protection for any altered circuits or at least for the altered section.

pps. You also supposed to have the correct test equipment to make sure everything tests ok and is safe, and building control would test it before they signed it off.
 
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The question here should not be asking what you are allowed to do yourself (You may do virtually anything yourself), but rather be what is notifiable to building control (i do not know the answer to this, i do all of my own electrical work, it is un-policed).

Just crack on, take your time, you will probably do a better job than the resultant work from a rushed cheap quote from a Part P certified sparky anyway :)
 
Robbie G said:
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.
Click to expand...

Sounds ok in real terms.

By regs, if your spurring off a 30/32A ring you should test it to make sure its a true ring, then you can only spur once from each point, you can't take a spur from a spur unless you use a fuse spur with 13A fuse, then you can extend as much as you like.

Ps. You not supposed to notch joists now, so would need to drill through the centre of them to pass the cable through, unless your lucky enough the have them running the right way.
 
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Robbie G said:
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.
Click to expand...

Should be using, fire-rated downlights to keep the fire barrier of the ceiling, don't place too close to joists, cables or pipes and don't have insulation too close to the lights, check manufacturers instructions but you probably want about 12" from any woodwork or insulation. Best to check this first before buying parts, if you cant get clearance then surface fittings on the ceiling need to be used.

For a door switch you would want a push to break switch, so when the door closes it breaks the circuit and door opens it completes the circuit, light come on etc
 
Robbie G said:
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.
[/LIST]

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 :p. 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.
Click to expand...

Wouldn't advise using the shower circuit for a ext fan, probably easier to use the lighting circuit anyway tbh. Using the shower circuit may cause problems in future and you would need to do more work overall.

You could always wire the ext fan from the light in different ways, on/off with lights, have it overrun with timer or even put a 2nd pull cord for the fan if you wanted. You can also buy fans with switches fitted to them but these are for wall mount really not ceiling mount

Ceiling mount would be easier as wall mount would require a 4"+ core drill though the wall unless there is already a hole.

You could use a normal ext fan mounted on the ceiling, or use an inline fan in the loft if its the top floor and it will be quieter.

If you don't want to lose a spotlight then cutting a 4" hole in the ceiling is pretty easy.

ps. You supposed to use a fan isolator switch but a lot of places don't have this, it basically isolates the fan wiring from the lights if needed, usually mount this above the outside of the bathroom door.
 
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For guides try here http://www.diynot.com/pages/el/

As always Make sure the power is off and if your not comfortable attempting this then get a pro in

Work in a location containing a bath or shower is notifiable, should have either supplementary bonding or RCD protection for all circuits in the bathroom.
 
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Using shower circuit for a fan, is a no no.
Ceiling fan must have a fixed switched fused connection unit with 5amp fuse outside the bathroom, on/off with lights, or a seperate pull switch in bathroom, it's ok to come off the lighting circuit or a spur off a ring main.

As to 13amp socket, if you need to drill through joist keep hole small enough to feed one or two 2.5mm cables through, hole need to be 50- 75mm from top of joist, to avoid nailing in to cable when refitting floorboards.

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

Toolstation do a dinky junction box 52mm diameter & 25mm high with 4 terminal 20amp for downlighters, might be suitable.

http://www.toolstation.com/shop/Electrical/Junction Boxes/Lighting Junction Box/d190/sd3071/p55716
 
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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.
Click to expand...

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?
Click to expand...

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*
 
Shower iso is designed for 10mm cable, using it for 1mm the cable would need to be doubled over a lot, also its an isolator not a switch, not really designed to be used often although some people switch the shower every time and need the iso changing when it wears out.

You could fit a normal light switch pullcord for on/off switching not as an isolator, really easy to fit.

To fit a normal timed ext fan:

What you want to do is find where the bathroom lights start, take live, neut, earth and switch live from here with 3 core + e cable to a fan isolator, then take 3 core + e to the fan.

If you don't want a timed fan you can just use 2 core not 3 core but you might as well run 3 core to future proof it.

You seem keen to have a switch for the fan rather than on/off with lights or timed. to do this you could either:

1- Wire it the normal way for a timed fan but place a pullcord in the permanent live, switching this even with the lights on would turn the fan off - this way you can either let it run on the timer for a few mins or turn it off or leave it off unless its steamy etc.

2- Wire the fan as on/off with lights no timer and place the pullcord in the switch live and link the perm and switch live terminals out on the fan pcb - light have to be on for fan to work but fan doesn't have to come on

3- wire it independent of the lights and the pull cord is on/off
 
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.
 
Robbie G said:
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.
Click to expand...

You might be better off leaving the old shower iso and putting the new pullcord in somewhere else.

The old iso will be bigger and have a bigger hole in the ceiling, swapping them might leave a hole or mean you cant get a good fixing.

If screwed into wood you might get the new switch to cover the hole
If screwed into the plasterboard the size of the hole would be too close to the fixing holes on the new pullcord so wouldn't be able to use plaster board screws as the ceiling would be too weak.

To fit a new pullcord all you need to do is poke through the ceiling with a medium screwdriver, just enough to get a 2 x 1mm cable through, the shower would have a bigger hole to fit 2 x 10mm cables though, might be a 2" circ hole and the pullcord base isn't much bigger, i would say you need minimum 1" from edge of hole to the fixing, ideally more or the fixing will just rip the hole bigger
 
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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!):

ZexSHDZl.jpg

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):

Mr5D3nTl.jpg

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).

9FCmjROl.jpg

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.

GhBRMvcl.jpg

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.
 
Good job, I think you found the job easy than you expected .:)

Those Appleby dry lining boxes in Screwfix are the best ones to use,& the only ones I will use.

If the plasterboard is skimmed I always score with a Hacking Knife, or you could use a Stanley knife, but blade isn't so heavy & strong, first before using a pad saw, (see my reply in Man Jobs).
 
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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.
 
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