Lighting and sockets diagrams

[jamie765]

I'm running 1.5mm and 2.5mm cables for lighting and sockets in my loft conversion and wanted to double check what I'm doing is correct. The lighting and power supply cables have already been run from the consumer unit on ground floor into the loft. Lights will be on loop and sockets on ring.

Have attached a diagram showing lighting and socket wiring.

The brown lines are floor joists in the sockets diagram and dormer roof joists in the lighting diagram.

Are my diagrams correct?

 

[AndyPRK]

shaver and fan would (should) normally be off lighting circuits.


1mm cable is adquate for lighting, but if you have 1.5 already then fine.

I guess you would want 2 way switching for the stair light, so run 3 core and E between the swtiches.


Not sure down lights are suitable for a loft conversion???
e.g limited roof height and non flat ceiling?

consider uplighters at the sides ???

 

[jamie765]

OK will run shaver and extractor fan off the lighting.

Re: downlights, I've had a rear dormer constructed on the roof (contractor did the shell of the loft rear dormer and I'm doing the rest myself). Hence there are two light switches in the bedroom - one goes to the 3 lights in the pitched front roof at the bottom of the image, and the other switch goes to the 6 lights in the rear dormer flat roof.

Does everything else look correct in my diagram?

 

[AndyPRK]

Yes.

A ring circuit is excessive for 2 rooms. (particularly bedrooms) but if you already ran 2 cables in then leave it.


The extractor fan should have 3 core and E cable from the light switch.
Normally a fan isolator is fitted inline. (3 pole switch marked fan)

 

[EFLImpudence]

What is this length of cable for?

 

[jamie765]

What is this length of cable for?

View attachment 168626

Is it not required? I thought the lights had to go from one light to the next. I didn't want to drill more holes in the joists than needed (ie. go horizontally across between those top two downlights) so thought I needed to still run that cable?

 

[EFLImpudence]

Connect three cables to the bottom right light.

 

[EFLImpudence]

Is it not required? I thought the lights had to go from one light to the next. I didn't want to drill more holes in the joists than needed (ie. go horizontally across between those top two downlights) so thought I needed to still run that cable?

If by joists, you mean the rafters - you are probably not allowed to drill any of them.

 

[jamie765]

Thanks, will connect 3 cables to bottom right corner light.

The whole of the top section is the rear dormer with a flat roof, (where there are 6 downlights in bedroom and the bathroom), so it's flat roof joists there. The bottom area (where the 3 lights are on their own switch) have a pitched roof so it's rafters there.

 

[sparkwright]

Connect three cables to the bottom right light.

Wouldn't this make second fixing awkward? Downlights now often only have provision for two sets of cable.

 

[RF Lighting]

Click flow connectors. The best invention for a long time.

 

[winston1]

You'd be better off using 1.0mm for lighting. Easier to get 2 cables into those downlights. Also save copper and save money.

 

[jamie765]

You'd be better off using 1.0mm for lighting. Easier to get 2 cables into those downlights. Also save copper and save money.

Thanks, but I had other work done in the house a few years ago and builders ran lighting and power cable up to the loft from the consumer unit by builders at that time, as I knew I'd do a loft conversion at some point. I just assumed it was 1.5mm and 2.5mm so purchased the same to do the first fix in loft.

On that note, how can I actually tell if the supply from the consumer unit is 1mm or 1.5mm?

 

[jamie765]

I have redrawn the diagrams taking the advice here into account.

Are they now correct? The extractor fan will have a timer so it continues to operate for a while after the light is turned off. I assume 3 core and Earth cable from the light fitting to the fan isolator, and 3 core and Earth cable from the isolator to the extractor fan?

I'll also have this mains powered interconnected smoke alarm in the landing:
https://www.screwfix.com/p/aico-ei141rc-ionisation-smoke-alarm/167fp
There are two existing interconnected smoke alarms (same product I think) on the ground floor and first floor.
For the loft smoke landing smoke alarm, do I just use 3 core and Earth cable connected to the smoke alarm on the floor below?

 

[winston1]

Thanks, but I had other work done in the house a few years ago and builders ran lighting and power cable up to the loft from the consumer unit by builders at that time, as I knew I'd do a loft conversion at some point. I just assumed it was 1.5mm and 2.5mm so purchased the same to do the first fix in loft.

On that note, how can I actually tell if the supply from the consumer unit is 1mm or 1.5mm?

With twin and earth 1.0mm all 3 wires will be the same size. With 1.5mm the earth wire will be smaller. To be absolutely sure measure the diameter of one of the wires with a micrometer or accurate calliper and using pi x diameter squared divided by 4 to get the csa.