replacing dimmer with a std 2gang switch

[monkeyboyuk]

Hi folks, a quick and easy (or at least I hope!) query re a light switch i'm trying to replace.

a while back i took the original white 2gang socket off the wall and replaced it with a dimmer switch. the dimmer switch is knackered and i'm trying to replace it with a straight 2gang switch instead of dimmer.

i've got a pair of cables for each ceiling light (red/live and black/neutral). i've also got an earth (yellow/green). each new switch has l1, l2 and com.

having looked at some of the other forum posts i think i may have wired it wrong initially which is why the dimmer wasn't working so i just wanted to check what should go where.

i have/had it wired up as - red to l1 black to com, the same then for the second switch. and the earth connected to the metal faceplate. (this was the way i read the instruction that came with the new faceplate!)

with the new plate connected as mentioned above, one switch works, the other trips back at the mcb.

Any help with this would be muchos appreciated!!

 

[bongos]

I'm a bit confused with your description.

You have two 2c+e cables (in effect two red cores and two black cores)? Is it one way switching or can the light be switched on from another place?

Usually the red/black would be a live feed and a switch feed (the black should have red sleeve on it to identify it as live not neutral).

However, you wouldn't normally have a neutral at the switch in this setup but if your MCB is tripping as soon as you flick the switch then you must have.

Any chance of a pic of the exisitng cables? Have you changed anything away from this switch?

 

[monkeyboyuk]

thanks for the quick reply bongos, lemme get a pic and i'll post it up in a second. nothing has changed from the original other than the actual switch itself. there are 2 ceiling lights. this 2gang switch is the only control for them. def only 2 pairs of black/red one for each light.

 

[monkeyboyuk]

right heres a couple of pics, had to take them on phone as i left my cam at my sis' house. and of course only flash light as the lights not working lol

 

[ban-all-sheds]

Can't see an earth core in either of those cables....

 

[monkeyboyuk]

in the pic there is a separate earth to the faceplate. its the very top wire. the wiring in the house is probably 30 odd years old.

 

[ban-all-sheds]

I can see an link between the faceplate and the back box.

If you want to trust your life, and those of anybody else in the house, to 30+ year old wiring and an assumption that it was installed with an earth for the lighting circuit in the first place, and an assumption that in the 30+ years since it went in nobody has done anything which might have damaged the integrity of the conduit system providing an earth then go ahead.

But my advice is to get the whole lot inspected and tested, and not use metal switches or metal light fittings until you know it's OK.

 

[bongos]

I would have suggested the red/black from one cable in C/L1 on one side, copied again by the red/black in the other cable in the other gang. But you say this is causing the MCB to trip?

It is definitely the MCB tripping and not an RCD...?

Have you got a multimeter?

 

[monkeyboyuk]

no multimeter bongos, i assume for testing which is live to make sure i've got them right?

not sure about rcd. just had a new mcb put in and the downstair lights is tripping sorry not the entire board