2 gang switch/dimmer problem. Help plz

[Simon_]

I don't know if I'm going mental or just having a bad day but I just couldn't figure this out today...
Went to a house today where a guy had a 2 gang dimmer switch each switch turned on a separate wall light. One works ok but the other keeps blowing straight away and tripping the mcb. Had a look at the light connections all ok checked the switch and it's wired as follows. The side that works has red sleeved red to common with a loop to the other common. Sleeved grey to L1 switched live. The other one has red to common with the loop and black to L1. It still trips with a normal switch too. Any help?

 

[Edd]

sounds like a fault not at the switch but at the fitting or cable too, also you say red and grey??? this cant be a normal 3 core. did you mean brown?
only 1 incoming live and 2 outgoing sw lines, this is normal. and as you say L to grey works but L to black blows.. trace the black to joints off to fitting or check fitting...

 

[Simon_]

The grey is the old single cable that is usually sleeved black or red under the grey sleeving.

 

[trev]

Has it ever worked mate? This has the smell of the rotting corpse of a diy job gone bad

 

[highspark]

Get the tester out!

 

[nickblake]

Best way to sort this out is to check the wiring bell the ends of the cables out see where they are going you could well have connected a neutral up thinking it was a live

 

[Edd]

yer this sounds like the blacks been droped in thinking its a neutral at a joint or fitting, think its a lights down job or boards up,, beg the ocupier to tell the truth as to wether his played trying to do somthing himself....
spent hours tracing lights blowing only to find all the red in one block and all the blacks in another,,, only to be told its always been like that and always worked... no honest we never touched a thing!!!!! 5 mins work into 3 hrs...

 

[Simon_]

Has it ever worked mate? This has the smell of the rotting corpse of a diy job gone bad

The guy said its been a problem for a while, the previous owner of the house was a builder and he was a bit dodgy apparently. I've got other stuff to do at the house tomorrow so I'll dig a bit deeper.

 

[Jel]

Black is being used as a neutral somewhere.

 

[Octopus]

If a dimmer is going bang and taking out the MCB it sounds like the dimmer is connected to live and neutral.