Can anyone help with my bathroom light pull chord switch?

Avo Mk8 said:

OK I understand better, thanks.
It seems obvious to concentrate on there being something wrong in or around the new switch.
The way you've described wiring it is how I would have done it!

Do the lights work all of the time, and the mcb trips only sometimes, or how does the tripping manifest itself?

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Bgy333 said:

As it is now ( or was when wired as everyone including me assumed was the correct way) it would work for a bit then trip out, I’ve decorated since the dodgy switch started being dodgy and as a typical tradesmen the wife keeps reminding me every f’n year to sort it it and this year seems the year ! So basically recently the lights have been removed and wires hanging down ( it’s fine it’s adults only house!) and the string tied up . When some one not familiar with it would pull the cord it would trip and you have to pull again otherwise it would constantly trip.

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davesparks said:

What was wrong with the old switch? Could it have been the fault making the old switch appear to be faulty when it actually isn't?

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Bgy333 said:

photo of the wiring in the loft it leads to this switch

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Bgy333 said:

I’ve just got my multi meter in the wires in the loft the blue and brown is showing no reading and the read and black a tiny one I’ll include a pic and show the settings on my multi meter, obv the wires are all dangling so if I’m supposed to be connecting 2 lives I’m not. Cos ones not live and the other minimal

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Avo Mk8 said:

I'm trying to make sense of those first two pics. This seems to be the problem.
the metal clad switch with the red, yellow, blue wires coming out of it seems to be a two way switch to operate the bathroom light in conjunction with the pull cord.
If the brown and blue wires leading off to the left go to your pull cord, then the old (broke) pull cord switch was being used two way. The bare copper earth wire is being used as the common live.
So it's not an earth wire at all!
If you want to continue to use that metal switch in pic 2, then that bit of brown/blue cable in pic 1 needs repacing with 3 core to the light switch. I think the problems you have been having are all because the earth wire is being used as a live wire, and now that is a problem at the new pull switch.
Is your new pull switch 2 way?
Can you replace the 2 core cable with 3 core without too much difficulty?

getting somewhere now !

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Avo Mk8 said:

In addition to the other recent discoveries, the leakage across red and black just using a multimeter is a bad sign.
You need an insulation resistance tester to check the resistance at 500V. Have you got a friendly sparky who could do that for you?

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Bgy333 said:

Like I said in original post I did my P16th papers (20 odd years ago like) so not up to date but yes replacing 2 core to 3 core no problem but I’ve no issues not using the light switch on the wall and just the pull cord.

When I was testing the wires one the earths was showing live and someone comments don’t trust pen testers!

I’m able to do whatever I just don’t know where to put which wires - one of the earths is scorched so maybe that’s the live one!

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Bgy333 said:

I’ve got this if you tell me how to set it or what to do?

So basically forget the silver switch how would I connect just my pull cord to work the lights ! I can access the wires. In the loft to do any messing up there is not an issue!

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Avo Mk8 said:

So

The problem is a multimeter won't stress the cable with a high enough voltage to do a proper test. My concern is the old black/red section of cable might have be a problem, but putting that aside, there's the correct connection of the pull cord to sort out first.

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