Can anyone help with my bathroom light pull chord switch?

[Bgy333]

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?

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.

 

[Bgy333]

Tbh it could possibly have been the wiring but I just assumed the switch was broken so replaced it but just coped with no bathroom light for about 4 years lol

 

[Avo Mk8]

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.

Well from everything you've said it seems there has been, and still is, a long standing fault, where if the switch was on, the MCB would trip. That implies somewhere between the light switch and the last light fitting, there is a problem with the wiring. The fact that an MCB trips and not the RCD (assuming the latter works - have you tried the test button recently?) implies to me a more serious problem.
I think either you should get a professional in with a multifunction tester to investigate, or as a minimum, replace the cables in the ceiling with new, all the way from the switch to the first light and then to the second light.

 

[Avo Mk8]

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?

Sounds like you're right!

 

[Bgy333]

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

 

[Bgy333]

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

 

[Bgy333]

So maybe this is where the issue is as there’s only one live wire here and I’m assuming there were 2 lives needed connecting, maybe the switch was being used as some kind of junction box and the switch was thswitch?

The switch isn’t in the bathroom and obv that wiring is new , I’ve discounted that switch as nothing as it “didn’t work”, it’s in a room connecected onto the bathroom by a door and this room was knocked into one massive bedroom before we moved in. I redid the partition and that switch never worked and so that’s where my problem maybe?

 

[Bgy333]

Whwre the switch is near the door into the bathroom

 

[Avo Mk8]

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

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 !

 

[Avo Mk8]

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

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?

 

[Bgy333]

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 !

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!

 

[Bgy333]

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?

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!

 

[Avo Mk8]

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!

So

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!

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.

 

[Bgy333]

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.

That’d be sound pls do you want me to test the “earth / live “ see what that shows?

 

[Bgy333]

The red and earth is showing live on my pen tester but I don’t know how to test how much current on the earth wire like I say it shows minimal on the multi meter