Light circuit tripping breaker

mattyfez · 16 Jan 2024 at 13:54

Plot twist 2..
Replaced MCB, it tripped again after a few mins, but I noticed whilst it was still on, my table lamp in the living room came on by itself.

I'm wondering if that mains socket is running off of a spur from the 6a MCB... as I've disconected the lamp, but then it tripped again, also plugged into that socket is a router, and ONT and a printer.. I checked a router can pull about 2amps, along with the other stuff it may have overloaded the MCB @6a. they were plugged into a very old one of these.. https://cdn.manomano.com/images/images_products/26397136/P/72603032_1.jpg

So I've removed that incase it's faulty, so the socket is now only directly powering the router and ONT.

Touch wood, it hasn't tripped again yet...

mattyfez · 16 Jan 2024 at 14:06

Fek, and it's just tripped again

Diggsy · 16 Jan 2024 at 14:09

Looking like you may need to get a sparky out…

mattyfez · 16 Jan 2024 at 14:12

Diggsy said:
Looking like you may need to get a sparky out…

Looks like it, I'm out of ideas and skills.

Diggsy · 16 Jan 2024 at 14:53

mattyfez said:
Looks like it, I'm out of ideas and skills.

You could literally end up driving yourself mad trying to find the source of the problem, whilst a sparky will come in with the correct gear and sort it in no time.

Gaijin · 17 Jan 2024 at 16:26

Yep a sparks should be able to come in and test each circuit. Definitely would advise that as it could be a safety issue.

LuckyBenski · 18 Jan 2024 at 10:10

This does sound a bit like its veering i to "dangerous to mess with" territory... but TBF there's been some very poor unmethodical testing going on.

If you think the lamp and ONT/printer socket is on the lighting circuit, turn off just that circuit and test the sockets.

If you think there's an extractor fan that might be damp causing issues, isolate it using the isolator switch.

You need to rule things out one by one with certainty. That said you've separately tripped for current (MCB) and earth leakage (RCD) so I suspect over current is involved which suggests short circuit not damp. I had a repeatedly tripping RCD and it turned out there were lights on my roof terrace that were blown, but the fitting leaked current to earth when it rained. Took ages to track down as it was weather dependent and on a circuit I didn't even know existed.

Wouldn't blame you for getting a sparks in at this point. I'd buy a socket tester and go hunting though.

mattyfez · 18 Jan 2024 at 13:49

LuckyBenski said:
This does sound a bit like its veering i to "dangerous to mess with" territory... but TBF there's been some very poor unmethodical testing going on.

If you think the lamp and ONT/printer socket is on the lighting circuit, turn off just that circuit and test the sockets.

If you think there's an extractor fan that might be damp causing issues, isolate it using the isolator switch.

You need to rule things out one by one with certainty. That said you've separately tripped for current (MCB) and earth leakage (RCD) so I suspect over current is involved which suggests short circuit not damp. I had a repeatedly tripping RCD and it turned out there were lights on my roof terrace that were blown, but the fitting leaked current to earth when it rained. Took ages to track down as it was weather dependent and on a circuit I didn't even know existed.

Wouldn't blame you for getting a sparks in at this point. I'd buy a socket tester and go hunting though.

It's just the way I wrote it, I have actually methodically tested everything...

The Lamp/ont/printer socket is actually on a ring main, that was a red herring.
There is no extractor fan.

It is ONLY the light circuit that has a problem, the only thing on that circuit other than ceiling lights is the electronic ignition button on the gas cooker.
Somtimes it just the light circuit (6amp) MCB that trips, but sometimes the MCB tripping, trips the RCD too, but not always.