Rats....electrical fault…now sorted

[RogerS]

..thankfully metaphorical rats.

Woke up this morning to no downstairs lights. Breaker tripped and keeps tripping when reset - even though no lights are switched on. With a bit of luck it will be the RCBO.

Else it's head-scratching time. There are two wires coming out of it. In an ideal world they would be two distinct radial circuits. But knowing what the previous owner has done to the rest of th electrics, he could just as easily have tried to form a lighting ring 'main'. Waiting for a bit more light before venturing further.

I have no smart switches connected. There is an old dimmer switch but that is mechanically switched on. Ditto a newer one that I fitted,

 

[RogerS]

The good news is two separate circuits. The even better news is that it’s not in the kitchen extension where ceiling access is from the room. It’s in the old part of the house and I have a suspicion that it might be one of his many outside non-working security lights filling up with water. He had a habit of leaving old stuff still there and carried on bodging with new stuff.

 

[RogerS]

Mmmmm…very high impedance >20M ohms..live to neutral and live to earth. But that is with my multimeter so possibly mains voltage is needed to break down the insulation and cause the fault.

I don’t have a Megger.

Spectric ? Help !!!

 

[RogerS]

The fault lay exactly where I suspected. Outside security light …one of those IR sensor ones. Disconnected. Fault gone, Who’s the Daddy

 

[Spectric]

I have a suspicion that it might be one of his many outside non-working security lights filling up with water.

Having external lights supplied from the internal lights is never good practice.

But that is with my multimeter so possibly mains voltage is needed to break down the insulation and cause the fault.

Insulation testing has to be performed whilst applying a voltage to the circuit, 500 volts domestic with a proper tester.

But at least you have found the fault, knowing the last owner was a bodger helps because you will look at everything with suspicion and I assume they are cheap outside lights that have been badly fitted, maybe even with any rubber seals or gaskets omitted.