Ground floor lighting trips circuit breaker.

RicoRepairs · Sep 20, 2022

Hi all, so just moved into a new property, the light fitting/rose was removed from the living room, nothing looks to be shorting (But there is a single neutral with no connector block?) but the breaker trips straight away. There are 4 fittings on this floor, none with bulbs in, none with any sign of issues with the fittings.

So is there an easy way to diagnose where the short is? (If that's what it is)

Thanks for any help here

westward10 · Sep 20, 2022

The most common thing to have happened here is a dead short has been created across live and neutral. One of the blacks is likely to be a live return from the switch and not a neutral. Why one is not connected is not clear but it may have broken off, an electrician should be able to fathom it out and test to ensure all is okay. If they are all connected by way of those unenclosed block connectors then that also needs addressing.

RicoRepairs · Sep 21, 2022

Ok :/ I was kind of thinking as only one light has been removed, and it was more than likely all fine before that, that i wouldn't have to get a spark round ... i would like the chance to be able to fathom it out myself (With a small amount of help/advice from the internet)

littlespark · Sep 21, 2022

As mentioned, there is a dead short between live and neutral.
I’m not sure why one red is on its own though??? They maybe just couldn’t fit all 3 together.

Search Loop-in ceiling rose, or 3-plate wiring to see diagrams… but what you need is a red and black coming from source… a red and black going to next light….. and a red and black going down to the switch.

3 reds together are all live… 2 blacks are neutral, remaining black is the switched live.

You could put each of the reds and blacks in separate connectors until you can organise an electrician.

Then the lights up to this point would work…. But the rest of the circuit would be functionally disconnected.

brianmoooore · Sep 21, 2022

My guess is that the previous owner removed a light fitting without carefully marking what was what, then decided to make it "safe" by fitting a connector block on the bare wires. Unfortunately, they got it wrong, and the cable to the switch has ended up connected directly to the incoming supply cable, with the result that there's a dead short if the room light switch is on.