Intermittent lighting fault

[littlejohn]

Hi folks

I have a lighting ring that occasionally stops working; when this happens, there is no power at any of the switches or ceiling roses. I've identified the feed wire, and it disappears inside the ceiling in the general direction of the consumer unit. There's no loose connections or anything obvious that I can find, and when this happens my pen tester says that the feed cable is dead.

What's odd is that sometimes, when I come in and switch the light on, the lights will come on for a fraction of a second and then shut off, and then stay dead. Last night I walked back in hours later and all the lights were on, until I switched them off and the next day they didn't work again.

Nothing trips in the consumer unit, ever - I'm about to lift the floorboards upstairs and follow the cable looking for breaks, but I had a thought - could this be caused by a faulty MCB in the consumer unit? It's quite old.

For what it's worth, I did not install this - so as far as I am aware it's professionally installed years many ago, and it's just recently that it's started to fail.

Any tips would be great

Thanks
John

 

[Petej999]

Hi folks

I have a lighting ring that occasionally stops working; when this happens, there is no power at any of the switches or ceiling roses. I've identified the feed wire, and it disappears inside the ceiling in the general direction of the consumer unit. There's no loose connections or anything obvious that I can find, and when this happens my pen tester says that the feed cable is dead.

What's odd is that sometimes, when I come in and switch the light on, the lights will come on for a fraction of a second and then shut off, and then stay dead. Last night I walked back in hours later and all the lights were on, until I switched them off and the next day they didn't work again.

Nothing trips in the consumer unit, ever - I'm about to lift the floorboards upstairs and follow the cable looking for breaks, but I had a thought - could this be caused by a faulty MCB in the consumer unit? It's quite old.

For what it's worth, I did not install this - so as far as I am aware it's professionally installed years many ago, and it's just recently that it's started to fail.

Any tips would be great

Thanks
John

Sounds like you have a loose connection at either the switch, ceiling rose or the CU best advice would be to call a professional Electrician to come and check out the circuit, step by step advice over the internet for something like this, is not advisable

 

[7029 dave]

I would say its the feed cable because its affecting the whole circuit including possible mcb, could be loose connection or damaged cable rodent damage etc, best get Electrician to investigate.

 

[littlejohn]

thanks dave, i think it's a given that it's either the feed cable or the MCB, unless it turns out that there is a junction box between where the feed cable appears by the rose and where it arrives at the consumer unit.

I could just replace the MCB and see if that fixes it I guess, I was just wondering if it was likely that was the cause.

 

[littlejohn]

Sounds like you have a loose connection at either the switch, ceiling rose or the CU best advice would be to call a professional Electrician to come and check out the circuit, step by step advice over the internet for something like this, is not advisable

Thanks pete, but it seems like a loose connection is the kind of thing which is well within the capabilities of DIY like me. IMHO it's fairly straightforward to test for live, examine connections without touching bare wires, etc - I'm happy to be corrected on that because I'm not pretending to be an electrician, but it's a lot easier and cheaper to not take a day off work and pay for a visit if it is really something very simple. If nothing else, I have a lot of shifting of furniture and lifting of floorboards ahead ...

 

[7029 dave]

thanks dave, i think it's a given that it's either the feed cable or the MCB, unless it turns out that there is a junction box between where the feed cable appears by the rose and where it arrives at the consumer unit.

I could just replace the MCB and see if that fixes it I guess, I was just wondering if it was likely that was the cause.

Yes it is possible that a joint is in-between

 

[Petej999]

Thanks pete, but it seems like a loose connection is the kind of thing which is well within the capabilities of DIY like me. IMHO it's fairly straightforward to test for live, examine connections without touching bare wires, etc - I'm happy to be corrected on that because I'm not pretending to be an electrician, but it's a lot easier and cheaper to not take a day off work and pay for a visit if it is really something very simple. If nhing else, I have a lot of shifting of furniture and lifting of floorboards ahead ...

OK Good luck, and be careful

 

[brianmoooore]

Don't underestimate the seriousness of this fault. If the lights are working at full brightness, or not working at all, then things are relatively safe, but if all the lights are operating at half brightness, then there is a lot of heat being generated somewhere.
This is the kind of fault that causes fires.