Faulty circuit or MCB

umborne · 6 Aug 2008

All the lights on a lighting circuit now fail to function, although a flicker was seen to continue from a fluorescent light after the fault occurred. I have measured a voltage of about 20 to 30 volts across the terminal of a switch suggesting (to me) that the circuit is intact and the fault lies elsewhere, probably in the MCB (type B6). Before I call in an electrician, could anyone suggest an alternative explanation?

Thanks

JohnD · 6 Aug 2008

lighting circuit failure is most often a loose connection in a ceiling rose. Start by looking at the first one on the circuit, probably nearest to the consumer unit. the fittings that get hottest (e.g. downlighters) are more likely.

You need a multimeter, a neon screwdriver will not do.

If you have any junction boxes hidden away inside the ceiling it might be there

Chri5 · 6 Aug 2008

You could move the circuit wires to a 'known' working MCB just to confirm the fault is on the wiring and not at the MCB.

umborne · 6 Aug 2008

Problem fixed! I took the cover off the consumer unit prior to checking the MCB as suggested, and saw that the neutral wire had broken from its terminal. A few seconds work and all is well again. A good job too as I didn't fancy locating and checking the junction boxes. Is this a cautionary tale for not overtightening terminal screws?

Thanks for your help

ban-all-sheds · 6 Aug 2008

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Here's a cautionary tale for not under-tightening them...
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RF Lighting · 6 Aug 2008

So is this...

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Faulty circuit or MCB

umborne

JohnD

Chri5

umborne

ban-all-sheds

RF Lighting

DIYnot Local

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