Problems with RCD

[StephenMorris]

I needed to switch off the power going to the lights. I went to the little box under the stairs and flicked down the two switches labelled 'lighting' and 'downstairs lighting'.

I've now flicked the switches back on and the 'downstairs lighting' switch seems to have tripped and wont turn back on.

I've removed all of the light bulbs that link to the downstairs lighting switch but it still won't flick back on, so I'm now without lighting but have no idea how to stop the RCD tripping.

Any ideas?

Thanks,

Stephen.

 

[Iggifer]

what did you change that required isolating the lights? I would start there

 

[riveralt]

Are you talking about the MCB not resetting or the RCD will not reset.
Do you know the difference?
The RCD/RCBO will have a test button as well as a rocker switch on it while the MCB will just have a rocker switch.

 

[Iggifer]

I'm gonna vote MCB as he says 'the one labelled 'downstairs lighting' won't trip back on'

MCB

RCD

 

[riveralt]

A picture(s) saves a thousand words - or in this case 25

 

[Iggifer]

not the clearest pictures though in all honesty

 

[StephenMorris]

Thanks for the replies. I'm going to say that it's the MCB wont flick back up.

As for the work I did that required the lights to be turned off in the first place, I never actually started the work - I just flicked off the downstairs lighting and flicked it back on 20mins later.

Can this be changed? Would an MCB just stop working and require replacing? I've removed all the light bulbs attached to what I now know is an MCB, so if one blew and caused a surge and caused the MCB to trip, I should have now eliminated the problem.

The only other possibility is that perhaps my extractor fan (in the bathroom, comes on when the light comes on) is causing an issue.

Thoughts?

 

[slippyr4]

As for the work I did that required the lights to be turned off in the first place, I never actually started the work

Not wishing to be rude, but are you sure you didn't get started? You didn't disconnect some wires and then decide it was a bit complex and put them back where you (thought) you found them?

If you really have touched nothing, then it's probably time to get an electrician in, because you've got a fault somewhere and it needs to be found.

 

[flameport]

Would an MCB just stop working and require replacing?

They can fail, either due to overloads/faults on the circuit, or just because they are mechanical devices which will eventually break anyway.

If there is a fault on the circuit, attempting to switch on should cause a certain amount of noise and possiblly a spark or flash from inside the MCB.
If the lever moves but won't latch, or is sloppy, then the MCB has failed internally.

 

[StephenMorris]

As for the work I did that required the lights to be turned off in the first place, I never actually started the work

Not wishing to be rude, but are you sure you didn't get started? You didn't disconnect some wires and then decide it was a bit complex and put them back where you (thought) you found them?

If you really have touched nothing, then it's probably time to get an electrician in, because you've got a fault somewhere and it needs to be found.

I turned the lights off and gently chiseled into the wall above the light switch to see if there were cables there. There weren't, just a brick wall. So then I flicked the switch back on, but it tripped down again.

 

[StephenMorris]

Would an MCB just stop working and require replacing?

They can fail, either due to overloads/faults on the circuit, or just because they are mechanical devices which will eventually break anyway.

If there is a fault on the circuit, attempting to switch on should cause a certain amount of noise and possiblly a spark or flash from inside the MCB.
If the lever moves but won't latch, or is sloppy, then the MCB has failed internally.

Knowing nothing about MCBs, can they be individually replaced? I have somebody in mind who's 'fairly handy' but if he can't fix it then it's probably time to call an electrician.

 

[riveralt]

I turned the lights off and gently chiseled into the wall above the light switch to see if there were cables there. There weren't, just a brick wall. So then I flicked the switch back on, but it tripped down again.

MCB's very rarely break so it is odds on that you may well have nicked a cable with your chisel. Have you had a look at the backplate behind the switch you can normally see which way the wiring is going.
The wiring for most upstairs and downstair switches will normally go up to the ceiling or loft.
The safe zone for a light switch is up/down or sideways from the switch as outlined in wiki.
In the unlikely event it is a broken MCB then changing it is a ten minute job - but I would advise against you doing it yourself unless you are both competent and confident in your abilities.

 

[StephenMorris]

Conclusion: The MCB stopped had just stopped working!

If you remember, I'd flicked it off to turn the power off and do some work and it wouldn't flick back on again, it kept jumping to the off position. We took the wire from one the broken MCB and placed them in a working breaker to determine whether there had been a wiring fault or whether the MCB was broken.

We went to B&Q to buy another one and my girlfriend had the old MCB in her pocket and had been playing with it, idly flicking the switch (that's not a euphemism!) back and forth until low and behold, the switch loosened up and now it works ok. I've put it back in the wall and we have power.

Thanks for everybody's help.

 

[RF Lighting]

I bet it's one of those breakers you have to manually reset like the MK sentry ones (the short lived model they went to after the merlin shaped ones) and Square D KQ used to need.