Just had an MCB trip.
It's a 6A MCB with only 1 fluorescent fitting on it. Turned off the switch to the light and the MCB would not re-set. I then removed the started for the light and the MCB still won't re-set.
Anyone got an idea what the problem might be?
As the switch is off to the light, that rules that fitting out (Unless it has be wired to switch the neutral, rather then the live!)
If this is the only thing on the circuit, then there must be a cable fault, or the MCB is faulty.
Does it trip immediately, or is there a delay?
Have you knocked any nails into the wall recently!?
Any other DIY work done recently?
Sparks...
Swap it with a working MCB. If that trips, you've got a fault.
It trips immediately. Was working fine until this evening and I've not done any DIY work that would affect it.
I guess that means it is probably a faulty MCB. Think I will leave it until tomorrow before I try another one ;)
Try turning off the main isolator or RCD for this part of the CU, does the MCB still trip then?
Sparks...
Possibly a faulty switch, or the wiring in the switch box. Make sure there aren't any loose wires in the switch box, such as the incoming line, which may have jumped out and made contact with the back-box. You don't state whether or not you have an RCD as well.
In >95% of cases it means a fault that draws far more current than the mcb's rating, simple as that. So faulty wiring.
NT
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