Electrics. Beyond annoying!

[AJB Temple]

Couple of days ago a MCB tripped. MCB runs the boiler circuit and a few other bits and bobs. Its a 32amp B rated Hager MCB. CU is in my old kitchen (one day to be decommissioned) and is Hager and installed in 2018. Part P compliant etc.

No idea why 32amp was fitted as the load is just a boiler pump motor really and there is no way that is drawing 32A.

Only the MCB trips, not the RCD (of which there are several) so not an earth fault. Hence I assumed a live/neutral issue such as short circuit. MCB would not reset.

I am not an electrician, but I am not clueless either. Pulled every socket on the circuit, checked every connection. Isolate the external boiler at the boiler and the switch in the house. No dodgy appliances. Stumped. Mrs AJB did not let me strip the CU in case the rest of the power went off. 8)

Electrician came out and though it took a while, he eventually diagnosed faulty MCB. Switched over and all is fine. In my whole life I have never encountered an MCB failure, especially from a decent manufacturer. :roll:

 

[Myfordman]

They do sometimes die as you have found. One sure way of premature death seems to be using them a a switch- not saying that you've been doing this!

 

[AJB Temple]

Ha! No. Generally the CU is hidden behind a mountain of detergents etc so is never touched.

 

[deema]

Dirt gets into them. A good shake often revives a ‘faulty’ MCB.

 

[AJB Temple]

New one is about £2.50 on Amazon. Electrician £100. I wish I had just swapped it out! I could have used a C rated one temporarily as there is a spare in the CU. Oh well.