Much weirdness occurring

[timhoward]

Last week I was working in a house changing a socket. When I turned the main switch back on and the MCB on the socket didn't energise. I went and turned off again, checked all connections, and 2nd time around it worked for no particular reason.
I put it down to maybe turning on the wrong circuit or somehow getting confused and thought no more about it.

I got called back today, no power to hob (different circuit) . When I got there I used a plug in tester on the cooker plate and it was dead. I walked to the consumer unit turned off the MCB, walked back to the cooker plate, took it off, checked all connections (and noted the was N-E continuity) and there was nothing wrong.
Then I turned the MCB on again and it worked.

I've checked all CU connections. It's an older Crabree Starbreaker board.
I thought it was worth a post to see if anyone has ever have Starbreaker MCBs play up in a random way. Or any other random issues with the insulated bus bar.
If it happens again I think first port of call is CU and test top of breaker...

I hate it when you don't know why something starts working again!

 

[Rockingit]

Ockham's Razor and all that. It's improbable (though admittedly not impossible) to have multiple, separate, instances of the same fault. Therefore you have one fault that's common to all the symptoms, my money would be on a loose busbar.

 

[happysteve]

Strangely, something similar recently, yes. Asked to replace an outside light, "while you're here could you also replace a breaker that's gone, the guys who installed the solar panels the other week says the downstairs sockets breaker has died and they've temporarily doubled up the circuit." They (the "solar guys") weren't working on the downstairs sockets (they put in a separate little DB) but I guess they turned everything off while they split the tails etc and it must not have powered back up again. Was an older (but not ancient) Starbreaker DB. Odd for an MCB to fail, but I guess they do occasionally.

 

[timhoward]

Therefore you have one fault that's common to all the symptoms, my money would be on a loose busbar.

Exactly, though in this case it's that insulated bus bar affair that the devices plug into. I've generally thought of these boards as some of the best that exist but I suppose it's got to be possible for either the sockets or the MCB's to become faulty.

It's a waiting and wondering game now.

 

[pc1966]

If it was just the MCB you switched off and back on I would suspect an internal stickiness and possibly trying a few off-load cycles of the toggle.

However, another circuit going off randomly with similar behaviour is weird and really points to another common cause, like loose tails/main switch/bussbar sort of thing.

 

[littlespark]

Possible dampness getting into the breakers to make them stick?

Doesn’t need to be much

 

[timhoward]

However, another circuit going off randomly with similar behaviour is weird and really points to another common cause, like loose tails/main switch/bussbar sort of thing.

Exactly, the thing is other things on that side of the board were working, and they are plug-in breakers, so not much I can check really.
I did check all the CU terminals were tight. I guess these MCBs are so cheap I might as well get a couple so I can try replacing them if it happens again. Sometimes being able to do something looks better than just shrugging!