Consumer Unit - Strange Sound When Trips

[pbar]

I've recently had an extension and the wiring added/changed in the consumer unit. I've had a new 32amp breaker added for the new sockets. The electrician moved the combi-boiler to another fuse by moving the live cable over, but never changed the neutral to the other side, therefore when the boiler came on it tripped the consumer unit.
But when it did, there is a strange sound coming from the unit. I can best descibe it as a loud clockwork toy unwinding. Like a fast clockwork whirring.
The wiring has been put right and it no longer trips, but can anyone offer a clue to what that sound might be please.
When I've had occasional trips previously to any work done, that sound has never happened.

 

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Can anyone offer any advice on this strange noise please?

 

[Lectrician]

MEM fuseboard?

The DC sence RCD's in these do make a strange noise when they trip due to crossed neutrals - a kind of buzz. Even once tripped it continues to buzz.

Move the neutral!

 

[pbar]

Yes, you are dead right! It is a MEM consumer unit.
The neutral has been moved to the other side and all is well.
Thanks for putting my mind at rest, thought I might have had a problem somewhere, it was such a hideous sound.
Cheers.