mcb buzzing on shower circuit

[steve.t.]

Hi
Swapped a consumer unit over today, everything checked out ok but getting a loud buzzing sound from mcb when shower is turned on, all worked ok before, checked all connections were tight.
Any ideas.

 

[MarkieSparkie]

If you are certain that there are no loose connections. Then it maybe something in the internal MCB mechanical mechanism is vibrating, probably in sympathy with the supply frequency or a harmonic. Try a another new MCB, hopefully that will not buzz and you will be able to return the "old" one to the wholesaler for a refund. If this is the case indelibly mark the "old" MCB faulty to minimise the chance of it being resold to some unfortunate person.