Popping MCB

Oct 12, 2009 6 Replies

Hi all



Noticed a light pop when I reset an MCB yesterday - is this usual? The MCB is protecting the upstairs ring main and I guess that there are a few pieces of kit "turned on" ready to draw power as soon as the breaker is latched in (clock radios, alarm panel etc).



TIA



Phil


When lamps go, they usually go when tuned on, due to the sudden temperature shock to the filament, so I would expect the fact it went when you turned it on via the MCB, rather than the normal switch was just chance!

Toby...

Ooo, I read the first as a small popping noise from the MCB when it was reset not a lamp failing at switch on. Which is it?

"Dave Liquorice" wrote

Yes, Dave, as the subject header, it was the MCB making a popping noise as it was reset. Any thoughts?

Phil

If there is a load on it when you close it, then yes, you might get a noise. It normally needs to be a fairly high load and/or a fairly inductive one though.

"John Rumm" wrote

Thanks John - can you give me examples of likely inductive loads in domestic setting please? I am not sure now whether it was the upstairs or downstairs ring that caused this issue.

Phil

Inductive loads in domestic settings are not that common. Some would be having a reasonable number of non power factor corrected strip lights, some coiled element electric bar fires, induction motors in things like fridges, fans etc.

A largish load (13A or so) might do it...

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