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[michael0]

HI,
IVE WIRED IN SOME LIGHTS INTO A HOT CUPBOARD.
THERE ARE OTHER CIRCUITS IN THE POWER SUPPLY.AFTER AN HOUR THE LIGHTS TRIP,ANY IDEAS

[ericmark]

A MCB is made up of two sections one will trip without delay at a set overload (normal 5 times marked current with C type) and the other uses heat and takes some time to trip how long depending on amount of overload there are graphs to show time against amount of overload.
Eric

[michael0]

hi,thanks very much.

the mcbs are B rated.
the hot cupboard has three 12 v spot lights wired into a transformer.
the transformer is rated to 105 .each light is 35 so on the maximum.
we have only tried the spot lights.
could the anwser be something simple.like a break in the wire or a dodgy mcb.or maybe overheating,or maybe has been wired up wrong

[ericmark]

Ups my mistake B = x5, C = x10 and D = x20 but that does not really affect your problem a 6 amp MCB tripping on 0.5 amp points to something being wrong I would start with clamp on ammeter but without test gear I can’t think how to progress maybe remove one bulb and see how it goes then!
Eric