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80% loading in Small power / Lighting Circuit breakers

Nick Parker
Is the 80% loading rule apply on lighting / socket outlet loads on a circuit breaker?, for example, if the circuit breaker rating is of 15A, the maximum load on that breaker would be 12A and you cant load more than that.

I think this rule is more common in Americas. How about this rule in Europe? Why 80% loading and not to the maximum capacity?
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    wallywombat:

    Just wild speculation here, as I know almost nothing about US circuit breakers; but maybe in the US, CBs are labelled with the current they will eventually trip at, as opposed to here in 60898 land, where they are labelled with the current they can continuously handle .


    My head has the same idea in it. BS EN MCBs are guaranteed not to trip at below 113% of their rating (at least for 'conventional time ' - usually an hour) - I suspect the Americans don't have a similar margin.


    That said, some manufacturers do recommend de-rating MCBs when they're next to other heavily loaded MCBs - due to them heating each other.


      - Andy.


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    wallywombat:

    Just wild speculation here, as I know almost nothing about US circuit breakers; but maybe in the US, CBs are labelled with the current they will eventually trip at, as opposed to here in 60898 land, where they are labelled with the current they can continuously handle .


    My head has the same idea in it. BS EN MCBs are guaranteed not to trip at below 113% of their rating (at least for 'conventional time ' - usually an hour) - I suspect the Americans don't have a similar margin.


    That said, some manufacturers do recommend de-rating MCBs when they're next to other heavily loaded MCBs - due to them heating each other.


      - Andy.


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