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Energy let-through for Type 2 MCB's ?

justinneedham

I'm nursing an elderly installation containing MK brand Type 2 breakers.

Does anyone have let-through energy curves for MK Type 2 32A MCB ? - Specifically LN5932.

Without any better data I'm likely to expect it to have I^2t no higher then a type C BS60898, and (based on 7x multiplier for instantaneous trip..), perhaps somewhere between a B and  C? Is that a safe assumption? 

I have curves for Wylex BS60898 and for one or two other brands. 

It's a bit of hand-waving I'd sooner not do if there are measured curves somewhere out there?

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  • 0

    well it will still disconnect safely on a 1mm CPC at higher let through if the PSSC is quite a lot higher - the risk is not that it will not trip, just the insulation will be damaged and then the cable between the breaker and the fault will replacement.  That may be acceptable in many cases - the old cable would need changing soon anyway.

    Mike.

  • 0 in reply to mapj1

    Why will the old 70s T&E ring final cables need replacing soon Mike?

    Z.

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  • 0 in reply to mapj1

    Why will the old 70s T&E ring final cables need replacing soon Mike?

    Z.

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