How to prove an MCB functions correctly?

It has often struck me that we have complex test kit to measure RCDs and related devices, and yet the humble, but critical MCB is not considered testable.

I can only assume that this is I presume a hang over from the days of fuse wire, where a functional test would have been destructive, and so pointless.


Certainly the instant trip aspect of an MCB, although requiring a large current, only needs it to flow for a fraction of a second, and it should be possible, at least for currents up to a few hundred amps, to derive this in a portable test instrument (consider that a car battery will deliver 100a for several seconds, and 1000A long enough to weld the screwdriver to the terminals and raise the acid to boiling. Perhaps more sensibly, the super high discharge LiPo cells used in remote controlled models can be discharged at  up to perhaps 30 C rates, so some  very modest sized 2AH cells may be pushed for more than 60A, at least for some tens of seconds.

It has often struck me that we have complex test kit to measure RCDs and related devices, and yet the humble, but critical MCB is not considered testable.

I can only assume that this is I presume a hang over from the days of fuse wire, where a functional test would have been destructive, and so pointless.


Certainly the instant trip aspect of an MCB, although requiring a large current, only needs it to flow for a fraction of a second, and it should be possible, at least for currents up to a few hundred amps, to derive this in a portable test instrument (consider that a car battery will deliver 100a for several seconds, and 1000A long enough to weld the screwdriver to the terminals and raise the acid to boiling. Perhaps more sensibly, the super high discharge LiPo cells used in remote controlled models can be discharged at  up to perhaps 30 C rates, so some  very modest sized 2AH cells may be pushed for more than 60A, at least for some tens of seconds.