Energy let-through for Type 2 MCB's ?

Anything above 3kA fault current will probably blow the breakers up. They are M3 rated.

OK do the calculation for a 2kA or 1.5kA  fault current then if you prefer - it's still likely to be more than would reasonably be expected.

Besides these MCBs are presumably in a CU that has an overall rating of 16kA, so it's probably not a safe assumption that all fault currents will be below 3kA.

And prey tell please, why do we need the energy let through info. on these domestic sized M.C.B.s?

Presumably to confirm that reduced c.s.a. conductors meet the requirements of the adiabatic?

   - Andy.

AJJewsbury said:

And prey tell please, why do we need the energy let through info. on these domestic sized M.C.B.s?

Presumably to confirm that reduced c.s.a. conductors meet the requirements of the adiabatic?

I think that the point that Zoomup is making is how often in a domestic installation would you be selecting the conductor size of the CPC? How often would you be wiring in singles?

AJJewsbury said:

And prey tell please, why do we need the energy let through info. on these domestic sized M.C.B.s?

Presumably to confirm that reduced c.s.a. conductors meet the requirements of the adiabatic?

I think that the point that Zoomup is making is how often in a domestic installation would you be selecting the conductor size of the CPC? How often would you be wiring in singles?

As Andy says. And there are a lot of old installations about, often needing judgements, especially for EICR and minor upgrades to poorly structured installations.