recoomendation code for breaking capacity

opm electrical · Apr 22, 2010

what is the recommendation code for a mcb rated at 1KA and the pfc on the installation is 1.8 ka

Sintra · Apr 22, 2010

None if you have an upstream device with a higher breaking capacity.

opm electrical · Apr 22, 2010

as in the main cut out rated at 33 ka?

pevvers · Apr 22, 2010

opm electrical said:
as in the main cut out rated at 33 ka?

Yup, that's certainly what he means...

Benny_Boy · Apr 22, 2010

opm electrical said:
what is the recommendation code for a mcb rated at 1KA and the pfc on the installation is 1.8 ka

I might be being a bit thick here (has happened before, will happen again), but doesn't that mean that the MCB can't safely break more than 1KA and with a Pfc of 1.8KA you have a protective device which is incapable of safely interrupting a fault current?

Sintra · Apr 22, 2010

The device upstream with the higher rated fault current will break. The MCB with the 1kA rating would then need to be replaced as it could have been damaged with the higher than rated fault current.