Prospective fault current

[Electrifying]

Basically any large presumed fault currents in a domestic situation are more than likely way over what will actually occur.

This I don't dispute - but if you measure the maximum and all your switchgear/breaker's capacities are above this, then happy days

 

[ricicle]

Basically any large presumed fault currents in a domestic situation are more than likely way over what will actually occur.

This I don't dispute - but if you measure the maximum and all your switchgear/breaker's capacities are below this, then happy days

Yep - keep your ar$e covered....

 

[ban-all-sheds]

Sparkybird's turn...

 

[Spark123]

Some MCBs are also marked with an ICU rating (ultimate fault current) which is the maximum it can withstand but not be servicable again afterwards....

I thought the Icn value was the maximum value for the breaker but it may not remain servicable.
Ics - the in-service maximum capacity
Icu - I think comes from another standard?

 

[ricicle]

Some MCBs are also marked with an ICU rating (ultimate fault current) which is the maximum it can withstand but not be servicable again afterwards....

I thought the Icn value was the maximum value for the breaker but it may not remain servicable.
Ics - the in-service maximum capacity
Icu - I think comes from another standard?

Yeah, it could be BSEN60947-2 (MCCBs)

 

[ktmjunkie]

by calculation to obtain psc 230v div by ze 0.15 = 1.53Ka correct ????

does the same apply for 3 phase at 400v

ie 400v div by ze say 0.15 = 2.6Ka is this the correct calculation for a 3 phase supply ???

sorry im a newbe think i posted this in the wrong place help

 

[Spark123]

You should maybe have started a new thread.
The PSCC (prospective short circuit current) is the maximum available current which can flow in the event of a fault between live conductors, (phase-phase or phase-neutral) it is either directly measured or if your meter wont do direct phase-phase then phase-neutral doubled will suffice.
PEFC (prospective earth fault current) is the max fault current between a live conductor and earth. This can be measured directly or by dividing the max phase-earth supply voltage by Ze.
PFC (prospective fault current) is either the PSCC or PEFC - whichever is greater.