Hello

Thanks to some encouragement I have decided to ask some questions as time goes of things I don't understand or feel I need more info on.

I would rather look dumb but know the answer than act smart and be wrong.

So to start:

I was taught that when we do the PSCC, we switch off the main breaker in the main DB in the house, and run the test. Let's say we get 2.8kA. So with that then the KA rating of the main switch we tested and then every circuit breaker in the DB must then have a KA rating of 3KA as minimum. So if we found a 2.5KA CB we would then note it to change for the CoC as needs to be 3KA.

Now I have been reading more and trying to apply logic but surly that PSCC test is testing the current rating of the supply cable to the transformer and that then the circuit breaker at the meter point or kiosk out side should only be the breaker that must be 3KA. ? Usually a 80A CB in domestic homes.

And that the circuit breakers in the DB would have to have their own PSCC done (by means of getting an ohm reading of Line and Neutral as it is a dead test and then doing Ohms law go get Amps. I.e 230 / 0.45= 511Amps thus the minimum of a 2.5KA CB is fine.

I would prefer to do a PSCC of the full circuit including the external loop as that is then the true resistance of all cables involved and transformer etc.

Hope this makes sense and sorry if looking dof hahah.

On a caviet I have booked for the unit standards course in April, so if all this is covered in detail there then that is great but if not would rather get a head start so to say on my questions.

The P1 and P2 course I did did not cover any of this, at least to the detail that I required to understand. The language used is not always easy to understand in the book and if you don't know what to look for it can be easily missed and confusion can happen.


Also I don't know many other wireman to ask in person and the ones I do know don't quite catch my drift or at least don't know the nitty gritty of formulas or reasons.

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