chrisjudd

hi, i am studying for 2391 i hope i am grasping most things but am rather confused over
where exactly to test for pscc and pefc i.e does one test at the cu only or at ceiling roses and socket outlets, i am new to this forum any help gratefully rxd
chris judd

LukeScotty

I think you test it at the farest ie ceiling rose/socket point of the circuit. don't quote me on the that. i'll get you an accurate answer very soon

EasyFox

PEFC & PSCC (or PFC) are the prospective fault currents under short circuit & earth fault conditions & should be tested at the cu, pscc = phase/neutral (double result for 3phase) & pefc = phase/neutral/earth.
You should also test at everyrelevent point of the installation, such as remote db's or basicaly where a protective device has to operate under fault conditions.
If you haven't got it, get a copy of Guidence Note 3 & you'll find all the info you need under section 2.7.15
Hope that helps

You are on about Zs (earth fault loop impedance)