how to work out prospective fault current

[wsoppitt]

hey fellas , i did know this but im having a dumb moment and need the info for a condition report im filling out . How do you work out the prospective fault current of a domestic installation ?

 

[m4tty]

Voltage devide by Ze will give you pefc

---------- Post Auto-Merged at 22:53 ---------- Previous post was made at 22:52 ----------

That was Ze with bonding connected so zdb

 

[NozSpark]

Ok,, with all the bonding and earths connected do an earth loop impedance between L+E and L+N,, then divide the 230 by the results

The highest is your PFC.... This is for single phase

 

[m4tty]

I thought he needed to work it out as he missed it. Sorry

Unless its tncs then it's not possible without measurement. Its in osg and gn3

 

[ProDave]

The form does (or used to) say "by measurement / by enquiry"

So you could ask your DNO but I'll bet they won't give you an accurate measurement.

m4tty, how can you work it out on tncs without measurement? The only significant thing about tncs is that you will (should) get the same loop impedance L-N and L-E