High pfc readings

[bobsteroo]

just installed cooker cct, rcd fuse box,earth bond main services etc. tested ze which was 0.02ohms
and the pfc reading was 12.2 ka which i thought was very high, i asked a few electricians
at wholesalers what they thought, no one has had a reading like that, i have borrowed a mates meter, tested the cable again with a similar reading. i have been back 3 more times and the reading varies from 11.6 to 12.2 ka. i have phoned united utilities and told them they said they are only concerned mainly about the ze and they are happy with 0.02 ohms.
the mains is a tncs will this be acceptable if i issue a wiring completion cert and make a note that united utillities have been informed.
i have changed the m.c.b to a 10 ka [capacity] any advice would be helpful thanks

 

[Amp David]

You will have a high PFC with such a low Ze.

The service fuse will have a high enough ka rating to take the brunt though

 

[telectrix]

basic ohms law here I=V/R, 230/0.02=11.5kA . or 240/0.02=12kA .... spot on

 

[olly w]

I've come across this quite often especially when testing close to (or even inside) the substation.
You don't have to worry too much about the Ka of the MCB as long as the main fuse is capable of breaking the fault current.
You could test the PFC at the cooker point itself to see what the fault current is likely to be if it were to short circuit.