Pfc test

[V]

can anyone tell me when its unnecessary to perform one at each sub-main DB on an installation ?

 

[Sintra]

can anyone tell me when its unnecessary to perform one at each sub-main DB on an installation ?

Each schedule of test results requires the Pfc reading to be entered along with the Zs for the DB.

 

[Des 56]

Look at guidance note 3 page 54
Where the the protective devices used at the origin have the neccessary rated breaking capacity,and devices with similar breaking capacity are used throughout the installation,it can be assumed that the regulations are satisfied in this respect for all distribution boards

The reason being, the PFC reduces further down the line in installations

 

[ryanryan]

i think that i have read that in Sub Mains, if there is a device capable of breaking the pfc upstream then this is ok.
I have this problem at site, due to having a HV ring main, thus being close to transformers (always giving a higher pfc).

 

[V]

thanks everyone

 

[trix]

i think that i have read that in Sub Mains, if there is a device capable of breaking the pfc upstream then this is ok.
I have this problem at site, due to having a HV ring main, thus being close to transformers (always giving a higher pfc).

Just be careful using this reading on bread and butter work as opposed to domestic.

 

[ian.settle1]

When testing in a domestic you only need to put down the PFC for the CU.

When you test a commercial/industrial you have to put doen the PFC for every DB submain within the building as they are on a different test sheet.

 

[Des 56]

The pfc for any distribution sub main will be less than the pfc at origin
As long as all protective devices throughout the installation have a rating equal or more than the origin main protective device,then the origin pfc will suffice