PFC reading

[LC Electrics]

Carried out a ccu replacement and then started testing, my PFC was 38A & 6.11 ohms. Just wanted to have some thoughts as mine was that there must be a poor connection or break in the main cpc?

Thanks

 

[SparkyAndGeorge]

What earthing system was it?

 

[LC Electrics]

What earthing system was it?

It’s a TN-S system but was unable to locate earth as up to the head it’s boxed in

 

[James]

What is the Ze in the property?

 

[LC Electrics]

That is taken from the ccu for the property

 

[Strima]

Did you do any testing before swapping the CU?

 

[LC Electrics]

Did you do any testing before swapping the CU?

No i don’t, and no previous records available

 

[Grant webber]

So if you cant see it, you dont know. Could be no main earth connection. And your getting a reading off a bonding connection.

 

[Risteard]

Carried out a ccu replacement and then started testing, my PFC was 38A & 6.11 ohms. Just wanted to have some thoughts as mine was that there must be a poor connection or break in the main cpc?

Thanks

Presumably that was the Prospective Earth Fault Current (PEFC) as opposed to the Prospective Fault Current (PFC). The Prospective Short Circuit Current (PSCC) must have been substantially greater otherwise the volt drop on the loads would have been enormous to the point where things just wouldn't have functioned.

PFC is the greater of the PEFC and the PSCC.

If it was a TN-S supply then an emergency call to the DNO would be in order assuming that the Earthing Conductor is correctly connected at the MET.

 

[Strima]

No i don’t, and no previous records available

It is advisable to test before carrying out any work to identify any issues and ensure the installation is fit and safe for continued service.

You need to check the main earthing conductor terminations, if at the DNO end you will need to call them out to rectify. What sort of installation is it?

 

[JK-Electrical]

Carried out a ccu replacement and then started testing, my PFC was 38A & 6.11 ohms. Just wanted to have some thoughts as mine was that there must be a poor connection or break in the main cpc?

Thanks

Anytime I've had readings like that it has always been down to an external fault on the DNO's side. As Strima mentioed, it is always wise to do your testing before a board change rather than afterwards!

 

[LC Electrics]

Anytime I've had readings like that it has always been down to an external fault on the DNO's side. As Strima mentioed, it is always wise to do your testing before a board change rather than afterwards!

Yeah that’s what I was thinking, as for testing prior I usually recommend this to all my customers.

 

[Des 56]

You could try and get the supplier to sort
Considering that they are only obliged to maintain a existing earth,they may politely tell you to provide your own

Perhaps rip off that boxing and see whats going on yourself