High ze reading pefc and pscc

[sidekick]

I have just done a consumer unit change and on testing for Ze, PEFC and PSCC got the following results -

Ze - 2.20 (This is very high - what might be the problem and what can I do?)
Test with main earth disconnected L-PE 135 KA ( Very high ?)
Test with main earth connected L-PE 111 KA (Very high?)
Test with main earth connected L-N 0.906KA

Not clear on which should be PEFC, PSCC, and PFC

 

[Sparky Ninja]

Not a lot of sense being made with those readings?

What earthing system is it?

 

[Des 56]

If you use ohms law with your Ze reading of 2.2 ohms,the Pefc would be just over 100 amps
Have you stated the correct readings

 

[Bigboy247]

Have you checked your tester is working as it should. I had a megger that played up when the battery was low.

 

[SimpleSimon]

As Des says should be just over 100A. You sure you read it correctly? Not rated on your tester as 111A (0.11kA)?

 

[sidekick]

Sorry. That does make sense 0.135 KA and 0.111 KA
Fluke tester just calibrated.

 

[sidekick]

should the Ze be that high though ? TNS

 

[sparks1234]

I would check your meter first off, check the earth connection for tightness etc

 

[sidekick]

Main Earth only appears to be 4 or 6 mm. Dont want to mess with it incase I do more harm than good. Should I get YEDL out to upgrade/sort it? Meter tails also aliminium conductors so need changing anyway.

 

[IQ Electrical]

The DNO will make reasonable attempts to give you a Ze of less than 0.8 Ohms on a TN-S system.

Your reading of 2.2 Ohms does align with a PFC of around 100 Amps.

You should contact the DNO on behalf of the client, it sounds like a corroded joint etc, what were your Zs readings once protective bonding conductors were connected?

You can see why it's desirable to do a few tests before doing the consumer unit change.

 

[mechelec]

its no good getting YEDL out if it is a TT earthing system. You need to determine the type of earthing system for a start and then decide how to procede. Are you sure the tails are aluminium? I have to say I have never come accross them before, are you sure they are not stranded tinned copper. If so as long as they comply size wise why change (they may be imperial size and actually larger than required)

 

[IQ Electrical]

He said it was a TN-S

 

[sidekick]

its no good getting YEDL out if it is a TT earthing system. You need to determine the type of earthing system for a start and then decide how to procede. Are you sure the tails are aluminium? I have to say I have never come accross them before, are you sure they are not stranded tinned copper. If so as long as they comply size wise why change (they may be imperial size and actually larger than required)

System is TN-S and the tails could be tinned copper not sure but they are very old and black rubber sheathed. That aside the main problem is the earth I would say which does need upgrading and should then sort any bad connection at same time.

 

[mechelec]

sorry missed the TN-S bit in the previous post. Yedl will sort this for you and should respond within a few hours as it is a safety issue.
Tails sound like they need replacing regardless of conductor material as you say.