Low earth resistance continuity test

[billy]

I’ve just carried out a continuity test on a rfc. And I’m getting a lower earth resistance Reading than the reading on both the live and neutral wires.
its a circuit in a house converted into two flats and the circuit is wired in 2.5/1.5 twin and earth.

Live and neutral are both 0.46
earth is 0.37, obviously I expect earth to be 1.67x higher not lower.

Ive opened up every socket and all looks fine, I’ve also done continuity with Live and neutral and live and earth connected, and the figures for these are spot on at every socket. (From the terminals)

All the wires are out of the cu, and there’s not a boiler connected to the rfc. It’s all normal twin and earth into metal back boxes there’s no metal conduit etc

The ze for the circuit is fine.

I assume it must be a parallel earth some where but no idea where or how, anyone got any ideas because I’m at a loss and I hate things not being right lol.

I assume as everything else is okay I just need to accept the lower reading.

 

[westward10]

Dual supply storage heaters, immersion any supplementary bonding connected.

 

[billy]

Dual supply storage heaters, immersion any supplementary bonding connected.

Nope none

 

[westward10]

Have you got r2 continuity at a socket with the cpcs disconnected at the CU.

 

[billy]

Have you got r2 continuity at a socket with the cpcs disconnected at the CU.

 

[billy]

Nope none

Have you got r2 continuity at a socket with the cpcs disconnected at the CU.

Yes, It’s measuring 1523 ohms. Guess that means a very slight parallel earth some where.

 

[westward10]

Reconnect one of the cpcs at the CU.

 

[billy]

What am I looking for?

Reconnect one of the cpcs at the CU

 

[westward10]

Connect one cpc back at the CU and see if you have r2 continuity at the socket, try both cpcs at the CU.

 

[billy]

Connect one cpc back at the CU and see if you have r2 continuity at the socket, try both cpcs at the CU.

Both fine

 

[westward10]

Both fine

So with one or the other connected at the CU do you get any continuity of the cpcs at a socket.

 

[Petej999]

I’ve just carried out a continuity test on a rfc. And I’m getting a lower earth resistance Reading than the reading on both the live and neutral wires.
its a circuit in a house converted into two flats and the circuit is wired in 2.5/1.5 twin and earth.

Live and neutral are both 0.46
earth is 0.37, obviously I expect earth to be 1.67x higher not lower.

Ive opened up every socket and all looks fine, I’ve also done continuity with Live and neutral and live and earth connected, and the figures for these are spot on at every socket. (From the terminals)

All the wires are out of the cu, and there’s not a boiler connected to the rfc. It’s all normal twin and earth into metal back boxes there’s no metal conduit etc

The ze for the circuit is fine.

I assume it must be a parallel earth some where but no idea where or how, anyone got any ideas because I’m at a loss and I hate things not being right lol.

I assume as everything else is okay I just need to accept the lower reading.

Could be a loose connection at one of the sso???

 

[Risteard]

Any dual boxes? This could be connecting cpcs of other circuits to the ring final circuit cpc through the backbox.

 

[billy]

So with one or the other connected at the CU do you get any continuity of the cpcs at a socket.

 

[billy]

So with one or the other connected at the CU do you get any continuity of the cpcs at a socket.

Continuity is fine on both legs of the cpc going to the same socket, the ring is intact for the cpc.

Any dual boxes? This could be connecting cpcs of other circuits to the ring final circuit cpc through the backbox.

There no dual bb’s. Surly that wouldn’t matter with CPC’s out of the consumer unit. (Unless different circuits are linked at multiple points). Its very strange lol. Ins only a small flat with only 5 circuits as well it’s not as though it’s a massive installation.

 

[billy]

Could be a loose connection at one of the sso???

A bad connection would surly give a higher reading not lower. R1 and r2 are exactly the same they both can’t have a equally bad connection to give higher readings!!’

 

[PEG]

Hi,if you had one hidden accessory or JB,which bridges the ring somewhere,and it had a poor connection on the cpc,you could get this....

You could clip a signal generator on the disconnected cpc,and CAT the whole gaff,to see if there are unexpected cable runs....

Now and again,in circumstances like this,i find that not worrying or thinking about it,works wonders

 

[billy]

Hi,if you had one hidden accessory or JB,which bridges the ring somewhere,and it had a poor connection on the cpc,you could get this....

You could clip a signal generator on the disconnected cpc,and CAT the whole gaff,to see if there are unexpected cable runs....

Now and again,in circumstances like this,i find that not worrying or thinking about it,works wonders

To be honest that’s kind of where I’m at now lol. At the end of the day it’s not a safety issue.

 

[Petej999]

Could be a loose connection at one of the sso???

A bad connection would surly give a higher reading not lower. R1 and r2 are exactly the same they both can’t have a equally bad connection to give higher readings!!’

Yes I realised that after I posted sorry my bad