Earth Loop Impedence Increases

[sbelec]

Anyone got any ideas?

Measured R1, Rn, R2 end to end and 0.34, 0.35 and 5.6 ohm.

Measured R1, R2 crossed and got between 0.21 and 0.23 ohm at the back of each socket on the ring.
Measured Rn, R2 crossed and got between 0.20 and o.23.
All results random and probably caused by pressure / probe connections so no consistant flowing error. This is a new ring I had just installed and I am a happy bunny.

As a final check I always go round and do earth loop impedence when I have powered up (throwback from doing condition reports) and hey presto my ELI goes from 0.12ohm to 0.27 and back to 0.12 at the final socket. This indicates a broken ring and radial style results but I have retested my continuity, stripped down the highest socket, retrimmed my cables and reconnected and still the problem exists - driving me nuts.

There are no appliances plugged in so its a raw ring. The only thing I can think is that the natural earth loop through the brickwork is increasing from the front to the back of the house, due to the layout the furthest physical socket is the highest reading and is the 7th socket from the CU down one leg but the second in the reverse leg.

Any thoughts would be appreciated.

steve

 

[telectrix]

your efli will increase the further you get from the CU. theoretically, the highest reading will be at the mid point of the ring. don't confuse the live readings with the R1+R2 as you don't hasve the legs cross connected for live tests.

 

[rattlehead85]

You will get readings increasing up to the mid point of the ring and then decreasing back down on live loop testing. The high r2 reading must be a loose connection. Have you used wagos or crimps on the cpc somewhere along the ring? Do you have parallel earth paths connected before you performed the cross connection tests?

 

[telectrix]

hmm. re-read op. i assumed the 5.6 was a typo and should read 0.56.

 

[sbelec]

Sorry, yes 0.56.
Always test before connecting into CU so no parallel paths in circuit.

Never seen ELI so different along length but with 7 sockets in 50% of the cable length! Many thanks guys drove me mad on site but the more I looked the more I missed it.