Can anybody think of a good reason for the DNO to disconnect TNS with Ze of 0.25ohms?

[LlandrilloSpark]

Whilst looking at the supply intake at a house rented by my mate I noticed the Main earth which was clamped to the sheaf of the supply cable was disconnected, the service head is a TNCS, the main earth from each small 3036 CU goes to this head as well as the two main bonding conductors, curiosity got me so a did a Ze at the service head earth block and the line at the (unsealed!) henley block, Ze was 19.9ohms

I moved the earth probe over to the old TNS lead and hey presto a Ze reading of 0.25ohms:yes:, I stopped short of re connecting it

Did an engineer from the DNO attempt to convert to a PME but missed out the link in the head?, if so why convert when TNS had a good Ze.

My mate is contacting the DNO today?

Cheers

 

[telectrix]

Re: Can anybody think of a good reason for the DNO to disconnect TNS with Ze of 0.25o

did you get the 19.9 with bonding out of the equation. if not that reading could be from the services bonding and the tnc-s not connected , as you say. need dno to come and sort it out.

 

[IQ Electrical]

Re: Can anybody think of a good reason for the DNO to disconnect TNS with Ze of 0.25o

did you get the 19.9 with bonding out of the equation. if not that reading could be from the services bonding and the tnc-s not connected , as you say. need dno to come and sort it out.

I agree, there's no way the PME is connected with that reading.

Sometimes TN-S is disconnected on failing supply cables and street joints and PME offered as an alternative.

 

[LlandrilloSpark]

Re: Can anybody think of a good reason for the DNO to disconnect TNS with Ze of 0.25o

Thanks

Straight ze of 19.9 with bonding disconnected, house still has rubber two core feeding lights, I dont think the supply cable is original, forgot to mention that also performed zs on the downstairs ring and it was 21ohm again bonding in place, I'll have to come clean here!!, i crimped a 10mm eyelet on the end of the old TNS lead and screwed it to the earth block on the head......zs on ring 0.65ohm, put it all back as it was then got him to ring SP soon as, the house is 1894!