Suppliers Earth TN-S

Roger · Jun 2, 2011

Is it ok for you to connect to it ? earth clamp to sheath.

I had a call tonight and a customer could not reset his RCD so no power at all.Ok fixed the fault unlpugged the kettle and it reset as soon as we plug it in it tripped so power all restored.Bid disadvantage of having 1 RCD for whole house.
Double checked earth loop and got over 8.2 ohms on 32amp ring main and thought it could be a loose connection so did cooker socket and got 7.92 for a 40 amp MCB.
Nice bit of 10mm cable on gas and water but no EARTH at meter head,no MET nothing.Had board changed about 10 years ago he said.
All the houses roughly the same in the street all built same time so popped next door and they had a TN-S.Soldered to a wide strip of woven braided steel strap.
So fitted a clamp on cable sheath ,16mm to a MET and 16mm to CU and gas and water connected ,rechecked and got 0.62 ohms on ring so happier now.
I am amazed that it had no earth at all and had been like it for years.It has even had a new digital meter fitted and you would have thought that the meter fitter might have noticed.
No cup of coffee as kettle knackered but £10 tip for coming out.
Should i inform DNO ?

Deleted member 26818 · Jun 2, 2011

Yes you should inform the DNO, although whether it will achieve anything is anyone's guess.
What type of clamp did you fit, it should have been a constant tension spring clamp.

Roger · Jun 3, 2011

spinlondon said:
Yes you should inform the DNO, although whether it will achieve anything is anyone's guess.
What type of clamp did you fit, it should have been a constant tension spring clamp.

Oh no it was a Legrand Tenby rapid clamp ultra
http://www.legrand.co.uk/en/en/liblocal/pdf/Tenby%20Rapid%20Clamp%20Ultra%20DL.pdf

I like them and use them all the time,I also crimp the 16mm cable as opposed to just clamping it.Looks more professional.
That reminds me i need more crimps ! With the suppliers cable and the soft sheath it really did feel like i got a good purchase.
Can you paste a link so i can see what one of those constant tension clamps look like,sounds like a jubilee clip .
Thanks

Geordie Spark · Jun 3, 2011

Roger said:
Is it ok for you to connect to it ? earth clamp to sheath.

I had a call tonight and a customer could not reset his RCD so no power at all.Ok fixed the fault unlpugged the kettle and it reset as soon as we plug it in it tripped so power all restored.Bid disadvantage of having 1 RCD for whole house.
Double checked earth loop and got over 8.2 ohms on 32amp ring main and thought it could be a loose connection so did cooker socket and got 7.92 for a 40 amp MCB.
Nice bit of 10mm cable on gas and water but no EARTH at meter head,no MET nothing.Had board changed about 10 years ago he said.
All the houses roughly the same in the street all built same time so popped next door and they had a TN-S.Soldered to a wide strip of woven braided steel strap.
So fitted a clamp on cable sheath ,16mm to a MET and 16mm to CU and gas and water connected ,rechecked and got 0.62 ohms on ring so happier now.
I am amazed that it had no earth at all and had been like it for years.It has even had a new digital meter fitted and you would have thought that the meter fitter might have noticed.
No cup of coffee as kettle knackered but £10 tip for coming out.
Should i inform DNO ?

This is exactly like a house I've been working on.

I called the DNO & asked them to sort an earth out & they wanted £150 for doing it.

I told them that the supply comes looped from next door via two bits of VIR with a csa of about 6mm.

They said they would come out to change it, but would only change "like for like" i.e. nice new cables, but still no earth unless they were paid £150.

So far, they have been to the premises 3 times - the latest was today - & each time they have been unable to do the work because of paperwork problems.

Today, they were at the premises for less than 5 minutes, but were allocated 3 hours to do the job so they moved their van up the street & spent the remainder of the time sunbathing !!!

DNO's? ........ Total waste of space, skin & oxygen.

flukey · Jun 3, 2011

compression clamps shouldnt be used on cable sheath for obvious reasons, but then again last time i had this problem thats exactly what my dno fitted

aptsys · Jun 3, 2011

Roger said:
...With the suppliers cable and the soft sheath it really did feel like i got a good purchase...

****ing hell! Just one more turn... bang!

alanl · Jun 3, 2011

Christ, fitting that clamp looks far worse, safety wise for you, than fitting a normal BS951 earth clamp.
For future reference, order a couple of the proper earth sheaf clamps from here:
Sicame Electrical Developments Hepworth products

It is product 'CE/B' that you want. They are made to order, so you'll probably have to wait a few weeks until there are enough in to make them.

Alan.

BlueToBits · Jun 3, 2011

Easier and a lot safer to TT it. "You must not tamper with the the supplier's equipment"... as the actress said to the bishop.

malcolmsanford · Jun 3, 2011

aptsys said:
****ing hell! Just one more turn... bang!

Agree entirely he is a braver lad than me ..........................nothing as embaressing as a nice big bang lot's of flashes and the DNO sueing you after you call them up and tell them what you tried to do ...................