Distributors earthing?

Grayza · May 31, 2018

Hi, Came across this the other day when looking to quote for a CU change. I can't figure out how the installation is earthed. There is bonding to the water pipe. I didn't take the cover off the existing CU as it wasn't practical when I visited. Measured a Zs of 0.3 from a socket. Its a terrace house, so wouldn't think its a TT. Does anyone have any thoughts?
Thanks

SparkyChick · May 31, 2018

Looking at the age, it may be using the water pipe as the earth. Is it a lead pipe?

MJPD29 · May 31, 2018

Probably earthed off the water pipe as above

Wilko · May 31, 2018

I do like the idea that the bonded pipe here connects through to neighbour's pipes which are bonded there and the neighbour's installation has been updated to TNCS/PME. Giving your nice Zs result

Midwest · May 31, 2018

I'd ask the DNO.

telectrix · May 31, 2018

DNO being short for I Dunno, before my time. what plans there were were destroyed in 1941 by Luftwaffe.

The Ghost · May 31, 2018

Did you look around for an earth rod?

Midwest · May 31, 2018

Vortigern said:
Did you look around for an earth rod?

OP's username is Grayza?

Grayza · May 31, 2018

No sign of an earth rod. You may be onto something regarding water pipe and next door.
Think I'll go back and take the cover off the existing CU, disconnect the bonding and test Ze to see what I get

Gavin John Hyde · May 31, 2018

be careful if you have quoted for a visit by the seal fairy on this job... I saw one of these once and the DNO were upgrading the cut out anyway, but they said just as well as were they going to pull the fuse they would have refused due to something amiss inside. The fuse looked like it had degraded around the ends and almost become joined to the holder.they would have cut the wires outside hot and rejoined afterwards.

Grayza · May 31, 2018

I was airing on the side of caution. May get the customer call out the DNO to check and upgrade if possible

Octopus · May 31, 2018

How old is the house?

buzzlightyear · May 31, 2018

Murdoch said:
How old is the house?

its date of birth ,and when is next birthday party .

buzzlightyear · May 31, 2018

Grayza said:
so wouldn't think its a TT. Does anyone have any thoughts?

the computer says yes.

bigspark17 · May 31, 2018

May be a tncs, have you got a pic of cu with cover off? If you took it off?but get the customer to phone up supplier and request a new head (a little exageration say its cracked ) will get it changed pronto for you cu change.

ChipFanDave · May 31, 2018

I find when asking for an upgrade i helps if you say you are fitting electric showers and induction hobs.

Octopus · May 31, 2018

buzzlightyear said:
its date of birth ,and when is next birthday party .

There is an estate in Byfleet of 1950's houses where the earth is from a random socket to the pipework under the floor - not ideal!

Grayza · May 31, 2018

Not sure how old the house is maybe 50's or earlier. I didn't take the cu cover off, as wasn't convenient.
I will get the customer to request a new head.
Cheers for the replies everyone.

bigspark17 · May 31, 2018

Grayza said:
Not sure how old the house is maybe 50's or earlier. I didn't take the cu cover off, as wasn't convenient.
I will get the customer to request a new head.
Cheers for the replies everyone.

Puzzled how you can offer a price on cu change without taking the cover off?

ChipFanDave · May 31, 2018

bigspark17 said:
Puzzled how you can offer a price on cu change without taking the cover off?

Million pounds per circuit. No need to remove cover.

Grayza · Jun 1, 2018

Firstly as I said it wasn't convenient to take the cover off and secondary, I don't see why its necessary. Do you always take the cover off when quoting for a Cu change? Apart from maybe all the circuits with fuses/MCBs may not be connected. Please do enlighten me?

telectrix · Jun 1, 2018

you take the cover off to do some basic testing , mainly to ensure that you won't get anty poor IR readings /OC rings/ etc. which would entail additional costs. then you quote accordingly, knowing what extra work may be involved.

Dave OCD · Jun 1, 2018

I quote based on all tests being satisfactory with the agreement that any issues found during testing that need sorting out will be done at additional cost. But the original quote will include earthing/bonding upgrades if necessary.

Grayza · Jun 1, 2018

That's what I quote, CU replacement + any faults found whilst testing will be carried out at an additional cost.
I'm not going to carry out any tests without being paid for it. I may advise testing be carried out before and provide a separate quote for that.

Octopus · Jun 1, 2018

What have you said to the customer about the earth or lack of?

Grayza · Jun 9, 2018

I've asked the customer to call his suppliers and have them check it out and also mention that the cut out looks damaged.

paleosparky13 · Jun 9, 2018

DAvid Prosser said:
I find when asking for an upgrade i helps if you say you are fitting electric showers and induction hobs.

It's integrated earthing/conduit. It predates all the cpc normal bonding arrangements. Use gn8 for acceptable readings of continuity and impedance etc.