no earth wire from meter box

[a-z electrics]

Had this job today which i need to finish tomorrow - consumer unit change in a bungalow, TT system, all on a 30mA rcd.
There is no earth wire going from the earth stake to the fuse box. It is connected to a henley block within the meter cupboard just above and there is a twisted wire (uninsulated) about 4 strands going from the incoming mains cable into the same henly block. There is also a connection from mains cable into the neutral henly block but it is all wrapped up and cant see whether its another part of the twisted wires.
I thought "this cant be right, there must be an earth cable going to the fusebox surely". so with great difficulty I ran an earth wire to the new con unit, connected into the same henly block. There are 2 earth wires which appear to go from water and gas meter (bizarrly gas meter is next to fuse box and is underneath/next to kitchen sink unit, so I am extending all the house wires to a new position on the end of the kitchen unit run, so is more accessible.}
Anyway, the first test I did before power up was to measure Ze - with the new earth wire disconnected from bus bar, the meter wouldnt let me test it (came up with question mark). So i put the test lead on the earth bus bar (same as original setup) with new wire still disconnected - measured 6.3 ohm, so not bad.
Measured voltage between new earth wire and busbar - measured 16 volts; measured new wire to neutral and measured 1 volt.
From this I assume the the earth stake and neutral has been commoned up. Is this right - I never seen this before and my house is TT but not done like that..?

 

[Jay Sparks]

I am really sorry if I am having a brain fart but I cant follow your post. If you are unsure about the earthing arrangement, you should contact the DNO and ask them to confirm if its a TNCS, TNS or TT, it maybe that someone has messed with.
But like I said, I may be having a brain fart and someone may be able to understand your post better than me and advise you better.

 

[ChrisElectrical88]

When you were getting the 6.3 ohms were the gas and water bonds connected? I to am struggling to understand this post so might as well start somewheresomewhere

 

[a-z electrics]

I am really sorry if I am having a brain fart but I cant follow your post. If you are unsure about the earthing arrangement, you should contact the DNO and ask them to confirm if its a TNCS, TNS or TT, it maybe that someone has messed with.
But like I said, I may be having a brain fart and someone may be able to understand your post better than me and advise you better.

Yes thanks, will do that in the morning - was too late when I finished today.. but whether its TT or TNS, surely there should be an earth wire to the fusebox?

 

[jaydee81]

there wasnt a link between neutral and earth in fusebox seen that done a few times someone idea of home made pme

 

[telectrix]

it's got me befuddled as well. (OK, that's not too hard with the old age altzeimers kicking in after 5 pints), but a better description with a pic. or 2 might help.

 

[Guitarist]

Yes thanks, will do that in the morning - was too late when I finished today.. but whether its TT or TNS, surely there should be an earth wire to the fusebox?

Erm...yes.
Are you a qualified electrician?

 

[a-z electrics]

When you were getting the 6.3 ohms were the gas and water bonds connected? I to am struggling to understand this post so might as well start somewheresomewhere

Yes, sorry its not as easy to tell in words, should have taken a photo but it has been a long day....the 6.3 ohms was to the earth bus bar with the 2 original earth wires connected - I need to investigate further exactly where all these wires go but the customer was sure that the wire coming up from under the decking and connected into the henly block was the stake wire. I will query the DNO as suggested elsewhere but it didnt seem right to me that there was no earth wire as is usual from the meterbox along with the tails?

 

[ChrisElectrical88]

So the Ze reading you got was due to the gas and water pipe I'm guesting. Have you seen the earth rod yet or are you just going off what the customer says?

 

[jaydee81]

definately would be gaining access to check if there actual is an earth rod my reckoning is that the water main is being used as an earth

 

[a-z electrics]

Thats what it appears, although as I say ran out of time (had to leave customer with some power, so left the earthing in effect as it was before until the morning). I have seen part of the earth rod where it goes into the ground but its been bent over and the top disappears under some decking, most weird - will check tomorrow.

- - - Updated - - -

definately would be gaining access to check if there actual is an earth rod my reckoning is that the water main is being used as an earth

My thinking also..

 

[jaydee81]

be prepared to install new rod or two

 

[Jay Sparks]

If the DNO say its TT, get another rod installed, (two screwed together if needed) and run a brand new earth cable to the CU. You mentioned ONE 30mA rcd covering the whole install in your first post....I hope this was a misprint!!! You need a dual 30mA rcd board for your final circuits, with a 100mA time delayed upfront rcd. Again, this maybe me miss understanding your post.lol

 

[Des 56]

There is no earth wire going from the earth stake to the fuse box.
Thats easy to digest,its not at the fuse box but it does exist,what size by the way?
It is connected to a henley block within the meter cupboard just above got this bit as well and there is a twisted wire (uninsulated) about 4 strands going from the incoming mains cable into the same henly block. got this as well There is also a connection from mains cable into the neutral henly block is this the same henley block as above but it is all wrapped up and cant see whether its another part of the twisted wires. can you not test and determine one way or the other
I thought "this cant be right, there must be an earth cable going to the fusebox surely" Surely. so with great difficulty I ran an earth wire to the new con good on you



I will never win the lottery but getting this one right has slightly better odds,only slightly but there is always a chance

You have a lead sheathed cable with an obsolete Tns connection.the system is now Tnc-s with the twisted bare wire connected to earth via the rod and now its also connected to your cons unit
You now have a TnsTnc-sTT earthing system simples

 

[a-z electrics]

be prepared to install new rod or two

Quite..