I had my water supply moved about 2 years ago but this only occurred to me today.
The original supply was through copper pipes fed underground and into the house. The new feed is through plastic pipe. I can find no earth 'spike' and was wondering if I have 'lost' the earth. Is this a problem or a potential problem (no pun intended)?
I am not having any shocks or problems of any sort.
Thanks in advance.
There is no requirement to main bond an incoming plastic pipe. However, you must still main bond your house piping if it is metal.
You may not use incoming water pipes as an earth. However, a really old electrical installation may have done so. If this is the case, you will need to get another earth.
We need to see what type of earthing your installation uses. There are 3 main types of earth commonly seen in houses:
Can you determine which system you have? If not, could you post a link to a photograph showing the incoming cable, the meter and your consumer unit?
Commonly, a TT system is likely with overhead cables, a TN-S system is found with older underground cables, whilst TN-C-S is found with recent underground cables. However, this is by no means a rule and all types of earthing systems could be found with both underground and overhead cables.
Christian.
Black box? I assume there's something in the box, and that the colour isn't critical to its functioning
I don't have a digital camera so I cant post a photograph sorry.
It is not 1) TN-S. Two separate wires come in from outside. Along the roof line.
There is a black box near the meter, about ½ X 3 inch, but no wire to the consumer unit from it. There is a heavy gauge (green) wire coming from between the floors into consumer unit but I can not see where it comes from easily. Where the 'main' fuse is it says protective multiple earth, is this any help?
Your earth is connected to the neutral and is sometimes called TN-C-S as described earlier. You need to have a look at the main fuse and see if a large green/yellow cable is connected from this to your CU.
-- Adam
snipped-for-privacy@blueyonder.co.uk
large green/yellow cable is connected from this to your CU.
The link has probably been put across in the cutout (main fuse) then...
"AlterEgo" wrote | > > It is not 1) TN-S. Two separate wires come in from outside. Along | > > the roof line. | > > There is a black box near the meter, about ½ X 3 inch, but no wire | > > to the consumer unit from it. There is a heavy gauge (green) wire | > > coming from between the floors into consumer unit but I can not see | > > where it comes from easily. | > > Where the 'main' fuse is it says protective multiple earth, is this | > > any help? | > Yes. | > Your earth is connected to the neutral and is sometimes called TN-C-S | > as described earlier. You need to have a look at the main fuse and see | > if a large green/yellow cable is connected from this to your CU. | I can not see one at the fuse end, but there is a heavy gauge green wire | coming in to the consumer unit though. Is it safe to suppose it is this?
I have my doubts. Your twin separate wires along the roofline from outside, and a green wire disappearing below the floor, sounds very much like a TT installation (overhead supply) with the green wire going to a water pipe or earth rod.
If it's PME there should be a very obvious green-and-yellow wire coming from the main fuse - it will look like a third meter tail - to the CU.
I do wonder if that PME sticker is an error - or it is just possible that the *supply* has been upgraded to PME but your *installation* is still on TT. If the 'black box' has a heavy green-and-yellow wire to the main fuse that may intended to connect to your CU when your installation is upgraded to PME.
The fact that your earth wiring is in green suggests it is at least 20 years old, and earthing is one area where the Regulations have been tightened up considerably.
Owain
I have cross posted the question on both diy boards so please forgive any confusion I am causing by putting the same answer on both in the event that someone else may benefit from replies to this question.
The grey box where the main fuse is, says ?series 7? on it and ?official? labels from the supplier saying P.M.E. there is no green / yellow wire from this into my consumer unit, and the green wire I mentioned in the earlier post goes to the back of the house then between the original building and an extension added about 20 years ago ( before I lived here ) Would it be the best option to add an earth rod anyway, or get the PME connected up? Would the electricity board have to do this? Would they do it without making me get rewired throughout?
"AlterEgo" wrote | "Owain" wrote | > I have my doubts. Your twin separate wires along the roofline from | > outside, and a green wire disappearing below the floor, sounds very | > much like a TT installation (overhead supply) with the green wire | > going to a water pipe or earth rod. | > If it's PME there should be a very obvious green-and-yellow wire | > coming from the main fuse - it will look like a third meter tail - | > to the CU. | > I do wonder if that PME sticker is an error - or it is just possible | > that the *supply* has been upgraded to PME but your *installation* | > is still on TT. If the 'black box' has a heavy green-and-yellow wire | > to the main fuse that may intended to connect to your CU when your | > installation is upgraded to PME. | > The fact that your earth wiring is in green suggests it is at least | > 20 years old, and earthing is one area where the Regulations have | > been tightened up considerably. | I have cross posted the question on both diy boards so please forgive | any confusion I am causing by putting the same answer on both in the | event that someone else may benefit from replies to this question.
Your message only appeared to be sent on uk.d-i-y; if you wish to cross-post you can do so, this is preferable to separately posting on different groups.
| The grey box where the main fuse is, says ?series 7? on it and ?official? | labels from the supplier saying P.M.E.
That suggests your *supply* is PME
| there is no green / yellow wire from this into my consumer unit,
and your *installation* is not PME
You can see that the earth is very clearly tied into the neutral in the supplier's fuse assembly.
| and the green wire I mentioned in the earlier post goes to the | back of the house then between the original building and an | extension added about 20 years ago ( before I lived here )
Gawd knows.
| Would it be the best option to add an earth rod anyway, or | get the PME connected up?
If you have the option of PME that is what would usually be taken, although there are some cases where using an earth rod in conjunction with PME is now preferred. There are also locations where PME *cannot* be used eg petrol stations and static caravans.
| Would the electricity board have to do this? Would they do it | without making me get rewired throughout?
You have to get the electricity company to provide the PME earth terminal, and although you may not have to get rewired throughout (it depends on how bad your wiring is ...) you will have to pay attention to earth bonding pipework and services. The main protective conductor to the CU must be 16mm [1](assuming 25mm meter tails) and equipotential bonding conductors will have to be a minimum of 10mm2.
Owain
[1] Calculation using the adiabatic equation per Regs may give a smaller size but is hardly worth it for this short length of cable.
I think the best option would be to get the electricity board to come and put the PME link in or advise me what I need.
Many thanks Owain, and to all who replied.
But upgrading to PME from a TT installation may require upgrading and/or adding to the earth bonding. We have a PME/TN-C-S supply but I've left the system as TT because I know quite a bit of the earth bonding isn't in heavy enough wire to conform to PME requirements.
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