Purchased a house which is insufficiently earthed

Markbfc22

Hi all

Just after a little advice following the somewhat surprising discovery that our house we purchased 2 months ago isn't earthed properly. Apologies if the terminology is incorrect below, I'm far from knowledgeable in electrics!

The problem:
It looks as though the electrical system has previoisly had a TN-C-S arrangement, but at some point has been changed to a TT system. The current earthing consists of a 10mm rod which goes around 1 foot into the ground. A local electrician said the rod should be 16mm and go around 1.5 meters into the ground. There is also no bonding on the gas pipes to make them safe in the event of an electrical fault. The reading when tested on sockets was 200ohms.

The question:
When we purchased the house, we decided to get the more expensive detailed survey by RICS. We also had local solicitors acting on our behalf throughout the purchase. Before I check back through the paperwork and email trails, I was after a little guidance to understand if this should have been picked during the searches/surveys, or if it was our responsibility.

The electrician advised that it wouldn't pass a gas safety certificate due to the gas pipes not being bonded, and would obviously also fail the electrical safety check. The good news is the RCD box is working correctly to trip if anything did go.

Thanks

m0bov

Did you pay for a gas survey? A buildings survey does not go into much detail if any on electrics. Its always worth getting an ECIR done as you now know. I would still get one done ASAP.

00ec25

your responsibility rests with whatever survey you commissioned. If that was an electrical survey from a qualified electrician then it comes down to what your ordered him to do.

I have no idea how my house is earthed, although i do recall a tradesman (gas fitter? ) did once tell me that the bonding on the water pipes under the bath was not how it was done anymore. That said he then left them as they were saying there was no reason to change it.

what is your actual problem? You think the survey missed something that you now want to get the surveyor to pay for? You think the vendor lied? Good luck with either of those battles.

cjmillsnun

I don't see how you would've gone from a TN-C-S to a TT.

The property will be either TN-C-S or TT.

It may be upgraded to TN-C-S from TT but never the other way. The reason for this being that the responsibility for the earthing changes and there are different safety requirements.

There are three different types of earthing present in UK homes. I'll describe each in a single phase supply as very few residential supplies are three phase.

In all cases one outlet of the transformer (we'll call it the neutral from now on), is referenced to the ground (this is done by literally connecting the outlet to a rod in the ground.)

TN-S (Terre Neutral - Separate). Terre is the French for ground or earth (and is pronounced terra) The armouring of the cable into the home is the earthing conductor. This is either lead or steel armouring. The live and neutral conductors (not the current terminology but for ease of explanation) are in the centre. The responsibility for the earth loop back to the transformer is with the distribution network.

At the house, the live and neutral wires enter the cut out, the live is fused (either 60, 80 or 100A) and both wires leave the cut out and go to the meter.

The earth wire is clamped to the armouring and enters either a main earthing terminal (basically a terminal block that all the bonding will come from) or direct into the consumer unit.

There are lots of houses like this and this type of arrangement was common in installs right up to the 70s.

TN-C-S (Terre Neutral - Combined - Separate. Also known as PME - Protective Multiple Earthing). A concentric cable supplies the house (The live wire is in the centre, surrounded by the neutral). Both enter and leave the cutout as before. However the earth wire going to the main earth terminal or consumer unit also goes to the cutout and connects to the neutral terminal. All along the cable from the transformer to the properties supplied, at regular intervals, the neutral is referenced to the ground again. This is normally what is used for new installations nowadays. It replaced TN-S mainly on the grounds of cost, and on the fact that the copper conductor used for the neutral and earth has a much lower impedance than lead or steel. Again the responsibility for the earth loop back to the transformer is with the distribution network.

T-T (Terre-Terre). With this setup the electric distribution network's responsibility for earthing stops at the transformer being referenced to ground. This often happens when your electricity is brought in via a pole and overhead line rather than from underground cables.

Instead it is the consumer's responsibility to provide the earthing, in the form of an earthing rod driven into the ground. The resistance is high, into the 10s of ohms. An RCD in the main supply is compulsory as a fault current may not blow fuses or trip breakers as it will be low.

Lesson over.

Sorting out the issues isn't insurmountable. A new earthing rod (you may as well leave the old one in as well) and putting the bonding in will sort it. It'll cost a bit, but unless you ordered a specialist electrical survey, no-one is responsible.

[Deleted User]

What does the survey say about the electrics? I suspect, even though you paid for a full survey it will just say electrics don't conform to current regulations and a specialist electrical survey is recommended. That is all they have to do.

Davesnave

Markbfc22 wrote: »

The question:
When we purchased the house, we decided to get the more expensive detailed survey by RICS...... I was after a little guidance to understand if this should have been picked during the searches/surveys, or if it was our responsibility.

An RICS surveyor isn't qualified to assess electrics.

Searches have nothing to do with it.

If you didn't commission an electrical report, you have no come-back.

Surrey_EA

deannatrois wrote: »

What does the survey say about the electrics? I suspect, even though you paid for a full survey it will just say electrics don't conform to current regulations and a specialist electrical survey is recommended. That is all they have to do.

Exactly, virtually every survey I have ever seen says something along the lines of: "the electrics have not been tested, and a specialist inspection is recommended."

Part of surveyor backside covering, as they are not electricians.

ProDave

A few points.

Did you get an EICR (Electrical Installation Condition Report) done before you bought it? If not then tough, you chose to buy it as seen and untested.

200 ohms on TT WILL pass an EICR as long as there is an rcd on all circuits.

It should be a trivial job to change the earth rod for a better one but depending on your ground it might not make much difference.

It is also easy put the earth bonding in place for the gas pipe. Again if you did not have a gas test, then you chose to buy it as seen, untested.

Perhaps now is the time to get an EICR done, I suggest NOT by the electrician who told you 200 ohms is no good as he does not seem competent.

I would also want to know from that competent electrician if there really was an TNS or TNCS earth presented, that is no being used. He could test such an earth and if found to be good, re connect it. If there is a TNS or TNCS earth presented that is not testing okay, then it is a fault to report to your DNO for them to fix.

ReadingTim

Markbfc22 wrote: »

The question:
When we purchased the house, we decided to get the more expensive detailed survey by RICS. We also had local solicitors acting on our behalf throughout the purchase. Before I check back through the paperwork and email trails, I was after a little guidance to understand if this should have been picked during the searches/surveys, or if it was our responsibility.

Given you went ahead and purchased the house anyway, it's your responsibility now. Accordingly, your time, energy and money are probably better spent rectifying the problem rather than trying to apportion blame for it.

Furthermore, if you think you're going to be able to get the surveyor to foot the bill for sorting it out on the basis they "missed it", you're going to be sorely disappointed. Sorry that this isn't what you want to hear.

ProDave

Almost certainly, the surveyor would have recommended an EICR for the electrics and a gas safe test. That's standard boiler plate stuff on a survey report.

silvercar

The electrician advised that it wouldn't pass a gas safety certificate due to the gas pipes not being bonded, and would obviously also fail the electrical safety check.

If that was the only issue, it would pass but with an advisory that the gas pipes weren't bonded.