TT earth system?!

[dandb]

Hello fellow sparkies

Been asked to change a CU in an old persons home, he said it had a re-wire 20 years ago but the earthing method I have not come across before.

The main earth is on a lead water pipe coming from ground, this goes to the main terminal on DBoard and then equipotential bonding and also the linked circuit bonding run off there.

My question is, when running earth tests do I do the same tests as it were a TT system? Or should I install an Earth rod to be on the safe side? I did a quick ZE check just of incoming and was only 8.54 ohms, this was with all earths disconnected, except the one going to earth.

Just wondering if you older...er i mean more experienced chaps on here who have come across this know about it.

The house is an old cottage and neighboring proterties are on rods

Thanks for you time in advance.

Dan

 

[vitoboy]

yep...
for sure you need to put in a stake or rod..old gas/water pipe is no good..
after all a plumber may come along after and take it out

 

[Guest123]

The use of public service supply pipes as installation earth electrodes is not permitted, 542.2.4.

You will need to install an installation earth electrode and an MET for the installation.

 

[telectrix]

used to be common to use lead water pipe for earthing. not now, as new mains are put in they are in plastic. your options are .1. Put an earth rod in . you need the Ze to be<200ohms. , but everything in the property MUST be on RCD to meet disconnectin times. 2. Contact DNO ( supplier ) and ask them if they will PME it.

 

[dandb]

Thanks for the quick responses chaps. All really helpfull and I wanted to put the ROD in as the owner didnt want the cost of going PME.

Thanks again chaps

 

[Jurassic Sparks]

in the old days the lead water pipes ran for miles and got bigger and bigger, in short an excellent earth
older properties used to have 2 wire circuits to immersions and the like, using the water pipe as the earth
but not now its probably been changed to PVC outside or will do soon
plus you will need to bond the incoming water pipe and the gas if fitted
20 years ago we did not use water pipes as an earth on TT systems people tell you any old rubbish to save money
I had one tried it one with his old lead sheathed cables!!!!

 

[Des 56]

I will try and stir this thread up a bit by asking you for an interpretation of 542.2.4

My interpretation is that an obsolete water pipe may very well be used as an electrode, if the pipe is on your property,unused and unlikely to be removed by others
Your veiws ?

 

[Bigboy247]

No don`t use the old lead pipe because some tatter will steal it, or in afew year they will put a bigger drive in and remove it with the digger and then some clever sod will sue you. Always cover your back. Put the rod in the ground if it meets all the ticks all is well and you have done a good job.

 

[Jurassic Sparks]

mm seem to recall that subject, but i was told that only if the water pipe was on land owned by you
a farm would be suitable , but as the other chap says the robbing toe rags would be round
I have just had to run the bonding to the gas and water pipes outside a listed property (not allowed inside) however i ran them in pvc conduit and then it ws painted over to match, it was a pig to do but the roaming copper thieves will not see it so easilly
locally we have had a great many earth cables removed from agricultural buildings and the like, even supply cables between buildings

it does go wrong for them now and then But I cannot make a statement on a public forum as I dont want to help them!

 

[Guest123]

I will try and stir this thread up a bit by asking you for an interpretation of 542.2.4

My interpretation is that an obsolete water pipe may very well be used as an electrode, if the pipe is on your property,unused and unlikely to be removed by others
Your veiws ?

If it is a private water supply i.e you own it and it is on your land and there is no chance of it being dug up and/or replaced by anyone except yourself then you are permitted to use this pipewrok as an earth electrode.

Like I said in my previous post though, if it is a public, utility company supply pipe then absolutely not.