Main Earthing conductor

[too old to learn]

Hi,
Is it acceptible to connect the main earthing conductor that is ran from a earth rod on a TT system to the gas pipe on route to the main earthing terminal?
The cable is not broken, just a small part of the outer sheath removed.
Or would you have to run the main earthing conductor all the way to the MET and then have main bonding conductor ran back to the gas pipe?
Thanks

 

[ColJack]

NO!!..

 

[too old to learn]

Thanks ColJack.
I did suspect that. My friend has a property he is renovating and this is the situation in his house.
He is an electrical engineer and was stating that since the cable is not broken it still provides the main earthing bond as well as connecting the gas pipe.
Do you know / or does anyone know the regulation number stating this

Many Thanks

 

[holmslaw]

..

 

[ban-all-sheds]

He is an electrical engineer and was stating that since the cable is not broken it still provides the main earthing bond as well as connecting the gas pipe.

What kind of electrical engineer would think that was OK?

Do you know / or does anyone know the regulation number stating this

He's an electrical engineer, refurbishing his house, and he does not have a copy of the Wiring Regulations?

Does he wear a stetson and commute to work on a horse?

 

[too old to learn]

thanks holmslaw,
I understand that you are not allowed to use the gas or water as a main earth electrode. But he has a main earth electrode in place. At present the main earthing conductor enters the property with the vicinity of the gas pipe and as i have stated has been connected to the gas pipe on route to the MET.
I understand that this will also affect the test results due to parallel paths etc. I just wondered if there was a regulation stating that this can not be done, which is sort of the reg you stated (even tho not 100%) guess its down to that interpretation rubbish again.

BAS, I have never said that he is changing the wiring in the house so why would he need the book for?. I noticed this when i went round to see how things were coming along and I thought id ask the question to improve my knowledge. And i am sure you are aware that a lot of people have a day time job and then renovate properties in what ever spare time they have. So no, he ain't a cowboy!!!

 

[ban-all-sheds]

OK - fair enough - it's just that usually when people refurbish houses they do tend to do the electrics too.

But then we do get some people fetching up here saying that they have just finished papering, painting and putting down wood floors and would like to add sockets & switches without spoiling the decor...

 

[too old to learn]

and there goes the familiar saying
"its not an electrician you need, its a magician"

Still though, just to confirm
Is it a complete no no or just an interpretation of the regs?
after all, as said, it is not using the gas pipe as a earth electrode

 

[bongos]

Is it a complete no no or just an interpretation of the regs?
after all, as said, it is not using the gas pipe as a earth electrode

I'd have thought it was a no no.

You might not be planning to use the gas pipe as an electrode but as soon as you connect it in series with the electrode then you are effectively using it to provide your main earth also.

 

[too old to learn]

But effectively this is what you do anyhow.
main earthing conductor runs up to MET then protective earth runs back down to gas / water pipe. all are joined up.
when testing you have to test the main earthing conductor and you need to remove the protective earths.
to do this on this situation you would remove it off the gas pipe.

Now I know it is not correct and I will inform him that he should change the situation. Again, im just looking for advice etc and thanks to all for the info supplied

 

[Taylortwocities]

The issue will be with 542.4
In this (and in Guidance Note 3) there is a requirement to be able to disconnect the MAIN EARTHING conductor at the MET.

This is a requirement to determine the external Ze and other earthing arrangements (the impedance of the earth electrode, for instance).

It will not be possible to do this if the the main earth goes via sundry other earthy points.

 

[ColJack]

if at some point, for whatever reason, someone disconnects the earth rod, then the gas becomes the main earth and anyone testing the main earth will still see it as to earth..

we've seen main earths disconnected before by builders etc when building an extension that goes over where the earth rod is, or gardeners etc when hard landscaping such as driveways and concrete paths etc..

 

[riveralt]

But effectively this is what you do anyhow.
main earthing conductor runs up to MET then protective earth runs back down to gas / water pipe. all are joined up.
when testing you have to test the main earthing conductor and you need to remove the protective earths.
to do this on this situation you would remove it off the gas pipe.

Now I know it is not correct and I will inform him that he should change the situation. Again, im just looking for advice etc and thanks to all for the info supplied

You haven't said, or I missed it, but is the gas pipe earth clamp/cable on the consumer side or the supplier side of the meter?

Remember the purpose of the main protective bonding of metal services is to reduce the voltages between the various exposed conductive and extraneous conductive parts of an installation, a fault to earth and in the event of a fault on the distributors network.

There are various sections of the 17th edition that refer to this but 542.4.1 specifically mentions that protective bonding conductors shall connect to the main earthing terminal .

Edit: must type quicker

 

[electronicsuk]

Who ever said the MET has to be located in the same position as the consumer unit? It normally is, but I'm not aware of any regulation that says it HAS to be. Therefore, relocate MET to a convenient position between the gas pipe and the earth electrode, and run a suitably sized conductor to both along with the CU.

 

[Taylortwocities]

Yes, but then the bonding for the water supply will need to connect there.