Gas Bonding

[glenmac]

Hi I’m still doing my apprenticeship, and I was wondering if you guys can help me.
There are 2 flats, one above the other.
Both gas meters are side by side out the front of the ground floor flat.
The gas bond for the ground floor flat has taken the 10mm earth cable from the CU to the gas meter box and bonded, it then continues to the gas meter for the top floor flat and bonded (with no break in cable).
The top floor flat has a 10mm earth cable from its own CU to the gas pipe within 600mm of point of entry of the dwelling.
In short this means that both CU’s are earthed to the same gas pipe. Is this acceptable.

[1767sb]

I would have to ask the question of are the 2 installations fed from the same supply and are they PME?

If they are I would suggest that it is not acceptable as the neutral on the way upto the 2nd floor flat may become damaged at some point and start sending 230v through all the exposed / extraneous conductive parts of both flat 1 and 2. The main problem being in flat 1 whereas there will be 230v between both L-E and E-N.

for what it is worth, I would remove the link between the meter and have both installations independent of each other.

[spinlondon]

I would have to ask the question of are the 2 installations fed from the same supply and are they PME?

If they are I would suggest that it is not acceptable as the neutral on the way upto the 2nd floor flat may become damaged at some point and start sending 230v through all the exposed / extraneous conductive parts of both flat 1 and 2. The main problem being in flat 1 whereas there will be 230v between both L-E and E-N.

for what it is worth, I would remove the link between the meter and have both installations independent of each other.

I think you need to re-think what you have said here.
If the neutral were damaged in such a manner that it came into contact with exposed or extraneous-conductive-parts, it wouldn't matter whether the gas meters were linked or not.
Both neutrals and earths are connected at the origins of the installations, so bonding the two gas meters will make no difference.
As for getting 230v between L-E, that sounds fairly normal to me.
I don't see however how if the earth and the neutral are connected together at the origin, how there will be 230V between E-N?

If the gas pipework for the upstairs flat can in anyway introduce a difference in earth potential to the ground floor flat, then it has to be equipotentially bonded to the ground floor flat earthing.
Again if the pipework can introduce a difference in earth potential to the upper flat, then it to has to be equipotentially bonded to the upper floor flat earthing.
This is not only acceptable, it is required.