Gas Meter earth bonding help

[luke1234help]

Hi all, I know this may of been covered but I can't see my particular situation. My gas and elec meter are half a foot apart in external plastic cabinets. The elec meter is bonded but not the gas. Please can you help with the easiest way to earth the gas meter, is this something I can do? Thank you in advance

 

[CBW]

Do you know what material the incoming gas pipe is? Check the bonding hasn’t been made on the point of entry.

 

[EFLImpudence]

Check the bonding hasn’t been made on the point of entry.

Where the regulations state that it should be connected.

 

[EFLImpudence]

The elec meter is bonded

Electric meters aren't bonded - nor earthed.

but not the gas.

As above

Please can you help with the easiest way to earth the gas meter,

The gas meter does not require earthing.

is this something I can do?

No.

 

[ericmark]

With a TN-C-S supply to connect the DNO earth to some thing already grounded can cause fires with loss of PEN, in the main the gas will have some where some isolation bit to stop the PEN being connected to metal parts with are connected to true ground, I would be very wary of adding earth wires in case you earth the wrong side of some isolating unit.

Best leaving the connection of earth wires down to some one gas safe so they know where they can be added safely.

 

[JohnW2]

With a TN-C-S supply to connect the DNO earth to some thing already grounded can cause fires with loss of PEN ...

Maybe, but if that "some thing" enters the building, then to not "connect it to the DNO earth" would create a risk of electric shock (particularly in the fault scenario you mention) which would be a serious non-compliance with BS7671 - at least a C2 on an EICR.

, in the main the gas will have some where some isolation bit to stop the PEN being connected to metal parts with are connected to true ground,

Are you sure about that?

Best leaving the connection of earth wires down to some one gas safe so they know where they can be added safely.

I would fear that "leaving it to someone gas safe" would be no guarantee that the result would be (electrically) safe or compliant with electrical regulations.

Would you be saying something similar about the main bonding of water supply pipes in a TN-C-S installation -and, if so, exactly what sort of person do you feel the bonding of that should be "left to"? It is surely electricians who usually do that - so why is it different when the supply is of gas rather than water?

Kind Regards, John

 

[bernardgreen]

Is there an Emergency Shutoff Valve in that gas supply ?

Maybe, but if that "some thing" enters the building, then to not "connect it to the DNO earth" would create a risk of electric shock

When the "some thing" is inside the gas meter box and can only be touched when the box is open then the only person at risk of electric shock is a meter reader. ( some wear gloves ), But when a long run of un-insulated copper gas pipe installed along the outside wall from meter to gas boiler then the risk of electric shock is extended to anyone touching that exposed pipe.

The bottom line is that the electrical connection to the gas pipe is NOT earthing the copper pipe but is bonding ( connecting ) the copper pipe to the Neutral of the incoming electricity supply. As already mentioned a fault on the local electricity network can raise the voltage on the Neutral to a voltage high enough that all items bonded to that Neutral present the risk of electrical shock to someone standing on the ground and touching that bonded item.

 

[ericmark]

I have not read of any cases of water supplies going on fire, and since water cooled, for a water pipe to carry enough current to melt the pipe is very unlikely, and if all water pipes to every property are bonded to the DNO PEN then any current will be shared between the homes so no home will have a large enough current flowing for there to be a problem.

Gas clearly needs bonding when it enters the home, but I would not say a box assessed from outside is entering the home, all in the box belongs to gas supplier and they need to ensure it is to their standards.

Gas pipes in the home need bonding, but I could not recognise any insulating block in the meter cupboard, so would not be sure the earth wire was the correct side of the insulating block.

Picture shows both feed and return to box are outside the house, the meter cupboard has simply used a handy wall to be mounted on, seem to remember all my instructions is for the gas supply to be earthed near to where it enters the house. Likely some gas stop tap.

 

[polesapart]

I would fear that "leaving it to someone gas safe" would be no guarantee that the result would be (electrically) safe or compliant with electrical regulations.

Totally agree.

“Any person who connects any installation pipework to a primary meter
shall, in any case where equipotential bonding may be necessary, inform the responsible person that
such bonding should be carried out by a competent person.”

The responsible person is (usually) the homeowner and the competent person (in this context!) is the electrician.

https://www.gassaferegister.co.uk/media/2197/tb-102-location-of-protective-equipotential-bonding-on-gas-pipework-in-domestic-premises.pdf

 

[bernardgreen]

I have not read of any cases of water supplies going on fire, and since water cooled, for a water pipe to carry enough current to melt the pipe is very unlikely,

but bonding wires to those water pipes have been known to overheat and caused damage to adjacent gas pipes when the PEN is lost

 

[JohnW2]

When the "some thing" is inside the gas meter box and can only be touched when the box is open then the only person at risk of electric shock is a meter reader.

You appear to be talking about the situation when bonding of gas pipework downstream of the meter IS present, whereas my comment (which you quoted) related to the situation which would exist if the gas pipe provided to path to earth and were NOT bonded within the property. As I said, that would be a situation unacceptable in terms of regulations, since it would present a risk of electric shock within the building - particularly in the presence of a supply-side fault such as eric and you have mentioned.

In practice, of course, even in the absence of explicit 'bonding' conductors, internal gas pipework is almost always going to be connected tothe installation's 'earth', by virtue of the boiler, pumps, CH controls etc. However, that connection is via CPCs which might melt, and hence become ineffective, in the presence of very high fault currents.

The 'solution' to this potential problem would presumably be to do everything possible to eliminate extraneous-c-ps - 'structural' ones (such as the 'damp walls' you so often mention) are more of a problem, but the regs could at least insist that any metal supply pipe (gas, water, oil or whatever) entering a building should have an 'insulating section', so that there was no electrical continuity between inside and outside of the building?

Kind Regards, John

 

[JohnW2]

I have not read of any cases of water supplies going on fire, and since water cooled, for a water pipe to carry enough current to melt the pipe is very unlikely ...

Indeed, but I would imagine that the probability of a gas supply pipe "going on fire" as a result of any credible electrical current flowing through its walls would also be incredibly low.

However, as I've just written, the way to avoid all these theoretical risks (no matter how small) and discussions would surely be for there to be insistence that there was an (electrically) insulating section in ANY pipe travelling from outside a building to inside it?

Kind Regards, John

 

[plugwash]

However, that connection is via CPCs which might melt, and hence become ineffective, in the presence of very high fault currents.

I'd be less worried about the conductors themselves becoming ineffective and more worried about what they might do to stuff around them.

 

[JohnW2]

I'd be less worried about the conductors themselves becoming ineffective and more worried about what they might do to stuff around them.

That might well be true bur, in any event (as I implied) there is no excuse for relying on 'incidental CPCs' to take the place of absent (but 'requred') main bonding.

Kind Regards, John

 

[bernardgreen]

so that there was no electrical continuity between inside and outside of the building?

That would be the ideal set up for an installation with a CPC derived from the incoming Neutral