gas meter earthing

[kenr0991]

Assuming the gas meter is in a standard wall-mounted cabinet (either recessed, semi-recessed or surface-mounted) then it should be OK to fit a bonding strap to the pipe inside the cabinet (within 600mm of the meter) and run the cable back to the MET.

If you prefer, you could connect the strap to the gas pipe where it enters the property (inside), as long as this is accessible.

gas meter is in standard surface-mounted cabinet.

do i disconnect the earth stake or leave connected ? and also connect the earth cable back to met, if i make this connection within the house it will be under the floorboards

 

[Electrifying]

Firstly, you're not 'earthing' your gas pipe, you are bonding it to the MET.

This needs to be done, as near as practicable, to where the pipework enters your home - not in the external gas cupboard - no excuses....there must be some point in your house where the gas pipe appears.

If you bonded in the external gas cupboard, you would be creating a hazard that doesn't yet exist.

As for the 'earth rod' - leave it where it is - it makes no difference either way.

 

[securespark]

Why not the external cabinet?

What if the gas pipe does not reappear for several metres, before which are some tees off the main pipe?

QUOTE:"the connection shall be made...before any branch pipework"

"Where practicable, the connection shall be made within 600mm of the meter outlet..or at the POE...if the meter is external."

 

[Electrifying]

Why not the external cabinet?

Gas fitters and their regulations may require that their meter/pipework needs earthing or bonding in the external meter cabinet - but from an electricians point of view - it doesn't.

We are trying to maintain an 'equipotential' zone within the property - it doesn't extend to the garden.

544.1.2

The main equipotential bonding conductor to any gas, water or other service shall be made as near as practicable to the point of entry of that service into the premises.

Then the last line reads.........

Where practicable, the connection shall be made within 600mm of the meter outlet union or at the point of entry to the building if the meter is external.

 

[JohnW2]

We are trying to maintain an 'equipotential' zone within the property - it doesn't extend to the garden.

Indeed, but where does the property (and its equipotential zone) start? A good few properties have flush external meter cabinets, so the gas meter is within the walls of the building, very close to the interior finished surface of the wall. Could it not be argued that this is 'within the property' and within what one wanted to be an equipotential zone? - or do you feel that only starts at the interior surfaces of the walls?

Kind Regards, John.

 

[EFLImpudence]

Where practicable, the connection shall be made within 600mm of the meter outlet union or at the point of entry to the building if the meter is external.

That is somewhat ambiguous as are so many of the regulations. It depends where you put the emphasis.

It could be argued that -

WHERE PRACTICABLE the connection SHALL be made within 600mm of the meter outlet

or
(IF NOT PRACTICABLE) at the point of entry to the building if the meter is external.

Not UNLESS the meter is external. In other words it's your choice.

 

[kenr0991]

Firstly, you're not 'earthing' your gas pipe, you are bonding it to the MET.

This needs to be done, as near as practicable, to where the pipework enters your home - not in the external gas cupboard - no excuses....there must be some point in your house where the gas pipe appears.

If you bonded in the external gas cupboard, you would be creating a hazard that doesn't yet exist.

As for the 'earth rod' - leave it where it is - it makes no difference either way.

re-gas bonding
If i bond to the nearest accessible point (which is about 20metres into the house) this is right next to suppliers met. Would this satisfy 17th edition? but who has final say over gas meter re-their regulations???

 

[Electrifying]

Firstly, you're not 'earthing' your gas pipe, you are bonding it to the MET.

This needs to be done, as near as practicable, to where the pipework enters your home - not in the external gas cupboard - no excuses....there must be some point in your house where the gas pipe appears.

If you bonded in the external gas cupboard, you would be creating a hazard that doesn't yet exist.

As for the 'earth rod' - leave it where it is - it makes no difference either way.

re-gas bonding
If i bond to the nearest accessible point (which is about 20metres into the house) this is right next to suppliers met. Would this satisfy 17th edition? but who has final say over gas meter re-their regulations???

Without knowing where the pipe runs for this 20 metres, I'd bond it at the point you suggest anyway - regardless of the bonding in the meter cupboard.
For all you know (over a 20 metre run), it could still introduce a potential to the house, regardless of the bonding at the meter.

It's a bit like if you had two building with shared metal pipework - the pipework would be bonded at the point of entry to each building - if that makes sense.

As for gas regulations and bonding, I did read these - but it was a while ago.
They will normally satisfy their own regs when they install the meter - which possibly explains the earth rod - I can't remember what their regs specified.

I suppose there's nothing actually wrong with bonding the pipe in the external meter cupboard - but just for arguments sake, let's change your scenario for a second.

Where would you bond if the gas meter was in your detached garage ten foot from the house (with no electrics in the garage)??

You wouldn't bond within 600mm of the meter - you'd bond where it enters the house - that's the whole point of the bonding.

 

[JohnW2]

Where would you bond if the gas meter was in your detached garage ten foot from the house (with no electrics in the garage)??
You wouldn't bond within 600mm of the meter - you'd bond where it enters the house - that's the whole point of the bonding.

I agree (provided there were no electrics in the garage). However, even without electrics in the garage, I would personally want the gas pipe bonded to other metalwork in the garage. Otherwise, because of the presence of the bonding in the house (and presumed continuity through the pipes), under some fault conditions the potential of gas pipework within the garage could rise to considerably above the potential of other nearby metalwork (quite possibly implicitly connected to true earth).

In other words, the existance of the house's MPB would in some senses introduce part of the electric installation of the house into the garage - so I would want the garage to be constituted as an equipotential zone. Do you think that's over-cautious?

Kind Regards, John.

 

[holmslaw]

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[JohnW2]

Also 10mm bonding cable is restricted to about 27 mts for MET to gas meter, bigger distance need bigger cable.

Although I can't currently find it in either regs or OSG, I'm sure I've read that the maximum permissible resistance is 50mΩ (i.e. 0.05&#937, but with 10mm² cable having a resistance of about 2.2mΩ per metre, that would imply a maximum of about 22.7m. can you tell me where your 27m figure come from? Thanks.

Kind Regards, John.

 

[ban-all-sheds]

20°C

 

[JohnW2]

20°C

Ah, right. Thanks. However, one surely could not design an MPB conductor such that it had acceptably low resistance only at 20°C. Even in the UK the ambient temperature can rise appreciably above that, not to mention that bonding conductors often travel through potentially fairly warm places.

Kind Regards, John.

 

[holmslaw]

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[holmslaw]

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