Gas meter earthing

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skipperab

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Please bear with me as it is the fist time posting on the forum, and apologies if I have posted in the wrong forum. I badly need advice regarding the earthing of a gas meter. My daughter is currently contemplating the purchase of a flat, the seller has given her sight of a electrical condition report that says all is well apart from a couple of C3 faults regarding minor faults that the seller will remedy.  However during the inspection of the flat with her I noticed that the gas meter was earthed to the cold water supply to the house.  I am sure that I have read that the Gas meter must be earthed to the fuse box, I am a total layman regarding electrical procedure and would appreciate the advice of the professionals on the forum.

Thank you.

skipperab

 
Welcome,

If there is just an earth cable from the water to the gas then this serves no purpose. However if the earth cable goes from the consumer unit to the water pipe then to the gas pipe then this is fine. 

 
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Essex 1 

Thank you for the quick reply.  If I understand your reply correctly, if the Gas meter earth is connected to the same pipe that the consumer unit is earthed to all is OK? 

Once again thanks.

skipperab.

 
Essex's statement is only partially correct. You should have either; two individual bonding conductors from water and gas back to electrical earth, or you can have one continuous (unbroken) bonding conductor looping both gas and water back to electrical earth. But it must not be electrical earth to pipe'A' then second bonding conductor from pipe'A' to pipe'B'. So if the pipe clamp at the water pipe was disconnected there must still be earth continuity to the gas pipe.

Doc H. 

 
Essex 1 

Thank you for the quick reply.  If I understand your reply correctly, if the Gas meter earth is connected to the same pipe that the consumer unit is earthed to all is OK? 

Once again thanks.

skipperab.


Essex's statement is only partially correct. You should have either; two individual bonding conductors from water and gas back to electrical earth, or you can have one continuous (unbroken) bonding conductor looping both gas and water back to electrical earth. But it must not be electrical earth to pipe'A' then second bonding conductor from pipe'A' to pipe'B'. So if the pipe clamp at the water pipe was disconnected there must still be earth continuity to the gas pipe.

Doc H. 


Doc is 100% correct.  Sorry.  I should have been clearer.

 
Doc H

Thanks for the info, I can see where you are coming from having two individual earth connections for gas and water if the water bond was disconnected for some reason the gas meter would still be earthed.

I have googled this and could you please confirm for me that the clamp on the gas meter must be on the consumer pipe and within 600mm of the meter.

 As previously stated I am a total novice on electrical installations and this is certainly enlightening me and I think I will be advising my daughter to have her own electrical  condition report carried out on the property.

Thank you all for your expert advice.

skipperab.

 
A couple of points,

The 600mm 'rule' is only a recommendation,  it's not hard and fast,

2nd, I do a lot of EICRs,  (inspections),  I would always recommend the buyer has their own, the seller will usually try and get the inspector to be sympathetic, I've had it a few times where they ask for the very bare minimum to be inspected so that few, if any issues get spotted they hope, I usually end up not doing them if I get that sort of feeling. 

 
What about this external meter boxes that electricians have taken the earth bond outside to?

comply?  Or not comply?

 
Essex's statement is only partially correct. You should have either; two individual bonding conductors from water and gas back to electrical earth, or you can have one continuous (unbroken) bonding conductor looping both gas and water back to electrical earth. But it must not be electrical earth to pipe'A' then second bonding conductor from pipe'A' to pipe'B'. So if the pipe clamp at the water pipe was disconnected there must still be earth continuity to the gas pipe.

Doc H. 


That is a myth and not stated in BS7671 AMD3 It can be 2 pieces, joined at one of the clamps.

It is written like that in GN3 if my memory serves me correctly.

 
GN3

Extraneous-conductive-parts may be, and often are, connected to the MET individually, as shown in Figure 5.4. However, it is permitted to connect them collectively or in groups where the main protective bonding conductor is looped from one extraneous- conductive-part to another. Where bonding is undertaken in this way, the bonding conductor should remain unbroken at intermediate points, as shown in Figure 5.5, thus maintaining continuity to other extraneous-conductive-parts should one be disconnected for whatever reason.
Bolted link
Means of earthing
Bolted link
Means of earthing
T Figure 5.4 The MET
T Figure 5.5 An unbroken main protective bonding conductor
Guidance Note 8: Earthing & Bonding © T

 
The 600mm is measured from the point of entry into the building or as close as is reasonably practicable and NOT within 600 mm of the meter.....unless they have changed it again!....after all,it is only wednesday




unless the company issuing the gas safety certificate & covering the boiler is a bunch of money grabbing twats then 800mm will NOT suffice! :|

 
unless the company issuing the gas safety certificate & covering the boiler is a bunch of money grabbing twats then 800mm will NOT suffice! :|
Tell them it complies with BS7671 which is what YOU work to. If however you wish me to,make it comply with some spurious regulation of yours  then you will invoice them accordingly! 

 
That's what I did but they refused to issue a gAAs safety cert and renew the ins cover on the boiler :| so I moved the cable about a bit and luckily there was just enough slack to bring it within the golden 600mm.

It only took 1/2 hr so customer was happy and so we're the...

  :animal: :animal: :animal: .

:)

 
That is a myth and not stated in BS7671 AMD3 It can be 2 pieces, joined at one of the clamps.

It is written like that in GN3 if my memory serves me correctly.


To be frank I thought exactly the same. I have never seen this written anywhere but was always taught this way. 

 
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I had the head of the gas depth from an LA on a newbuild site with me as hus guys refused to commission the gas as no bond,

external meters, gas run about 4meters along wall before entering property, all our bonds inside,

I showed him our regs, he told his guys they had to run another bond to meter if they wanted one there,

Magically none of the properties needed this bond anymore. 

 
Guys thanks for the education in things electrical I have read everything with interest.  Another question if I may, please bear in mind that I have never seen the inside of a distribution box in my life, the extent of my electrical expertise is changing a fuse or light bulb..

Could you earth the Gas meter box directly into the distribution box?  lets say if it was more accessible to the gas meter than the water pipe where the electrical system was originally earthed.

skipperab.

 
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