Gas meter not bonded, what diameter (4mm/6mm/10mm) GY earth wire should be used?

[Agile]

I demur to your qualifications. It has always been my understanding. In fact, I understood that when the cable is ran from the meter to a clamp on the water, then to the gas, that the cable had to be looped around the clamp terminal rather than using 2 lengths.

But I am always prepared to accept that I can be wrong.

Nothing wrong with that at all.

May well be quicker as well. And it prevents any chance of any high resistance contacts at intermediate earthing points.

I wonder how many mains water pipes are still made of metal nowadays?

 

[JohnW2]

I demur to your qualifications. It has always been my understanding. In fact, I understood that when the cable is ran from the meter to a clamp on the water, then to the gas, that the cable had to be looped around the clamp terminal rather than using 2 lengths.

Nothing wrong with that at all. May well be quicker as well. And it prevents any chance of any high resistance contacts at intermediate earthing points.

As you say, there's nothing wrong with it, it may be quicker and it reduces the risk of one of the joints having a high resistance. However, my point was that, contrary to what an awful lot of people seem to believe, there is nothing in the regulations which require it.

Kind Regards, John

 

[AndyPRK]

What isn't in the regulations ? which people think is required ?

 

[JohnW2]

What isn't in the regulations ? which people think is required ?

That bonding conductors have to be in continuous lengths all the way from MET to the extraneous-c-p being bonded, even when one bonding conductor loops from one service to another.

As has been said, it probably 'makes sense', but is not required by regs.

Kind Regards, John

 

[PrenticeBoyofDerry]

In fact, I understood that when the cable is ran from the meter to a clamp on the water, then to the gas, that the cable had to be looped around the clamp terminal rather than using 2 lengths.
But I am always prepared to accept that I can be wrong.

Ideally it should be, although BS7671 (aka wiring regs) don't actually specify this, but guidance note 8 (earthing and bonding) did or does (don't have latest edition)!

For what's it worth. I would have thought the person disconnecting the earth bonding, would have a responsibility to ensure measures are taken for it to be reconnected?

 

[PTS2]

Thanks for the replies. The gas meter is still inside, it just moved in between the metal garage door and middle wall. 10mm seems too thick, is it in regulation? I will visit the property on this Wednesday when I can check whether there is any bonding outside of the building. But I thought the bonding need to be in the consumer side?

The "bonding" regulation (544.1.2) isn't totally clear but if you think what it's trying to achieve then it makes more sense. What is it trying to achieve? It wants all metalwork inside the house to be at the same potential so if you put your left hand on the tumble dryer and your right hand on the water tap you don't get current flowing across your body. Your tumble dryer case, remember, should be connected to the MET with the CPC in the twin and earth.

Therefore you also want all metal coming in from the outside has to be brought to the same potential as the master earth terminal at the CU as soon as it enters the equipotential zone. To do this you connect the metal pipes to the MET with a nice thick cable as close as possible to the point when it comes inside your house (first sentence in 544.1.2).

The rest of 544.1.2 just helps to confuse the good advice given in the sensible sentence one - so if you can satisfy the first sentence just ignore the rest. If the meter is inside the property (so inside the equipotential zone) and you have bonded the pipe at the point of entry, the meter itself doesn't need any special bonding attention. It's just another lump of metal with no external electrical potential. So from your description, which I still thinks needs further clarity, you might just 'rebond' the gas pipe in the same place it was previously (assuming the electrician bonded it in the right place in the first place, which often they don't).

Regarding jointing the bonding cable. It's just another piece of cable, it's not special, it doesn't have magic properties. If the cable isn't long enough and you need to extend it then just do so. As with all cables, when you joint/connect it Regulation 134.1.4 applies so you need to do it 'properly' and if the joint is accessible then a correctly screwed connection is perfectly OK.

 

[JohnW2]

... To do this you connect the metal pipes to the MET with a nice thick cable as close as possible to the point when it comes inside your house (first sentence in 544.1.2). ... The rest of 544.1.2 just helps to confuse the good advice given in the sensible sentence one - so if you can satisfy the first sentence just ignore the rest.

I couldn't agree more. Indeed, the remainder of the regulation not only confuses but says some daft things - there is no point in applying main bonding to pipework downstream of an "insulating section or insert". One can but assume that whoever wrote that had no real understanding of the concept of Main Equipotential Bonding or equipotential zones.

Kind Regards, John

 

[EFLImpudence]

If the meter is inside the property (so inside the equipotential zone) and you have bonded the pipe at the point of entry, the meter itself doesn't need any special bonding attention.

Whilst I agree with what you say, 544.1.2 does state that the bond be connected to the consumer side (within 600mm. for some reason) of a meter when it is inside the premises.

This is in fact not the best place for the bond but I have always assumed it is because the Gas Supplier does not want it on their pipes and the wishes of huge companies are more important than the safety requirements.[/QUOTE]

 

[JohnW2]

... Whilst I agree with what you say, 544.1.2 does state that the bond be connected to the consumer side (within 600mm. for some reason) of a meter when it is inside the premises. This is in fact not the best place for the bond but I have always assumed it is because the Gas Supplier does not want it on their pipes and the wishes of huge companies are more important than the safety requirements.

Possibly, but, regardless of commercial pressures, it makes no sense for BS7671 to talk about "main protective bonding" in a manner which does not serve the purpose of main protective bonding. I don't know about gas meters (I don't have one) but my water meter is entirely plastic. Unless you're going to start talking about the conductivity of water, there is no real point in 'main bonding' pipework on my side of that meter. In contrast, there are 4-5 metres of totally exposed and touchable metal pipe on the supplier's side of the meter, and that is what needs to be (and, in my case, is!) bonded!

Kind Regards, John

 

[JohnD]

This is in fact not the best place for the bond but I have always assumed it is because the Gas Supplier does not want it on their pipes

I believe it is also because the gas meter may be removed at any time, and there is no guarantee that a gas meter, and pipes which may be jointed with paste or washers, will give a good electrical connection under fault conditions.

I can remember seeing bonds bridging over the meter to connect the incoming and domestic pipes, but I don't know if this used to be a requirement or even a recommendation.

 

[JohnW2]

This is in fact not the best place for the bond but I have always assumed it is because the Gas Supplier does not want it on their pipes

It was actually EFLI, not I, who wrote that!

I believe it is also because the gas meter may be removed at any time, and there is no guarantee that a gas meter, and pipes which may be jointed with paste or washers, will give a good electrical connection under fault conditions.

... but, in terms of the point of main equipotential bonding, that doesn't matter. Provided that the incoming supply pipe were main bonded close to where it entered the property (on the supplier's side of the meter) any 'poor connections' downstream of that would not detract from the effectiveness of the bonding (for its intended purpose). The purpose of MEB is not to connect internal pipework to the MET.

I can remember seeing bonds bridging over the meter to connect the incoming and domestic pipes, but I don't know if this used to be a requirement or even a recommendation.

In their wisdom, Anglian Water have, within the past few years, installed a 2.5mm² (I think) G/Y cable across their (plastic) water meter in my house!

Kind Regards, John

 

[Taylortwocities]

10mm seems too thick, is it in regulation?

Just a point of clarification, and I see from the title of the topic, you are expecting the 4/6/10mm of the conductor to be the DIAMETER.
Not so, it is the cross sectional AREA of the conductor that you need. So you would require 10mm² cable.

Like this: https://www.tlc-direct.co.uk/Products/CA10SGY.html

 

[JohnW2]

In fact, the water pipe can be used as the bonding conductor so, in the right situation, the cable may run from Gas pipe clamp to Water pipe clamp and go no farther.

Really?? And not back to the MET? Never heard of that one..

Yes. Of course, the water pipe must be properly bonded.

Is there not an inconsistency there? If (as I agree appears to be allowed by the regs) the water pipe can be used as the main bonding conductor for the gas supply (but not vice versa), why can't it also be used as the main bonding conductor for itself?

Kind Regards, John

 

[sparkwright]

I have no issue with a join in a 10mm bonding conductor if an in-line crimp is used.

I have no issue with one length of cable serving more than one service, for example gas and water - providing at the first service the cable is not cut, and is continous.

One has to use common sense here.

 

[JohnW2]

I have no issue with a join in a 10mm bonding conductor if an in-line crimp is used. I have no issue with one length of cable serving more than one service, for example gas and water - providing at the first service the cable is not cut, and is continous.

Fair enough, and (although not ideal) the regs, per se, would "have no issue" with one or more (accessible) join(s) using screwed connections or with the cable being cut where it looped between two services.

One has to use common sense here.

Indeed. As I've said before, there will usually be four or five screwed connections in the path between the service pipe and the incoming neutral of a PME supply (which is the context in which it probably matters most) - so, in context, one or two additional screwed connections are not necessarily any great deal.

Kind Regards, John