Earth wire runs to gas meter and electrical distribution box

hughs · 26 Oct 2008

I have just had the boiler replaced. I am told that the gas pipes need to be earthed. The engineer proposes to run an earth wire (10mm) from the mains water pipe (where it enters the house) to the gas meter. He also wants to use an earth block at the electrical distribution box and run earth wire (10mm) to the mains water pipe. The access is not difficult and the earth wire runs, I estimate conservatively, would be approx 10 metres in total for both of the above.

I would have thought that the electrical distribution box would be earthed anyway – an absolutely basic requirement. I do not know how to check this. I have looked around the box to see if I can spot the earth wire anywhere – however I do not know what I should look for as the wires all have sheaths around them. Any thoughts or ideas?

If he has to carry out the work he proposes, what would be the likely cost, noting he would not make a separate visit to complete the above (i.e. it would be part of other work)?

Steve · 26 Oct 2008

Can you put up a picture of your electrical consumer unit and mains intake?

The earth wires the man proposes to fit are also basic requirements, they keep all the incoming metal services at the same potential. They will be connected to the mains earth (which may come from an earth rod, or the supplier's neutral terminal)

electronicsuk · 26 Oct 2008

Your plumber is probably already aware if this, but just to point out, if you are going to run a single earth from the MET to the water and then the gas, it must be one continuous length. He will be able to strip the outer insulation to connect at the water meter, but the copper conductor should not be cut.

As above, could do with a picture of your mains incomer. You want to be sure the main earth into the house is up to scratch.

GaryMo · 26 Oct 2008

electronicsuk said:
Your plumber is probably already aware if this, but just to point out, if you are going to run a single earth from the MET to the water and then the gas, it must be one continuous length.

Is that must or preferable?

Lectrician · 26 Oct 2008

Your consumer unit is likely already earthed, but the cable to the gas/water has to COME from somewhere

electronicsuk · 26 Oct 2008

GaryMo said:
electronicsuk said:

Your plumber is probably already aware if this, but just to point out, if you are going to run a single earth from the MET to the water and then the gas, it must be one continuous length.

Click to expand...

Is that must or preferable?

That would be a must, otherwise, there is a risk that work to one point of bonding in the future (for example, if mains gas to the property were removed) could potentially disrupt bonding to the incoming water supply, or vice versa.

GaryMo · 26 Oct 2008

I understand the reasoning and it's why I always run separate conductors but can you come up with a regulation condoning connecting two conductors at one point with lugs?
It's something that's always been good practice to me but I've never seen a regulation relating to it.

In any case, if an incoming supply was removed, what's wrong with connecting the two ends with through crimp to make the protective bonding conductor continuous?

Spark123 · 26 Oct 2008

Nothing wrong with using a through crimp to connect 2 pieces of cable together, the only problem arises when it isn't done.
I'm not 100% sure which the reg it comes from, probably derived from a preservation type reg.

Lectrician · 26 Oct 2008

There is a reg stating the bonding conductor must be a single continuous piece, or words to this effect.

It is fine to through crimp, but many believe you can use two lugs and connect two cables to the bonding clamp. You cant. You must use a single length as mentioned above.

I can't quote the exact reg, or even the 17th re-wording (if any), as regs books are at work.

Defo more than good practice though

GaryMo · 26 Oct 2008

I believe it's noted in GN8 (only have GN3 here) but that's guidance and not regulatory.

543.2.2 (vii) does direct you to 543.2.6.
Would a legible warning notice (Safety electrical connection - do not remove) aid compliance with 543.2.6 (iii)?

NotHimAgain · 26 Oct 2008

Lectrician said:
There is a reg stating the bonding conductor must be a single continuous piece, or words to this effect.

It is fine to through crimp, but many believe you can use two lugs and connect two cables to the bonding clamp. You cant. You must use a single length as mentioned above.

I can't quote the exact reg, or even the 17th re-wording (if any), as regs books are at work.

Defo more than good practice though

No they don't - there is no such regulation. In fact, there is a regulation (543.3.3) that requires that joints in protective conductors (a generic term that includes protective bonding conductors) shall be accessible for inspection, testing and maintenance.

Just another urban myth I afraid.

Spark123 · 26 Oct 2008

Think it's mentioned in the 16th ed Onsite Guide on the pics of earth types.

electronicsuk · 26 Oct 2008

GaryMo said:
I understand the reasoning and it's why I always run separate conductors but can you come up with a regulation condoning connecting two conductors at one point with lugs?
It's something that's always been good practice to me but I've never seen a regulation relating to it.

I'm afraid I can't come up with any such regulation, although I would, like you, consider it best practice to run a continuous length or,preferably, two separate conductors.

BS3036 · 26 Oct 2008

Spark123 has it right. It was mentioned in the 16th On-Site Guide in figs. 4a 4b and 4c. Presumably as recommended good practice, as no reg number was referred to. Apparently dropped from 17th On-Site Guide, possibly because it clashed with 543.3.3.

NotHimAgain · 26 Oct 2008

In many situations the use of unbroken runs for protective bonding conductors is a good idea, and can be considered to be good practice. However, on very large sites, this may not always be practicable or even desirable. This is why there is no regulation.

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Earth wire runs to gas meter and electrical distribution box

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