Earthing

[DARTHVADER]

I'm currently updating my house electrics and have a question.
The gas pipe to the property is currently not earthed. It runs under the floorboards in the living room which are soon to be covered over and laminate flooring laid. The position at which the pipe enters the house is very close to the cu and the met but as I have said will be covered over soon. My understanding is that the clamp should be accessible and if I situate the clamp under the floorboards this will not be the case.

I have been thinking along the lines of installing the clamp at the other side of the living room inside a recessed cupboard where the gas pipe continues its run to the combi in the loft and then cutting a small hole in the plasterboard so the clamp is visible and then running 10mm earth cable back to the met, a run of approx 15 feet.

I know the regs state the cable should be as close as possible to where the service (s) enters the property but if I do this then it will be under the floorboards.

Please advise.

Thanks.

 

[bernardgreen]

Best place is at the gas meter which one assumes is accessible

 

[securespark]

However, if it's outside, you need to use a suitable clamp.

 

[DARTHVADER]

Cheers for the help. The meter is outside in a box so I assume a slightly more robust earthing clamp suitable for withstanding the elements? The CU is close to the outside wall so I should be to run the cable through the wall with the gas pipe.

 

[holmslaw]

..

 

[DARTHVADER]

A corgi gas installer fitted the combi and didnt mention the position of the gas pipe. It will be very difficult to re route this anywhere without seeing it. As you have said it could be run outside in galv pipe and then taken in via the eaves at the loft and then on to the combi, but to be fair this is more hassle and cost and also does not allow me to pick up a gas coonection very easily later on if I want to change the electric hob to gas. Is there actually regs against having the pipe under the floor or is it just good practice to run outside? (the pipe run seems to be well clipped and soldered)

 

[DARTHVADER]

I think I have sorted the earthing to the gas meter which I will do via the external meter with a suitable clamp.

The other issue I have is that the incoming water stop cock is situated adjacent to the kitchen in one corner of the small dinning room. This is boxed in as the floor in the kitchen/dinner is concrete. The box section where the stop cock is situated is accessible. Do I need to run a cable via a clamp from here to the met which would be routed partly in the box section and then under the living room floor. A run of approx 25 (well over 600mm) feet I would say. The other option if permissible would be to run from the stop cock to the downstairs bathroom (a shorter run) and then link this to the coldwater feed in there which in turn is all going to be bonded properly when I refurb the bathroom. I am aware that the bathroom bonding need not go back to the met, so I'm now wondering if I can go via the bathroom route via the stopcock.

 

[empip]

Gas pipes should not be run in floor voids. Because gas is heavier than air and a gas leak under the floor could be unnoticed until there is large BANG.
If I were you I get it moved outside the house.

Natural gas is lighter than air If natural gas escapes into the atmosphere, it dissipates rapidly.

A heavier-than-air gas, such as of propane or petrol, would settle and accumulate near the ground.

 

[Spark123]

I think I have sorted the earthing to the gas meter which I will do via the external meter with a suitable clamp.

The other issue I have is that the incoming water stop cock is situated adjacent to the kitchen in one corner of the small dinning room. This is boxed in as the floor in the kitchen/dinner is concrete. The box section where the stop cock is situated is accessible. Do I need to run a cable via a clamp from here to the met which would be routed partly in the box section and then under the living room floor. A run of approx 25 (well over 600mm) feet I would say. The other option if permissible would be to run from the stop cock to the downstairs bathroom (a shorter run) and then link this to the coldwater feed in there which in turn is all going to be bonded properly when I refurb the bathroom. I am aware that the bathroom bonding need not go back to the met, so I'm now wondering if I can go via the bathroom route via the stopcock.

Does another water supply enter the premises in the bathroom? If not the cable should run directly from where the water supply enters the premises directly to the Main Earthing Terminal. If it does then the same cable can be used to main bond both services providing the cable is one single length i.e. uncut throughout the entire run.

 

[DARTHVADER]

I think I have sorted the earthing to the gas meter which I will do via the external meter with a suitable clamp.

The other issue I have is that the incoming water stop cock is situated adjacent to the kitchen in one corner of the small dinning room. This is boxed in as the floor in the kitchen/dinner is concrete. The box section where the stop cock is situated is accessible. Do I need to run a cable via a clamp from here to the met which would be routed partly in the box section and then under the living room floor. A run of approx 25 (well over 600mm) feet I would say. The other option if permissible would be to run from the stop cock to the downstairs bathroom (a shorter run) and then link this to the coldwater feed in there which in turn is all going to be bonded properly when I refurb the bathroom. I am aware that the bathroom bonding need not go back to the met, so I'm now wondering if I can go via the bathroom route via the stopcock.

Does another water supply enter the premises in the bathroom? If not the cable should run directly from where the water supply enters the premises directly to the Main Earthing Terminal. If it does then the same cable can be used to main bond both services providing the cable is one single length i.e. uncut throughout the entire run.

Thanks 123. There is not another incoming water main to the bathroom (only hot/cold feeds from the kitchen) the only actual incomer is the one I mentioned in the kitch/diner. So I guess I'll have to run from there to the met. One question though and that is the length of run being well over 600mm which I believe you have to maintain, so is it still ok to go ahead with this lengthy run, which as I have said will be partly in the diner along two walls and then across the living room to the met?

 

[Spark123]

The bonding needs to be carried out within 600mm of the stoptap/service entry to the building. 25 feet shouldn't be too much of a problem for a 10mm cable run (assuming you are using 10mm² and this has been verified as being the correct size for supply type).

 

[DARTHVADER]

The bonding needs to be carried out within 600mm of the stoptap/service entry to the building. 25 feet shouldn't be too much of a problem for a 10mm cable run (assuming you are using 10mm² and this has been verified as being the correct size for supply type).

Yes I'm using 10mm for this. The supply to the house is either tns or tncs supply. Not sure which, but I reckon it's tncs (pme) as the earth does not appear to be clamped to the sheath of the armoured cable but the earth is shrouded off under the plastic cover of the electricty providers cable.

So the actual earth clamp has to be within 600mm of the service to the building and therefore the run to the met does nor equate to the length. Now I'm clear on that, Thanks 123.

 

[Spark123]

That's about the size of it, for PME (TN-CS) you need to contact your network operator and check the size of the main bonding with them. The resistance of an MEB cable should not exceed 0.05ohms. Given the short distance and providing your network operator is happy with the size, 10mm will almost certainly be OK.

 

[DARTHVADER]

That's about the size of it, for PME (TN-CS) you need to contact your network operator and check the size of the main bonding with them. The resistance of an MEB cable should not exceed 0.05ohms. Given the short distance and providing your network operator is happy with the size, 10mm will almost certainly be OK.

Thanks again 123. The short piece of earth cable from the electricity supplier (running from under the cover of the swa cable to the met)
looks to be 16mm. I'll check with them as you have suggessted and they can tell me if its tns or tncs at the same time.

I know someone with a meter so I'll check the resistance when the earth is attached. I think in reality the run will be shorter than 25 feet.

I asked earlier about earthing the gas supply earlier and I'm going to run a cable (10mm) from the external gas meter (my side of the pipe) to the met which is a short run of about 3/4 feet. I know from replys earlier that this is OK but it has been suggested by securespark that a suitable clamp be used which I took to be suitable for ext. application. Can you advise further and if so where to obtain. Thanks.