Water Mains - Bonding - SubMain Earth

[cabinman]

Hi,

Quick question, I need to bond the water mains into the house, that comes up into the concrete kitchen floor.

A submain CU in our extension, is installed high up in a cupboard, supplied with 2-core 16mm SWA with a separate 16mm main earth cable.

This runs down the plasterboard wall - poping out under the plinth of a kitchen cupboard, curving and out thru the outside wall back to the Earth Block installed next to the service head, approx 4mtrs away along outside wall.

This is obviously one complete cable from point to point.

It passes the water mains, would it be possible to cut / splice this cable here (there is plently of slack) into a suitable clamp, in order to provide bonding to the water mains (in 16mm)

Will this affect the earth to the submain CU? Should that be complete all the way back to the earth block?

Therefore, should I run a 10mm seperate line along the outside wall to a new clamp on the water mains, connecting to the earth block at service head/main CU area?

Or something else all together??


Thanks for advice,


Will take pic later, as everyone loves pics

 

[RF Lighting]

You must not cut into / splice the main earth tou your submains.

You can either take the MEBs back to the MET at the intake position, or you can take them to the submains MET (probably the earth bar in the CU) as the main earth is >10mm²

 

[Adam_151]

or you can take them to the submains MET (probably the earth bar in the CU) as the main earth is >10mm²

Wondered about this before:

1) Is it a MET in the subboard? I thought it was just a CPC bar as I thought there was only one MET per equipotential zone?

2) What about voltage drop on the submain CPC/ main equipotential bonding conductor during an earth fault?

Anyone know what GN8 says?

 

[cabinman]

Thanks guys


Looks kinda difficult to fish through the plasterboard wall to run back to submain CU, due to noggins

so, I will simply run a 4m cable along the outside wall to the water mains using 10mm cable and earth clamp back to the intake earth block


10mm is correct for water supply?

 

[cleverspark]

not sure if i have read all the info correctly but it seems to me that as long as the 16mm cable is connected back at the MET, and that you do have plenty of slack in the 16mm cable, then what you could do is strip back the insulation and then attach this to the mains water pipe.
Be aware though, I just mean strip the insulation back, all earth have to be a continuous cable.

 

[Taylortwocities]

Not so clever, spark.

You kust keep the earth wires separate otherwise when you come to test Ze at origin, you'll lift the 16mm from the MET to test expecting it the be raw phase, neutral and DNO earth. Instead, using your suggestion, you will get a measurement including the connection to the water main.

Separate cables back to the MET, preferably marked so the next spark can test and assertain the earth bond continuity for EACH,.

 

[cleverspark]

so could you not label it at the MET as the main water bonding?

You only do Ze readings at the main service head do you not?

therefore you should know which is the main earth for this and not just pick the largest available earth cable.

Or do you mean if you are doing a Ze reading at the other CU then you will take into account of the connection at the water main?

The trade of the spark, you learn all the time

 

[JohnD]

OOI, TTC, some installations have a single (unbroken) 10mm main bond running from MET to gas and then to water; you are not saying this is forbidden, are you? In some houses the gas and water are at the opposite end of the house to the MET so running two would be more effort and expense.

 

[Taylortwocities]

Maybe I misunderstood the purpose of the 16mm. If its not the main earth there shouldnt be a problem.

 

[JohnD]

sorry, on re-reading, I think it was me that misunderstood.

 

[cabinman]

update

have run a 10mm earth single back to earth block


what I wanted to check, is if what I have done is correct... pics

cleaned up pipe with wire wool, clamped on earth clamp at this position

previously the CU was near here (before moving up high, out of water reach... now is this still required? bonding of these pipes?? cold supply upstairs and hot supply from boiler feed

thought this would be best, keep cable out of harms way - now has washing machine sat in front... all cables tied up before washing machine slotted in place - cable clipped etc..

view from sink cupboard... hope this counts, no other choice for accessiblity. should the warning label cover the screw or not? I have split the cores of the cable to 'slot' around screw and be held by the washer pressure


Many thanks

 

[ban-all-sheds]

 

[cabinman]

Deceptive picture BAS - that is the exit point through the wall of the extension, this is where the submain SWA and 16mm earth come in and where the 10mm earth exits along the outside wall and back inside to the earth block.

the white cable is telephone cable and what looks like a metal connection is actually orange telephone cable sized Scotch-Blok's in order to extend the telephone cable. the other grey cables are Cat5E network feeds.


Looking back at it, looks like an earth is connected there to some metal connector, this is not the case!!

 

[ban-all-sheds]

You ought to tidy it up, and introduce some trunking to separate the comms cables from the electrical ones...

 

[cabinman]

I may consider doing that


Main question, have I bonded this correctly?