Bonding to a gas meter outside flat.

[Stevesplatto]

Doing a CU change on a ground floor flat in a bock of low rise flats.
The flat is next to a plant cupboard that houses a cabinet of 1361's with what I think is MICCs (copper covered, two cores) feeding each flat.
It's a TN-S.
The gas meter for the flat is next to the cabinet and bonded to it with 10mm csa and a row of tenby style clamps across all the MICCs where they enter the cab.
The gas is bonded on the consumer side which disappears into the concrete and comes up in the kitchen. (and is a pig to get to>.)
I've also run a 16mm main earth from the cable for the flat where it enters the cabinet (couldn't get to the original clamp to upgrade the cable although I can see it)
So I have a connection to the main earth via the cabinet which is excellent.

Can this be interpreted as sufficient as I have taken a connection from within 600mm of the meter to the main earth even though it's outside the flat?

Cheers
s

 

[Geoffsd]

You should have a main bond from the MET in the flat to the entry point of the gas pipe in the flat.

Not sure about the rest of the post.

 

[Ducksy]

I'm sure if you can't access 600mm from Main valve then bond to where its practical to access.....think about it what you gonna do rip up someone's wooden flooring because the valve in under it in the hall?

Oops I strangely saw water where you said gas......well it's easy done.....isn't it ?

 

[Stevesplatto]

Just to be clear:
The bond to the gas meter is within 600mm of the meter
It's connected to the main incomer cabinet as is the MET for all the flats connected to the company head (TN-S) by a 25mm thick cable.
I've run a 16mm CSA cable from the cabinet to the MET in the CU replacing the 2.5 from the clamp on the cable I could see but not access.

The entry point to the flat is more than 600mm fro the meter...

Thinking about it. I've included the gas pipe in the equi-potential zone.. Job done!

 

[Geoffsd]

The bond to the gas meter is within 600mm of the meter

You should have a main bond from the MET in the flat to the entry point of the gas pipe in the flat. 544.1.2

It's connected to the main incomer cabinet as is the MET for all the flats connected to the company head (TN-S) by a 25mm thick cable.

That is not main bonding in the flat.

I've run a 16mm CSA cable from the cabinet to the MET in the CU replacing the 2.5 from the clamp on the cable I could see but not access.

If you mean this is the earthing conductor - ok,

The entry point to the flat is more than 600mm fro the meter...

So would it be if the flat was on the tenth floor, it doesn't matter, therefore -
You should have a main bond from the MET in the flat to the entry point of the gas pipe in the flat.

Thinking about it. I've included the gas pipe in the equi-potential zone..

Which equipotential zone? Not the flat's.

Flats are treated as individual dwellings.

 

[Geoffsd]

I've run a 16mm CSA cable from the cabinet to the MET in the CU replacing the 2.5 from the clamp on the cable I could see but not access.

Just reading this again - are the flats not PME?

 

[Stevesplatto]

Just reading this again - are the flats not PME?

Nope, it's TN-S at the 3phase head using the cable mentioned to the cabinet. Each flat has a tenby clamp on the outer sheaf of the MICCs providing the earth. I needed to upgrade the earth so I used 16mm csa to the cabinet on the other side of the wall to the flat.

You havent quoted the entire 544.1.2 which actually gives some leaway for common sense. Running a cable from the gas pipe where it emerges in the flat is a longer path than from the meter, over twice as long at least. Running from the meter also ensures a connection before any branch metalwork.

I don't think anyone will be dragging me in front of a judge on this one..

 

[Geoffsd]

You havent quoted the entire 544.1.2 which actually gives some leaway for common sense.

Not that much.
The first sentence is quite clear and then there is -
...or at the point of entry to the building if the meter is external.
Flats are considered as separate buildings.

Running a cable from the gas pipe where it emerges in the flat is a longer path than from the meter, over twice as long at least

That's too bad.

. Running from the meter also ensures a connection before any branch metalwork.

That doesn't matter if it is outside.
The bond must be from the entry point to the MET in the flat

I don't think anyone will be dragging me in front of a judge on this one..

No need to do it properly, then. Why did you post the question?

 

[Knobhead]

Nope, it's TN-S at the 3phase head using the cable mentioned to the cabinet. Each flat has a tenby clamp on the outer sheaf of the MICCs providing the earth. I needed to upgrade the earth so I used 16mm csa to the cabinet on the other side of the wall to the flat.

Why do you need to upgrade the earth? You’re never going to better the sheath of a MICC.
There’s a sticky somewhere regarding the CSA of MICC’s.

 

[Stevesplatto]

I said:
"I've also run a 16mm main earth from the cable for the flat where it enters the cabinet (couldn't get to the original clamp to upgrade the cable although I can see it)"
The original cable from the clamp is only 2.5csa. Direct to the clamp definitely the better option if I could have got to it.

@ Geoff. Appreciate your comments.
++
"Running a cable from the gas pipe where it emerges in the flat is a longer path than from the meter, over twice as long at least"




"That's too bad."
++

No, we are supposed to use common sense, the regs arent mandatory. I think typing this out has convinced me that for this scenario a better more efficient bonding connection is made giving a lower resistance fault path therefore faster trip times.

Thanks for the comments..

 

[Engineer54]

"Running a cable from the gas pipe where it emerges in the flat is a longer path than from the meter, over twice as long at least"

"That's too bad."

Stevesplatto;769986] No, we are supposed to use common sense, the regs arent mandatory. I think typing this out has convinced me that for this scenario a better more efficient bonding connection is made giving a lower resistance fault path therefore faster trip times.

Thanks for the comments

Actually Geoffsd is basically correct, as each flat/apartment is classed as a separate installation, with it's own equipotential zone. The bonding of services by the way, has nothing to do with trip times of protective devices, that relies on earthing provision. So in essence any bonding of services, should be conducted within that installations equipotential zone, not outside of it, as you have done...