Earth bonding to gas and water mains from communal fuse board in a block of flats

[idiom77]

Hello Gents. I'm new to this forum so please bear with me if I do not make my question very clear.

i am testing a communal DB for a block of flats.

There is no earth bonding to the water and gas main coming into the building before it branches off to individual supplies , meters and the each flats own installation (which I am not testing)

There is no meter before the gas water go to each of the flats.

Does the communal electrical earthing arrangement require a 10mm earth bonding to these services on entry to the build as described in 7671 Amm 3 544.1.2 or is it only necessary in each of the flat's own installations?

Thanks for your help

 

[malcolmsanford]

Is there an individual main header coming into the building with say a Ryfield board then feeding each flat?

Or is each flat totally separate ie have their own individual headers going direct to the flat?

If it is a Ryfield type board then I would class that as the origin of the installation and class the Earth Terminal there as the MET and therefore bond the services. Then I would expect if each flat as it's own meter ie electric/gas and metallic water pipe to have them bonded to what should be called the Earth Marshaling Point (EMP) in each flat

If though each flat is totally independent ie DNO cable going to each flat separately then there is nowhere to bond to.

 

[idiom77]

The communal DB services only the communal areas so each flat has it's own DNO cable. So it is the latter case.

Thanks for your quick reply, you have put my mind at rest.

 

[mhar]

Your DNO will have a policy document detailing their supply policy for flats which includes their bonding requirements.
The main bond to the BNO's earth terminal is sized in relation to the supply neutral

 

[davesparks]

The services should be bonded as the enter the building and also as they enter each individual installation. GN8 has pretty pictures to illustrate this.

 

[idiom77]

Thanks for that, I have just ordered a copy of GN8 to have a good look at it all

 

[Leesparkykent]

+1 for bonding the services as they enter the building and also as they enter each flat.

 

[LankyWill]

If this is a new communal installation all of the services will be in plastic pipes so no need to worry.

 

[DNS1]

If I've ensured I've bonded as the supplies have entered "my" bit of the installation (ie the flat itself) then not worry about bonding on the buildings incoming supply.

 

[benthespark]

I have a block of flats with 1 incoming water main and 1 supply from the dno to a main plant room. Sub main to each flat with a copper water main to each flat that becomes plastic/ copper and plastic in each flat can I get away with just bonding in the plant room?

 

[Leesparkykent]

If the water is extraneous as it enters the building and the run in to each flat is copper in its entirety then its needs bonding at point of entry to each flat and also bonding at point of entry to the building.

 

[benthespark]

If the water is extraneous as it enters the building and the run in to each flat is copper in its entirety then its needs bonding at point of entry to each flat and also bonding at point of entry to the building.

So if the water main to each flat is plastic it doesn't need bonding other than in the plant room?

The flats also have a hot supply, heating flows and returns and a hot return to the plant room so will they need bonding to?

 

[Leesparkykent]

So if the water main to each flat is plastic it doesn't need bonding other than in the plant room?



The flats also have a hot supply, heating flows and returns and a hot return to the plant room so will they need bonding to?

If the main to each flat is plastic, are they going to be an extraneous conductive part?

And to the second part of your question.....are they an extaneous conductive part?

 

[Deleted member 26818]

To my mind, the services should be bonded at the point of entry to the building.
Whether they then also require bonding at the point of entry to individual flats is another matter.

 

[davesparks]

So if the water main to each flat is plastic it doesn't need bonding other than in the plant room?

The flats also have a hot supply, heating flows and returns and a hot return to the plant room so will they need bonding to?

Yes, every extraneous part needs bonding at its point of entry to each installation. GN8 has very good diagrams of this.