Communal heating bonding

[ryan24]

Hi all,
need to do main bonding in a flat that has none at the minute. It is on communal heating and the hot water has two entry points. Also the heating pipes enter the flat in numerous positions in the rooms and leave to feed other flats. My question is do all these need bonding? Thanks in advance (forgive me I'm still learning )

 

[Pete999]

Are the extraneous parts?
https://www.youtube.com/watch?v=v38PfIVy2rI

 

[ryan24]

yes the reading is below 0.02. Going to be next to impossible to bond every single pipe as each room has two incoming pipes to supply each rad which feed upstairs and downstairs aswell etc.

 

[bigspark17]

yes the reading is below 0.02. Going to be next to impossible to bond every single pipe as each room has two incoming pipes to supply each rad which feed upstairs and downstairs aswell etc.

Is there one dno supply into the building with submains to each flat.?

 

[ryan24]

Yes I believe so big spark. Thanks

 

[bigspark17]

Yes I believe so big spark. Thanks

This being the case then youd only need to bond once from MET at origin or suitably EMT to any extraneous conductive part being gas, water, oil, structural steel,

 

[Richard Burns]

Main bonding in multiple occupancy buildings can be complex, especially if the services are shared between the flats.
Ideally all extraneous conductive parts should be bonded within each property. Each property having an earth marshaling terminal that will connect back to the MET at origin.

In your case the situation is complicated by the heating arrangement, however it is relevant to consider if the part is capable of introducing a different potential into the flat. Because upper floor flats will not be connected to earth it is only the introduction of differing potentials from other flats that are of concern.

I would have though that it would be best to check the bonding of the heating system at origin and consider the continuity of the heating system and the maintenance arrangements for the flats.
If the heating system is metal pipework and is main bonded at origin and is electrically continuous and the maintenance is undertaken by a central agency such that it is very likely that the continuity would be maintained then in this case the heating bonding within the flat could be a direct connection to the existing heating system which would then be securely connected to the entire metallic pipework run.
Heating and hot water should both be bonded back to the flat MET.

 

[bigspark17]

Main bonding in multiple occupancy buildings can be complex, especially if the services are shared between the flats.
Ideally all extraneous conductive parts should be bonded within each property. Each property having an earth marshaling terminal that will connect back to the MET at origin.

In your case the situation is complicated by the heating arrangement, however it is relevant to consider if the part is capable of introducing a different potential into the flat. Because upper floor flats will not be connected to earth it is only the introduction of differing potentials from other flats that are of concern.

I would have though that it would be best to check the bonding of the heating system at origin and consider the continuity of the heating system and the maintenance arrangements for the flats.
If the heating system is metal pipework and is main bonded at origin and is electrically continuous and the maintenance is undertaken by a central agency such that it is very likely that the continuity would be maintained then in this case the heating bonding within the flat could be a direct connection to the existing heating system which would then be securely connected to the entire metallic pipework run.
Heating and hot water should both be bonded back to the flat MET.

If there is only one DNO supply and one gas supply into the building and this was bonded back to MET via a suiable csa conductor within 600mm of entering building/isolator then i see no need to bond at each flat, (but would do no harm)

heating and hot water pipes would only give potential earth path via the boilers metalic incoming gas pipe or water pipe.

 

[Richard Burns]

It is the maintenance of an equipotential zone within the flat and the prevention of fault voltage from another flat appearing in this flat that become of concern rather than the introduction of earth potential into the flat.
I would tend to agree with you regarding the bonding but the regulations and guidance note 8 do not agree.