eicr flats bonding situation

[Welchyboy]

I am undertaking an eicr on 20 odd blocks of flats and would like people's opinion on this set up

The blocks are separated be about 30-40 meters apart, each in a typical square shape with stairs in the centre

Have external stairwell areas only, a ground floor and 2 other storys on top, each block has 6 flats, 3 on each side of the stairwells

The supplies/meters for the flats are in flush mounted meter cabinets at the bottom of the stairs
1x TPN 60a PME supply for each side, one phase per flat

I'm only testing the landlords supply!

This is supplied by one meter in a block to a small c.u. Then has 2x 2.5mm SWA sub mains to 2 other blocks each, so one meter supplies 3x landlords blocks, these are in small cupboards on each Block around 600mmx400mm

now I'm happy with most things apart from the fact that each flats water supply comes through this cupboard with the small cu in it

The water incoming is plastic but out going to the flats is copper

If the flats are bonded back to their local supply then the exposed copper
In this small cupboard will bring in a
Different earth potential which is simultaneously accessible to the mini cu earth fed from the PME from the other block


What action would you take if you found this

I know it's long winded, sorry just wanted to give a good picture of the situation

 

[malcolmsanford]

To get an handle on this WB you have each block with it's own individual water supply which is plastic. Then after the stop cock/valve inside the block the installation to the 6 flats are done in copper?

So I would assume that the first piece of copper pipe after the plastic is the main branch in what 32/40MM and then it 'T's into each flat in what 22mm

So is that main branch (32/40mm) bonded? Is the 'T' once it enters into the flat bonded to the CU in flat? Where do you think this copper installation is getting it's potential from if the incomer is plastic? Is the stairwells Metal? Is the construction pre-cast/concrete?

 

[Welchyboy]

Hey malcomsford hope this makes things a little clearer

Each flat has an individual 22mm PVC about 1ft long from the floor to 15mm copper then stop cock then water meter then up into cavity into each of 3 flats

I believe the earth potential will be from the local PME supplying the flats, the pipe work will/should be bonded back to this inside the flats

The landlords cu, next to all the pipework in the cupboard outside is supplied via a PME supply from another block

so a potential difference should exist between the pipe work and the landlords supply and cu

I am considering binding the pipe work to the cu and back to the local PME but wanted other opinions first

 

[Engineer54]

Bond the exposed copper pipe to the landlords CU in each of the buildings. These copper pipes will probably be earthy from the buildings they are run in, especially if passing through, or run in floor slabs/columns etc...

When talking about concrete framed/constructed blocks of flat's, it doesn't matter if the incoming water supply is plastic, all flats metal water supply pipes should be bonded back to the flat's CU.