lead water supply, but straight to plastic - bonding?

[John McLean]

I don't make the law, this is an irresponsible statement.

Regards

[John McLean]

Definition of Fortuitous: -

1 Occurring by chance 2 Fortunate, Lucky

This is not relevant for a designed feature.

Regards

[Richard Conway]

What does the onsite guide specify to be done in a mixed environment? Our water supply changes to plastic shortly after the stopcock (so should presumably be bonded just after the stopcock before it changes to plastic). The plastic pipe then goes straight up to the loft where a plastic branch serves the header tanks and a copper branch comes back down to the first floor and feeds the rest of the house via copper.

Would a bond be required between the initial bonding at the stopcock and the point in the loft where the plastic changes to copper?

[John Rumm]

That was *exactly* my point.

Main equipotential bonding is just that. It purpose is not to enhance the earth loop impedance, it it there to provide an equipotential bond. The fact that in some cases it *may* provide a collective impedance reduction is fortuitous, but not a design aim.

The main earth connection should be tested in isolation with any equipotential bonds disconnected at the main earthing block so as to eliminate any fortuitous benefit that is offered by these bonds. Circuit design ought to be carried out using the impedance of the main earth as a reference, and not take into account any reduction gained by these other parallel connections which are far more likely to be accidentally or unwittingly disconnected.

[John Rumm]

Yes that is right - close to the stopcock on "your" side of it.

(having said that I am not sure which stopcock they count if like many places you have two - one in the garden and another one in the house).

Not explicitly (although by bonding the CPCs of circuits feeding "special locations" you would ultimately achieve this by a roundabout route). You would also want supplimentary equipotential bonds in the usual places.