bonding across plastic pipe joint, instead of supplementary bond

[1Justin]

New shaver socket outside zone in bathroom. (FCU outside the room,17th ed'n board).
Checking the bathroom to see if any supplementary bonding needed, turned out the sink and bath taps were hovering at about 5K Ohm (ie >1667 and < 22K).

Turns out the owner had interrupted the hot and cold Cu pipes with single push-fittings in the loft, and that was the source. (Main equipotential bonding was very effective before then, rest of the house all in Cu). So Supplementary bonding required in bathroom, but this would have been VERY disruptive, and customer wouldn't take it on.

Easy however to bond across the two plastic joints in the attic with 10mm strap and clamps. Nice and neat, very effective and safely out of the way. Bathroom taps are no longer Extraneous, at a small fraction of an ohm.

So technically I don't see this as any different to what I might have found had the plastic parts not been there, and (just say) a compression joint had provided a low enough resistance. I'd have measured it, then been none the wiser and equally wouldn't have fitted any Supplementary bonding.

Where do I sit with this re 701.415.2? Part Vi just says "effectively connected", which it is. - but it's not supplementary bonding.

Chasing walls/tiles off etc to get the cable in wasn't going to happen.

Might I record this as a departure, and get on with things?

 

[Geoffsd]

New shaver socket outside zone in bathroom. (FCU outside the room,17th ed'n board).
Checking the bathroom to see if any supplementary bonding needed, turned out the sink and bath taps were hovering at about 5K Ohm (ie >1667 and < 22K).

Turns out the owner had interrupted the hot and cold Cu pipes with single push-fittings in the loft, and that was the source. (Main equipotential bonding was very effective before then, rest of the house all in Cu). So Supplementary bonding required in bathroom, but this would have been VERY disruptive, and customer wouldn't take it on.

It does not affect the Main Bonding either way.
Supplementary Bonding doesn't have to be IN the bathroom as long as it bonds parts which are.

Easy however to bond across the two plastic joints in the attic with 10mm strap and clamps. Nice and neat, very effective and safely out of the way. Bathroom taps are no longer Extraneous, at a small fraction of an ohm.

They are still extraneous but now effectively bonded.
You didn't need 10mm.

So technically I don't see this as any different to what I might have found had the plastic parts not been there, and (just say) a compression joint had provided a low enough resistance. I'd have measured it, then been none the wiser and equally wouldn't have fitted any Supplementary bonding.

They may be now effectively connected to the MET (if <50/Ia) but have you checked that the measurements between parts and between parts and CPCs are also less than 50/Ia?

Where do I sit with this re 701.415.2? Part Vi just says "effectively connected", which it is. - but it's not supplementary bonding.

Yes it is.

Might I record this as a departure, and get on with things?

No, it does not affect the Main Bonding requirement.

 

[Geoffsd]

Just to add for clarification -

As far as Main Bonding is concerned, it does not matter what happens within the premises.

Because it is a bathroom, Supplementary Bonding may be required to ensure there is no (or the allowed maximum) potential difference between simultaneously accessible extraneous and exposed parts - 50/Ia.

You may have been able to achieve the same result by connecting the pipe to another which did not have a plastic joint but it's the same difference.

 

[1Justin]

• Where do I sit with this re 701.415.2? Part Vi just says "effectively connected", which it is. - but it's not supplementary bonding.
  ​

Yes it is.

Hmm, but this bonding strap doesn't connect to local CPC of "Each Circuit" (except via the MET via main bonding where it does connect then to all circuits). This is why I would hesitate to call it "Supplementary Bonding". It is nonetheless "Effective" (as might have been a plumbing compression joint in the same location).
(BTW between parts and to local CPC all now very solid and low resistance)

 

[Geoffsd]

Hmm, but this bonding strap doesn't connect to local CPC of "Each Circuit"

If the results are that it is now satisfactorily (supplementery) bonded, then it does.
Other parts - pipes and CPCs can be used as the supplementary bonding conductors.
You don't have to individually connect each extraneous and exposed part and CPC to every other extraneous and exposed part and CPC (lots of stars) - just connect them together (ring).
So this pipe entering the bathroom with unsatisfactory connection to earth could have been made satisfactory by connecting it to other parts.
You achieved the result by bridging the plastic joint which is fine.

(except via the MET via main bonding where it does connect then to all circuits).

Then it does which is acceptable.

This is why I would hesitate to call it "Supplementary Bonding". It is nonetheless "Effective" (as might have been a plumbing compression joint in the same location).

But it is Supplementary Bonding because you did it to ensure satisfactory bonding in the bathroom.
If it were not a bathroom, you wouldn't even have tested it and it wouldn't matter.

The pipe is Main Bonded where it enters the premises - no more Main Bonding (10mm to the MET) is required inside the premises.

If it had been a compression joint then perhaps Supplementary Bonding would not be required at all because the pipe was the conductor.
Certainly no more Main Bonding would be required.

(BTW between parts and to local CPC all now very solid and low resistance)

Good, so mission accomplished.

Just a confusion in terms.