Supplementary Equipotential Bonding Q

[John D v2.0]

Here is a better solution for you

 

[bernardgreen]

it's the only reasonable thing to do given an existing ecp.

The regulations seem to assume there will be an extraneous ( and harmful ) potential on every incoming gas and / or water supply pipe. With plastic mains there may be an extraneous potential but the electrical impedance of the plastic pipe means the current that can flow is far below anything that could be harnfull.

 

[John D v2.0]

Plastic is not an extraneous CONDUCTIVE part ie below approx 20k ohm

 

[ban-all-sheds]

We should all bear in mind that none of Chapter 54 needs to be considered unless there is an e-c-p .

If downstream of a meter is not an e-c-p then it does not need bonding, and what 544.1.2 says is irrelevant.

If upstream of a meter is an e-c-p, and that meter is not in the way at the point where you would attach the MPB then 544.1.2 does not apply.

 

[EFLImpudence]

We should all bear in mind that none of Chapter 54 needs to be considered unless there is an e-c-p .
If downstream of a meter is not an e-c-p then it does not need bonding, and what 544.1.2 says is irrelevant.

Ok, so far.

If upstream of a meter is an e-c-p, and that meter is not in the way at the point where you would attach the MPB then 544.1.2 does not apply.

...but it says that IF there is an insulating section in that e-c-p then the bond must be connected to the part which is NOT an e-c-p - or at least NOT to the part which is an e-c-p.

If what you say is correct then what does that sentence of 544.1.2 mean and/or relate to?

 

[ban-all-sheds]

I was taking it to mean that if there was something in the way at the point as near as practicable to the point of entry where you would want to attach the bond...

 

[JohnW2]

OK but that means it is also Earthed, so we now have taps that are earthed ( and possibly the stainless steel sink they are fitted in ) thus making them "hazardous" to anyone touching them while also in contact with an item that, due to a fault in that item, is Live. ... If the taps were not earthed then they could not enable current to flow when touched.

This appears to be the opposite of what you usually say (thing metal baths etc.), and precisely the point that the likes of EFLI and myself frequently make.

We are not supposed to earth or bond metal sinks to reduce the risk of a shock, yet they can be connected to earth via the bonds fitted to the incoming pipe work to prevent the extraneous "Earth" potential being imported into the building via the water supply pipe.

There is no prohibition of earthing or bonding things which don't require it, even if there is an argument that, in the interests of safety, it is preferable not to. 'Incidentally' earthed things (i.e. extraneous-c-ps) are a fact of life, and unavoidable unless one puts insulating inserts into them where they enter the property, so all one can then do is to bond them so that at least the inside of the building is more-or-less an equipotential zone. In such a situation, one can do nothing to remove the hazard which is created by the touchable earthed metal (as a 'second point of contact' for someone also touching something live).

In practice, of course, in this day and age, virtually all all-metal pipework will be earthed via attached appliances and equipment, whether one likes it or not.

Kind Regards, John

 

[JohnW2]

If upstream of a meter is an e-c-p, and that meter is not in the way at the point where you would attach the MPB then 544.1.2 does not apply.

Look carefully at the punctuation of 544.1.2.

Kind Regards, John