Replacement of lead water supply pipe with plastic - bonding

[ban-all-sheds]

It's just a word.

Don't be so precious over words.

Are you David Cockburn?

 

[bernardgreen]

Why not remove as much of the lead pipe as possible and trade it in at a scrap metal dealers.

If you leave it in place then it needs to be bonded to the main "earth" terminal in case the pipe brings true earth potential into the property when the pseudo "earth" potential of the main earth terminal is not at true earth potential. The bond will ensure that the pipe and the "earth" wiring are kept at the same potential. This can involve the bonding cable carrying quite high currents. The extreme is a PME installation when there is a network fault ( open circuit neutral ) and the lead pipe is metallic to a metallic main with extremely low impedance to the neutral at the sub station

So my opinion is to remove the pipe to the point that it cannot be considered as possibly introducing true earth into the house. Cutting it level with or just below ground level so it cannot be touched.

 

[SaladFingers]

It's just a word.

Don't be so precious over words.

Are you David Cockburn?

No, I'm Salad Fingers.

 

[bernardgreen]

Was this a burnt earth wire due to extremely high currents in bonds between a neutral derived "earth" and a low impedance extraneous conductive part when a fault occured in the local network ?

Untitled

• bernardgreen
• 15 Feb 2013
• 1

//www.diynot.com/forums/electrics/should-i-contact-my-dno.353050/#2656704

 

[EFLImpudence]

I assume 544.1.2 states what it does is because the disconnection for testing is not going to be done and the regulations still consider that the pipe may be liable to introduce a potential because it is still connected to all of the above mentioned parts.

If anyone else thinks differently perhaps they will say. i'm sure they will

Can anyone clarify with certainty why 544.1.2 states that, even if there is an insulating section, the bonding should still be connected to the insulated side of the pipework and not the part which is still in the ground?

I assume this would still be the case if all the services had insulated sections.

 

[bernardgreen]

Bonding on the outside side of the isolation section would be in-effective in bonding the internal pipe work. It also means the bonding is protected from having to carry high currents coming in from the service pipe during fault condtions.

Interesting that bonding cable cross sectional area is determined by the cross sectional area of the incoming and un-fused neutral conductor

Table 54.8
Minimum CSA of the main Protective bonding
conductor in relation to the neutral of the supply

 

[ricicle]

but without going to in-depth discussions with the op about why MPB is carried out and why it may not need doing I advised him to do what 99% of electricians would do who don't have an ounce of engineering judgement.

Says it all, really, doesn't it.

Excuse me ?

 

[EFLImpudence]

As no one has answered my question regarding 544.1.2 I shall assume no one knows.

So -

544.1.2

Which talks about main bonding to services entering the building, not metallic parts running through the building.

But it does when there is an 'insulating section'.

It is still connected to -
boiler inc. cpcs., CH inc. valves inc. cpcs., gas pipe inc. bonding, MET,

So basically you want a self-fulfilling prophecy.

Pragmatism.

If it's only "earthed" because you connect a cpc to it then intrinsically it is not an extraneous-conductive-part.

True, but as it cannot, without total disconnection which will not be done, be determined that it is NOT extraneous I assume the powers that be consider it could still be liable to introduce a potential if the complete run of the pipe cannot be verified.

consider it supplementary bonding.

But we aren't talking about supplementary bonding, and there is no indication that this location requires it.

Agreed, but I only said that to facilitate picturing its purpose.

It will be <22k&#937;.

And why would that be?

Because it is connected to various equipment and CPCs.
Therefore main bonding, whether required or not, will not be detrimental and may unknowingly be required.

In order to establish if the water service were not now an extraneous conductive part it would be necessary to disconnect it from all of the above mentioned parts to test.

Indeed you would, for it cannot be an e-c-p if you've connected it to the electrical installation.

Does that reasoning not preclude all pipework from being an e-c-p?
Conversely, is there not a difference between connecting a pipe to the installation and the pipe forming part of the installation?

I assume 544.1.2 states what it does is because the disconnection for testing is not going to be done and the regulations still consider that the pipe may be liable to introduce a potential because it is still connected to all of the above mentioned parts.

How can it be considered to be introducing a potential when what you've done is to connect it to the electrical installation which by definition it must not be part of for it to be an e-c-p?

Badly worded.
I assume 544.1.2 states what it does is because (THOUGH it is still connected to all of the above mentioned parts and the disconnection for testing is not going to be done) the regulations still consider that the pipe may be liable to introduce a potential.

That is not a consideration for main bonding.

So first you want a self-fulfilling prophecy, and then you want it both ways.

In a way, both apply because of the situation.

Either way - 544.1.2 says to connect the bonding.

No it doesn't.

Do you mean the considerations for a plastic supply and an insulating section are different when it is not possible to verify that a pipe is definitely NOT extraneous?