Lack of supplementary bonding - what’s the danger ?

[Harry Bloomfield]

Why ? Do you doubt the conductivity of the copper ?

Because someone might at some point disconnect the pipe, and/or introduce a section of plastic pipe.

There have always been two schools of thought where this issue is concerned - Everything earth bonded, or everything fully insulated. The latter is unachievable, so I like to be sure that as much as possible is well bonded.

 

[equitum]

Well if a section of plastic is introduced in the pipe work it is no longer extraneous and would be better not bonded, so your logic is somewhat floored here ?

 

[equitum]

Well if a section of plastic is introduced in the pipe work it is no longer extraneous and would be better not bonded, so your logic is somewhat floored here

 

[Harry Bloomfield]

Well if a section of plastic is introduced in the pipe work it is no longer extraneous and would be better not bonded, so your logic is somewhat floored here ?

Really?

You have a copper pipe appearing at the washbasin, feeding the cold tap, which is isolated be a section of introduced plastic pipe. Under the floor, that section of pipe, accidently makes contact with a live cable. The tap on the wash basin is now live. Someone walks in turns the tap on whilst also turning the hot tap which is still connected to earth.

How would not being bonded help?

 

[EFLImpudence]

Really?

Yes.

You have a copper pipe appearing at the washbasin, feeding the cold tap, which is isolated be a section of introduced plastic pipe. Under the floor, that section of pipe, accidently makes contact with a live cable. The tap on the wash basin is now live. Someone walks in turns the tap on whilst also turning the hot tap which is still connected to earth.

That is not a consideration regarding bonding.

If you think that is likely to happen then the pipe would be considered an exposed-c-p and should be earthed rather than bonded.

 

[EFLImpudence]

There is a lot of confusing and irrelevant information in the replies in this thread.

I would advise the OP to search for "touch voltage" to answer the actual original question.

 

[Harry Bloomfield]

Yes.

We've had this discussion before. My opinion has not and will not change..

 

[EFLImpudence]

We've had this discussion before. My opinion has not and will not change..

Then you are still and will be wrong.

 

[equitum]

There is a lot of confusing and irrelevant information in the replies in this thread.

I would advise the OP to search for "touch voltage" to answer the actual original question.

I’m aware of what touch voltages are. Please read my original post. Please explain why supp. Bonding in an adjacent room or cupboard for example has any significant benefit to that of the main bonding and cpcs connected together in a consumer unit

 

[equitum]

Yes.

That is not a consideration regarding bonding.

If you think that is likely to happen then the pipe would be considered an exposed-c-p and should be earthed rather than bonded.

That is incorrect - a section of metal pipe which is insulated from earth does not form part of the electrical installation and therefore cannot be an exposed conductive part

 

[EFLImpudence]

That is incorrect - a section of metal pipe which is insulated from earth does not form part of the electrical installation and therefore cannot be an exposed conductive part

I agree it is NOT an exposed-c-p but Harry thinks you must consider it becoming live by being touched by a live wire which is what makes parts exposed-c-ps.

 

[equitum]

Really?

You have a copper pipe appearing at the washbasin, feeding the cold tap, which is isolated be a section of introduced plastic pipe. Under the floor, that section of pipe, accidently makes contact with a live cable. The tap on the wash basin is now live. Someone walks in turns the tap on whilst also turning the hot tap which is still connected to earth.

How would not being bonded help?

By connecting metal items that do not form part of the electrical installation or are not extraneous conductive parts to earth your are introducing voltage potentials under non fault conditions. Woukd you/have you also bonded your window frames , kitchen sink , metal fire surround etc etc ?

 

[EFLImpudence]

I’m aware of what touch voltages are.

But that is what you are asking about and why/how they are negated by supplementary bonding.

Please read my original post. Please explain why supp. Bonding in an adjacent room or cupboard for example has any significant benefit to that of the main bonding and cpcs connected together in a consumer unit

Because the only way to negate/reduce touch voltage is to join the parts by supplementary bonding.

During a fault with a high current flowing in, say, one CPC, does not mean that all earthed and bonded parts are at the same potential.

 

[Harry Bloomfield]

By connecting metal items that do not form part of the electrical installation or are not extraneous conductive parts to earth your are introducing voltage potentials under non fault conditions. Woukd you/have you also bonded your window frames , kitchen sink , metal fire surround etc etc ?

Yes, anything which had the potential to accidentally live.

 

[equitum]

But that is what you are asking about and why/how they are negated by supplementary bonding.

Because my question is, I’d like to know a scenario where touch voltage is going to exceed let’s say 50 V main bonding is in place and all circuits in the location have a CPC