Bonding Radiators

[ban-all-sheds]

So if you have any metal work in a house that could possibly connect to true earth, it must be bonded to the neutral/earth path.

Surely that should be any metalwork which IS connected to earth, i.e. IS an e-c-p?

Shouldn't you test for that and then see if main equipotential bonding is needed rather than bond and see if the bonding worked?

In some houses it might be impossible that the central heating can come into contact with true earth, I'm thinking a completely wooden house and all the pipework securely fixed to the timber ie not extraneous. But you still have to ensure that it is ALL at neutral/earth potential.

What about a metal shelf bracket securely fixed to the timber, i.e. not extraneous - would you bond that?

My house has a concrete floor (true earth) and some of the pipes run in the screed ie they are extraneous.

You have bare copper pipes embedded in concrete?

And the same applies to any metal services or structure.

What about a metal door handle securely fixed to a wooden door, would you bond that?

And that is why in ANY building you bond all metalwork and then test to prove it is bonded. And thats what I have always done and will continue to do and as previuosly stated that is what every consiultant I have worked for specifies and contractors comply - and I assure you the larger contractors will not do anything unless they have to do

So what happens when you've bonded something which was not an extraneous-conductive-part, i.e. was not at local true earth, and then you get a neutral break, and your nearest PME tie-down is a little way off, so your installation earth is not at local true earth either. Have you not, by bonding, created a potential difference between some exposed metal and local true earth when if you hadn't bonded there would have been no PD?

 

[equitum]

If the piping is plastic you do not have to bond them.

If the piping is copper then link all the pipes around the boiler together using earth clamps and 4mm earth cable.

So I'm wrong.
All the electrical consultants I've worked for are wrong, and all the electrical contractors who did the installs are wrong.

I'll get on the phone tomorrow to let them know!

The reg definition of extraneous metalwork is crystal clear as is 413-02-02 - hope you never have to test your arguments for not earthing in a court - because you wil most definitely lose.

Did you phone them and let them know ?

As has been pointed out to you 413-02-02 is main bonding. You have become confused between this and supplementary bonding. A boiler does not require supp. bonding. Neither does a radiator, or other ECP or metalwork in a room other than one containing a bath tub or shower, or otherwise a special location.

 

[holmslaw]

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[equitum]

.....which is why a main bonding conductor connects the MET to all ECP of that installation such as the gas service pipe and the water service pipe.

 

[ban-all-sheds]

As previously stated, during a cable fault it is possible that your pme earth path is broken and becomes connected to true earth.

True earth where?

This could cause voltage to appear on your pme earth inside the house and a potential difference with any supposely unearthed metal work.

Or. if you've bonded metal that wasn't an e-c-p, between that metal and the true earth that surrounds it.

Putting it another way their methods are based on what could happen, your methods are based on what hopefully will not happen.

So what happens to an exposed metal item which was not an e-c-p when you've connected it to a broken PME earth path?

I've ignored your most ridiculous comments re door handles etc.

Fine.

Now consider them again and explain the difference between a door handle and a radiator which is not an extraneous-conductive-path.

 

[holmslaw]

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[RF Lighting]

What are you testing the resistange of the metalwork to?

The MET or any other random adjacent piece of metalwork?

What about a kitchen sink? Do you still cross bond that?

What about a stainless steel kitchen cabinet?

 

[ban-all-sheds]

There's not much point in this, I'm not one for arguing with people who refuse to see someone elses point of view. My previous posts clearly demonstrate my point of view, but you don't respond to the bits you don't like or understand eg why do consultants specify my way?

I do see your POV, but I could just as easily say to you that you haven't responded to my questions about what happens if you bond something metal that is not an e-c-p. The example of the door handle was to make the point that you can easily have lumps of metal that are not e-c-ps, and I question whether they should be bonded just in case they are.

As for what consultants specify, I wouldn't know, but I do know that I've never seen anybody here suggest that you have to run main equipotential bonding conductors to every radiator in the property.

To-day, I checked the cibse and bsria guides and they both agree with my stance, as of course do the regs.

The regs, AFAIK, say that you have to apply main equipotential bonding to exposed conductive parts where they enter the equipotential zone, not at every point within the zone where they exist.

So let me ask you do you carry out any earth continuity checks on metallic services/structure in a building, and what do you do if you find a high reading, say above 0.5ohms.

Not much point asking me that....

 

[holmslaw]

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[holmslaw]

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[RF Lighting]

Now you see this is where I'm getting confused.

You say you would bond a metal kitchen cabinet. This is a piece of metal which is screwed to a studwork wall (a piece of wood), and in no way what-so-ever in contact with earth of any sort, and it is never going to introduce a potential.

Yet you dismissed BASs comment about bonding a door handle which is also a piece of metal which is screwed to a piece of wood, and in no way what-so-ever in contact with earth of any sort, and it is never going to introduce a potential as being flippant.

Where do you draw the line then?

Would you bond a metal carpet edging strip if it were screwed into concrete?

 

[holmslaw]

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[sm1thson]

No you probably wouldn't earth it

Probably? I how about definitely! and you definitely wouldn't bond it either!

grasping the reasons for bonding can be a pain, especially when you already have preconceptions as to why it is there and why everybody else has been doing it, but really holmslaw you need to forget everything you have ever thought about bonding and start from scratch.

sorry to chip in like that but this thread has been bugging me as i have watch it grow.

 

[holmslaw]

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[sm1thson]

no I am another one that thinks you are wrong and that you have probably misunderstood what consultants, cibse and bsria have been doing with bits of yellow and green wire. Anyway I have said my bit I will sit back too many cooks spoil the broth and all that.