main bonding to external boiler.

[sparkygg]

This is my first post and hoping someone can help?

Just wired an external combi oil boiler. I ran a 10mm bond from CU to the incoming pipes which are all 22mm and 28mm copper. They come through the wall from outside and I have put an earth bonding clamp on each pipe and looped the bond between them all. Now I am not sure if I should have run the bond out to the oil line entering the boiler? It comes through the ground for 20m or so and pops up just beside the boiler which is mounted on a paving slab plinth. The oil pipe doesn't enter the building and as i said any metal pipes which do are now bonded. The incoming water is in blue polypipe and is bonded where it turns to copper further into the installation. What should I have bonded? I am confused!

Any guidance would be appreciated.

 

[Q.S.]

Wirepuller is correct - your equipotential zone is within the house, you do not want to make it any bigger, or you can get to the stage where you put a potential where there is no need for one.
It is always correct to bond at point of entry to the building(s) and if it does not come into to the building leave it alone.

 

[Engineer54]

I'll take issue with this.
It is not possible to have an 'equipotential zone ' in an external situation...(such as surrounding an external boiler).....in such a situation the boiler is surrounded by the general mass of earth so it would be pointless trying to create an equipotential zone by bonding the oil line.
The equipotential zone is in the building , and the heating pipes coming from the boiler introduce an earth potential...(possibly from the oil line)....therefore it is correct to main bond the heating points at the point of entry.

Maybe i didn't read the OP's post too well!! lol!! I was under the impression that the boiler was situated/located within an external outbuilding of some kind, or even an outside cupboard type affair that is within the house boundaries but only accessible externally. Can't say i've ever seen an outside/externally mounted combi boiler, so never considered such an installation.

So if this is indeed the case, Yes your correct in what your saying above...

 

[Deleted member 9648]

To my mind, if the oil pipe is considered an extraneous-conductive-part, it will require bonding.
If the boiler is within the building, the oil pipe will require bonding as close as practicable to where it enters the building, preferably within 600mm.
If the boiler is in another building, then it may be that it should be treated as a separate installation, and will require it's own earthing and bonding arrangements (i.e. TT).
In any event the oil pipe should be bonded.

I disagree......if it's in an external situation it is impossible to create an equipotential zone,thats the whole point of bonding. If the boiler is completely external the potential from an oil line will be introduced to the equipotential zone via the heating flow/return....they will need bonding at the point of entry to the building.

@E54.......external stand-alone boilers are quite common around here...and I always bond incoming pipes at the point of entry to the building.

 

[Engineer54]

@E54.......external stand-alone boilers are quite common around here...and I always bond incoming pipes at the point of entry to the building.

That's fine wirepuller, it's just that i've personally never seen them, so didn't consider such an installation/situation in my reply/post!! I would still earth any metal oil tank and/or pipes though, if only for tanker equalisation filling purposes.

 

[Q.S.]

ERRRHHH NO - The tanker will if necessary earth to the tank , how ever if you have earth leakage (parallel paths and all that) from any electronic equipment or a low fault you will be putting a potential into the tank which may or may not cause a problem.

 

[Engineer54]

Every filling station, commercial or private that i have been involved with (and their have been many) had the fuel tanks earthed via Rod mat or other form of electrodes connected to both the tanks and a common reel lead position ( a statutory requirement in most of the countries i've worked within).

Because the reel lead is connected between the tanker and the underground tanks first, before any filling pipes are connected, both the tanker and tanks will be at the same potential!! It doesn't matter if the reel lead is mounted on the tanker or the installation being filled...

 

[Knobhead]

Not really relevant in this situation but every tanker discharge/loading point I’ve dealt with would have the static equalisation point fitted. In our case we were dealing with granulated or powdered product. Where the danger is after the pipe is connected and the product is travelling through causing some nasty static build up.