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Topic Title: Main Bonding In Commercial/Industrial Premises
Topic Summary: 2 Points of Entry Into Building
Created On: 04 July 2013 04:13 PM
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 04 July 2013 04:13 PM
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rougediablo

Posts: 112
Joined: 09 November 2011

Premises has a single gas meter with the supply running under ground (plastic pipe) to a single large(ish) building. The common gas supply enters the building in steel pipe at 2 different points (1st is 1 1/2" & the 2nd 3") but is only bonded (35mm2) at the largest one. There is no common connection between the gas pipe within the installation. The smaller supplies a larger conventional wet system boiler & the bigger supplies gas fired heaters etc for all the rest of the premises.

The bond is high up (so more than 600mm from point of entry) & after a branch in the pipe work. It would have been practicable to bond lower down so not sure why it wasn't.

1 Should both points of entry be bonded?
2 Would this be a C3?
3 Is it acceptable to extend the existing 35mm cable using a crimped connection to pick up the 3" pipe lower down & then continue on to the small pipe entry point thereby creating a single "technically" unbroken conductor?

Edited: 04 July 2013 at 04:23 PM by rougediablo
 04 July 2013 05:06 PM
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OMS

Posts: 19551
Joined: 23 March 2004

1 Should both points of entry be bonded?

Yes

2 Would this be a C3?

C2 in my book

3 Is it acceptable to extend the existing 35mm cable using a crimped connection to pick up the 3" pipe lower down & then continue on to the small pipe entry point thereby creating a single "technically" unbroken conductor?

Of course it's OK - you could connect them together via the building steel frame (if present) or any other suitable pipework if you don't fancy running cable


Regards

OMS

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Failure is always an option
 04 July 2013 05:12 PM
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AJJewsbury

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If the external buried pipe is plastic, I wonder how extraneous the unbonded pipe is.....
- Andy.
 04 July 2013 05:55 PM
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OMS

Posts: 19551
Joined: 23 March 2004

The common gas supply enters the building in steel pipe at 2 different points


Probably just enough to be dangerous I suspect, Andy - although it will depend on where the transition from plastic to steel takes place

Regards

OMS

-------------------------
Failure is always an option
 04 July 2013 09:54 PM
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UKPN

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in one building? only one bond reqd. not within 600? perhaps its as near as practical?

in any event, bolted lugs not permitted, as are not bits of pipe/steelwork
to connect other services.

Regards.

consultants? we look after them.
 04 July 2013 10:30 PM
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Fm

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Originally posted by: UKPN

in one building? only one bond reqd. not within 600? perhaps its as near as practical?



in any event, bolted lugs not permitted, as are not bits of pipe/steelwork

to connect other services.

have a read of gn8


Regards.



consultants? we look after them.
 05 July 2013 09:08 AM
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rougediablo

Posts: 112
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Originally posted by: OMS

you could connect them together via the building steel frame (if present) or any other suitable pipework if you don't fancy running cable



Never thought of that, sometimes an easy solution doesn't always spring to mind!

Regards
 05 July 2013 09:10 AM
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rougediablo

Posts: 112
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Originally posted by: UKPN

not within 600? perhaps its as near as practical?

Not really, it just needed another 3-4m of cable.


Edited: 05 July 2013 at 09:54 AM by rougediablo
 05 July 2013 09:39 AM
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OMS

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Originally posted by: UKPN

in one building? only one bond reqd. not within 600? perhaps its as near as practical?

Ohhh dear me - I know your not a fan of BS 7671 but perhaps you migjht have a browse at regulation 411.3.1.2, with the understanding that it's the extraneous service we are concerned with - if it has multiple points of entry, then it requires multiple points of bonding - ie at each intake location. You could then perhaps have a look at 544.1.2




in any event, bolted lugs not permitted, as are not bits of pipe/steelwork

to connect other services.

Ohh dear, ohh dear ohh dear - you really don't understand this do you.

Would you like to point out to me where bolted lugs are not permitted - and have you not read, and understood, Regulations 543.2.2 and 543.2.6



Regards.



consultants? we look after them.

Of course you do, you demonstrate it every time you post.


Regards

OMS

-------------------------
Failure is always an option
 05 July 2013 05:52 PM
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UKPN

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we are talking industrial and commercial.
supplementary bonding, which is what is being discussed here
ie onto one pipe etc and then to another, is usual in domestics.
we would expect a copper earth bar with insulators, with link for the earth lead for testing, and equipotential bonds identified on the bar, water, oil, gas, steel, air con, compressed air, i could go on, for this project.
the notion that one wire strung from service to service and the roof all likely to come loose in time is amusing.

Regards.

GNs?
 05 July 2013 06:10 PM
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OMS

Posts: 19551
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Originally posted by: UKPN

we are talking industrial and commercial.

Yes I know.

supplementary bonding, which is what is being discussed here

ie onto one pipe etc and then to another, is usual in domestics.

I beg to differ - we are clearly discussing main equipotential bonding of multiple inlet points of extraneous services into the building.


we would expect a copper earth bar with insulators, with link for the earth lead for testing, and equipotential bonds identified on the bar, water, oil, gas, steel, air con, compressed air, i could go on, for this project.

Would there be lugs on the end of those cables ? - like the ones on the ends of the cables I've just designed for one of your transformer bases (earth bar in the pit, before you ask, not left dangling 600mm above the grillage as you also seem to accept on your drawing for Unit/Package substation with standard plinth detail and GRP enclosure ) - and the drawing for the re bar connections looks supiciously like it has lugs on the bare copper tails to me

I think I might just have worked out how to deal with system earthing, LPS earthing and bonding in a commercial or industrial building


the notion that one wire strung from service to service and the roof all likely to come loose in time is amusing.

Amusing to you maybe - bit it's only funny if you don't understand it - using structural members, or other extraneous parts to act as bonding conductor is a perfectly valid, acceptable and BS 7671 compliant solution - I think it was you who mentioned "strung" not me. Read the regulations "particularly the bits that say "considerd for such use" and "subject to precautions aginst removal" - that doesn't suggest "strung" from the roof or likely to come loose in time to me - does it to you

Regards.

GNs?


Back to the bolted lugs - who says they are not permitted - and if not permitted, how do you expect to terminate conductors to an earth bar or to the service - or are you just waffling

Use of steelwork or other services - which bit of that don't you understand - or are you one of those nutters who insists on clipping a 25mm2 bit of copper to a significant steel member for tens or hundreds of metres inside a building to get to say the gas intake, without recognising that a bond to the steel work at one end and a bond from the steel work to the gas the other end is perfectly acceptable and quite normal engineering practice. If, by analysis, it's good enough for LPS, it'll be more than good enough for a bit of bonding - trust me on that one - I'm a consultant

Best Regards

OMS

-------------------------
Failure is always an option

Edited: 05 July 2013 at 06:16 PM by OMS
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