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Topic Title: Main Protective Bonding of Plastic Services - with internal metal
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Created On: 11 February 2013 08:14 PM
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 13 February 2013 11:33 AM
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AJJewsbury

Posts: 11288
Joined: 13 August 2003

and another thing! 0.05, was a figure in a previous GN book, that for some
reason disappeared overnight,

It hasn't disappeared (and certainly not over night - the changes took months!) - it's just the that wording was (hopefully) changed to try and make it clearer that the 0.05 Ohms referred to a connection, rather than the length of the bonding conductor. Or if you prefer - if you measured 0.05 Ohms or less, you can take it that the bond is sound without further ado; if you measure more you're going to have to think about it a bit and perhaps do a bit of calculation to check.

- Andy.
 13 February 2013 11:46 AM
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UKPN

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perhaps they will now make the 22k/10ma "clearer"!

until then, we in the supply industry will stick to the official rules.

Regards
 13 February 2013 12:07 PM
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rocknroll

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until then, we in the supply industry will stick to the official rules.


So what do your 'official rules' state?

regards

-------------------------
"Take nothing but a picture,
leave nothing but footprints!"
-------------------------
"Oh! The drama of it all."
-------------------------
"You can throw all the philosophy you like at the problem, but at the end of the day it's just basic electrical theory!"
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 13 February 2013 12:47 PM
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AJJewsbury

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perhaps they will now make the 22k/10ma "clearer"!

What's unclear about it? It's been in GN8 for a long time now.

until then, we in the supply industry will stick to the official rules.

I thought the law says you need to accept BS 7671 as definitive for the safety of installations?

- Andy.
 13 February 2013 01:25 PM
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Parsley

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It's the designer's responsibility to decide what value is acceptable.

22K 10ma is probably ok for domestic installs, but other types of installation may require higher Rcp and lower ma values depending on the risk.

Regards
 13 February 2013 11:20 PM
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OMS

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Joined: 23 March 2004

Originally posted by: UKPN

perhaps they will now make the 22k/10ma "clearer"!

until then, we in the supply industry will stick to the official rules.

Regards


What official rules - there is nothing in any of the earthing manuals that requires bonding of metallic parts that are not extraneous.

From your document, EDS 06-0017 - Customer Installation Earthing Design

Equipotential Bonding
An electrical connection maintaining various exposed conductive parts and extraneous conductive parts at substantially the same potential (voltage).


Note reference to extraneous and exposed conductive parts !

And the definition of extraneous conductive part:

Extraneous Conductive Part
A conductive part (metalwork) liable to introduce a potential (voltage), generally earth potential, into the site but not forming part of the electrical installation, e.g. pipework, scaffolding etc.


Note the refernce to "liable to introduce a potential"

and then from table 2:

At customer's premises the main bonding conductor between the main earthing terminal and all metal structures, metal pipes and other extraneous conductive parts - Refer to BS 7671:2008 Table 54.8


Note the reference to BS 7671, table 54.8


So if you think that tells you that bonding of plastic services is required than I simply can't see it - would you care to point it out ?

Regards

OMS

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Failure is always an option
 05 March 2013 08:13 PM
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UKPN

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"complete bloody nonsense"

IEE 15th ed 547-3 refers

Regards

Edited: 05 March 2013 at 09:54 PM by UKPN
 05 March 2013 09:43 PM
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AJJewsbury

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"complete bloody nonsense"

IEE 15th ed 547-2 refers

Blimey, you don't half dredge up some history - the 15th has been out of date since 1991!

If you're referring to the note suggesting that the supply undertaking be consulted - you will note that refers only to the size of protective conductors - not what should be bonded. Even in the 15th (reg 413-2) - the requirement is to bond "extraneous-conductive-parts" - and the definition of an extraneous-conductive-part is identical to the current (17th Ed) wiring regs.

Of course that note disappeared from later editions where the table for PME bonding conductors (currently 54.8) was introduced.

- Andy.
 06 March 2013 09:08 AM
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OMS

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Originally posted by: UKPN

"complete bloody nonsense"

IEE 15th ed 547-3 refers

Regards


15th Edition ??

The laws of physics haven't changed - and I quoted at length from your Earthing manual above and asked for where, in that manual, you require bonding of plastic services on PME installations - your rsponse does appear to fail to address, even at a basic level, whwre you believe that requirement is. As I said, I've read the manual from cover to cover and back again - and failed to find it.

Regards

OMS

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Failure is always an option
 06 March 2013 09:14 PM
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UKPN

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"complete bloody nonsense"

IEE 14th ed refers.

Regards
 07 March 2013 10:28 AM
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Avatar for OMS.
OMS

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Originally posted by: UKPN

"complete bloody nonsense"



IEE 14th ed refers.



Regards


I doubt it - 14th edition pre dated PME in the UK generally

What a star - now then, back to your earthing manual and the requirement for bonding plastic pipes on a PME system ?

regards

OMS

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

Edited: 07 March 2013 at 10:34 AM by OMS
 07 March 2013 02:34 PM
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rogersmith7671

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Regulations for the electrical equipment of buildings
Fourteenth edition 1966 incorporating amendments 1974

D13
Note 2 where P. M. E. conditions apply (see Regulation D34(iii)) the supply undertaking shall be consulted to determine any special requirements for the` bonding of metalwork of other services.
Metalwork being the "operative word"here

Regards

Edited: 07 March 2013 at 03:34 PM by rogersmith7671
 07 March 2013 02:48 PM
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rogersmith7671

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Regulations for the electrical equipment of buildings
Fourteenth edition 1966 incorporating amendments 1974

D34 (iii) Where Protective Multiple Earthing (P.M.E.) is provided by the supply undertaking, in accordance with conditions laid down by the Minister of Technology of the Secretary of State for Scotland, with the conncurence of the Minister of Posts and Telecommunications, the earthing lead shall be connected to the consumer's earthing terminal and together with the neutral conductor of the consumer's installation, shall be so arranged that connection to the neutral conductor of the incoming supply can be carried out by the supply undertaking.

Regards

Edited: 07 March 2013 at 03:35 PM by rogersmith7671
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