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Topic Title: PNB. (protective neutral bonding)
Topic Summary: (for practical electricians)
Created On: 30 July 2012 09:24 PM
Status: Post and Reply
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 30 July 2012 09:24 PM
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Avatar for UKPN.
UKPN

Posts: 519
Joined: 17 January 2012

this is for electricians who, faced with the very rare situation
of this special form of supply need to know the bonding
requirements.
PNB can be recognised by the fact it is found mainly in rural
areas.
it is ALWAYS an overhead line, pole transformer, single phase
or multiphase type of supply.
the neutral earth is NORMALLY crimped at the point at which
the insulator bracket is fixed to a consumers external wall, but
in rare situations can be in the neutral block of the DNO service.
because PNB is non-statutory, the consumers bonding requirements
are less onerous than PME regulations.
while the ELI is expected to be low, (less than 0.5) as with all DNO
ELI parameters external to the installation, this cannot be guaranteed.
an ideal situation, particularly as these are mainly rural installations
would be to use the PNB connection as an earth path with RCCD/S.

Regards
 31 July 2012 09:12 AM
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Avatar for OMS.
OMS

Posts: 19738
Joined: 23 March 2004

Originally posted by: UKPN

this is for electricians who, faced with the very rare situation

of this special form of supply need to know the bonding

requirements.

PNB can be recognised by the fact it is found mainly in rural

areas.

it is ALWAYS an overhead line, pole transformer, single phase

or multiphase type of supply.

the neutral earth is NORMALLY crimped at the point at which

the insulator bracket is fixed to a consumers external wall, but

in rare situations can be in the neutral block of the DNO service.

because PNB is non-statutory, the consumers bonding requirements

are less onerous than PME regulations.

while the ELI is expected to be low, (less than 0.5) as with all DNO

ELI parameters external to the installation, this cannot be guaranteed.

an ideal situation, particularly as these are mainly rural installations

would be to use the PNB connection as an earth path with RCCD/S.

Regards


Nonsense - try here for an example of PNB being offerd on a large (ish) supply. This example is SSE - see section 7.2

Regards

OMS

-------------------------
Failure is always an option
 31 July 2012 09:47 AM
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John Peckham

Posts: 7506
Joined: 23 April 2005

"It is ALWAYS an overhead line, pole transformer, single phase
or multiphase type of supply. "

No it's not I have seen plenty of PNB installations from transformers situated in basements in the next room to the LV panel.

-------------------------
John Peckham

http://www.astutetechnicalservices.co.uk/
 31 July 2012 10:16 AM
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Avatar for ebee.
ebee

Posts: 5725
Joined: 02 December 2004

I think I`m just about getting my head around why PNB is TNS not TNC-S as we`ve always been taught.

If at the TX the conductor is earthed right after the N winding then that N conductor is taken any distance to the installation where it is split as N & E then it is a PEN and therefore TNC-S.

But if the N extends (unearthed) to the installation and then it is earthed at the installation then it is only a N conductor up to that point where it becomes earthed (in other words it is Tx star point right at the earth reference) thereby TNS.

Of course I might be wrong!

-------------------------
Regards,
Ebee (M I S P N)

Knotted cables cause Lumpy Lektrik
 31 July 2012 01:27 PM
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Avatar for ebee.
ebee

Posts: 5725
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How very dare you?

I am not Mr Cockburn!

-------------------------
Regards,
Ebee (M I S P N)

Knotted cables cause Lumpy Lektrik
 31 July 2012 01:29 PM
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Avatar for ebee.
ebee

Posts: 5725
Joined: 02 December 2004

I reckon that means I am wrong or I have worded my question badly?

I am not Mr Cockburn though I promise you

-------------------------
Regards,
Ebee (M I S P N)

Knotted cables cause Lumpy Lektrik
 01 August 2012 03:09 PM
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Avatar for ebee.
ebee

Posts: 5725
Joined: 02 December 2004

Wow that`s a relief, mind you I would not call anybody David Cockburn

-------------------------
Regards,
Ebee (M I S P N)

Knotted cables cause Lumpy Lektrik
 01 August 2012 03:39 PM
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Avatar for OMS.
OMS

Posts: 19738
Joined: 23 March 2004

Originally posted by: ebee

Wow that`s a relief, mind you I would not call anybody David Cockburn


Except David Cockburn perhaps, Ebee -

OMS

-------------------------
Failure is always an option
 01 August 2012 04:08 PM
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Avatar for ebee.
ebee

Posts: 5725
Joined: 02 December 2004

OMS,
I so very nearly stated "Even if he is actually David Cockburn"

-------------------------
Regards,
Ebee (M I S P N)

Knotted cables cause Lumpy Lektrik
 01 August 2012 04:26 PM
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Avatar for OMS.
OMS

Posts: 19738
Joined: 23 March 2004

LoL -

OMS

-------------------------
Failure is always an option
 02 August 2012 06:47 PM
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Avatar for BigRed.
BigRed

Posts: 558
Joined: 10 November 2006

ebee, i've taken my post down , in the interests of keeping the peace.
 05 August 2012 02:18 PM
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Avatar for sparkingchip.
sparkingchip

Posts: 6171
Joined: 18 January 2003

Leaving it looking like Ebee is talking to himself, nothing being wrong with talking to yourself of course, so long as you don't start a argument!
 05 August 2012 05:59 PM
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Avatar for ebee.
ebee

Posts: 5725
Joined: 02 December 2004

I do sometimes argue with myself but I usually win

-------------------------
Regards,
Ebee (M I S P N)

Knotted cables cause Lumpy Lektrik
 05 August 2012 06:52 PM
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GB

Posts: 359
Joined: 04 September 2002

How can you win an argument with yourself??
unless of course you win by winning and win by loosing, like whos round is it!!
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