[TCUG] Re: Installation Earthing
- From: David B Thompson <DBT@xxxxxxxxxxxxxxxxxxxx>
- To: tcug@xxxxxxxxxxxxx
- Date: Mon, 23 Sep 2002 19:05:00 +0100
===== Original Message from tcug@xxxxxxxxxxxxx at 23/09/02 01:57
>Provided armoured cable is properly terminated with good quality glands ,it
>is our experience that this will result in ELI readings well within the
>maximums allowed by the regulations .This is backed up by a preventative
>maintenance routine which acts as a "catch all" for issues such as corrosion
>,movement due to vibration etc ,this of course applies irrespective of the
>type of cabling used .I agree with Ian Wallis that this method properly
>applied as above has stood the test of time .
>Reg Hill
>Cardiff County Council
>
>-----Original Message-----
>From: Wallis, Ian [mailto:Ian.Wallis@xxxxxxxxxxxx]
>Sent: 20 September 2002 15:32
>To: 'tcug@xxxxxxxxxxxxx'
>Subject: [TCUG] Re: Installation Earthing
>
>
>In my experience those who "believe" that there is a problem just cost
>themselves a lot of money. Do your ELI tests show a problem? In my
>experience using the armouring as an earth still gives readings far lower
>than the maximum allowed by the regs even when 25 years old even with
>surface corrosion.
>
>Ian Wallis
>Derby City Council
>
>
>
>-----Original Message-----
>From: Probert, Norman (Environmental Services)
>[mailto:NProbert@xxxxxxxxxxxxxxxxxxxxx]
>Sent: 20 September 2002 15:25
>To: tcug@xxxxxxxxxxxxx
>Subject: [TCUG] Installation Earthing
>
>
>
>
>We have been looking into providing better earth continuity at
>installations, we believe that the existing method using the armouring is no
>longer sufficient and can lead to high readings therefore a separate 10mm
>earth conductor should be used from each pole. There are two options either
>build this into the existing cable or install a separate armoured cable
>containing earth only. Our problem is that this is a non standard cable and
>would have to be purchased in significant quantities 5,000 metres at a go,
>we are finding it hard to convince our suppliers that they could offer this
>cable to others and we are also reluctant to make the purchase ourselves.
>
>My question is
>
>A Does anybody else agree that it is a good idea (if enough took it up it
>could become standard instead of special).
>
>B Does anybody currently use this type of cable already and if they do who
>makes it.
>
>C Has anybody got a better idea
>
>
>Norman Probert
>Senior Engineer Traffic Control Systems
>
>Tel 01905-766822
>Email nprobert@xxxxxxxxxxxxxxxxxxxxx <mailto:nprobert@xxxxxxxxxxxxxxxxxxxxx>
>
>
>
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>
> RE: [TCUG] Installation Earthing
>
>
>
>In my experience those who "believe" that there is a problem just cost
>themselves a lot of money. Do your ELI tests show a problem? In my
>experience using the armouring as an earth still gives readings far lower
>than the maximum allowed by the regs even when 25 years old even with
>surfacecorrosion.
>
>Ian Wallis
>Derby City Council
>
>
>
>-----Original Message-----
>From: Probert, Norman (Environmental Services)
>[mailto:NProbert@xxxxxxxxxxxxxxxxxxxxx[1]]
>Sent: 20 September 2002 15:25
>To: tcug@xxxxxxxxxxxxx
>Subject: [TCUG] Installation Earthing
>
>
>
>
>We have been looking into providing better earth continuity at
>installations, we believe that the existing method using the armouring is no
>
>longer sufficient and can lead to high readings therefore a separate 10mm
>earth conductor should be used from each pole. There are two options either
>build this into the existing cable or install a separate armoured cable
>containing earth only. Our problem is that this is a non standard cable and
>would have to be purchased in significant quantities 5,000 metres at a go,
>we are finding it hard to convince our suppliers that they could offer this
>cable to others and we are also reluctant to make the purchase ourselves.
>
>My question is
>
>A Does anybody else agree that it is a good idea (if enough took it up it
>could become standard instead of special).
>
>B Does anybody currently use this type of cable already and if they do who
>
>makes it.
>
>C Has anybody got a better idea
>
>
>Norman Probert
>Senior Engineer Traffic Control Systems
>
>Tel 01905-766822
>Email nprobert@xxxxxxxxxxxxxxxxxxxxx
><mailto:nprobert@xxxxxxxxxxxxxxxxxxxxx[2]>
>
>
>
>
>**********************************************************************
>Privileged/Confidential information and/or Copyright Material
>may be contained in this email. The information and Material
>is intended for the use of the addressee(s) only.
>
>If you are not the addressee or the person responsible for
>delivering it to the intended addressee(s), you may not copy or
>deliver it to anyone else or use it in any unauthorised manner.
>To do so is prohibited and may be unlawful. If you receive this
>email by mistake, advise the sender immediately by using the
>reply facility in your email software.
>
>Any views or opinions presented are solely those of the author
>and do not necessarily represent those of Worcestershire County
>Council.
>
>Although this email and attachments are believed to be free of any
>virus or other defects which might affect any computer or IT systems
>into which the are received, no responsibility is accepted by
>Worcestershire County Council for any loss or damage arising in any
>way from the receipt or use thereof.
>
>**********************************************************************
>-----------------------------------------------------------
>A message from the TCUG mailing list. For information about
>the list visit //www.freelists.org/webpage/tcug[3]
>
>**********************************************************************
>The views expressed in this email are personal and may not
>necessarily reflect those of Derby City Council, unless explicitly
>stated otherwise
>
>This email, and any files transmitted with it, are confidential and
>intended solely for the use of the individual or entity to whom they
>are addressed. If you have received this email in error, please
>notify me immediately.
>
>If you are not the intended recipient of this email, you should not
>copy it for any purpose, or disclose its contents to any other
>person.
>
>This footnote also confirms that this email message has been
>swept by MIMEsweeper for the presence of computer viruses.
>However, we cannot accept liability for viruses that may be in
>this e-mail. We recommend that you check all e-mails with an
>appropriate virus scanner.
>
>www.mimesweeper.com
>**********************************************************************
>
>
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>
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>Mae'n bosibl bod gwybodaeth gyfrinachol yn y neges hon. Os na chyfeirir y
>neges atoch chi'n
benodol (neu os nad ydych chi'n gyfrifol am drosglwyddo'r neges i'r person a
enwir), yna ni chewch gopio na throsglwyddo'r neges. Mewn achos o'r fath,
dylech ddinistrio'r neges a hysbysu'r anfonwr drwy e-bost ar unwaith.
Rhowch wybod i'r anfonydd ar unwaith os nad ydych chi neu eich cyflogydd yn
caniatau e-bost y Rhyngrwyd am negeseuon fel hon. Rhaid deall nad yw'r
safbwyntiau, y casgliadau a'r wybodaeth arall yn y neges hon nad ydynt yn
cyfeirio at fusnes swyddogol Cyngor Dinas a Sir Caerdydd yn cynrychioli barn
y Cyngor Sir nad yn cael sel ei fendith. Caiff unrhyw negeseuon a anfonir
at, neu o'r cyfeiriad e-bost hwn eu prosesu gan system E-bost Gorfforaethol
Cyngor Sir Caerdydd a gallant gael eu harchwilio gan rywun heblaw'r person a
enwir.
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===== Comments by DBT@JDT-BIRM (David B Thompson) at 23/09/02 10:52
I agree with Reg, that the use of a 10mm earth core would seem excessive. Is
there some confusion over main equipotential bonding and Circuit Protective
Conductor?
The Main Equipotential Earthing conductor does need to be 10mm cable,
particularly when PME (TNCS) is used (6mm is permissible on TNS). However,
the connections to signal poles have always been considered Final Sub
Circuits, which only need an earth core of the same size as the phase, if
within the same cable. It is also permissible to use the armour.
The usual cause of poor line loop impedance is:
Trying to cable too large an installation with too small cable cores.
Poor maintenance or installation. I have found cable joints in the past,
where installers have connected 2 or 3 strands of armour into a connector
and cut the rest off.
Dave Thompson
Mott MacDonald
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