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Topic Title: electromagnetic effects
Topic Summary: is the regulation required
Created On: 18 December 2012 01:17 PM
Status: Post and Reply
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 19 December 2012 07:21 PM
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maltrefor

Posts: 110
Joined: 01 November 2009

Originally posted by: AJJewsbury

I was always taught to use brass bushes and locknuts and to run a cut with a jigsaw blade between the holes in the steel glandplate to stop electromagnetic effects.



Is not this the correct procedure ?


It's certainly one correct procedure - other options include substituting the gland plate (or part of it) with a non-ferrous alternative.



(I guess slotting might fall foul of 416.2.2 these days if the cables enter at the top)



- Andy.


This was for tails with a bottom entry!

A top surface entry would be made with trunking slotted and protected with paxoline.
 19 December 2012 07:25 PM
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Avatar for OMS.
OMS

Posts: 18943
Joined: 23 March 2004

A top surface entry would be made with trunking slotted and protected with paxoline.


So why not for both top and bottom entry then ?

Regards

OMS

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Failure is always an option
 19 December 2012 08:19 PM
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maltrefor

Posts: 110
Joined: 01 November 2009

Originally posted by: OMS

A top surface entry would be made with trunking slotted and protected with paxoline.




So why not for both top and bottom entry then ?



Regards



OMS


It depends on the circumstances and layout of the installation and the top entry would have to be IP4X but the OP was:-

'The tails are installed via bushed single entry holes
When I mentioned electromagnetic effects others insist that this is normal practice and nothing gets the slightest bit warm.
So while in the UK if we came across an installation installed in this manner it would be a pointing finger and a sharp intake of breath.'

So this is what I was replying to!
 20 December 2012 08:37 AM
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Legh

Posts: 3435
Joined: 17 December 2004

This was for tails with a bottom entry!

A top surface entry would be made with trunking slotted and protected with paxoline.


I would have thought that running a trunking along the top of the DB would allow a decent size hole protected by grommet strip. Much easier for installation of larger tails/single core cables.

Legh

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 30 December 2012 07:04 PM
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ArthurHall

Posts: 735
Joined: 25 July 2008

I had a job a couple of years ago to investigate signs of heating in a transformer cable box. It was a 2MVA transformer 11kV to 600V IT supply.
At the transformer 600V box the singles were taken through individual holes in the steel and the phases were neatly bunched. The steel gland plate had overheated to the extent that some of the paint had burnt off.
At the other end of the singles they had again been taken through individual holes into the switchboard, but this time the phases were intermixed, no sign of any heating.
Fitting a brass gland plate at the transformer cured the problem but was a hell of a job to do.
 30 December 2012 07:31 PM
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johno12345

Posts: 169
Joined: 22 October 2005

its the same as the chap that replaced part of my ring circuit with 1mm t&e. it worked fine for years, doesnt mean its right.

we have some at work running at 300a per phase though a ferrous enclosure and it gets hot, no more than 50 degrees though
IET » Wiring and the regulations » electromagnetic effects

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