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Topic Title: Submains cable in top or bottom of panel board
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Created On: 30 January 2013 09:18 AM
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 30 January 2013 09:18 AM
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CPC

Posts: 32
Joined: 16 February 2011

Morning all

A new 150mm2 4 core swa cable is going to be installed to supply a new 12 way TP&N panel board.
The main switch of the panel board is at the bottom and the cable was going to be terminated/glanded into the top of the board with the cables being dress/tiewrapped down the inside of the board.

I am wondering if there is any regulation which states that the cables should not come down though the inside of the board?

Thanks to all.
 30 January 2013 09:40 AM
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unshockable

Posts: 853
Joined: 18 May 2007

I have never had to terminate anything bigger than a 25mm. Are you sure you can bend and terminate a 150mm?

The sort of setup you mention sounds like max 35mm.

I hope your concern is unfounded cause I am guilty! Very! I find it the only way to dress in my cable.

Simon
 30 January 2013 09:43 AM
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Avatar for OMS.
OMS

Posts: 19837
Joined: 23 March 2004

It's poor practice for sure - when you turn off the board mainswitch, you still have live conductors surrounded by just basic insulation running the full length of the enclosure.

The other point is that the load current on the sub main causes heat - you are liberating much more of that heat into the enclosure - and you also have the oputgoing way cables running near it - has somone accounted for that extra bit of grouping in the calcs

Personally I'd have the cable run down and then enter from the bottom of the board and into the main switch assembly - all behind the terminal shroud usually.

Regulation - no - other than good workmanship and proper materials should be used.

Like all these things, when I see it on site, I raise an eybrow and then I go looking at other things - it sends a signal to people like me that the installer may just not be that competent

Regards

OMS

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Failure is always an option
 30 January 2013 10:02 AM
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John Peckham

Posts: 7573
Joined: 23 April 2005

Not a good idea as there is no often enough space for the outgoing ways without clogging what space is available with 4 x 150mm. Bottom entry but you may need and extension box to spread the conductors to go in to the switch.

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

http://www.astutetechnicalservices.co.uk/
 30 January 2013 10:10 AM
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CPC

Posts: 32
Joined: 16 February 2011

Thanks for you replys and thoughs.

Yes i did think it was bad practice and thats why i was needing abit of a helping hand to confirm it.

Ok i will get the contractor to gland the cable in from the bottom as if your going to do a job do it right

Many thanks unshockable, OMS & John for the help.

Thank you.
 30 January 2013 10:13 AM
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Avatar for OMS.
OMS

Posts: 19837
Joined: 23 March 2004

You may also want to consider the form of seperation intended for the panel board by the designer - running the sub main through the outgoing way enclosure may well compromise that.

Regards

OMS

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Failure is always an option
 30 January 2013 10:25 AM
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eclipse

Posts: 152
Joined: 03 November 2006

Yes have to agree with all of the comments, we regulary terminate large sub main cables into panel boards ect, glanding into the top although might look nice but it is poor practice when you take into account potential heat build up and the reduction of space for any outgoing circuits, we have in the past installed a large trunking along the bottom edge of the board so it protudes past one end of the board and enough to terminate the cable into, a peice of tray or ladder run to this will contain the cable nicely this then acts as a spreader box and makes the job much easier, obviously ensure you use a large enough metal trunking,

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Thanks

Alan.

Now what was that reg no?
 30 January 2013 12:13 PM
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rougediablo

Posts: 112
Joined: 09 November 2011

Have also seen TP&N boards completely surounded by metal trunking on all 4 sides with couplers into the board at various points to allow easier access for circuits.
 30 January 2013 11:14 PM
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Avatar for Martynduerden.
Martynduerden

Posts: 3211
Joined: 13 July 2008

I take it you cannot get a top incommer kit for the panel board?

You won't have much issue bending a 150 in a PB usually loads of room and they aren't that big really, I usually go parallels though - even easier 2*70mm etc

As others have said not a great design detail especially as you will need the space for outgoing services...

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Regards

Martyn.

Only a mediocre person is always at their best



www.electrical contractors uk.com
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