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#84368 - 03/25/03 03:54 PM Conductors In Parallel
gbbrwh Offline
Junior Member

Registered: 03/25/03
Posts: 6
Loc: Seattle, WA
I have an energy guiding drag chain that needs to be modified. My solution is to parallel two #8 conductors (for power not control.)
I am required to follow NEC in this modification and 310.4 pretty much destroys my options.
Does anybody know anyway of bypassing 310.4 based on the fact that this is a drag chain? Or are there any better ideas?

Thanx ... Richard

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#84369 - 03/25/03 06:21 PM Re: Conductors In Parallel
Ron Offline
Member

Registered: 03/13/02
Posts: 577
Loc: White Plains, NY
Pardon my ignorance, but what is a energy guiding drag chain?
_________________________
Ron

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#84370 - 03/26/03 07:15 AM Re: Conductors In Parallel
gbbrwh Offline
Junior Member

Registered: 03/25/03
Posts: 6
Loc: Seattle, WA

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#84371 - 03/26/03 07:48 AM Re: Conductors In Parallel
Ron Offline
Member

Registered: 03/13/02
Posts: 577
Loc: White Plains, NY
Great links, although I still don't follow the application. The energy guiding drag chain seems to be a flexible cable tray that moves with an operator.
If you need 80 amperes of conductor (parallel #8awg), what prohibits you from using #3awg instead of paralleling #8 (which as you mentioned is not permitted)?
_________________________
Ron

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#84372 - 03/26/03 08:15 AM Re: Conductors In Parallel
gbbrwh Offline
Junior Member

Registered: 03/25/03
Posts: 6
Loc: Seattle, WA
http://www.portofoakland.com/pdf/mari_reso_crane_02.pdf

If you look at the above link, this crane is in its operating condition. When it returns to its stowed position, the boom retracts away from the water - the energy chain moves with it.
The energy chain is already in place on the crane and these chains require to be load balanced and careful design goes into them. We have no other conductors available other than the #8 AWG. If I cannot use them, I will have to remove the chain.

Thanks for your help ... Richard

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#84373 - 03/26/03 10:36 AM Re: Conductors In Parallel
Bjarney Offline
Moderator

Registered: 04/10/02
Posts: 2561
Loc: West-Southern Inner-Northeast ...
gbbrwh — Ron has given you accurate information. Is there any way the load could be divided so that part of it was left on the presently-energized set of 8AWG conductors and part on the 8AWG spares?

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#84374 - 03/26/03 10:53 AM Re: Conductors In Parallel
Trainwire Offline
Member

Registered: 03/15/02
Posts: 364
Loc: Strasburg,PA,USA
I think I understand, the chain comes premade with the cables already in it. There isn't any wire existing with the capacity to do what he needs to do.

If this is required to code, your stuck, unless there is room in the chain to add some welding cable, (to give you the flex you need) into the chain.

good luck, did you spec the chain? or did some engineer do it.

TW

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#84375 - 03/26/03 11:25 AM Re: Conductors In Parallel
gbbrwh Offline
Junior Member

Registered: 03/25/03
Posts: 6
Loc: Seattle, WA
Yes - the chain arrives premade with the cables installed. The chain was getting so heavy and wide, we had to remove numerous spare conductors before it was built.
One simple mistake has led to this problem. All we have left are the #8s and various #10s and #12s. We can't split the load. The only option I can think of is to parallel two #8s together - otherwise the chain has to come back down and sent back to the factory in Germany
Adding a cable would be difficult as these chains are designed in such a way to avoid cables contacting one another.
An engineer I know spec'd it but the responsibility falls right at my door.

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#84376 - 03/26/03 11:54 AM Re: Conductors In Parallel
Bjarney Offline
Moderator

Registered: 04/10/02
Posts: 2561
Loc: West-Southern Inner-Northeast ...
I would try it and see just how currents share. Sometimes "engineering supervision” can justify practices that aren't exactly what everyone is used to in industrial facilities. It's not perfectly code compliant, but It may not kill anyone or damage anything. Careful documentation is in order to "CYA" and lessen confusion to future troubleshooters. It would be a deviation, but unquestionably in a “location accessible to qualified persons only” and “In industrial establishments… where conditions of maintenance and supervision ensure that only qualified personnel are involved” that the NEC uses to justify special cases.

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#84377 - 03/26/03 12:34 PM Re: Conductors In Parallel
HotLine1 Offline

Member

Registered: 04/03/02
Posts: 6805
Loc: Brick, NJ USA
Gbbrwh:
Have you called your local AHJ?????
You have a piece of industrial equipment.
Your link states it was made in 1968

The #8's that you have in the track; what kind of wire/cable and what insulation??

Talk to your local AHJ! Explain the facts of the situation to him... Certain situations can receive "special permission", but get it in writing.

IF you presented your situation to me, and had engineering documentation to "back-it-up" more than likely, I would grant special permission.

John


Your link also mentions 4160 volt as the power supply, is that correct.
_________________________
John

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