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#83675 - 02/13/03 09:22 AM Size of terminal limitations
Joe Tedesco Offline
Member

Registered: 10/07/00
Posts: 3325
Loc: Boston, Massachusetts USA
If a 750 kcmil compact stranded conductor was terminated into a terminal that limits the size to 500 kcmil copper, for example, would that be acceptable?

I say NO because of rules in 110.14 and 110.3(B)
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Joe Tedesco, NEC Consultant

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#83676 - 02/13/03 10:28 AM Re: Size of terminal limitations
Len_B Offline
Member

Registered: 01/19/03
Posts: 56
Loc: New Hampshire
Joe,

I agree with two possible exceptions:

1) The terminals were supplied with or factory installed in a "listed" device or piece of equipment.

2) I think it could be "approved" by the ahj if the circuit ampacity were limited to a value allowable for 500kcmil, and the lugs provided enough room to deform(squash) the conductors enough to ensure good mechanical contact. A definite judgement call.

Len

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#83677 - 02/13/03 03:47 PM Re: Size of terminal limitations
HotLine1 Offline


Member

Registered: 04/03/02
Posts: 6833
Loc: Brick, NJ USA
Joe:
I have to agree with your decission.
If the lug is marked "500 KCMil, then that is the maximum size wire that the lug is rated for.

John
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#83678 - 02/13/03 03:51 PM Re: Size of terminal limitations
jes Offline
Member

Registered: 07/12/02
Posts: 103
Loc: CT
There are usually other considerations with Listed equipment other than just the terminal capacity...but related to it. Bending radius is evaluated on the basis of the largest size conductors the terminals are expected to accept. The withstand testing of the equipment is usually performed with the largest conductors. Etc.

Evaluation of the terminal performance under load does not presuppose incorrect size conductors nor does the torque spec and the engineering of the lug strength. So, NO!

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#83679 - 02/13/03 03:52 PM Re: Size of terminal limitations
frenchelectrican Offline


Member

Registered: 02/06/03
Posts: 938
Loc: Wi/ Paris France { France for ...
bonsoir joe :

i do agree with you but i see few places what they use the short adpater stub ( change from aluimin 750 to 500 cu ) due wire length and the 750 is allready derated to match the 500 on the device and there is no way i can put 750 cable in the 500lug c'est coco !! very simauar with europen rules too ps i have french licisene too so i am famiur with usa and french elctrcal rules

merci marc
_________________________
Pas de problme,il marche n'est-ce pas?"(No problem, it works doesn't it?)


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#83680 - 02/16/03 11:47 AM Re: Size of terminal limitations
Bjarney Offline
Moderator

Registered: 04/10/02
Posts: 2561
Loc: West-Southern Inner-Northeast ...
To side with HL1 and frenchelectrican, it’s apparent that there may be a size-restriction misapplication on the termination, but also there may be a conductor-material limitation—id est, 750-Al versus 500-Cu. Is the substitute larger cable aluminum?

Of course the termination would have to be so intended, unless [given Code termination dimensions] something like a Burndy AYPO adapter could be used. {T&B and Penn-Union have similar products.}

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#83681 - 02/16/03 12:04 PM Re: Size of terminal limitations
ga.sparky56 Offline
Member

Registered: 11/24/02
Posts: 582
Loc: young harris georgia usa
110.3(b) "listing or labeling" seems to pretty well narrow it down to me.

[This message has been edited by ga.sparky56 (edited 02-16-2003).]

[This message has been edited by ga.sparky56 (edited 02-16-2003).]

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#83682 - 02/16/03 10:30 PM Re: Size of terminal limitations
frenchelectrican Offline


Member

Registered: 02/06/03
Posts: 938
Loc: Wi/ Paris France { France for ...
bjarney you have very valid point for copper vs. alumuimane wire . yes you did point out clear who is the manufacter make that stub adpater . for long run most place use aluminane wire for cost reason but all ready increased the wire size by going at least one size or two bigger then derate what i say on the earlier forms

ga sparky56 : thanks for pointing that nec and i read it ( i tranlanasted from french to engish to get it right )

merci marc
_________________________
Pas de problme,il marche n'est-ce pas?"(No problem, it works doesn't it?)


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#83683 - 02/17/03 05:33 AM Re: Size of terminal limitations
Gwz Offline
Member

Registered: 04/29/02
Posts: 199
What about the current of an AC circuit being on the circumference of the conductor?

You cut the circumference strands off of the conductor and you've lost the current - No?

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#83684 - 02/18/03 01:29 PM Re: Size of terminal limitations
HotLine1 Offline


Member

Registered: 04/03/02
Posts: 6833
Loc: Brick, NJ USA
If you cut the circumference strands off of the conductor...you win a red sticker.

Yes there are adaptors made to "fit" larger wire into "factory" lugs...and the AHJ should find them acceptable if the conductor size was increased to voltage drop, ar a different material (Cu to Al). Bending radius has to be considered also. Usually, the job plans reflect VD calcs, and if a larger conductor is required, the PE/EE specs larger lugs.
John
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John

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