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#46399 - 12/21/04 10:29 PM Contactor as a fed through?  
elektrikguy  Offline
Member
Joined: May 2002
Posts: 132
woodstock,ga,usa
I have a question regarding contactors. Can you feed circuits through a contactor box via a nipple to another contactor?

Thanks


Work Gear for Electricians and the Trades

#46400 - 12/22/04 06:14 AM Re: Contactor as a fed through?  
iwire  Offline
Moderator
Joined: Jan 2003
Posts: 4,391
North Attleboro, MA USA
Sure can.

Look at 312.8 and be sure to read past the first sentence.


Bob Badger
Construction & Maintenance Electrician
Massachusetts

#46401 - 12/22/04 06:29 AM Re: Contactor as a fed through?  
Steve Miller  Offline
Member
Joined: Aug 2001
Posts: 325
Loudoun Cty, VA
Hey iwire ... in my area they quote this portion of 312.8 and don't allow it - "unless adequate space for this purpose is provided." I've never really pushed the issue, we just avoid the situation.


#46402 - 12/22/04 11:35 PM Re: Contactor as a fed through?  
Joe Tedesco  Offline
Member
Joined: Oct 2000
Posts: 2,749
Boston, Massachusetts USA
See Section [/quote]430.10 Wiring Space in Enclosures.

(A) General. Enclosures for motor controllers and disconnecting means shall not be used as junction boxes, auxiliary gutters, or raceways for conductors feeding through or tapping off to the other apparatus unless designs are employed that provide adequate space for this purpose.

FPN: See 312.8 for switch and overcurrent-device enclosures.[quote]

PS: The word adequate is vague and undefined and is not supposed to be used in the NEC according to the Manual of Style available from NFPA as a download.


Joe Tedesco, NEC Consultant

#46403 - 12/23/04 05:29 AM Re: Contactor as a fed through?  
iwire  Offline
Moderator
Joined: Jan 2003
Posts: 4,391
North Attleboro, MA USA
True enough Joe, if indeed he is talking about motor contactors. [Linked Image]

I assumed a lighting contactor. [Linked Image]

Steve it's up to you if you do not want to push it but the NEC is clear on this. [Linked Image]

They can not just quote the part they want want when it continues.


Part of 312.8
"The conductors shall not fill the wiring space at any cross section to more than 40 percent of the cross-sectional area of the space, and the conductors, splices, and taps shall not fill the wiring space at any cross section to more than 75 percent of the cross-sectional area of that space."

Here is the NEC Handbook Comentary, keep in mind the comentary is opinion also. [Linked Image]

Quote
Most enclosures are intended to accommodate only those conductors that will be connected to terminals for switches or overcurrent devices within the enclosures themselves. Where adequate space is provided for additional conductors, such as control circuits, the total conductor fill in the enclosure may not exceed 40 percent of the cross section of the wiring space in the enclosure, and no more than 75 percent if splices or taps are necessary.

Example

If an enclosure has a wiring space of 4 in. by 3 in., the cross-sectional area is 12 in.2 Thus, the total conductor fill (see Chapter 9, Table 5 for dimensions of conductors) at any cross section cannot exceed 4.8 in.2 (40 percent of 12 in.2), and the maximum space for conductors and splices or taps at any cross section cannot exceed 9 in.2 (75 percent of 12 in.2).
In general, the best way to avoid overcrowding enclosures is to use properly sized auxiliary gutters (366.5 and 366.8) or junction boxes (314.16 and 314.28). See 430.10 and commentary for wiring space in enclosures for motor controllers and disconnecting means. See also 110.59 for tunnel installations over 600 volts.


Bob


Bob




[This message has been edited by iwire (edited 12-23-2004).]


Bob Badger
Construction & Maintenance Electrician
Massachusetts

#46404 - 12/23/04 05:02 PM Re: Contactor as a fed through?  
elektrikguy  Offline
Member
Joined: May 2002
Posts: 132
woodstock,ga,usa
It is indeed for lighting contactors. Thanks for the info. Great site.



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