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#87235 02/04/04 11:37 PM
Joined: Jul 2001
Posts: 37
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RickG Offline OP
Member
Gretings
I am sure we have discussed this before...
I am of the opinion that 2 wire NM travelers for 3way & 4 way switching are not allowed by the NEC. I am hanging my hat on 300.3B. However, could 300.3B3 allow the use of 2 wire NM cable for 3 way systems? If so, was this a change from previous codes?
I have a contractor that did all 3 & 4 ways with 14-2 NM travelers. I red tagged citing 300.3B. I expect him to contest this, and he probably will argue that 300.3B3 allows this method. I do not believe that it does allow this, just looking for opinions/ reinforcement. I do not want to have him change this if somehow it meets minimum code.
Thanks
Rick

2017 / 2014 NEC & Related Books and Study Guides
#87236 02/05/04 07:57 AM
Joined: Aug 2001
Posts: 7,520
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Member
I see that 300.3(B)(3) refers to 300.20(B). Is the contractor going to claim that the latter rule allows this, so long as he has taken the necessary steps to reduce eddy currents?

Is it even practical to cut slots or otherwise modify a box where NM cable clamps are used?

#87237 02/05/04 04:00 PM
Joined: Jul 2001
Posts: 37
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RickG Offline OP
Member
Pauluk
Contractor is using plastic boxes.
Waddya think?
Rick

#87238 02/05/04 04:34 PM
Joined: Jan 2003
Posts: 4,391
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Moderator
I would not do this but I do believe it is allowed.

I think you will have to live with it.


Bob Badger
Construction & Maintenance Electrician
Massachusetts
#87239 02/06/04 09:18 AM
Joined: Jul 2001
Posts: 37
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RickG Offline OP
Member
300.3B states all conductors to be in the same cable, unless otherwise permitted by 300.3B 1-4. 90.5B (permissive rules) need the use of the twerms "shall be permitted", & "shall nmot be required". I do not see where this is specifically permitted.
Rick

#87240 02/06/04 12:18 PM
Joined: Nov 2000
Posts: 2,148
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Member
Rick,
300.3(B)(3) is the specific permission. With nonmetallic raceways or cables all of the circuit conductors are not required to be in the same raceway or cable as long as 300.20 is complied with for metallic boxes. There are no metallic boxes in this installation so there is no violation.
Don


Don(resqcapt19)
#87241 02/06/04 01:49 PM
Joined: May 2002
Posts: 1,716
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Member
Rick, even though this is code compliant, you should mention to the electrician the "net current" and EMF issues that would be associated with this wiring method.

Tell him that even though the research is not conclusive at this time, EMF is suspect by some to be a contributor in leukemia in children and let his conscience tell him what to do.

Roger

#87242 02/08/04 09:29 AM
Joined: Dec 2003
Posts: 751
E
Member
Assuming all cables for the run are in very close proximity to one another between plastic boxes, IMO there are no concerns about eddy currents or EMF. The intent of requiring all conductors to be together is to eliminate the EMF, this is met by running both cables side-by-side between boxes. What difference is there in this from running four conductors and a ground in PVC?

Earl


Earl
#87243 02/08/04 09:41 AM
Joined: Jan 2003
Posts: 4,391
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Moderator
Earl, for two wire travelers it is not possible to do what you suggest.

The neutral must have stayed at the fixture, feed the three ways at one end and from the other end back to the fixture. [Linked Image]


Bob Badger
Construction & Maintenance Electrician
Massachusetts
#87244 02/08/04 10:55 AM
Joined: May 2002
Posts: 1,716
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Member
Earl, as as Bob said, it would be unlikely that one set of two wire travelers would be running along side of current canceling conductors of which would pass by the end three way box.

If this was the case I agree that there would be no issue, but I just don't see where it would exist.

Roger

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