Interference issue with using common on dead end 3-way

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aelectricalman

aelectricalman

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KY
I was told by an inspector that there could be an interference issue when using the common of the dead-end 3-way to feed another light source. I see no problems for its just another potential feeder. At the feeder 3-way, all I've done is tie the feed into the black of the 3 wire traveller to get the hot to the dead end 3-way. Now that the hot is across the room I can use it to feed an outdoor lights. The hot is not broken at any point so where is the interference. (Note, this is a multiwire circuit and the neutral is already in the box from circuit 1. The hot from the 3-way grabs its neutral from the (Common neutral) in the multiwire Romex already in the box. What type of interference is he refering to? Weird to me. Thanks for any help on matter.

Editted to include neutral information.

[ February 13, 2005, 02:06 PM: Message edited by: aelectricalman ]
 
Re: Interference issue with using common on dead end 3-way

Where will you be getting a neutral from?
Remember the code requires supply and return of a circuit to be in the same cable assembley or race-way. The Interference he might be talking about is the magnetic field that having seperated circuit conductors will cause that can effect computer monitors TV screen's. While this Interference is not a code violation in it's self the grabing a neutral from another part of the circuit is.
 
Re: Interference issue with using common on dead end 3-way

I see now.
It is supplied from a multiwire circuit, so the neutral is already in the box from circuit 1. Note the 3 wire, 2 circuts was split at a different box. Is that permissable? We need to have a 4 wire Romex. I understnad it is in development, but it would be nice in this situation.
 
Re: Interference issue with using common on dead end 3-way

Our distributor stocks four wire romex. We use it all the time on bathroom fan/light/night light units. A red, black, white, and white with red tracer are the conductors. Can't think of the Brand name off the top of my head.
 
Re: Interference issue with using common on dead end 3-way

Originally posted by tedge:
We use it all the time on bathroom fan/light/night light units. A red, black, white, and white with red tracer are the conductors.
Click to expand...
How do you use it for that and remain code compliant?

[ February 13, 2005, 03:07 PM: Message edited by: iwire ]
 
Re: Interference issue with using common on dead end 3-way

Bob

I take it you are questioning using the white with a red stripe wire as an ungrounded conductor? If so that?s a good question. Can a white wire with a red stripe be used as a grounded conductor?
 
Re: Interference issue with using common on dead end 3-way

Originally posted by curt swartz:
Bob

I take it you are questioning using the white with a red stripe wire as an ungrounded conductor? If so that?s a good question. Can a white wire with a red stripe be used as a grounded conductor?
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Yes that was what I was thinking of.

It would be fine with permanent re-identification.

I was also thinking why not use 14/4 or 12/4 cable;

White, Black, Red, Blue, Bare.
 
Re: Interference issue with using common on dead end 3-way

The white with the tracer is a valid grounded conductor as far as I know.

Art.200.6 A
Sizes 6AWG or smaller. ... wires having their outer covering finished to show a white or gray color but have colored tracer threads in the braid identifying the source of manufacture shall be considered as meeting the provisions of this section.
 
Re: Interference issue with using common on dead end 3-way

red, black, white with red tracer reidentified on both ends as ungrounded conductors is how I do it. Code compliant as I see it.
 
Re: Interference issue with using common on dead end 3-way

Originally posted by hurk27:
Where will you be getting a neutral from?
Remember the code requires supply and return of a circuit to be in the same cable assembley or race-way.
Click to expand...
No different than feeding a light box and making a switch loop for a single pole switch.Only difference is that this is for a 3 way.Can be alot easier depending upon the installation :D
 
Re: Interference issue with using common on dead end 3-way

I think I've done what you're describing too, Ace. I'm thinking that having more amps consumed by the "common" of that dead-end threeway will result in an EMF effect, because the common would be the sum of the two lighting loads, where the traveller return would only be the amps of one.

I think the amount of EMF would be next to nothing, though. Just the difference between the common and the traveller. But I know jack about EMF. :D
 
Re: Interference issue with using common on dead end 3-way

O, I left town for a couple of days and forgot. Let me word it right and Ill post it soon.
 
Re: Interference issue with using common on dead end 3-way

Originally posted by georgestolz:
I think I've done what you're describing too, Ace. I'm thinking that having more amps consumed by the "common" of that dead-end threeway will result in an EMF effect, because the common would be the sum of the two lighting loads, where the traveller return would only be the amps of one.

I think the amount of EMF would be next to nothing, though. Just the difference between the common and the traveller. But I know jack about EMF. :D
Click to expand...
George are you saying that since there are 2 means of swithing there are two means of adding amperage to the circuit :D
 
Re: Interference issue with using common on dead end 3-way

I'm saying (with little confidence) that since the common is being used as the supply for a second set of lights not involved with the threeway, then there will be a difference in how many amps are on the common vs. travellers.

Threewayed lights = 8 amps
Non 3'd lights = 4 amps
The common would have 12 amps of load on it, where the traveller return cancelling the effect would only have the 8 amps on it, leaving four amps worth of uncancelled EMF being transmitted by the threewire between switches.

But again, I'm mostly chipping in here for confirmation or correction. :D
 
Re: Interference issue with using common on dead end 3-way

Who makes 4 conductor Romex? I've never heard of it, and people always tell me 2 or 3 conductor is all ya can get...that's weak. :( Although, some guy at Home Depot did try to sell me and a friend some "5 conductor Romex" when we wanted some CAT-5...lol...5 conductor?
 
Re: Interference issue with using common on dead end 3-way

Midget,

All of the major wire manufacturers manufacture it: Southwire, Essex, Encore and Cerro.

A good electrical supplier should have it in stock. If they don't, they can certainly order it.
 
Re: Interference issue with using common on dead end 3-way

There was a thread about 6 months ago that dealt with 12/14 - 4, i have never used it but it is avalable.Carol makes it 2 circuts 2 neturals,Afci issueTo me feed MBR with one circuit # 2 and 3 on another done deal.When code required smokes to be afci protected call backs went through the roof.We decidied to feed them off BR circuit :eek: Code allows this but some manufacturers are UL listed as dedicated.
 
Re: Interference issue with using common on dead end 3-way

Allen, what manufacturers detectors are only listed for a dedicated circuit?

Roger
 
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