Travelers in separate conduit?

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I am trying to convince the other electricians on my job that it is not safe to run the travelers of a threeway in a separate conduit with only a ground wire with them. In the past I was told by Mark Ode that this would cause induction in the conduit and cause it to get hot. I need some back up for this or they are going to continue to do this on their jobs. I have been contending that they need to run the neutral back in the conduit with the travelers. Any help you can give me would be appreciated. Thank You
Michael White
 

480sparky

Senior Member
Location
Iowegia
'They' obviously aren't paying for the extra conduit, associated fittings & boxes, wire and labor.;)
Oh, and welcome to the fourm!
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augie47

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Location
Tennessee
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State Electrical Inspector (Retired)
can it be safe and not meet Code ?:D
IMHO, it might not meet Code, but ,I for one, can't believ it's "unsafe" The amount of heat on a set of travlers just can't be that great, can it?
Not that it should be allowed if it doesn't meet Code.... but.....

You see lightyig contatcors often with just phase and load nippled into the contactor and the neutral trminated in the panel. Code ? Not!
Safe ? what say you, forum memnbers
 

raider1

Senior Member
Staff member
Location
Logan, Utah
can it be safe and not meet Code ?:D
IMHO, it might not meet Code, but ,I for one, can't believ it's "unsafe" The amount of heat on a set of travlers just can't be that great, can it?
Not that it should be allowed if it doesn't meet Code.... but.....

You see lightyig contatcors often with just phase and load nippled into the contactor and the neutral trminated in the panel. Code ? Not!
Safe ? what say you, forum memnbers

If a phase and a load (switch leg) are run in the same conduit the inductive fields cancel out because the current is flowing in oppsite directions.

With just travellers run in a conduit there is no conductor run with them that would have current flowing in the oppsite direction to cancel out the inductive fields.

Chris
 

ronaldrc

Senior Member
Location
Tennessee
I agree most installations inductive heating wouldn't be a problem.

I am retired now but when I installed flour. lighting in commercial Bldgs it was not uncommon to have a circuit loaded to the gilles.

But even if you don't consider this. The impendence of this circuit is going to be a lot higher
than if it had the neutral or a return in with it.

If the circuit is very long and developed a short circuit in one of the ballast or fixtures it might not trip the breaker because of this high impedance or AC resistance. :)
 

don_resqcapt19

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Staff member
Location
Illinois
Occupation
retired electrician
The rule in the Canadian code that covers this does not apply until the circuit current exceeds 200 amps so I don't see an electrical safety issue with the travelers in a conduit by themselves.
 

Jljohnson

Senior Member
Location
Colorado
How would this scenario be any different than a line/load switch drop from a ceiling j-box to a single-pole switch? I don't believe it would be a violation to install as described.
 

480sparky

Senior Member
Location
Iowegia
How would this scenario be any different than a line/load switch drop from a ceiling j-box to a single-pole switch? I don't believe it would be a violation to install as described.

Fields would be cancelled out in that case because current is flowing in opposite directions in relation to each conductor.
 

ronaldrc

Senior Member
Location
Tennessee
Since I can't edit that last post.

I need to change it.

We can not use the Canadian Code if we live in the USA.

Running a current carrying conductor in a EMT without a return conductor of the opposite
polarity or the neutral is a NEC code violation.
 

Jljohnson

Senior Member
Location
Colorado
Fields would be cancelled out in that case because current is flowing in opposite directions in relation to each conductor.

480, can you go into more detail on this one for me? I'm not wrapping my mind around it very well, considering the fact that it is alternating current. I don't see how the current would be flowing in "opposite" directions, but would rather just be "flowing".
 

480sparky

Senior Member
Location
Iowegia
480, can you go into more detail on this one for me? I'm not wrapping my mind around it very well, considering the fact that it is alternating current. I don't see how the current would be flowing in "opposite" directions, but would rather just be "flowing".

If current is flowing from the ceiling box down to the switch, it is also flowing in the opposite direction back up to the light on the other conductor. 1/120th of a second later, the whole thing reverses.
 

Jljohnson

Senior Member
Location
Colorado
If current is flowing from the ceiling box down to the switch, it is also flowing in the opposite direction back up to the light on the other conductor. 1/120th of a second later, the whole thing reverses.

So then a 1/2" conduit run to a 4-way switch with TWO sets of travelers would negate this effect, correct? 300.3(b) Says that the conduit must contain the grounded conductor, "WHERE USED". I still do not see the install as a code violation. Any inspectors care to speak up with an opinion?
 

480sparky

Senior Member
Location
Iowegia
So then a 1/2" conduit run to a 4-way switch with TWO sets of travelers would negate this effect, correct? 300.3(b) Says that the conduit must contain the grounded conductor, "WHERE USED". I still do not see the install as a code violation. Any inspectors care to speak up with an opinion?

If you've got two set of travelers (assuming they're for the same light), then one will be carrying power one direction, and another one will be carrying it back the other way.

Try to think of it this way: At any given point along a conductor, which way is the wire getting energized? In other words, where is the power coming from? Draw a mental arrow that direction. Now go to the other conductor and do the same. You'll see the arrows are in opposite directions.
 

Jljohnson

Senior Member
Location
Colorado
480, I uderstand what you are saying, I just see it a little differently. Take, for example, my scenario of a simple switch loop from a ceiling box to a 1-pole switch. You said that the current on the switch leg will be 1/120th of a second behind the current on the supply wire to the switch. Since no current will be flowing whatsoever until the switch is turned on, how can the sw. leg current be 1/120th behind the supply current? The current flow starts at EXACTLY the same time. In the OP's example, it seems to be the general consensus that IF you pulled a neutral wire with the travelers then all would be fine. How so? The N. wire will not be connected to a load in the switchbox thus will not be returning ANY current to the source thereby rendering it useless.
I'm not sure why this thread has me so worked up but it sure seems to have done it. I'll give another example for consideration. A customer has a warehouse area that has 6 250 watt low bay fixtures to be installed. For whatever reason, he wants the controls to be seperate for each fixture AND 3-wayed from each of 2 entrances. The warehouse also has exit lights at each entrance. What is wrong with powering the system with a hot and neutral at one fof the ceiling boxes, droppin H-N to the first 6-gang box (whch has another conduit containing H-N existing the box to feed the exit light, pulling all of the switch-legs from the 2nd 6-gang box into the lighting J-box system, then running a seperate conduit for the 12 travellers that go btween the switch boxes? The hot and nuetral fo the 2nd exit light will be fed from one of the lighting j-boxes as well. In this scnario, the addition of a N wire in the traveller conduit woud be pointless.
 

480sparky

Senior Member
Location
Iowegia
I didn't say power on one wire was 120th of a second behind the other wire. I stated that current flows one direction, then reverses in 120th of a second.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
Since I can't edit that last post.

I need to change it.

We can not use the Canadian Code if we live in the USA.

Running a current carrying conductor in a EMT without a return conductor of the opposite
polarity or the neutral is a NEC code violation.
Yes, it is an NEC violation, but I don't believe it is a safety issue...just a code issue.
 
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