the use of two wire romex in three-way switch loop
- Thread starter sparky902
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Re: the use of two wire romex in three-way switch loop
Hello Ronald, I hope you and the family are having a nice holiday. Your name came up in mention of diagrams the other day.
The way I see it is, if we feed a light fixture with a 12/2 from the source, with all associated conductors in this cable, we are code compliant.
If we picked up the ungrounded, grounded, or the grounding conductor from diferent cables we would be in code violation.
From the fixture to the switch, or between two three ways, we would use a single cable to run two condutors and a grounding conductor (reidentify the white) and this is all that is needed.
Roger
Hello Ronald, I hope you and the family are having a nice holiday. Your name came up in mention of diagrams the other day.
The way I see it is, if we feed a light fixture with a 12/2 from the source, with all associated conductors in this cable, we are code compliant.
If we picked up the ungrounded, grounded, or the grounding conductor from diferent cables we would be in code violation.
From the fixture to the switch, or between two three ways, we would use a single cable to run two condutors and a grounding conductor (reidentify the white) and this is all that is needed.
Roger
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Re: the use of two wire romex in three-way switch loop
Bob
Roger I think you would like the MA amendments, I think they use common sense in making our amendments.
And
The reasons I have heard for these amendments have been "it has worked for years why change now".
Bob
Re: the use of two wire romex in three-way switch loop
Hello Bob,
It seems as though I saw another situation recently where MA displayed common sense in a code issue.
You guys might get your federal funding cut off if you keep this reckless disreguard for foolishness up.
Roger
[ July 06, 2003, 06:06 PM: Message edited by: roger ]
Hello Bob,
with the rest of your post,
I certanly do agree.
It seems as though I saw another situation recently where MA displayed common sense in a code issue.
You guys might get your federal funding cut off if you keep this reckless disreguard for foolishness up.
Roger
[ July 06, 2003, 06:06 PM: Message edited by: roger ]
Re: the use of two wire romex in three-way switch loop
Hello Roger
Just got back from bike riding the Creeper trail in Virgina. Hope everyone had a good fourth of July.
I think the codes purpose on this subject is to keep eddy currents to a minimum and I agree.
Like most on the subject I don't think the amperage put on most threeway switching would not generate very much eddy current with out a neutral running along side of it or in the same cable.. Unless it was maybe a large room full of metal halide lights or some thing of the sort.
But you know if we didn't have this code you would probably see 30 amp. circuits loaded to the gills and wired with this method it would get out of hand.This is the only reason I agree with the code.
Ronald
[ July 06, 2003, 08:51 PM: Message edited by: ronaldrc ]
Hello Roger
Just got back from bike riding the Creeper trail in Virgina. Hope everyone had a good fourth of July.
I think the codes purpose on this subject is to keep eddy currents to a minimum and I agree.
Like most on the subject I don't think the amperage put on most threeway switching would not generate very much eddy current with out a neutral running along side of it or in the same cable.. Unless it was maybe a large room full of metal halide lights or some thing of the sort.
But you know if we didn't have this code you would probably see 30 amp. circuits loaded to the gills and wired with this method it would get out of hand.This is the only reason I agree with the code.
Ronald
[ July 06, 2003, 08:51 PM: Message edited by: ronaldrc ]
karl riley
Senior Member
Re: the use of two wire romex in three-way switch loop
Roger, there seem to be two threads being discussed here, but to get back to "not needed", I think I understand what you are saying. Correct me if I'm wrong.
You are saying you don't need a neutral in a switch leg. Right. This is part of the design of a three-way. Noone disagrees.
You are also saying you don't need a neutral (grounded conductor)to run with the travelers. I agree that you can wire this way (two wire)as long as you think it's OK to use a hot from one end (and cap the neutral) and use a neutral from the other end (and cap the hot).
No contemporary books on wiring show this as an accepted practice, but you can make a case that it is allowed by 1999 Code and after. I would agree, and that is what bothers me, since most electricians I know are not aware of the strength of the magnetic field caused by the net current loop set up by using two-wire travelers. (I am talking about more than a single light bulb).
The loop effect generates a high and even magnetic field within most of the loop. The travelers are one half of the loop. The psrt of the circuit which goes between the two switches is the other part of the loop, since this section contains either a hot carrying current or a neutral carrying current, but not both. So you have the loop effect.
The magnetic field strength needed to make a computer monitor jitter and to increase a child's chanced of leukemia (according to the World Health Organization - WHO)is about the same, starting at 5 milligauss. This can be generated by one amp of net current depending on distance to the conductors.
So my point is(sorry if I'm too far off Code discussion)that why do this to a building just to save the difference between two-wire and three-wire NM cable?
Karl
Roger, there seem to be two threads being discussed here, but to get back to "not needed", I think I understand what you are saying. Correct me if I'm wrong.
You are saying you don't need a neutral in a switch leg. Right. This is part of the design of a three-way. Noone disagrees.
You are also saying you don't need a neutral (grounded conductor)to run with the travelers. I agree that you can wire this way (two wire)as long as you think it's OK to use a hot from one end (and cap the neutral) and use a neutral from the other end (and cap the hot).
No contemporary books on wiring show this as an accepted practice, but you can make a case that it is allowed by 1999 Code and after. I would agree, and that is what bothers me, since most electricians I know are not aware of the strength of the magnetic field caused by the net current loop set up by using two-wire travelers. (I am talking about more than a single light bulb).
The loop effect generates a high and even magnetic field within most of the loop. The travelers are one half of the loop. The psrt of the circuit which goes between the two switches is the other part of the loop, since this section contains either a hot carrying current or a neutral carrying current, but not both. So you have the loop effect.
The magnetic field strength needed to make a computer monitor jitter and to increase a child's chanced of leukemia (according to the World Health Organization - WHO)is about the same, starting at 5 milligauss. This can be generated by one amp of net current depending on distance to the conductors.
So my point is(sorry if I'm too far off Code discussion)that why do this to a building just to save the difference between two-wire and three-wire NM cable?
Karl
Re: the use of two wire romex in three-way switch loop
Are you mixing Grounded Circuit Conductor(s) up with Equipment Grounding Conductor(s) [ EGC ]?
As long as one of the EGC's that is with the circuit conductors is properly sized, I do not see a problem with multiple paths of EGC, especially of an single circuit.
If multiple parallel runs are involved, then there should be a properly sized EGC with each run.
It seems to me that almost all installations where equipment is grounded, there will be multiple paths thru the earth, building steel, other metal raceways in the building and other EGC's to other near-by equipment on a conductive floor such as concrete.
[ July 07, 2003, 07:16 AM: Message edited by: gwz2 ]
Are you mixing Grounded Circuit Conductor(s) up with Equipment Grounding Conductor(s) [ EGC ]?
As long as one of the EGC's that is with the circuit conductors is properly sized, I do not see a problem with multiple paths of EGC, especially of an single circuit.
If multiple parallel runs are involved, then there should be a properly sized EGC with each run.
It seems to me that almost all installations where equipment is grounded, there will be multiple paths thru the earth, building steel, other metal raceways in the building and other EGC's to other near-by equipment on a conductive floor such as concrete.
[ July 07, 2003, 07:16 AM: Message edited by: gwz2 ]
karl riley
Senior Member
Re: the use of two wire romex in three-way switch loop
gwz: I was not refering to the EGCs of a three-way switch circuit. I am talking about the current carrying conductors.
Karl
gwz: I was not refering to the EGCs of a three-way switch circuit. I am talking about the current carrying conductors.
Karl
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