Neutral as a hot in switching.

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82angelfan

Member
Location
Hesperia, Ca
I am working a commercial T.I. build out. My lighting system changed from CAT5e LV switches to Line Voltage dimmer. I am trying to adapt luminaire cable to the EMT stubs using a Bridgeport adapter. I have ton of 12/2 luminaire cable. Can I tape my neutral orange (277) and use as the line side of switch, similar to the way it is done in residential? Is there a code preventing this. I also have the option of a 12/4 mc and using the neutral as a 0-10 leg.
 
AC\DC said:
I’ll have to look I don’t think you can switch the neutral- can do the phase- why would you want to do that vs the phase?
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He is not switching the neutral. He is wanting to re-identify the white wire in a cable wiring method as an ungrounded conductor to use a 2 conductor cable down to a switch. The re-identified white will be the supply to the switch and the ungrounded conductor the return to the lights. See 200.7(C)(1).
 
As others stated you are allowed to re-identify the white/gray conductor but you also have 404.2(C) to consider.
 
AC\DC said:
I’ll have to look I don’t think you can switch the neutral- can do the phase- why would you want to do that vs the phase?
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I am trying to avoid ordering more luminaire cable, or flexing in the switch to the box. I have a ton of 12/2 Luminaire cable from another job. My plan is to phase tape neutral and use it as the hot. The switch does not require a neutral.
 
Little Bill said:
404.2(A) exception says switch loops don't require a grounded conductor
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Two different things.

404.2(A) is titled three and four way switches. The exception is referencing keeping all circuit conductors together in ferrous metal raceways as required in 300.20(A).

404.2(C) requires a grounded conductors at the switch location unless you meet one of the exceptions.
 
curt swartz said:
Two different things.

404.2(A) is titled three and four way switches. The exception is referencing keeping all circuit conductors together in ferrous metal raceways as required in 300.20(A).

404.2(C) requires a grounded conductors at the switch location unless you meet one of the exceptions.
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I see that the exception is under paragraph A only.
I think the whole rule is dumb and unneeded.
Also, you don't normally think of a switch loop in a 3-way, or 4-way circuit.
 
Little Bill said:
Also, you don't normally think of a switch loop in a 3-way, or 4-way circuit.
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Seen a lot on older installations that the power went to fixture first then to the switch and back. Probably dates to when most lights having pull string, or fixture mounted switches. Was in an old mfg building that hadn't been updated since electric was initially supplied in the early 30's or 40's that every light on the mfg floor had pull string lights.

82angelfan said:
Can I tape my neutral orange (277) and use as the line side of switch, similar to the way it is done in residential?
Click to expand...
Just need to remember that besides reidentifying the neutral, it is suppose to be the full hot side not the switched side (200.7(C)(1)). Seen many mistakes made resulting from both it not being marked and it being "dead" with switch "off" so assumption that it is still a neutral. such is bad enough in a resi system, but when you get into a larger multi light setup in a commercial application it can become very dangerous especially when you get into the 277 size.
 
Fred B said:
Seen a lot on older installations that the power went to fixture first then to the switch and back. Probably dates to when most lights having pull string, or fixture mounted switches. Was in an old mfg building that hadn't been updated since electric was initially supplied in the early 30's or 40's that every light on the mfg floor had pull string lights.


Just need to remember that besides reidentifying the neutral, it is suppose to be the full hot side not the switched side (200.7(C)(1)). Seen many mistakes made resulting from both it not being marked and it being "dead" with switch "off" so assumption that it is still a neutral. such is bad enough in a resi system, but when you get into a larger multi light setup in a commercial application it can become very dangerous especially when you get into the 277 size.
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Yeah, This is the reason you should use the neutral as the hot, not the switched side.
 
A lot of European equipment is wired like this. Switched neutral. They do it because there is less of a coronal arc on the contacts. Lasts longer.
 
herding_cats said:
A lot of European equipment is wired like this. Switched neutral. They do it because there is less of a coronal arc on the contacts. Lasts longer.
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The switch interrupts the same current and sees the same open circuit voltage in a series circuit regardless of where in the circuit it’s positioned. How can any arcing be different?
 
My parents home in Brooklyn had some switched neutrals but not to get sidetrack--the original poster is not using a neutral. Often times people think a white wire is a neutral.
If the run to the switch was in conduit then he would not be allowed to use a white wire and reidentify it.
 
Dennis Alwon said:
My parents home in Brooklyn had some switched neutrals but not to get sidetrack--the original poster is not using a neutral. Often times people think a white wire is a neutral.
If the run to the switch was in conduit then he would not be allowed to use a white wire and reidentify it.
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Yeah, its become quite pervasive. The electrons don't know what color the insulation of the wire is. In a cable assembly, its just a wire that is color coded, that typically means one thing, but not always. I learned what a switch loop was and that a white wire isn't always a neutral when I was 14 changing light fixtures, and the lesson was quite shocking, and I haven't messed it up since.
 
infinity said:
This entire group of sections is a mess and needs to re-written as:
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Why? Last I checked the standard switch installed to control lighting doesn't need a neutral, its just a switch. I would be willing to bet that less than 5% of lighting control devices in wall boxes require a neutral.
 
Little Bill said:
I see that the exception is under paragraph A only.
I think the whole rule is dumb and unneeded.
Also, you don't normally think of a switch loop in a 3-way, or 4-way circuit.
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If your three/four way arrangement has a "dead end" three way instead of feeding on to the load after the last switch in the series, you have a loop, it just has two possible paths as one side of the loop using the OR logic function through those two possible paths
 
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