I want to install a light switch shutoff in my house for a yard light that is on the shop and is fed electrically from the shop panel across the driveway. We shut the light off when we are using our hot tub in the back of the house. I have run conduit under the driveway and want to know is it better or legal to use the neutral wire for the light switch or does it have to be the hot wire?
Use of hot or neutral for light shutoff
- Thread starter ken Horn
- Start date
- Status
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
The NEC generally does not allow you to switch a grounded conductor unless you simultaneously open all hot conductors in the circuit too.
Switching the grounded conductor can lead to safety problems. One such result would be putting line voltage on the shell part of a light bulb socket.
If you are talking instead about which insilated conductor in a piece of NM used as a switch leg you should use for which side of the switch, it does not matter.
jaylectricity
Senior Member
- Location
- Massachusetts
- Occupation
- licensed journeyman electrician
Back in the days before we included an equipment ground conductor it was "basically" safer to switch the neutral than it is now. But I have no idea why anybody ever thought that switching the neutral was better than switching the hot.
In fact, I'm curious as to why you're even considering it.
In fact, I'm curious as to why you're even considering it.
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The reason I was considering it was I bought this house a year ago and that was how it was wired. It used the neutral for the disconnect of the light in the house. I am putting a new panel in the shop and pulling new wires in underground conduit for the panel. I will then also pull two thhn wires for the light so I can shut it off. I thought it was against code to use the neutral but was also looking at the fact of current carrying conductors and wire derating in amperage. With the light wires in the conduit I would have to derate my amperage on my main feed wires as I will have 5 current carrying wires, two #2's,one #6 for the neutral feeding the 100 amp panel and two #12's for the light. I am grounding the panel at the shop separately.
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The reason I was considering it was I bought this house a year ago and that was how it was wired. It used the neutral for the disconnect of the light in the house. I am putting a new panel in the shop and pulling new wires in underground conduit for the panel. I will then also pull two thhn wires for the light so I can shut it off. I thought it was against code to use the neutral but was also looking at the fact of current carrying conductors and wire derating in amperage. With the light wires in the conduit I would have to derate my amperage on my main feed wires as I will have 5 current carrying wires, two #2's,one #6 for the neutral feeding the 100 amp panel and two #12's for the light. I am grounding the panel at the shop separately.
I think that is a good question. Ken, please clarrify what you are asking, is it the use of the white conductor or are you asking if you can switch the grounded (neutral) conductor?
Roger
jaylectricity
Senior Member
- Location
- Massachusetts
- Occupation
- licensed journeyman electrician
OK...just don't. Use the thhn switch legs to switch the ungrounded. I was always taught to be afraid of switching that was based on previous wiring.
This is your chance to fix it. To keep ungrounded conductors from being available with no disconnect.
I may be stupid, but I'm really interested in anybody's argument as to why anybody should use a switched neutral. I'm open minded. Anybody please tell me why switching neutrals offer any sort of advantage at all.
This is your chance to fix it. To keep ungrounded conductors from being available with no disconnect.
I may be stupid, but I'm really interested in anybody's argument as to why anybody should use a switched neutral. I'm open minded. Anybody please tell me why switching neutrals offer any sort of advantage at all.
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
It can be used for some interesting non-standard three-way switch setups
ggunn
PE (Electrical), NABCEP certified
- Location
- Austin, TX, USA
- Occupation
- Consulting Electrical Engineer - Photovoltaic Systems
My, my, that house afire is interesting...
readydave8
re member
- Location
- Clarkesville, Georgia
- Occupation
- electrician
I have also always wondered, have come across many handymen, homeowners, etc. who swear by it, see it often enough that I have to keep in mind when troubleshooting older and DIY wiring. Was there an advantage in K&T days that no longer exists? Seeing as how it was very common in old houses around here.
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
If you unscrewed the bulb(s), it made the switch touch safe for repair or troubleshooting without having to pull the fuse for the whole circuit. (There were not a lot of circuits in one house back in those days, so pulling the fuse could hit all of the lights.) My SWAG anyway.
- Location
- Tennessee NEC:2017
- Occupation
- Semi-Retired Electrician
If by what I highlighted in red you mean that the only EGC will be at the shop (from whatever electrode you use), then that is not allowed, you also need to run an EGC from the house. You will need to run 4 wires from the house, not counting the two for the light. You would need two hots, one neutral, and one ground (EGC).
Also, you need to isolate the neutral from the EGC at the shop sub panel.
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
If it will make a difference in your ability to get all of the wires you need through an existing path, you can save the two wires of the switch leg by using a wireless remote switch instead.
MichaelKelley
Member
I do not think this is standard use of using and I think the setup is completely irrelevant and you should find some other way of using this as mentioned by many here.
readydave8
re member
- Location
- Clarkesville, Georgia
- Occupation
- electrician
I don't want to sound condescending
But often when the person doing the wiring asks questions this basic, he may be unfamiliar with other issues, not be familiar enough with the type of wiring he is doing, to realize there are violations of code that others would not even have to think about.
I know this because of some of my screw-ups, thought I was doing good-quality work but didn't know enough about what I was doing to know that I did something wrong.
So break the hot, not the "neutral," and get someone to look at the work before covering up.
But often when the person doing the wiring asks questions this basic, he may be unfamiliar with other issues, not be familiar enough with the type of wiring he is doing, to realize there are violations of code that others would not even have to think about.
I know this because of some of my screw-ups, thought I was doing good-quality work but didn't know enough about what I was doing to know that I did something wrong.
So break the hot, not the "neutral," and get someone to look at the work before covering up.
readydave8
re member
- Location
- Clarkesville, Georgia
- Occupation
- electrician
I finally realized that OP's question had to do with light switch in vicinity of hot tub, contactor with low voltage coil, low voltage to switch, would be a possible solution.
ptonsparky
Tom
- Occupation
- EC - retired
:thumbsup:
kwired
Electron manager
- Location
- NE Nebraska
I don't know that the switch was in close proximity to the hot tub, just much closer than the light location which was on/near a different building, and they wanted to turn this light off when using the hot tub.
kwired
Electron manager
- Location
- NE Nebraska
BB gun works great for turning the light off, but not so well for turning it back on:lol:
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