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Thread: Neutral for light wired to box of 3-way switch

  1. #1
    DIY Junior Member adamt1984's Avatar
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    Default Neutral for light wired to box of 3-way switch

    I opened up a switch box and found that a light fixture was added next to the switch which is at the top of my basement stairs. The switch is a 3 way. The hot for the added light is connected to the switch, and the neutral is screwed into the back of the switch box. I am not sure who wired this, but judging from the age of the fixture and wires i would say it has been this way for 30+ years. The house was built in the mid 40's and the wiring is in a metal jacket.

    My assumption is that this is a safety hazard that i was lucky to catch, and the light should be disconnected.

    Unfortunately the switch is original and pulling a new wire would be a nightmare. I would like to keep the light. Is it possible to disconnect the 2nd switch in the basement, and use the old 3 way wire as a neutral?

  2. #2
    DIYer, not in the trades LLigetfa's Avatar
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    I'm no code guru but do know that using the protection ground for a neutral return is wrong. As for using one of the other insulated conductors, I think code says it must be in the same jacket as the hot and if it is not white in colour that it probably needs to be identified, perhaps with white electrical tape. I do know when a white is used as a hot it has to be identified with tape or a SharpieŽ.

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    Electrical Contractor/Instructor jwelectric's Avatar
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    The white neutral conductor is never to touch in any way any type of metal after leaving the service equipment.
    There is an exception to this for ranges and dryers that originate in the service equipment.
    This has always been the rule.

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    DIYer, not in the trades LLigetfa's Avatar
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    Quote Originally Posted by jwelectric View Post
    The white neutral conductor is never to touch in any way any type of metal after leaving the service equipment.
    ...
    This has always been the rule.
    Has it been the rule for transformerless devices like TVs? I remember when they first came on the market that if the polarized plug was filed down and/or plugged into an improperly wired outlet that I'd get some nasty shocks from the rabbit ear antenna or external antenna terminal.

    What about the OP's question about using the old 3 way wire as a neutral?

  5. #5
    DIY Senior Member kreemoweet's Avatar
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    Nothing can be said about the 3-way switch wiring, until the OP provides more information. He/she gave no details at all about that, or what
    might be or was connected to the switch, etc. etc. It's certainly conceivable there might be a way to provide a usuable neutral for the new light,
    but its all sheer speculation at the moment.

  6. #6
    Electrical Contractor/Instructor jwelectric's Avatar
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    Quote Originally Posted by LLigetfa View Post
    Has it been the rule for transformerless devices like TVs? I remember when they first came on the market that if the polarized plug was filed down and/or plugged into an improperly wired outlet that I'd get some nasty shocks from the rabbit ear antenna or external antenna terminal.
    Even back in the day of tubes there was a transformer

    Quote Originally Posted by LLigetfa View Post
    What about the OP's question about using the old 3 way wire as a neutral?
    Don't know how it is wired. A couple of pictures of each switch would go a long way. It would still need to be on a three way due to there being stairs in the picture

  7. #7
    DIYer, not in the trades LLigetfa's Avatar
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    Quote Originally Posted by LLigetfa View Post
    I remember when they first came on the market...
    Quote Originally Posted by jwelectric View Post
    Even back in the day of tubes there was a transformer...
    LOL Did you just say that I am really really old? The vacuum tube TV was invented over a hundred years ago and became popular in the 40's. They drew a hefty current and did not have transformerless power supplies. It was the solid state TVs that came out with transformerless supply versions due to the lower current draw. Mind you, they still had flyback transformers.

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    Electrical Contractor/Instructor jwelectric's Avatar
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    Quote Originally Posted by LLigetfa View Post
    LOL Did you just say that I am really really old?
    Maybe I will tell my age but way back when I went to college we stuided the vacuum tube. My first saw tooth generator used tubes from an old spot welder.

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    Jack of all trades DonL's Avatar
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    On a lot of the much older houses the neutral wire was as close to ground as you could get.

    It was common to see the neutral wire connected to the electrical outlet box for ground.

    If you changed a 2 prong outlet to a 3 then the neutral was the only wire to use for ground, unless you ran a new wire.


    On new school stuff, If the switch is lit or requires power and is on a GFI, the GFI could trip if the the ground is used, in place of neutral. The GFI should see the difference.
    Last edited by DonL; 02-11-2013 at 04:27 PM.
    Theory only works perfect in a vacuum.

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    Retired Defense Industry Engineer jadnashua's Avatar
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    Quote Originally Posted by DonL View Post
    On a lot of the much older houses the neutral wire was as close to ground as you could get.

    It was common to see the neutral wire connected to the electrical outlet box for ground.

    If you changed a 2 prong outlet to a 3 then the neutral was the only wire to use for ground, unless you ran a new wire.

    Because neutral carries current, it should never be used as ground. Ground is a safety, alternative path to help ensure the protection device trips should there be a fault. The only two approved methods to use a 3-prong receptacle when there's no ground is to either totally rewire, or substitute a GFCI into the circuit. It affords that extra layer of protection the ground normally would. The only way to add a ground would be if it were run through a conduit, and you could fish a new lead through that, otherwise, the rules regarding within the jacket of the cable would apply.
    Jim DeBruycker
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  11. #11
    Jack of all trades DonL's Avatar
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    Quote Originally Posted by jadnashua View Post
    Because neutral carries current, it should never be used as ground. Ground is a safety, alternative path to help ensure the protection device trips should there be a fault. The only two approved methods to use a 3-prong receptacle when there's no ground is to either totally rewire, or substitute a GFCI into the circuit. It affords that extra layer of protection the ground normally would. The only way to add a ground would be if it were run through a conduit, and you could fish a new lead through that, otherwise, the rules regarding within the jacket of the cable would apply.

    I agree.

    People that fixed their own stuff in the old days, Did not even know the code. Or how electricity worked.

    They just knew it worked after they replaced the outlet that they bought at Montgomery Ward for 25 cents.

    Now you have to go to Walmart too get that price.
    Last edited by DonL; 02-11-2013 at 05:28 PM.
    Theory only works perfect in a vacuum.

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    Moderator & Master Plumber hj's Avatar
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    Whether you can disconnect both ends of the "spare wire" and use it for a neutral, depends on whether there is an available neutral in the other switch box. There does NOT have to be depending on how the wiring was done.
    Licensed residential and commercial plumber

  13. #13
    DIY Senior Member bluebinky's Avatar
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    Quote Originally Posted by jwelectric View Post
    Even back in the day of tubes there was a transformer
    There were AC/DC radios without a transformer. The filament voltages added up to 115V so they had weird tubes like 50C5, 12AV6, 35W4, instead of all the same like 6V6, 6H6, 6LS7 in an AC only set... If you plugged them in backwards, the chassis was hot. If you plugged them in correctly, the chassis was also sometimes hot when the power switch was off. I used to hate working on them...

    Sorry for the trivia!

  14. #14
    Moderator & Master Plumber hj's Avatar
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    A few times, I have gone past refrigertors, once in a restaurant, with my TicTracer turned on and it went "wild" when I went past them. They were plugged in, or wired, backwards and the cases were hot. The only thing that saved the customers was that there was no grounded metal nearby that they could touch at the same time. THe same thing happened with a friend's mobile home, but since they had wood steps they also could not ground themselves when they opened the door. They would have been in "bad shape" however if they had had wet shoes and were standing on the ground when they touched it.
    Licensed residential and commercial plumber

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