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  1. #1
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    Wire size reduction for branch circuits

    My company installed LED lights in a school. The branch circuit is a 20 amp breaker with 12-2 wire. We installed 40 watt LED panels and a ceiling sensor with 14-3 MC from the switch leg box. The inspector failed us do to the fact the breaker is 20 amp therefore all wire must be 12 gauge. The ceiling sensor only draws 3 amps and has 18 wire hooked up internally. I referenced 240.5 (B)(2) witch states 14 can be used as fixture wire on a 20 amp breaker, but also went to table 402.3 and THWN is no listed. Is there any other code I should reference?
    Thanks all

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    The reference is that the inspector is correct. The sensor is part of the branch circuit not part of the fixture wiring so it must be 12 awg, IMO @D_Norris
    Last edited by Dennis Alwon; 05-01-19 at 05:37 PM.
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    Quote Originally Posted by D_Norris View Post
    My company installed LED lights in a school. The branch circuit is a 20 amp breaker with 12-2 wire. We installed 40 watt LED panels and a ceiling sensor with 14-3 MC from the switch leg box. The inspector failed us do to the fact the breaker is 20 amp therefore all wire must be 12 gauge. The ceiling sensor only draws 3 amps and has 18 wire hooked up internally. I referenced 240.5 (B)(2) witch states 14 can be used as [Red]fixture wire on a 20 amp breaker, [Red]but also went to table 402.3 and THWN is no listed. Is there any other code I should reference?
    Thanks all
    Fixture Wire is the wire that is located on the inside of light fixtures. The Branch Circuit wiring is the wiring from the breaker to the outlet box.

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    I agree, the #14 conductors are part of the branch circuit and must be a minimum of 20 amps unless you want to install 15 amp circuit breakers.
    Rob

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    All responses based on the 2014 NEC unless otherwise noted

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    Quote Originally Posted by xformer View Post
    Fixture Wire is the wire that is located on the inside of light fixtures. The Branch Circuit wiring is the wiring from the breaker to the outlet box.
    But what is the wire in the whip of a troffer? I always thought that was "fixture wire", as I dont see how it could be so small if it isnt.
    Ethan Brush - East West Electric. NY, WA. MA

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    Quote Originally Posted by electrofelon View Post
    But what is the wire in the whip of a troffer? I always thought that was "fixture wire", as I dont see how it could be so small if it isnt.

    That would be a fixture tap and fall under 402.5 and 240.5(B)(2).
    Rob

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    All responses based on the 2014 NEC unless otherwise noted

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    Quote Originally Posted by infinity View Post
    That would be a fixture tap and fall under 402.5 and 240.5(B)(2).
    And 240.5(B)(2) requires the use of fixture wire. Building wire of the same size is not permitted for that application. The only permitted wire types for that application are found in Table 402.3.
    Don, Illinois
    (All code citations are 2017 unless otherwise noted)

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    Quote Originally Posted by don_resqcapt19 View Post
    And 240.5(B)(2) requires the use of fixture wire. Building wire of the same size is not permitted for that application. The only permitted wire types for that application are found in Table 402.3.
    I don't see it requiring fixture taps to be fixture wire, it simply states allowable sizes to be used with different branch circuit ratings.

    410.117(C) allows any conductor type with suitable temp rating for the application to be used as a fixture tap, though that section applies to flush and recessed luminaires.

    410.62 (cord connected luminaires)also allows, with conditions, the use of smaller conductors than the branch circuit conductors.
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    Quote Originally Posted by electrofelon View Post
    But what is the wire in the whip of a troffer? I always thought that was "fixture wire", as I dont see how it could be so small if it isnt.
    If it is part of the fixture and its listing it is not under the NEC.

    Roger
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    Wire from remote ballast can be #14, #16 depending on distance.
    It's considered part of the fixture. Or was code could have changed from the last time I did any work.

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