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Wire size reduction for branch circuits

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  • rondel4355
    replied
    Good piece of information posted here.

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  • don_resqcapt19
    replied
    Originally posted by kwired View Post
    So is it acceptable to use a fixture tap that is THHN in flex or AC/MC cable or must you run same size as branch circuit when using those methods?

    I think 410.117 is one place that specifically says you can, though that is a specific situation and not a general thing there.
    In my opinion if you want to protected the fixture tap wires at the ampacities specified in 240.5(B)(2) the conductors must be fixture wire and not THHN.

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  • kwired
    replied
    Originally posted by don_resqcapt19 View Post
    Correct, if it is not one of those, nothing in the section applies. However that means other than the very very limited branch circuit taps permitted in Article 210, those other conductors have to be protected at their ampacity.

    AC and MC are not flexible cables, and neither is THHN. Flexible cables are those found in Table 400.4.
    So is it acceptable to use a fixture tap that is THHN in flex or AC/MC cable or must you run same size as branch circuit when using those methods?

    I think 410.117 is one place that specifically says you can, though that is a specific situation and not a general thing there.

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  • don_resqcapt19
    replied
    Originally posted by kwired View Post
    Correction, 240.5 is titled "Protection of Flexible Cords, Flexible Cables, and Fixture Wires."

    If your tap conductor is not fixture wire flexible cord or flexible cable, nothing in 240.5 applies to it, is what I have been trying to say all along.

    Does AC or MC cable count as flexible cable? If so then I take back some of what I said. How about THHN in flexible metal conduit? Supposed to be a raceway not a cable?
    Correct, if it is not one of those, nothing in the section applies. However that means other than the very very limited branch circuit taps permitted in Article 210, those other conductors have to be protected at their ampacity.

    AC and MC are not flexible cables, and neither is THHN. Flexible cables are those found in Table 400.4.

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  • kwired
    replied
    Originally posted by kwired View Post
    Why? 240.5(B)(2) is titled "Protection of Flexible Cords, Flexible Cables, and Fixture Wires." If there is such a rule on other "tap conductors" to a luminaire they it can certainly be in some other section, this one is or fixture wire. I didn't find any specific general rule for tap conductors that are other than fixture wire or cord, but did find the couple specific applications I mentioned code sections for.
    Originally posted by don_resqcapt19 View Post
    (B)(2) is specific to fixture wire. (B)(1), (B)(3) and (B)(4) apply to flexible cords. (A) covers the requirements for flexible cable.
    I see nothing in the other sections that you cited that act to change the requirements of 240.5.
    Correction, 240.5 is titled "Protection of Flexible Cords, Flexible Cables, and Fixture Wires."

    If your tap conductor is not fixture wire flexible cord or flexible cable, nothing in 240.5 applies to it, is what I have been trying to say all along.

    Does AC or MC cable count as flexible cable? If so then I take back some of what I said. How about THHN in flexible metal conduit? Supposed to be a raceway not a cable?

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  • don_resqcapt19
    replied
    Originally posted by kwired View Post
    Why? 240.5(B)(2) is titled "Protection of Flexible Cords, Flexible Cables, and Fixture Wires." If there is such a rule on other "tap conductors" to a luminaire they it can certainly be in some other section, this one is or fixture wire. I didn't find any specific general rule for tap conductors that are other than fixture wire or cord, but did find the couple specific applications I mentioned code sections for.
    (B)(2) is specific to fixture wire. (B)(1), (B)(3) and (B)(4) apply to flexible cords. (A) covers the requirements for flexible cable.
    I see nothing in the other sections that you cited that act to change the requirements of 240.5.

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  • kwired
    replied
    Originally posted by don_resqcapt19 View Post
    After taking another look the rules in 240.5(B)(2) included conductors 14 and larger. I think the code language in 240.5(B)(2) needs fixing. As I re-read it, you must use fixture wire anytime you are protecting the conductors at the ampacities listed in that section. Some types of fixture wire is available in 12 and 14 AWG, but I think the code needs fixing here. Not sure there is any reason to have the OCPD rating based on the type of insulation on the conductors. The insulation type is the only real difference between other conductors of the same size and fixture wire.
    Why? 240.5(B)(2) is titled "Protection of Flexible Cords, Flexible Cables, and Fixture Wires." If there is such a rule on other "tap conductors" to a luminaire they it can certainly be in some other section, this one is or fixture wire. I didn't find any specific general rule for tap conductors that are other than fixture wire or cord, but did find the couple specific applications I mentioned code sections for.

    Leave a comment:


  • don_resqcapt19
    replied
    Originally posted by kwired View Post
    If you are using smaller than 14 AWG I agree, it must be fixture wire, my point all along here has been that use of tap conductors is not limited to fixture wire only.
    After taking another look the rules in 240.5(B)(2) included conductors 14 and larger. I think the code language in 240.5(B)(2) needs fixing. As I re-read it, you must use fixture wire anytime you are protecting the conductors at the ampacities listed in that section. Some types of fixture wire is available in 12 and 14 AWG, but I think the code needs fixing here. Not sure there is any reason to have the OCPD rating based on the type of insulation on the conductors. The insulation type is the only real difference between other conductors of the same size and fixture wire.

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  • kwired
    replied
    Originally posted by don_resqcapt19 View Post
    I stand by my statement that if you are using conductors smaller than 14 AWG and protected in accordance with the ampacities shown in 240.5(B)(2), you are required to use fixture wire. 410.117 says nothing about the required overcurrent protection of the "tap conductor".
    If you are using smaller than 14 AWG I agree, it must be fixture wire, my point all along here has been that use of tap conductors is not limited to fixture wire only.

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  • Gary11734
    replied
    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 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
    #14 in a school? I don't think so!

    Check their specs. I assure you, no #14. The code doesnt matter when you enter the ivory towers of school work...

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  • don_resqcapt19
    replied
    Originally posted by kwired View Post
    It does not say tap conductors must be fixture wire, it along with the table tell us what size/length fixture wire is acceptable on certain branch circuits.

    Other sections I mentioned have situations where tap conductors can be used and no mention of fixture wire - 410.117 even mentions MC or AC cable which won't have fixture wire in them.
    I stand by my statement that if you are using conductors smaller than 14 AWG and protected in accordance with the ampacities shown in 240.5(B)(2), you are required to use fixture wire. 410.117 says nothing about the required overcurrent protection of the "tap conductor".

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  • don_resqcapt19
    replied
    Originally posted by electrofelon View Post
    So I could take any light fixture and use up to 50 feet of 18 AWG fixture wire in a chapter three raceway to connect it to the branch circuit? OR does it have to come from the factory as part of the fixture to use 240.5(B)(2)?
    Yes, you are permitted to do that, as long as it feeds a single fixture.

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  • kwired
    replied
    Originally posted by don_resqcapt19 View Post
    The wording in 240.5(B)(2) says those sizes are fixture wire. When you buy a pre-made whip with conductors smaller than 14, they are always made up using fixture wire.

    The types of conductors that are fixture wire are listed in Table 402.3.
    It does not say tap conductors must be fixture wire, it along with the table tell us what size/length fixture wire is acceptable on certain branch circuits.

    Other sections I mentioned have situations where tap conductors can be used and no mention of fixture wire - 410.117 even mentions MC or AC cable which won't have fixture wire in them.

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  • electrofelon
    replied
    Originally posted by don_resqcapt19 View Post
    The wording in 240.5(B)(2) says those sizes are fixture wire. When you buy a pre-made whip with conductors smaller than 14, they are always made up using fixture wire.

    The types of conductors that are fixture wire are listed in Table 402.3.
    So I could take any light fixture and use up to 50 feet of 18 AWG fixture wire in a chapter three raceway to connect it to the branch circuit? OR does it have to come from the factory as part of the fixture to use 240.5(B)(2)?

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  • don_resqcapt19
    replied
    Originally posted by kwired View Post
    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.
    The wording in 240.5(B)(2) says those sizes are fixture wire. When you buy a pre-made whip with conductors smaller than 14, they are always made up using fixture wire.
    240.5(B)(2) Fixture Wire. Fixture wire shall be permitted to be tapped to the branch-circuit conductor of a branch circuit in accordance with the following: ...
    The types of conductors that are fixture wire are listed in Table 402.3.

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