Tap question

[robert pitre]

In a inspectors meeting we had,we were told by the chief building inspection that NEC tap rule allows that you can come off of a #12 gage wire with a 20amp breaker or a #14 gage wire with a 15 amp breaker feeding to a light switch and from the light switch to a junction box in the attic to feed lights with a #16 gage wire as a fixture wire as long as I don't exceed over 50 ft.
My question is ,once I put that#12 with 20amps or that #14 with 15 amps to that junction box can I run # 16 gage wire to light fixtures if I follow tap rule?:?

 

[charlie b]

I don't see anything in the code that would allow using the #14 wire on a 20 amp circuit or #16 wire on a 15 amp circuit.

 

[jumper]

I don't see anything in the code that would allow using the #14 wire on a 20 amp circuit or #16 wire on a 15 amp circuit.

Charlie, I believe OP is talking about fixture wire taps covered in 240.5(B)(2).

Personally, I am not real clear on how to apply these rules.

 

[charlie b]

Charlie, I believe OP is talking about fixture wire taps covered in 240.5(B)(2).

OK, that is a new thing to me. But I have to ask, since article 100 does not have the answer, and neither does article 310, what is "fixture wire"? I had thought that term applied to wire that was provided by the fixture manufacturer, and we connected our branch circuits to it. But the article you cited allows some fairly long runs of "fixture wire," and those runs are not provided by the manufacturer. So I am confused. :? Not the first time. :happyno:

 

[jstjohnz]

In a inspectors meeting we had,we were told by the chief building inspection that NEC tap rule allows that you can come off of a #12 gage wire with a 20amp breaker or a #14 gage wire with a 15 amp breaker feeding to a light switch and from the light switch to a junction box in the attic to feed lights with a #16 gage wire as a fixture wire as long as I don't exceed over 50 ft.
My question is ,once I put that#12 with 20amps or that #14 with 15 amps to that junction box can I run # 16 gage wire to light fixtures if I follow tap rule?:?

I believe so as long as you don't exceed the length limit and make sure the load is within the ampacity of the #16.

 

[jumper]

I know little more than you Charlie.

Fixture whips for troffers and such is the sum of my knowledge of this section.:ashamed1:

 

[GoldDigger]

OK, that is a new thing to me. But I have to ask, since article 100 does not have the answer, and neither does article 310, what is "fixture wire"?

Try Article 402 [2011] titled "Fixure Wire".
It has a table of wire types that qualify, as well as allowed amperages which are different from the Chapter 3 values. But the kicker is the usage restrictions:

402.10 Uses Permitted. Fixture wires shall be permitted (1) for installation in luminaires and in similar equipment where enclosed or protected and not subject to bending or twisting in use, or (2) for connecting luminaires to the branch-circuit conductors supplying the luminaires.

402.11 Uses Not Permitted. Fixture wires shall not be used as branch-circuit conductors except as permitted elsewhere in this Code.

The connecting to branch circuit wires part is the fixture whip you are thinking of.

 

[Smart $]

In a inspectors meeting we had,we were told by the chief building inspection that NEC tap rule allows that you can come off of a #12 gage wire with a 20amp breaker or a #14 gage wire with a 15 amp breaker feeding to a light switch and from the light switch to a junction box in the attic to feed lights with a #16 gage wire as a fixture wire as long as I don't exceed over 50 ft.
My question is ,once I put that#12 with 20amps or that #14 with 15 amps to that junction box can I run # 16 gage wire to light fixtures if I follow tap rule?:?

I believe the CBI is forgetting what fixture wires are for, i.e. a switch in a box by itself is not a fixture, and a j-box is also not a fixture.

External fixture wire must supply a fixture. That is, every fixture wire run, no matter where it originates, must terminate within a fixture. However, regarding the j-box, if the fixture wire is pulled through the j-box without splice (or tap ), then it is still the same run to the switch.

JMO

 

[infinity]

Long lengths of fixture wire would allow you to wire a long row of fixtures which are connected together. For example 240.5(B)(2)(2) would allow 100' of #16 fixture wire on a 20 amp circuit providing that the ampacity given in Table 402.5 is not exceeded. It's pretty common in commercial spaces to have long rows of fixture wired this way.