National Electrical Code Top Ten Tips: Article 402 -- Fixture Wires
by Mark Lamendola
Based on the 2020 NEC
Please note, we do quote from copyrighted material. While the NFPA
does allow such quotes, it does so only for the purposes of education
regarding the National Electrical Code. This article is not a substitute
for the NEC.
These are the 10 NEC Article 402 items we deem most important, based
on the pervasiveness of confusion and the potential costs of same.
- Donít dismiss flexible cords and fixture wires as not deserving your
attention. There's a reason why the NEC covers them in two separate
articles. Flexible cord requirements are in Article 400 and fixture wire
requirements are in Article 402.
- The NEC does not consider these "a wiring
method." You cannot use fixture wires where Chapter 3 wiring
methods are required.
- Just as Article 400 provides a large table listing
flexible cords, so it provides Table 402.3 to list fixture wire
requirements. It's a big table relative to the article. The table is 2 pages, the rest of the article is about half a page.
- If you need to know the ampacity requirements for fixture wires, look no
further than Table 402.5. It will tell you, for example, that the allowable ampacity of 12 AWG fixture wire is 23A. It is a small table, with only 5 rows of data.
- The smallest fixture wire you can use is 18AWG [402.6]. Anything smaller is a Code violation. And you can use this size fixture wire for a maximum ampacity of only 6A.
- You must size your raceways so they allow you to install and remove fixture wires
without damaging the
insulation. This may leave your raceways with a lot of empty space; if so, don't worry about it.
- Don't exceed the percentage fill specified in Table 1, Chapter 9 [402.7]. See 300.17 for additional details. If all conductors in a
raceway are the same size and insulation, refer to Annex C for the
maximum quantity per raceway type.
- If you read 402.10, you'll see that you can use fixture wires
to connect luminaires. Don't read into this any more than it says. You
cannot use fixture wires as branch circuit conductors [402.12].
- In addition to using fixture wires for luminaires, you can use fixture
wires for Class 1 control and
power-limited circuits [725.27(B)], nonpower limited fire alarm
circuits [760.27(B)], and elevators and escalators [620.11(C)].
- You will find the requirements for using fixture wires for motor control circuit
taps in [430.72(A)].