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National Electrical Code Top Ten Tips: Article 402 -- Fixture Wires

by Mark Lamendola

Based on the 2023 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.

  1. 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.

  2. The NEC does not consider these "a wiring method." You cannot use fixture wires where Chapter 3 wiring methods are required.

  3. 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. In the 2023 version, you wil see Article 404 starting on the same page where Article 402 resides. You turn the page, and there's that big table. It takes up two pages, so you turn the page again and you find Table 402.5 seemingly in the middle of Article 404.
  4. The far right column of Table 402.3 appears to be worthless, because "Fixture wiring" is repeated in seemingly every cell. But things are not what they seem, there are a couple of variations. One is "limited to 300 volts" and the other is "nickel or nickel-coated copper".

  5. 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.

  6. 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.

  7. 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.
  8. 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.

  9. 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].

  10. In addition to using fixture wires for luminaires, you can use fixture wires for Class 1 control and power-limited circuits [724.49(A)] and nonpower limited fire alarm circuits [760.49(A)]; these references changed with the 2023 NEC.