National Electrical Code Top Ten Tips: Article 410 -- Luminaires, Lampholders, and Lamps
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 410 items we deem most important, based
on the pervasiveness of confusion and the potential costs of same.
- You may need to comply with more stringent requirements for
lights than those contained in Article 410. For example, if the
illumination equipment is in a hazardous location, apply Articles
500 through 517.
- No luminaire can have live parts exposed to contact [410.5]. This rule does not apply to cleat-style lampholders that are at least 8 ft above the floor.
- If the location is anything but clean and dry, use a luminaire
rated for that environment. Details of what to use where are in 410.10.
- Clothes closets have special requirements [410.16]. Follow them
carefully. This is a key area for inspection failure. Also, DIY
homeowners try to "improve upon" existing closet lighting and create
a fire hazard. If you are doing residential electrical work, make a
note of closet lighting conditions and make the homeowner sign off
as being aware of any violations you find.
- With dimming controls and other nice additions to today's
lighting systems, a common code violation is insufficient box size.
Canopies and outlet boxes must be of sufficient size so as not to
crowd the conductors [410.20]. In older homes that were built with incandescent lighint installed, it was common to retrofit those with dimming switches to reduce energy use. When replacing incandescent fixtures with their LED retrofit counterparts (or if simply using an LED A19 or similar lamp as a direct replacement in the socket for an incandescent), those old dimmers are no longer safe. In many cases, they won't even work. Should you replace each one with an LED-compatible dimmer? Not if energy-savings is the only reason the dimmer is there. The LED running at full illumination will use less power than an incandescent dimmed way down. A lot less. So one solution to a box size violation is to replace the dimmer switch with a toggle switch.
- You cannot leave open outlet boxes in a luminaire installation.
Ensure the box is covered with a canopy, lampholder, receptacle, or
similar device [410.22].
- Secure support of the luminaire is essential. Improper support
is a leading code violation in luminaire installations. Don't use
the screw shell of a lampholder to support any fixture weighing more
than 6lbs [410.30(A)].
- You can use an outlet box to support a fixture [410.36(A)].
- You cannot mount luminaires into ceiling tiles (using them as
support). Luminaires must be supported by frame members [410.36(B)]. Think about the logic here. Now, what do you think about using drywall in a drywalled ceiling to support a luminaire? You don't have to think hard to get the right answer....
- All exposed metal parts must be bonded. The NEC used to say grounded, but now it says connected to an equipment grounding conductor [410.42]. That will bond it, which is what you want. See Part VI of Article 410, but also Part V of Article 250.