As addressed in the 2011 edition of the NEC, a 2-ft by 2-ft or 4-ft by 4-ft lay-in type fluorescent luminaire installed in a suspended ceiling shall be supported by which of the following means?
- Approved, independent support wires of appropriate strength and material installed on all four corners of the luminaire.
- Approved, independent support wires of the appropriate strength and material installed on two opposite corners of the luminaire.
- Framing members of ceiling support systems securely fastened to each other and securely fastened to the structure at appropriate intervals.
- The NEC does not permit you to add any additional support wires to support these type of luminaires.
Although some states and cities may require additional support wires for the luminaires as described above, the NEC does not require support other than that described in 410.36(B).
"Framing members of suspended ceiling systems used to support luminaires shall be securely fastened to each other and shall be securely attached to the building structure at appropriate intervals. Luminaires shall be securely fastened to the ceiling framing member by mechanical means such as bolts, screws, or rivets. Listed clips identified for use with this type of ceiling framing member(s) shall also be permitted."
However, it may be a good practice to install additional support for the lay-in luminaires. Note: Some fire marshals may also request additional support for the lay-in luminaires.
Owen is the owner and president of National Code Seminars and the holder of master electrician certifications in 46 states. He can be reached at firstname.lastname@example.org.