Q. Are outlet boxes allowed to be supported by the ceiling framing members of a suspended ceiling system or must independent support wires be added?

A. Outlet boxes can be supported by the structural or supporting elements of a suspended ceiling, if securely fastened by one of the following methods [314.23(D)]:

  1. Ceiling-framing members. An outlet box can be secured to suspended-ceiling framing members by bolts, screws, rivets, clips, or other means identified for the suspended-ceiling framing member(s). If framing members of suspended-ceiling systems are used to support luminaires, they must be securely fastened to each other and must be securely attached to the building structure at appropriate intervals. In addition, luminaires must be attached to the suspended-ceiling framing members with screws, bolts, rivets, or clips listed and identified for such use [410.36(B)].
  2. Independent support wires. Outlet boxes can be secured, with fittings identified for the purpose, to the ceiling-support wires. If independent support wires are used for outlet box support, they must be taut and secured at both ends [300.11(A)] (see Figure). See 300.11(A) on the use of independent support wires to support raceways and cables.