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Question:

Hard wired smoke detectors/suspended ceiling?

Is there any requirements regarding hard wired smoke detectors on a suspended ceiling?I know luminaires are supposed to be properly secured to the grid, do smoke and CO detectors need to be? If so how?Right now, all I have is some old work boxes for the splices.I'm looking for a correct answer, I'm not going to cut corners.NEC code references are a plus.

Answer:

Yes there are: Because the hard wired smoke detectors are connected to 120 volts they fall under the NEC Wiring methods NEC Article 300. The specific location is 300.11 It gives all of the rules about not using the grid support wires as a method of sole support. You do have to add a support wire the same as a luminary. The best way to attach the old work boxes is to use a bracket called a T-bar they are made by Caddy and several other companies. You also have to make sure that the suspended ceiling is not being used as a return air path for a forced air system because the NFPA 72 states that the minimum distance from a return air to a smoke or CO2 detector is 3 feet. Hope this answers your question :)
Apr 14, 2017
The cirping is the result of either a bad detector or other problem. Try turning off the breaker that supplies power to the detectors for 10-15 seconds and turning it back on. If it was nothing serious then this should clear the chirping but if the noise returns you may need to replace the detector and if you need to do that i would suggest a hard wired unit with battery back up.
Apr 14, 2017
Not sure what they are called but they make a bar that goes from grid to grid with a clip on each end that you can mount a 4square box to in a drop ceiling call your local elec supply Store they will know
Apr 14, 2017

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