Smoke detectors

Old 11-20-03, 11:27 PM
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Smoke detectors

Putting in smoke detectors(120 V.) in an old Sears and Robuck house. The panel is up to date however the wiring in house is early NM with no ground except for the garage witch was added on with the new panel. First question ... Do the smokes need to be put on an isolated circuit? Secondly... Do I need to place electrical boxes for each smoke or can I just run the wire strait into and out of each unit? Also. . plan to install a GFCI in the bathroom..can I use the exsisting circuit (NM no ground) to wire up the GFCI that has a ground?
Old 11-21-03, 06:19 AM
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Not sure about the smoke detector question.

As for the GFCI, yes you can use the wiring that is there with no ground. The GFCI should be marked "No equipment ground." The GFCI will still protect anyone using the outlet, there will just be no ground present in the event someone has a three prong device.
Old 11-21-03, 06:29 AM
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Check with your local fire department's prevention division on the smokes. Here in NH, they are NOT to be on their own circuit. The logic is that it's too easy to shut them off. Most are wired on a circuit with, say, a hallway light. The theory is that if the light stops working, someone will investigate and repair it, keeping the smoke detectors in service.

All splices/connections must be in a box.
Old 11-21-03, 06:29 AM
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Smoke detectors do not need to be on a dedicated circuit. In fact, it is preferrable that they share a circuit with a commonly used light so that you can tell if they have lost power.

You need an electrical box for each smoke detector. All electrical connections need to be made in permanently accessible junction boxes.
Old 11-21-03, 06:46 AM
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Nec 300.15 (a) says an electrical box complying with article 370 will be used at any splice point.
Couldnt locate anything specific about a smoke detector but is still considered a device, the ones in my house are installed with a switch box and 12/3 with ground for the interconnect between detectors...RL

Last edited by Rlfrazee; 11-21-03 at 07:03 AM.
Old 11-21-03, 02:08 PM
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Any line voltage wiring need to be in a box or enclosure. Period.

There is no reference to smokes in the NEC. They are a building code thing.

On that note. How does the code read for you guys with the smokes not dedicated. We need them interconnected. I run one in the basement and them 14/3 to each of the others. This way if one goes off they all do. I'm not personally fond of that method but I have no choice.
Old 11-21-03, 09:11 PM
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To everyone "Thanks"...great advice and "Logic" on this board....I finished the job under 6 hours today...had to jig saw out the holes and place the smoke in the hallway on the wall, duct work runs the entire hallway....Went ahead and installed the GFCI in the bathroom, used the existing circuit, receptical works but I hope inspector doesn't fail because of the open ground. May have to rewire from one of the garage circuits that is grounded.
Old 11-23-03, 08:20 AM
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If you were to run a new wire this would then need to be on a dedicated 20 amp circuit serving only receptacle loads in the bathroom.

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