[steveodiy]

Greetings;

I am faced with having to install 7 interconnected and hardwired detectors in a duplex / raised bungalow home. For fire code regulations all 7 - four on the main level in an insulated ceiling, and 3 in the basement ceiling will be all be inter-connected. I am aware of wiring requirements. 14/2 from the panel or power source to the first unit, and then 14/3 to the remaining.

Fortunately the entrance to each of the 3 bedrooms on the main level is within no more than 6 feet of the attic hatch in one of the bedrooms.

My question is what is the suggested box / octagon box to use for these? I assume a retrofit box of some sort since nailing or screwing to a roof rafter is not practical. And since there is minimal weight to bear, a retrofix box installed from within the room vs from within the attic is what I would think?

Also, Is a separate and dedicated circuit required or suggested?

Thanks for any ideas/suggestions.

 

[rjniles]

An old work round box will work fine. The NEC doesn't require a dedicated circuit for smokes but some local codes have requirements. Some require dedicated, some require connecting to an existing lighting circuit. You need to talk to your code office.

Have you looked at wireless interconnected smokes? Ask the code office if allowed.

Sent from my Moto E (4) Plus using Tapatalk

 

[Kevin_Essiambre]

I'm not sure where you are so I won't comment on the detector wiring itself.

For mounting the boxes for them, there are a few ways to do it.

Option 1) install a retrofit octagon box. This could be a plastic or metal box with "wings" such as this box. I have personally only used 1 of these boxes (the metal ones)... and it was for a smoke detector. But keep in mind how big the box should be. I like to use a deep box for smoke detectors that have 2 cable or more. 6+ wires plus the pigtail (kiddie 3-in-1 have a weird pigtail that has to be shoved into the box as well) can become very hard in a standard 1.5" deep box. For one cable, you're fine.

Option 2) cut the hole for the box beside a joist/rafter and fasten the box directly to the structure.

Option 3) this option we use for lights more than anything else. You can cut blocks from 2x material, screw them (or if you have patience, glue and clamp them) beside the hole you made for the box. Then screw the box into these boards. This trick is similar to option 1, but can hold more weight (I wouldn't advise trying to hang a ceiling fan with this method however). We use this method for installing pendant lights over island counters that were not decided upon during construction. Lately I've been gluing the blocks in, because then I have no screws to worry about patching... but with a smoke detector, it you do it right, the smoke detector could probably hide the screws.

Sent from my new phone. Autocorrect may have changed stuff.

 

[steveodiy]

I'm not sure where you are so I won't comment on the detector wiring itself.
For mounting the boxes for them, there are a few ways to do it.

Option 1) install a retrofit octagon box. This could be a plastic or metal box with "wings" such as this box. I have personally only used 1 of these boxes (the metal ones)... and it was for a smoke detector. But keep in mind how big the box should be. I like to use a deep box for smoke detectors that have 2 cable or more. 6+ wires plus the pigtail (kiddie 3-in-1 have a weird pigtail that has to be shoved into the box as well) can become very hard in a standard 1.5" deep box. For one cable, you're fine.

Thanks for your reply. I am in Ontario, Canada. The polycarbonate box you refer to from Home Depot is the exact one I have already seen and been looking for. It is made by Carlon, p/n B618RR. Since I am putting some of these in an isulated ceiling, I like the idea of using the right size hole saw for these round boxes, not going any deeper than the drywall, and hopefully doing minimal if any damage to the vapour barrier and insulation. For some reason though, Home Depot in Canada does not carry these, nor does Lowes and I have tried one electrical distributor as well... makes me wonder if there is some code requirement that prevents a polycarbonate / plastic box here in Ontario.. can anyone comment?

Thanks!