Ceiling elctrical box required for AC smoke alarm?


  #1  
Old 02-15-09, 11:51 AM
T
Member
Thread Starter
Join Date: Feb 2008
Location: US
Posts: 166
Received 0 Votes on 0 Posts
Ceiling elctrical box required for AC smoke alarm?

I would like to tap into ceiling light circuit and add wiring for an AC operated smoke alarm in the bedroom..

Is it necessary/required to make a regular large hole (say 3.5”) on the ceiling wallboard and install a regular ceiling fixture electrical box ?
 
  #2  
Old 02-15-09, 03:22 PM
W
Member
Join Date: Jun 2008
Location: VA.
Posts: 812
Received 1 Vote on 1 Post
Yes, you can use a round old work box, very simple to install and readily available at any home center.
 
  #3  
Old 02-15-09, 07:11 PM
pcboss's Avatar
Forum Topic Moderator
Join Date: Jul 2002
Location: Maryland
Posts: 15,259
Received 114 Votes on 99 Posts
Yes a box is required. I use a 4" hole saw and install a round old work box.

If you are adding alarms where there are already others they should be wired together so that if one goes off they all go off.
 
  #4  
Old 02-16-09, 01:13 PM
T
Member
Thread Starter
Join Date: Feb 2008
Location: US
Posts: 166
Received 0 Votes on 0 Posts
Thanks for the replies.

Some more questions came up…

1) After some searching I find a wide range of opinions/codes about smoke detector placement on the ceiling. Some suggest 4” min others up to 12” yet others suggest staying close to the center of the ceiling…not sure what to do…

2) I am planning to feed AC to smoke detector by tapping into ceiling light supply. So, I plan to cut AC supply to ceiling lights run and install a new junction box. Is it necessary to take extra care to keep the junction box away from insulation? Seems like a good idea, on the other hand, all my ceiling light boxes are buried under insulation ?!

P.S. I would have preffered to avvoid adding a new junction box but… tapping for new AC wire at closest ceiling light fixture does not seem feasible - too crowded in there with the light switch splices all inside these small older boxes.

Thanks
 
  #5  
Old 02-16-09, 06:22 PM
B
Member
Join Date: Oct 2008
Posts: 1,312
Received 0 Votes on 0 Posts
I've never seen rules change more than they have with smoke detectors! So probably best to check with your local electrical inspector and/or fire department and see what the rules of the day currently are. Also read the directions which came with the unit.

FYI - I have a battery smoke detector mounted on a wall just outside my kitchen (bedroom there) and it goes off with a quickness if any little amount of smoke! It was on the ceiling and I moved it down on the wall hoping it would not go off as much. But it still does!

As to electrical boxes... It is common for connections to fail and sparks to fly. So best that connections be contained within a metal box!
 
  #6  
Old 02-16-09, 06:54 PM
W
Member
Join Date: Jun 2008
Location: VA.
Posts: 812
Received 1 Vote on 1 Post
They usually just say between 4" and 12" from the wall or ceiling because smoke has a tendency to "roll" around the corners so if it's too close it will miss and if it's too far it will miss it.

Also, I want to say 3' from an HVAC return or supply register.

And no closer than 1' and no farther than 3' from the peak in a vaulted ceiling.
 
  #7  
Old 02-16-09, 07:17 PM
J
Member
Join Date: Sep 2000
Location: United States
Posts: 18,497
Received 0 Votes on 0 Posts
As Bill says, read the paperwork that comes with your smoke detector. It will very clearly tell you the good and bad places to put it. Sometimes the suggestions are a bit counterintuitive (e.g., don't put it anywhere near the furnace, which you might otherwise be inclined to do). And keep it out of air flows which might tend to blow the smoke away from it.

Be very careful tapping lines in your attic. Many, perhaps most, of them are unsuitable for a variety of different reasons (e.g., never tap the cable that runs between the ceiling fixture and the switch that controls it).

There's no need to keep electrical boxes away from insulation. Just make sure the box is covered. And make sure there's at least six inches of each wire inside the box. Most of the time there isn't enough slack in attic wires to allow this, so you sometimes have to add two boxes with a section of new cable between them.
 
  #8  
Old 02-17-09, 07:11 PM
T
Member
Thread Starter
Join Date: Feb 2008
Location: US
Posts: 166
Received 0 Votes on 0 Posts
The wire that is used to gang the smoke detectors together is yellow. I suspect that is a color convention for smoke detectors only? If so, do they make a 14/3 wire with white,black and yellow wires? I could not find any at the chain hardware stores. Or is this supposed to be a completely independent yellow wire connection?

P.S. Smoke detector instructions advise not installing closer to 4" from ceiling-wall edge. For wall installation it suggests installation only at a very specific height, 4" to12" from ceiling.
 
  #9  
Old 02-17-09, 07:22 PM
pcboss's Avatar
Forum Topic Moderator
Join Date: Jul 2002
Location: Maryland
Posts: 15,259
Received 114 Votes on 99 Posts
Just use the red from the blk/wh/rd and grd cable for the interconnect wiring.
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: