No power to smoke detectors.

Closed Thread

  #1  
Old 08-20-17, 09:50 AM
D
Member
Thread Starter
Join Date: Aug 2017
Location: USA
Posts: 9
Received 0 Votes on 0 Posts
No power to smoke detectors.

When we purchased our home two years ago, the smoke detectors had power supplied to them as all had steady green lights on. A few months ago, the alarms ( at various intervals) began to chirp indicating low battery. I noticed that the green (ac power ) lights were not lit. I have reset every breaker in the breaker box to no avail. All lights work in the house, appliances, etc.... I am baffled as to where the power is supplied to the detectors. Can anyone help? Our home was built in 1995.
 
  #2  
Old 08-20-17, 11:56 AM
ray2047's Avatar
Member
Join Date: Mar 2006
Location: USA
Posts: 33,582
Received 13 Votes on 11 Posts
Was any electrical work such as a ceiling light or switch being changed out done prior to noticing they were dead?
 
  #3  
Old 08-20-17, 12:26 PM
D
Member
Thread Starter
Join Date: Aug 2017
Location: USA
Posts: 9
Received 0 Votes on 0 Posts
I did change all of the outlets in one of the rooms I remodeled. I did try to reconnect the wires the same as they had come off the old ones. Can you explain how the wall outlet wiring might affect the detector functioning? I do not know much at all about home wiring. I will buy one of the outlet testers today and a multimeter to check for voltage. All the outlets work that I replaced.
 
  #4  
Old 08-20-17, 12:50 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 60,877
Received 1,342 Votes on 1,240 Posts
The smoke detectors should be interconnected with a three wire cable. The black and white are the AC power and the red is used to interconnect the alert. The smoke detectors are supposed to be powered from a lighting circuit so that the circuit won't be off without it being noticed.

You should have at least one three wire cable at each smoke detector. Where the cable bridges thru you will have 2) three wire cables. More than likely you will find a two wire cable at one of the locations. That should be power.

There is no wiring method written in stone which means you will have to investigate each smoke location and note the wiring.
 
  #5  
Old 08-20-17, 01:14 PM
ray2047's Avatar
Member
Join Date: Mar 2006
Location: USA
Posts: 33,582
Received 13 Votes on 11 Posts
Follow PJ's suggestion first then answer this:

Lighting circuit is more likely is why I mentioned it but a receptacle circuit is not out of the realm of possibility. Were any of the receptacles switched?
 
  #6  
Old 08-20-17, 01:27 PM
pcboss's Avatar
Forum Topic Moderator
Join Date: Jul 2002
Location: Maryland
Posts: 15,224
Received 105 Votes on 91 Posts
Are the receptacles on the same circuit as the lighting? Try the wall switch and see if the smoke alarms have power.
 
  #7  
Old 08-21-17, 05:55 AM
A
Member
Join Date: Mar 2014
Posts: 572
Received 23 Votes on 22 Posts
A house built in 1995 may not have had installed "wired" interconnected smoke detectors with battery backup.

Have you actually removed any of the smoke detectors from the ceiling (have not seen that you mention this in the post) to see if there are even any wires in them? My mind tells me if you did not it is quite possible they are interconnected "wireless" smoke detectors only powered by battery. Thinking that maybe the batteries lasted just long enough (over a two year period while you were living there) where all batteries were running low; thus the "chirping" sound.

Remove one from the ceiling and see if there are in fact any wires. And even if there are since they have battery backups replace the batteries this way at least you are protected and then when troubleshooting you can remove them during that process.
 
  #8  
Old 08-22-17, 01:02 AM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 60,877
Received 1,342 Votes on 1,240 Posts
When we purchased our home two years ago, the smoke detectors had power supplied to them as all had steady green lights on.
Doubtful that would be a wireless unit with a continuously lit LED.
 
  #9  
Old 08-22-17, 10:09 AM
pcboss's Avatar
Forum Topic Moderator
Join Date: Jul 2002
Location: Maryland
Posts: 15,224
Received 105 Votes on 91 Posts
A house built in the 80's would have had hard wired interconnected smoke alarms , let alone one built in the mid 90's.
 
  #10  
Old 08-22-17, 11:42 AM
Norm201's Avatar
Member
Join Date: Sep 2013
Location: United States
Posts: 9,488
Received 291 Votes on 261 Posts
Apparently, code (at least in my neck of the woods) require a wired in with battery back-up smoke detectors. If battery goes bad regardless of the AC power the unit will chirp endlessly. Change the battery. On mine the LED will go out if battery is low.
 
  #11  
Old 08-23-17, 01:09 PM
D
Member
Thread Starter
Join Date: Aug 2017
Location: USA
Posts: 9
Received 0 Votes on 0 Posts
I purchased a sperry outlet tester and every outlet in the home shows that they are wired properly. All outlets work, and all light switches work. I measured voltage for each of the breakers (including gfi breaker) and showed 120 V.
So I have no idea why the smoke detectors have no power. All the wiring in the breaker box looks intact.

Does each detector receive its own power from the source, or does the power to each detector come from the detector before it? Meaning if one lost power would they all lose power. I don't have power to any of the detectors.
It is a two story home with 2 detectors downstairs and 3 upstairs in each of the bedrooms.

All the detectors have three wires. Black and white power, and a red which is not connected (to interconnect the alarms. I know they had power before because there was a constant green power light, and the intermittent blinking red to show operation. A few of the alarms are of a different brand, but since they are not interconnected does this really matter? I will do what Pjmax suggested and note how many wires of each black and white there are at each detector. I believe more than one detector has 2 or more of each black and white. But I will document this

I haven't responded for a couple of days. This is the first time I have used this site and thought I would get an email for each response as I have from other forums. So I apologize for not responding sooner. I do appreciate the support. And if I find the solution, I will post it here.

Thank you
 

Last edited by PJmax; 08-23-17 at 04:29 PM.
  #12  
Old 08-23-17, 01:21 PM
D
Member
Thread Starter
Join Date: Aug 2017
Location: USA
Posts: 9
Received 0 Votes on 0 Posts
Yes I have replaced the batteries in all five now. All of the detectors are less than 2 years old. I didn't check for ac power until they each started chirping indicating low battery. After replacing the batteries, the chirping did stop, indicating sufficient batter voltage, but still no green power. I was not to keen on contacting an electrician. I wanted to figure this out on my own. I did work with electronics in the military, and power, but we had detailed schematics and manuals. I thought this would be an easy problem to solve. But I am struggling. I might have to bite the bullet and contact an electrician. But he would also have to determine the source. I was trying to save the possible 100's of dollars.
 
  #13  
Old 08-23-17, 02:37 PM
ray2047's Avatar
Member
Join Date: Mar 2006
Location: USA
Posts: 33,582
Received 13 Votes on 11 Posts
One smoke detector should have a single 3-conductor cable (black, red, white). Others should have two 3-conductor cables. One should have one 3-conductor cable and one 2-conductor cable (black, white). This will be where power comes in. Disconnect the 2-conductor cable and using a multimeter measure between black and white and between black and ground. Both tests should show ~120v.
 
  #14  
Old 08-23-17, 03:19 PM
D
Member
Thread Starter
Join Date: Aug 2017
Location: USA
Posts: 9
Received 0 Votes on 0 Posts
I will look when I get home. Thank you
 
  #15  
Old 08-23-17, 04:34 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 60,877
Received 1,342 Votes on 1,240 Posts
You need to subscribe to a thread to get email notices. I have subscribed you to this thread. At the bottom of the advanced edit page is place to subscribe. Also at the top of the thread is a little round "tools" wheel. Clicking on that will also get to thread subscription.

With a smoke detector system like yours.... and by code for a good many years.... the smoke detectors need to be interconnected by a three wire cable so that if one is tripped they will all sound. It sounds like yours are wired individually.

The batteries in that type of detector will only last a short time as they are only there for backup in case main power is out.
 
  #16  
Old 08-23-17, 06:21 PM
D
Member
Thread Starter
Join Date: Aug 2017
Location: USA
Posts: 9
Received 0 Votes on 0 Posts
Almost exactly as you stated, I did find the detector with one 2-conductor cable (black, white), although it has 2 three wire conductor cables. Probably to feed the down stairs. I understand now how from there the 2 conductor cable supplies the ac power to the other detectors, the additional red conductor interconnecting the simultaneous alarm function. The only problem is the 2-conductor cable has no readable voltage. So thanks to your help, I at least know which detector box supplies the ac. Now, I have to figure out where the other end of the 2 conductor cable is connected. Perhaps when I replaced the recepticles, I could have mistakenly left off the other end of the 2 conductor cable. And the outlet being properly wired (the green light on the sperry) would have no indication on whether the 2-conductor cable was properly attached.
So would I be correct in checking the outlet boxes for this?
 
  #17  
Old 08-23-17, 07:23 PM
ray2047's Avatar
Member
Join Date: Mar 2006
Location: USA
Posts: 33,582
Received 13 Votes on 11 Posts
Lights, switches and receptacles in that order.
 
  #18  
Old 08-25-17, 12:47 PM
D
Member
Thread Starter
Join Date: Aug 2017
Location: USA
Posts: 9
Received 0 Votes on 0 Posts
Hi Ray,
I did what you said and found that the outlet closest to the smoke detector in the room where the the 2 conductor (power) cable had the hot disconnected. When I changed all the outlets in the room, I missed that one because it had tucked back into the outlet box, I reconnected the conductor, turned the power back on and got the green power led back. I can't thank you enough for the help you have given me in troubleshooting this problem. Finding where the power was supplied to the detectors was key. We have four dogs. Each time the battery would drain on one of the alarms, the chirping would freak the dogs. We are going on vacation, having a dog sitter stay in the house with them. It wouldn't have been a good thing if one detector had decided to start chirping and the sitter not be able to stop it. (A few of the rooms have high ceilings). So now, we can rest knowing that this won't happen on our trip. Once again, thank you for your help.

Paul
 
  #19  
Old 08-25-17, 12:50 PM
D
Member
Thread Starter
Join Date: Aug 2017
Location: USA
Posts: 9
Received 0 Votes on 0 Posts
I forgot to mention a thanks to you that responded to my question. I appreciate and my wife appreciates it too.
 
  #20  
Old 08-25-17, 12:55 PM
D
Member
Thread Starter
Join Date: Aug 2017
Location: USA
Posts: 9
Received 0 Votes on 0 Posts
Ray, I just looked at your profile and saw that you lived on the gulf coast. Best wishes and safety from the coming hurricane.
 
  #21  
Old 08-25-17, 01:01 PM
ray2047's Avatar
Member
Join Date: Mar 2006
Location: USA
Posts: 33,582
Received 13 Votes on 11 Posts
Lived here a long time. I just cross my fingers and hunker down. Glad you found the problem. Thanks for letting us know. Your thread may help someone else.
 
 

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