Problem in smoke detector wiring

Reply

  #1  
Old 11-11-04, 09:43 PM
ccold
Visiting Guest
Posts: n/a
Problem in smoke detector wiring

Hi,

I noticed something unusual on my hard-wired smoke detector when I removed it recently. First of all, there are 3 wires coming from the ceiling (hot black, white neutral, and the red traveller) and they're all wired to a plastic 'outlet' which you plug your detector in. The unusual thing is that there is a noticable burnt, scarring-like mark around the outlet hole where the hot black wire is connected to. Is this considered 'normal'? Could this be the result of a shoddy detector, loose wiring, or a power surge? Anyone have any suggestions on what I should do?

Thanks,
Carlton
 
Sponsored Links
  #2  
Old 11-12-04, 04:59 AM
TomZ1's Avatar
Member
Join Date: Sep 2003
Location: New Hampshire
Posts: 174
Received 0 Votes on 0 Posts
I would say it's not normal.

Check for a loose connection, etc.

I would probably replace the pigtail and the smoke alarm as well. Make sure you use the same brand of alarm as not all will interconnect with each other.
 
  #3  
Old 11-12-04, 07:31 AM
Member
Join Date: Sep 2000
Location: United States
Posts: 18,497
Received 0 Votes on 0 Posts
Considering a smoke detector only uses about 6 watts, it would be unusual to create electrical burn marks even if the connection were poor. Could these marks be caused by something else?

If you have concerns, I would replace the detector. To ensure that the interconnect to the other detectors will still work properly, buy an identical make and model.
 
  #4  
Old 11-14-04, 12:26 PM
Savant
Visiting Guest
Posts: n/a
While it's hard to say what might of cased it (I also tend to think some kind of loose connection issue) the end result is that you should probably change it anyway. Also make sure that there are no other lights/outlets on the smoke alarm circuit. Only detectors should be wired on a detector circuit.

Most people have smoke detectors around that are far past their prime. Even hardwired models should be replaced every 10 years, every 7 if you want to err on the side of caution. (studies have been done that show reduced effectiveness of smoke alarms as they age) If you don't know when the detector was installed and there is no date on it, you may as well replace it.

A couple notes about hardwired smoke alarms. The 'red' is what they call a 'gang alarm' wire, which runs to all the other smoke detectors on the circuit. When one detector goes off, it sends a signal on the red and that causes all the other detector alarms to go off. So that way you will hear the alarm no matter what part of the house you may be in. It's a nice feature to have in larger houses.

Regards,

Savant
 
  #5  
Old 11-14-04, 12:32 PM
Member
Join Date: Sep 2000
Location: United States
Posts: 18,497
Received 0 Votes on 0 Posts
Only detectors should be wired on a detector circuit
I strongly disagree.

Most people have smoke detectors around that are far past their prime
I strongly agree.
 
  #6  
Old 11-14-04, 03:02 PM
TomZ1's Avatar
Member
Join Date: Sep 2003
Location: New Hampshire
Posts: 174
Received 0 Votes on 0 Posts
Savant writes:

"Only detectors should be wired on a detector circuit."


I urge you to check this with your local Fire-Rescue Department. For example, here in NH, the NH Fire Code specifically prohibits a "smoke alarm only" circuit. It requires something else on the circuit, usually lighting. The logic is that if the lighting doesn't work, someone will investigate why and fix the problem. A smoke alarm only circuit is an open invitation to shut it off when, say, you burn dinner. Chances are pretty good it won't be turned on again. Here in NH in 2004, of 11 fire deaths this year, 10 happened in a home with no working smoke detectors. The 11th had a detector but it is still undetermined if it was working.

"Most people have smoke detectors around that are far past their prime. Even hardwired models should be replaced every 10 years, every 7 if you want to err on the side of caution. (studies have been done that show reduced effectiveness of smoke alarms as they age) If you don't know when the detector was installed and there is no date on it, you may as well replace it."

I second that motion. Absolutely true. You can now buy 10-year lithium batteries so you can just replace everything at once.

tjz
 
  #7  
Old 11-14-04, 03:07 PM
Member
Join Date: Oct 2004
Location: Orlando, FL
Posts: 132
Received 0 Votes on 0 Posts
I usually put the attic access light on the smoke detector circuit, but perhaps it would be a good idea to put a hallway light on the circuit as well.

Although, in my area we're required to use smoke detectors that are hardwired and have battery backup, if power is lost the smokes' batteries will eventually die down and the detectors will chirp.

But the hallway light would be more likely to prompt an investigation into the wiring than just the replacement of batteries.
 
  #8  
Old 11-14-04, 04:34 PM
Savant
Visiting Guest
Posts: n/a
Originally Posted by TomZ1
I urge you to check this with your local Fire-Rescue Department. For example, here in NH, the NH Fire Code specifically prohibits a "smoke alarm only" circuit. It requires something else on the circuit, usually lighting. The logic is that if the lighting doesn't work, someone will investigate why and fix the problem. A smoke alarm only circuit is an open invitation to shut it off when, say, you burn dinner. Chances are pretty good it won't be turned on again.
The code in Canada has no prohibition on 'smoke alarm only' circuits, but does in fact prohibit wiring smoke alarms on a circuit that supplies power to any outlet/device in the kitchen or laundry room, any circuit that provides power to outdoor outlets, or any circuit that is GFI/AFCI protected. While I don't object to smoke detectors being placed on general lighting circuits, I do have a problem with smoke detectors on outlet circuits. The reason being that you could have a device (like a space heater) fail while starting a fire and tripping the breaker. The failure of the device could end up knocking out the smoke detector circuit that would warn the occupant of the impending fire!
A smoke alarm only circuit is an open invitation to shut it off when, say, you burn dinner. Chances are pretty good it won't be turned on again. Here in NH in 2004, of 11 fire deaths this year, 10 happened in a home with no working smoke detectors. The 11th had a detector but it is still undetermined if it was working.
The same could be said for smoke detectors that run only on batteries, probably moreso since many people forget to change them or just yank them out.

Smoke detectors on a circuit with lighting doesn't solve the problem of people shutting them off. A simple way to make sure that this isn't an issue is to use devices that have battery backup. Problem solved since shutting off power won't disable the detectors.

When I install detectors:
-I use a single circuit and include only fire prevention/safety devices.
-I only use hardwired devices that have battery backup
-I choose detectors based on where they will be installed, avoiding ionization based detectors near the kitchen
-I only use devices that have a 'hush' button to silence nuisance alarms
-I only use devices that have a 'gang alarm' function
-I will install a breaker lock-on to prevent casual switching of the circuit
-Optionally, I usually suggest the installation of at least one emergency lighting fixture, (ideally near an exit) to provide auxillary lighting and assist those escaping a fire. This device is also placed on the same circuit as detectors.

While I certainly agree that a single smoke alarm circuit for smoke detectors without battery backup is cause for concern, battery backup removes the incentive to disable the devices by switching off power, and as such negates any need to wire the devices with other household devices that could trip the breaker and disable smoke detection accidentally.

Instead of 'annoying' people by wiring smoke detectors on lighting circuits so that lights go off when they shut off the circuit, why not make it so that they never have to shut off the smoke alarm circuit in the first place?

-Install devices with 'hush' buttons so that they can silence the alarm for a short period of time when a nuisance alarm occurs
-Don't install 'regular' (ionization) smoke detectors near the kitchen or in other places where it may be subject to nuisance alarms. Choose a photoelectric model, which is less likely to trigger false alarms in those areas (I use dual-sensor detectors elsewhere)
-Install devices with battery backup, thus removing any incentive to shut off the circuit to disable an alarm.
-Install a breaker 'lock-on' to prevent casual switching of the breaker for the alarm circuit. The lock-on will still allow the breaker to trip, but requires a screwdriver to remove.
-Most importantly, instruct the homeowner on how they should deal with nuisance alarms. Many people have detectors installed but are never instructed on how to 'use' them.

For me battery backup is the big one. I won't install hardwired dectectors that don't have battery backup. (in a residential dwelling)

Regards,

Savant
 
  #9  
Old 11-14-04, 04:51 PM
Member
Join Date: Sep 2003
Location: Central New York State
Posts: 13,973
Received 0 Votes on 0 Posts
The reason that you put the smoke detectors on a general purpose circuit is so that the homeowner will know if the circuit is for some reason off. In the US this also cannot be a kitchen counter top circuit, or a bathroom receptacle circuit, or a laundry circuit, it can be most other circuits. It is recommended that it be a circuit that is used every day, such as a hallway light.

The reason for sharing a circuit is not so that the homeowner won't want to shut the breaker off, it is solely so that the homeowner will know if the breaker has tripped.

In the US on new installations, the smoke detectors MUST be interconnected. However, they can be on different circuits. There is some controversy as to whether they must be on an AFCI circuit if they are in a bedroom. Some inspectors will allow them not to be on an AFCI, others will enforce that they be. It all depends on the edition of the NEC that is being followed, local rules, and in some cases, the individual inspector.

Also, do not check with your fire department, check with your codes enforcement department. While some fire departments do know what codes are, many do not. It also may depend on who answers the phone at the fire department as to what answer you get. As a member of my local fire department, I know that most of the members have no clue what the local codes are. Unfortunately, some of them would not necessarily tell you that they have no clue, but would instead tell you what they think is the correct answer.
 
  #10  
Old 11-14-04, 05:56 PM
Member
Join Date: Oct 2004
Location: Orlando, FL
Posts: 132
Received 0 Votes on 0 Posts
I haven't had an inspector ask for the smokes to be arc fault protected and I hope they never do. Arc faults may provide some added safety, but they are usually more trouble than they are worth.
 
  #11  
Old 11-14-04, 06:17 PM
Savant
Visiting Guest
Posts: n/a
Originally Posted by racraft
The reason for sharing a circuit is not so that the homeowner won't want to shut the breaker off, it is solely so that the homeowner will know if the breaker has tripped.
I can understand the reasoning here, but wouldn't it make more sense to prevent this from happening by isolating the detectors from other household devices? (the liklihood of a detector causing a breaker to trip is remote compared to devices like space heaters)

However, the bigger concern is that a tripped breaker causing a 'light to go out' does not give the homeowner any protection should the breaker trip at night, should the light be in a room they are not in, or should the light be turned off. How does a light going off offer any fire protection? That's why I refuse to install detectors without battery backup. Dedcicated circuit or not, the risk isn't worth the few bucks of savings.

Regards,

Savant
 
  #12  
Old 11-14-04, 06:24 PM
Member
Join Date: Oct 2004
Location: Orlando, FL
Posts: 132
Received 0 Votes on 0 Posts
Originally Posted by Savant
However, the bigger concern is that a tripped breaker causing a 'light to go out' does not give the homeowner any protection should the breaker trip at night, should the light be in a room they are not in, or should the light be turned off. How does a light going off offer any fire protection? That's why I refuse to install detectors without battery backup. Dedcicated circuit or not, the risk isn't worth the few bucks of savings.
With battery backup the smokes will still work, but the light would alert the homeowner to a problem. If there isn't a light on the smoke circuit and it trips, the batteries will allow the smoke to work, but the homeowner will probably just keep replacing the batteries.

Now that I think about it, I went to a service call where the homeowners kept complaining about having to replace the smoke detector batteries every month or so. I found that there was a loose hot in one of the junctions, so the smokes kept running off battery power, thus they died very quickly.
 
  #13  
Old 11-14-04, 06:27 PM
TomZ1's Avatar
Member
Join Date: Sep 2003
Location: New Hampshire
Posts: 174
Received 0 Votes on 0 Posts
Racraft writes:

"Also, do not check with your fire department, check with your codes enforcement department. While some fire departments do know what codes are, many do not. It also may depend on who answers the phone at the fire department as to what answer you get. As a member of my local fire department, I know that most of the members have no clue what the local codes are. Unfortunately, some of them would not necessarily tell you that they have no clue, but would instead tell you what they think is the correct answer."

Good, bad, or indifferent, it's just the opposite here. The building/codes department has/had no idea of the "no smoke alarm only" circuit requirement because it's in the fire code, not any model building code. I hope not just anyone who answeres the phone at your fire department is handing out code info!

All the model building codes and the Life Safety Code now require interconnected hardwired smokes with battery back up. I'm pretty sure it goes back to at least 1993 (BOCA).

tjz
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


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