Smoke detecters

[Cwhyu2]

Rough in inspection today will keep you informed.

 

[Cwhyu2]

Rough in inspection approved.

 

[Sponsor]

 

[DougB]

The point to the code is that any acv input in a 'unit' must be controlled by its individual power panel. Running 120vac from a main panel into individual units fails that code. Look at it this way, you want to do some work, you shut off your main breaker, then get electrocuted trying to change out your smoke detector! Logic would tell you, my panel's main breaker is off, everything in my unit is now without power. This isn't a code violation if you're feeding a low-voltage circuit, but typical smoke detectors rely on 120vac (with battery backup).

Multifamily dwellings typically require fire walls and in many circumstances, are treated as stand-alone units. Then, there are some things that only apply to them as multi-family. It can get complicated quickly. WHere I live, electrical and plumbing on a multifamily dwelling can only be done by someone with a license, but in a single family unit, the homeowner can do work, in either case, a permit and inspection is required, though.

Unless there's an amendment to the national code (and that generally can only be more restrictive, not less), it sounds like the inspectors may have the intent correct, but not the implementation.

The smoke detectors are low voltage. The panels I've had (in several homes) have a 24v backup battery. So the detectors run off the 24v, if the power is off for less than several hours, the battery backup will provide protection. I've never seen a 120v smoke detector.

 

[Cwhyu2]

The smoke detectors are low voltage. The panels I've had (in several homes) have a 24v backup battery. So the detectors run off the 24v, if the power is off for less than several hours, the battery backup will provide protection. I've never seen a 120v smoke detector.

www.firstalert.com smoke detectors and smoke alarms are two different devices read the whole thread as JW has great imformation on this subject.

 

[Jadnashua]

Most new construction requires line voltage powered smoke detectors that are interconnected. My place is over 30-years old and has them. This is opposed to those that rely entirely on usually a 9-volt battery. Many of the 120vac units also have a battery backup, which is a very good idea. Alarm companies are the ones that are more prone to using low-voltage units to avoid the whole issue of the OP's problem. You can run low voltage into multiple units...the issue comes from shutting your main breaker off and still having 120vac in your unit.

 

[Molo]

And then there was wireless.....

 

[Jadnashua]

And then there was wireless.....

Wireless smoke detectors tend to be part of an alarm system.

 

[Molo]

Wireless smoke detectors tend to be part of an alarm system.

They can communicate with each other. Does this mean they are a system?

 

[Jadnashua]

Current code requires all of the smoke detectors in a home to be interconnected so that if one goes off, they all go off. I do not know if the code specifies how they are interconnected, but hardwiring them is certainly more reliable than wireless, especially if the power goes off. Many of them also have a battery backup, which would likely quickly discharge if it also had to keep up a wireless network. In a multifamily or closely spaced buildings, wireless could be problematic...you neighbor fries things a bit dark, and their alarm goes off...yours goes off, and if you're close to those next to you, maybe theirs as well. Won't happen if they are hardwired. If you have to 'register' yours, so they can talk to each other, many people never change things from the default as it comes from the factory.

 

[Molo]

Current code requires all of the smoke detectors in a home to be interconnected so that if one goes off, they all go off. I do not know if the code specifies how they are interconnected, but hardwiring them is certainly more reliable than wireless, especially if the power goes off. Many of them also have a battery backup, which would likely quickly discharge if it also had to keep up a wireless network. In a multifamily or closely spaced buildings, wireless could be problematic...you neighbor fries things a bit dark, and their alarm goes off...yours goes off, and if you're close to those next to you, maybe theirs as well. Won't happen if they are hardwired. If you have to 'register' yours, so they can talk to each other, many people never change things from the default as it comes from the factory.

The OP's code officers requested apartment units be interconnected, so the neighbor's burnt toast will cause detectors to alarm in neighboring units in that scenario as well. Also, they all have to be maintained. Hardwired units can be disabled (some more easily than others).

 

[Cwhyu2]

The OP's code officers requested apartment units be interconnected, so the neighbor's burnt toast will cause detectors to alarm in neighboring units in that scenario as well. Also, they all have to be maintained. Hardwired units can be disabled (some more easily than others).

Any alarm system can be tampered with,as I am just the installer and do not have a maintinance contract it is up to the owner of the property to maintain such systems.
And the fun part is that all of the smoke alarms are on 10 foot ceilings.

 

[Jadnashua]

The OP's code officers requested apartment units be interconnected, so the neighbor's burnt toast will cause detectors to alarm in neighboring units in that scenario as well. Also, they all have to be maintained. Hardwired units can be disabled (some more easily than others).

And, unless the local authorities have modified the national codes (they are allowed to make them more stringent, but not less), what they want is in conflict with the national codes. FIre walls between dwellings are designed to give you plenty of time to discover and get out of your unit should you need to if your neighbor's place goes up.

 

[Molo]

And, unless the local authorities have modified the national codes (they are allowed to make them more stringent, but not less), what they want is in conflict with the national codes. FIre walls between dwellings are designed to give you plenty of time to discover and get out of your unit should you need to if your neighbor's place goes up.

In this case the local code officers decision to be more stringent seems a good one. I wonder if the national code theory is that the neighbors alarm will be heard through the walls?

 

[Jadnashua]

A properly built fire wall is what is designed to protect your neighbors in a duplex or multi-family dwelling. This is different than say a hotel where everyone needs to use a common hallway. If the fire is not detected before that starts to get breached, your alarm should be going off on its own. If you follow their logic...burnt toast could have an entire complex's alarms going off. Anyone that thinks that's a good idea, I wonder about your reasoning skills. If it's a major thing, it's likely you'd hear the sirens and the fire department would be evacuating you long before your detectors would likely be going off when installed per the national codes.

I doubt the local code actually was written to require this, and if challenged, they could find no basis for their preference. I, at least, would like to see it written, rather than taking their opinion of how it should be done. Running 120vac through multiple units that is not turned off by the local panel is a constant safety hazard. Not hearing the smoke alarm go off until things start to get hot in your place is not an issue to me. The fire walls are designed to give you plenty of time to get out after being notified.

Had another thought on this...having all of the units powered and run to multiple dwellings from a single panel, something totally out of your control could turn off your smoke detectors, and you'd never know it, potentially too late. Having local control, i.e., having it powered from your local panel, is MUCH better, and safer for all involved.

 

[Molo]

If power is turned off and they have battery backup won't the detectors begin to chirp? Do they still communicate with one another if only on battery power?

 

[Jadnashua]

They still can trigger the other detectors if power is removed. At least on the ones I have, the battery will last a few years if there are no power outages, but they don't seem to last much more than an hour or so on battery alone. YEs, they chirp when a battery gets low. Don't remember if they all do, or only the one(s) with low batteries.

 

[Molo]

One hour on the battery isn't very long. Nonetheless, the chirp would indicate there is a problem such as a circuit being off.