Hello,

I realize that I can probably do the following safely without considering the Code, but I would really like to do it correctly and "per the electrical code".

I have three older ceiling smoke alarms in the house.
They are wired together so that if one goes off, they all do.
The run on 110 V.

They are not reliable and prone to false alarms, so I would like to replace them with modern units, but solely battery operated. No AC wiring.

The question is therefore how to handle the 110 V wiring that drops thru the ceiling plaster via a 2" hole, approx., to pick up the alarms.
There is no metal box for them at the ceiling; only the hole with the AC wires dropping thru the plaster.

I can put a good quality wire-nut on each lead, and some tape, and just push the wiring back into the ceiling via the hole.
Then the new smoke detector would cover up the hole.
They are, of course, essentially all plastic units.

But, I keep thinking, that I must, per the Code, have them terminated in a metal box.
Poking the 110 V leads, even though wire nuts on ends, back thru the hole would not be allowed. Is this true ?

They now run off of a branch circuit, with other stuff on it also, so just yanking the ckt breaker for it is not an option.

Don't want to enlarge the hole, or call in an Electrician to do it.

Any thoughts on how to handle this correctly, per Code, would be most appreciated.

Are there Very small metal boxes that I can perhaps put the unused wires in, and just push this (very small) box back thru the hole ?
Or,... ?

Thanks,
Bob

 

First of all, your local building code may mandate the use of AC powered smoke detectors with battery back-up.

Your installation is likely not in compliance with the electrical code and probably never was. You CAN install plastic "old work" boxes with minimal problems and that is what I would do.

(image courtesy of Aubuchon hardware)

 

I would advise you to install the plastic boxes shown above and install new dual powered AC/battery alarms.

Unless you install special battery alarms only the alarm nearest the smoke would sound. This greatly reduces the safety factor.

 

Code probably means having these hard wired (120 V) and interlinked, battery only is likely a code violation.

 

In my area hardwired 120V detectors are mandatory. By the way the wiring to the detector is covered in the electrical code; but the placement, number and style of detectors is covered by your jurisdiction's fire safety code. Smoke detector circuits are not particularly special -- all junctions must be in approved, accessible boxes, cables must be routed and stapled appropriately, etc. If you have any gas- or wood- fired appliances or an attached garage on your home it is a good idea to make at least one of your detectors a combo smoke & carbon monoxide detector. It is required in some jurisdictions to have a CO detector now.

This is only for my curosity, why do you not want A/C powered alarms?

 

You could use battery powered wireless interconnection detectors, but they are pricey (about $40-$50 each I think). But, why not go first class and just replace your old detectors?

 

Have to echo the other comments. Generally if you have hardwired ac/dc smokes you are not allowed to replace them with battery-only. Can't go backward...

 

I’m no expert Bob but I have hard wired First Alert Smoke detectors and I’ve only had one false alarm in 9 years when one started to go bad – and yes they are working, I test them periodically. So my point is you can get hard wired smoke detectors that are reliable.

 

Smoke alarms have a suggested life span of 10 years. They get less reliable as they age. The problem is not how the are powered, but the age.

 

Good to know about that 10 year age thing. Sounds like Bob doesn't have the problem of false alarms being sent to a monitor station. If mine false alarms the FDept. is called. Happened once when a detector failed, and once from dust when I was sanding floors with a drum sander and forgot to cover the detectors up. Couldn't hear a thing with the sander. Looked out the window and surprise, surprise - there was the FD. That makes you feel really bad and really guilty - and they aren't too crazy about it either. Someone could get hurt in that situation.

But I guess Bob or anyone else wouldn’t be too happy about false alarms just going off in the home. That could probably cause panic and possibly injury. Guess there isn’t much you can do except just not let your detectors get too old and I guess shop for ones that have a good track record?

 

The lifespan is due to how smoke detectors work; it affects all types and brands. The detector uses a small amount of radioactive material in the sensor, and once it has decayed below a serviceable amount the detector becomes unreliable. I believe the manufacturers' upper limit 10 years, some say 7 years in the package insert.

 

Hi All,

Just a quick thanks for all the replies, and good info.
Appreciate it very much.

Great Forum(s).

Bob

 

Actually Ben, system (panel powered) smoke detectors are photoelectric. Meaning they don't have the radioactive sensor, they rely on smoke particles reflecting infrared light into an ultra sensitive photocell. The heavier the concentration of particles, the faster it goes into alarm (system detectors have an automatic 'verification' period to prevent falses from occasional floating dust and whatnot that would trip a radioactive detector).

System detectors also don't usually have a deadline lifespan like the cheapo AC detectors (although some brands recommend a 10 year replacement). As long as the smoke detection chamber is kept clean and free from dust/bugs, they will continue to work unless the circuitry itself fails.

System detectors are also the only type that can (in most jurisdictions) completely replace hardwired AC detectors, provided they can either all sound when the alarm is tripped or the interior siren(s) meet the closed door volume requirement.

Now that said, I hope you don't have AC smokes tied into your alarm panel..

 

Is cigarette smoke an acceptable means for which to test a smoke alarm or a digital CO detector?

 

No. Cigarette smoke contains tar and other contaminants which can decrease the sensitivity of a smoke detector. You can use 'canned smoke' for photoelectric detectors, or a smoldering 'punk' stick to test either type (photoelectric or ionization/radioactive). Never use any type of open flame. A wooden match lit for several seconds then blown out usually provides enough smoke to trigger one detector.

The only acceptable way to test a CO detector is with the test button. They work by measuring concentration vs time, and can not be otherwise reliably tested without a source of CO and a known calibrated PPM meter. You can't just spray CO at it and have it go off immediately like a smoke detector.

 

Sorry Bob! I gave you bad info. I don’t have First Alert smoke detectors. I have no idea why that name stuck in my mind? I would have bet my last dollar they were First Alert. That’s why I didn’t even look at the name before I posted. Maybe a commercial brainwashed me?lol

My detectors are in fact “System Sensor” I3 Series Photoelectric smoke detectors and are tied into my alarm panel. They have been very reliable, but I guess as Matt points out these are the type that get tied to an alarm panel. You can get a discount on your home owners insurance, however, if you have a system that automatically calls a control station if smoke is detected. Don’t know what the Return On Investment period would be for an alarm system like that, it was in the house when I moved in.

 

System Sensor makes both photoelectric and ionization smoke detectors and duct detectors for use with fire alarm systems. The most notable I am aware of is sold under the Notifier brand, by Honeywell.

 

Are the duct detectors the little black boxes on the ducts wiht what looks like a smoke detector inside?

 

Justin: Yes. Generally they have pick-up tubes that extend into the ductwork.

 

Thanks Tom. I always wondered what they were.

 

Thanks for that info Matt.

 

As far as hard wired ac smoke detectors tied into the alarm panel,don't do it man.I know it will work if you do,but there are too many ways of something going wrong.In some cities you'll void your warranty and get your insurance dropped and the fire inspector will fail your system,and if you get a false alarm due to this set up and someone gets hurt responding you'll be in BIG trouble just go with what is made for the panel.You can have both AC detectors and low voltage detectors in the same house but not tied into the same system.