Wired Smoke Alarms

[MarkD]

Yet another non-gun question, because the folks here seem to know about just about everything.

Our new (five months today in fact) home is the first I've ever lived in with wired smoke alarms. Since I don't know how old the alarms are, I decided to replace them, so over the weekend I checked all of them to make sure they're all wired. All the alarms are the wired type, all have boxes, some weren't connected and one box was missing the connector.

Can anyone think of a reason why an alarm wouldn't be wired in? I'm assuming the missing connector just broke or something and the previous owners didn't bother to replace it. Is putting in a new connector a big deal for a non-electrician?

More generally, I assume the advantage to wired alarms is that if one detects smoke they all go off (because, for instance, if the basement alarm detected smoke it's possible you wouldn't hear it in the bedroom). Is that correct or are there other reasons?

[HTRN]

Can anyone think of a reason why an alarm wouldn't be wired in?

My first guess would be a short somewhere.

The advantage of wired systems is they'll automatically call 911 when wired into an alarm panel.

[Netpackrat]

Can anyone think of a reason why an alarm wouldn't be wired in?

My first guess would be a short somewhere.

The advantage of wired systems is they'll automatically call 911 when wired into an alarm panel.

If my home were wired with such a system, caller ID at dispatch would bring up a message to the effect of “Mrs. Netpackrat is cooking again.”

[Weetabix]

I'd assume the non-wired condition was a sloppy or cheap contractor followed by lazy inspection.

I've seen foundation vents installed over solid foundation walls - no hole cut for the vent to actually work.

Yes a normal guy can do it. Follow normal precautions - no power to what you're working on and the breaker locked out.

You may need a few tools to make it easier - crimper maybe.

You should also look them up or look for labels on them that tell you the voltage (I assume low voltage?). After the breaker is off, I'd be testing with a multimeter for current there just in case something is not wired right. I tend to be a belt and suspenders amateur electrician. I was doing electrical demo on a job site trailer one time. Panel off and locked out; all good. I came to an electric baseboard heater and went to cut the wire with side cutters, and it took big chunk out of them. I asked someone and "Oh, right. We wired that one from an adjacent trailer."

[Vonz90]

I am not an expert, but have had houses with wired detectors.

There are wired ones where the wire provides power only, where they are set to all go off if one goes up, or to also notify alarm service.

I have only ever replaced the first type. I bought the same model and it was drop in.

[evan price]

Most of the wired ones I've worked with were universal 3 wire design. The specific plugs may be incompatible between different brands but are easily swapped out. I put a first alert unit in as a replacement and it included adapters for the two major styles.
The three wires are hot, neutral, and interconnect which signals them all to go off if one sensed something. The color code is standard ac wire.