7 January 2010

Residential fire alarm wiring

| Ceej1973
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Hi all.

I am seeking some technical advice regarding the operational logistics of fire alarms in residential homes, particularly new homes which require them to be hard wired. As I am living abroad at the moment I have no availabiliy to technical/electrical advice, and I dare say my real estate agent has no idea either, so please if there is any blogger who has alarm/electical knowledge please respond.

Our house is around 2 years old (rented out), and has alarms installed by law, and hard wired also by law. I recently found out that one of the alarms went off in our house, not due to smoke. The Tenant could only stop the beeping, by removing the battery. I originally was of the opinion that hard wired smoke alarms are solely that, hard wired, but after this occurance in our home, I am a little confused.

Would I be correct in my latest assumption, that hard wired smoke/fire alarms actually run off a battery, and are backed up by the mains, and that when the battery is running low, then the mains kick in (and set the alarm off) in order to “alarm” the resident that the battery is flat. Apparently, the alarm was fine again (silent) when the old battery was removed and a new one replaced.

For knowledge in advance. Thanks

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ive got one wired into the mains and after a few days of having it the alarm started going off and would not stop and there was no way to turn it off so we had to leave the house for a day waiting for the repair person to come and get a new one

Hells_Bells74 said :

re: replacing batteries restoring peace – I smashed them because I couldn’t see where on earth it had a replacable battery, we even thought we had cut the wires on the only thing that passed as a battery in there.. nope, it was in many pieces and still going with all wires and such cut. Some of them are just pure evil.

Just give them a bath. that quietens them

Hells_Bells743:46 pm 08 Jan 10

>Oh it didn’t just beep all the time (yes that too) it went off a few times a day/night and refused for quite some time to be quiet. I had babies/toddlers over that time, I was exhausted and it was the last thing I needed. Just before their demise, they wouldn’t shut off after many many long hours.

Hells_Bells743:36 pm 08 Jan 10

re: replacing batteries restoring peace – I smashed them because I couldn’t see where on earth it had a replacable battery, we even thought we had cut the wires on the only thing that passed as a battery in there.. nope, it was in many pieces and still going with all wires and such cut. Some of them are just pure evil.

Alarms became compulsory in new homes around 15 years ago.
We built a house in 1994, and that was just before the deadline (iirc).
When the batteries run down, the alarm either chirps or goes off. It’s a low battery warning I believe. Replacing battery restores peace and equilibrium.

Hells_Bells741:50 pm 08 Jan 10

When the govt had two round hard-wired smoke alarms installed in my home, I near went insane and after being tormented for years with it, it was smashed and still going off on way to tip wrapped up in old doonas. Evil and possessed were they!

When the govt had two rectangle/square hard-wired smoke alarms installed in my home, I slept like a baby and haven’t heard from then since, except an odd smokey cooking occasion or test. LOVE THEM!

Apparently it wasn’t just me who had problems with the round ones, my friend at Housing told me there were many many people billed for replacing them (yes they charged me too at some point, think they dropped them when they had soooo many cause I don’t recall having to pay it).

troll-sniffer11:52 pm 07 Jan 10

I believe that only houses in Tuggeranong have this problem. The further north you go, the less problems you have. In the Inner North, we’re so tough we don’t need smoke alarms, we just huff and puff and blow the fire out. Unless of course you’re lighting a fire in a nice cozy house in Germany, then you’d have problems, because the Polezei would soon issue an inflammatory arrest warrant.

Mine is hardwired and have a backup battery, if battery goes off, replace it, problem solved.

I think you will find hardwired smoke alarms have been law for all NEW homes for a number of years in the ACT. Not retrospective for rentals or other homes.

Going back to the OP as others have said the battery is for back-up only on mains wired alarms. Having said that I beleive there are some models on the market that opening the battery compartment more or less turns the alarm off, so maybe that is why your unit did what it is alleged to have done.

@ Ceej – batteries die.This was a low battery warning. As Captainwhorebags said the battery is just a backup.
@ Captainwhorebags – smoke detectors can be linked so that if 1 goes off…they all go off.
If it is linked by an earth wire, some-one has been naughty.

For the past 5 – 10 years, Australia wide, it has been a requirement for a hard wired smoke detector within 1.5m of bedroom ( sleeping areas )doors.
NSW have made it compulsory for all dwellings, new or old.
ACT….not yet ( to my knowledge ).
Hardwired is 240v with battery back-up. Also wired into an alarm system, with the smoke detector having it’s own battery, can also be acceptable.

colourful sydney racing identity1:08 pm 07 Jan 10

CJ – there is no requirement in the ACT for rented homes to be fitted with a fire and or smoke alarm. It is outrageous that it is not a requirement in the ACT for every house to be fitted.

captainwhorebags10:23 am 07 Jan 10

I’ve got two hard wired fire alarms in my house (you have to have one near every sleeping area).

The battery is a backup for when the mains power goes out. If there is a blackout, my alarms will give a beep every now and then. They’ll also beep to let you know if the backup battery is going flat.

The alarms also communicate over the earth wire somehow, so if one alarm goes off, the other one does too.

Yep, I’m no expert, but our smoke alarm gives a small beep every 5 or 10 minutes when the 9V battery was dead.
After replacing it, the beeping stopped.

Is it only NSW where you legally have to have them? (saying this as the houses we’ve rented here in Canberra never have had them including the present one)

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