The other night I had a smoke detector warning.  The alarm sound went off.  Then, when I went to buy a new one I had a second warning!

The first warning was that one of my smoke alarms went off, and would not stop.  But it was not communicating with the others in the house, so I did not think there was a fire.  I checked the house anyway, but I was right.

However, when they go off like that it is not a low battery.  A low battery initiates a periodic chirp, typically every 30 or 60 seconds.

I had no choice but to remove it.

In the photo above, to the left is the siren for our security system and to the right one of two smoke detectors for that system.

The one smoke detector for the security system does NOT satisfy the fire codes that presently demand a smoke detector on each level and in sleeping each area that all communicate with each other. 

But I highly recommend a security system for many reasons.  One important reason, certainly, is that when the system is set and nobody is home, the house is being monitored for fire.  If a fire happens and nobody is home, without a security system nobody hears the squealing smoke alarms to call the fire department and the fire can grow.  A security system alarm will notify the monitoring company and the fire department is immediately called.

That peace of mind only costs me $19/month.

My smoke detectors/alarms are 10 years old.  You can see here that the plastic has yellowed somewhat, indicating age.

Most smoke alarm manufacturers recommend replacing their units every 10 years.  Why?  Because at that age the failure rate increases dramatically.  Pushing the test button proves that the unit makes a sound, but does not say if the unit still works to detect smoke or heat.

The National Fire Protection Association (NFPA) and the Consumer Products Safety Commission (CPSC) have independently tested smoke detectors and have come up with the same conclusions.  Due to dramatic increases in failure rates all smoke detectors should be replaced every 10 years.  You can read an article on that relationship here.

Notice the upswing in failure rates in the chart in that article.

But here was my SECOND warning!  My house is 15 years old and my smoke alarms were manufactured by FireX.  I went to purchase new ones and found out they are no longer made!

That is a problem because I have to buy units that match the wiring in the house.

Here is the back side of the unit I removed.  And the special connection is to the right.

This unit, and its connection, no longer exist.  The clerk at the electric supply store where I went to purchase them did not know why.  So I investigated.

FireX was acquired by Kidde.  In 2008 they discontinued the smoke detectors I have in my house!
This is the new Kidde unit the website recommends to replace my older FireX unit.

And this is the unit now being sold in the electric supply store!  So, I bought seven - one for each level and each sleeping area.

Easy peasy, right?

But wait!  It's not so easy!  Here's why.

The wiring of the new unit does not match the units I have in my house!  The pattern is different!

To replace my smoke alarms I will have to rewire each one.  Each one!  But, reading the instructions it isn't difficult.  Yes, some men actually do read the instructions.  And doing the rewiring isn't difficult either.

AFTER TURNING OFF THE CIRCUIT BREAKER (!) I pulled the old wiring out of the box.

Removing the old connection, I rewired the new connection, seen here on the left.  The base for the new unit is different than the old, and it needed to be replaced as well.

The rewiring is simple - black to black, white to white and red to red.  The red wire is the "traveler," and it is how the units all communicate one with another.  If a fire starts in the basement, as the unit in the basement sounds, the units in the bedrooms on the upper level will all go off at the same time.  The units talk to each other.

That system inter-connectivity is essential.  And that is the present code.

When the new unit is installed, it looks like this!

The little slot on the left is for the battery.  This is a hard-wired unit, but has a battery back up.  Of course.

My recommendation:  I did not know that my older smoke detector was no longer made!  You might check the make and model of the units in your house.  If they are no longer manufactured, try to find out which is compatible with your house wiring.  If there are none, you might have to buy and rewire a new system, as I did.  I have tested my system (with candle smoke) and it is working well.  Follow the instructions and done right your new system will too.