Smoke alarms have become very common appliances in most American homes. In many places they are required by law, but a good many are installed because homeowners realize what a vital part they play in keeping their families safe. To see the little plastic case and know it houses such amazing technology is mind-boggling. In fact, the bottom line is that that little case can contain the difference between people living or dying.

Smoke alarms come in two basic types, the photoelectric and the ionization. The photoelectric alarm uses a small beam of light. When there’s a fire, smoke particles block the light. This in turn causes the light to reflect off of the smoke particles and onto the sensor which then sounds an alarm alerting family members that there’s a fire.

Ionization detectors are the type of smoke alarms that people usually buy for their homes. Although there is a tiny bit of radiation in them, experts consider them perfectly safe for home use. This kind of detector operates using electric current generated by a battery. In the device, there are two small metal plates located approximately 1 cm. apart. The battery charges one of the plates with a positive charge and the other with a negative one. This causes electrons and ions to bounce back and forth between the plates.

By knocking electrons off the atoms of air in the chamber, alpha particles cause the oxygen and nitrogen atoms to ionize. When smoke particles enter the chamber, they block the activity of the electrons and ions which causes the alarm to sound.

Battery-operated smoke alarms are free-standing units that work independently of each other. Homes that were built during the last 10 years, however, will more often have smoke detectors that are powered by electricity and wired together so that they can intercommunicate.

These smoke alarms are connected by way of a three-way wire. The black wire carries the 120 AC current, the white wire is neutral, and the red wire is used to connect the units together using one single circuit from the fuse box. If an alarm goes off in one part of the house, a signal is sent to the other alarms over the red wire. The other smoke alarms will take their cue from the signal they received, and they’ll start making noise, too. How easy can you get, but it works!

Although you should never open a smoke alarm unit yourself due to the radiation inside, if you ever happened to see inside you’d be astounded at what you find . Smoke alarms are exceedingly simple, especially in view of their important function in society.