Household Smoke Detectors go from boring to AMAZINGLY INTERESTING at 2 moments in life!

Moment 1: When the shrill of a weak smoke detector battery startles you awake from a deep slumbering sleep.

Moment 2: When a Smoke Detector helps save life, property, or both during an unpredictable, unexpected fire.

Most Smoke Detectors contain an internal battery backup.  A few complex automation systems however typically don’t and store a large battery elsewhere. Change the internal batteries, before your smoke detectors become amazingly interesting, at least every 6 months.

If you like important Trivia… discover what shocking % of people, especially children, don’t wake up when a smoke detector is shrilling. We also posted a link in the Q&A forum at the end of this page.

They were invented by the Germans during World War II for the purpose of providing protection in their munitions and other factories.

Depending on the type you have in your home, generally, they work using one of two technologies. The two technologies household smoke detectors use are photoelectric and ionization.

Types of Fire

Today’s household smoke detectors are generally used to detect one of the two types of fire condition. One general fire condition is the heavier smoke producing, smoldering fire. The other type of fire would be consider more like a flash fire such as cooking oil catching fire on a stove top.    

Home Fire Escape Plan Available at this Link


A photoelectric detector works by periodically pulsing a tiny beam of light through the inside of the detector chamber. What causes this type of smoke detector to go into an alarm condition is when that beam of light is deflected by a sufficient amount of accumulated smoke inside the detector. This process is similar in nature to how car headlight beam will become deflected during foggy low light conditions.


An ionization detector works by measuring a small electrical charge inside the detectors detection chamber. This charge is applied and measured and when the charge remains at the correct level the smoke detector isn’t activated. When a change to the electrical charge inside the detector changes sufficiently then the smoke detector will go into an alarm condition.

Smoke Detector Placement

Minimum Recommended Placement

The National Fire Protection Association recommends placing smoke detector in a minimum number of locations inside a home. Its recommend you consult their website for further information regarding suggested placement. However, it is the most advantageous to place one inside each sleeping area as well as immediately outside each sleep area. As well, it is recommended a minimum of one be installed on each floor in the home.

False Alarms

The most common causes of false alarms can be (not limited to):

Improper placement – For example, a detector placed inside the kitchen/immediately cooking area could result in unwanted false alarms. Food particles, rising during the cooking process, can enter the smoke detection chamber and cause the household smoke detector to go into an alarm condition.

Low or No batteries – Depending on the type of detectors and how they’ve been installed, a low or no battery condition might cause a loud beeping noise etc. It is recommended batteries be change when they are found to be low or as often as the onset or retiring of day light savings each year.

Summary of Household Smoke Detectors

The two general types of are ionization and photoelectric. They can be used to detect flash fire and/or smoldering fires and it is recommended you refer to the manufacturer packaging to learn which type is best for a given fire risk. Batteries should be replaced when low or as often as the onset or retiring of day light savings each year.