First of all putting up a quality smoke alarm, whether it’s hard-wired or battery-powered is always a good idea. The dependability and sensitivity of each type of alarm is interesting, but remember any smoke alarm is better than no smoke alarm.
The differences between the two types can help you decide which is best for you.
1. Dependability. The battery-powered alarm will eventually run out of power and stop sounding the alarm. The length of time it takes to quit will depend on how much battery life was left when the alarm began. In apartments with thick walls or if you are not home when it starts up, you may wish you had had a longer-lifed alarm. Obviously, hard-wired alarms continue sounding the alarm until turned off.
2. Interconnectability. Battery powered alarms are stand alone and do not chain together. On the other hand, hard-wired alarms can be hooked together so that if one goes off, they all go off, creating a strong probability that wherever you are you will immediately become aware of a problem. A strong factor in the choice of hard-wired.
3. Battery Back-up: Hard-wired alarms have a battery-back up in case of loss of power. Battery-powered alarms do not have a back-up power source.
4. Maintenance. Battery-powered alarms are easier to maintain (no power shut-off to access) but they need maintenance more often.
Our recommendation is to consider each and determine what is best for you. As licensed electricians we know that hard-wired is better, but installation and maintenance expenses should be considered. There could be insurance benefits to hard-wired also, so check with your insurance agent to see if these savings could apply to you.
Sources: U.S. Fire Administration/FEMA, 2011.