My house was built in 2004 and came with fire alarms pre-installed and hardwired. The alarms also use a 9V battery backup, so we have to replace the batteries regularly (not an easy task with 9 ft ceilings, neither of us is exceptionally tall).

It's time to replace the alarms, and we were looking at the 10 year sealed lithium battery units (so we don't have to replace the batteries, we can test the alarms with a broom handle easily enough), but they don't seem to come in a hardwire variant.

Should we do something with the wires that are coming out of the ceiling? Would it be safe to not have them hooked up to anything? The circuit that feeds the alarms also powers the master bedroom (this house was built during the construction boom and it's terrible).

Would we loose any functionality by not using the hardwires?

  • Worry Free 120-Volt Hardwired Inter Connectable Smoke Alarm with 10-Year Battery Backup They do make them sealed and hardwired
    – user44362
    Oct 7, 2015 at 18:17
  • We have 9ft ceilings on our main level, and I've never had trouble using even something like a dining chair to reach the recessed light cans... No offense meant but I'm not sure that I 100% understand your concern with ceiling height.
    – alt
    Oct 7, 2015 at 23:46

3 Answers 3


Bad idea. Since the hard wiring was a building code requirement, a change could readily give your insurance company an excuse not to pay in case of a fire.

In addition your detectors are interconnected, so they all go off together. Wireless connected models are not available with ten year batteries ( I wrote on this topic at http://www.squidoo.com/you-have-three-minutes-to-escape-linking-home-smoke-alarms )

Instead consider pairing new detectors with ultra long life 9V or AA lithium batteries: such batteries cost more but last longer. And it's worth highlighting: smoke detector electronics generally come with a ten year rated lifespan (dating to 2004, as you note, yours are due for replacement).

Perhaps part of the problem was detectors that eat batteries? The hardwire alarm batteries only come into play when power is out: a two or three year lifetime for each battery is the minimum you should expect, even from a conventional alkaline.

  • Insurance companies would have a hard time making that an excuse. Smoke alarms don't prevent fires, and your mortgage company would have a fit if they tried.
    – Edwin
    Jan 17, 2014 at 21:46
  • Check your insurance contract, read in detail the section about code compliance. Smoke alarms can reduce reaction time and limit fire losses. Take the risk if you want, I will not advise anybody that way.
    – Bryce
    Jan 17, 2014 at 23:30
  • @Bryce Your article link is dead, though archive.org has a copy
    – gregmac
    Mar 29, 2017 at 21:15

Many jurisdictions mandate hardwired alarms because people forget to change batteries. You should check with your local building authority about the requirements.

If you change something away from code, in addition to the risk, you many also be jeopardizing your insurance coverage.

  • Eep! I found the code for single family units (I live in a townhouse) and hardwired smoke alarms are in that code, so they're probably in the multi-family home code as well (as soon as I find it). Thanks!
    – Zaralynda
    Jan 17, 2014 at 19:51
  • Yup, multi-family is almost always stricter, not more lax than single. More people to burn it down, more people to die if it does...
    – Ecnerwal
    Jan 18, 2014 at 2:15

I agree with the previous comments about not disconnecting the hard-wired. As a Certifed Fire Inspector, I would call this out as a violation and would also tell you that you are putting your family at risk since currently if one alarm sounds, you are warned throughout the house. Secondarily, it is not necessary to choose one over the other. The leading companies sell hard-wired smoke detectors with the 10-year batteries, so simply purchase the correct version. They are sold at your local big-box stores and several online retailers.

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