My local inspector has given me the option to install battery-operated smoke detectors, but he says they must be interconnected.

He would prefer that I run wires and put at least one hard-wired detector on each floor, and in a perfect world, all of the detectors in the house would be hard-wired to each other, but unfortunately, this is impractical without greatly expanding the scope of my original project.

The problem with hard-wiring, is that he is only requiring smoke detectors because I have completed gutted a room and have access to a lot of areas to run wires in that limited region of the house, and I cannot access every room in the same way. So he basically says, just hardwire where you can, or I can just go all wireless, but he prefers me to wire -- he isn't being staunch about the hard-wiring and isn't making it a hard requirement, but he is requiring that I install interconnected smoke detectors, even if they are only on batteries.

The problem with me opting to go with my inspector's preference is that it means most rooms would be wireless, while three would be wired, and I think this creates two separate groups of detectors that talk to each other, but not across both groups, unless of course there is a product that is compatible with being wired or not wired at the same time, communicates via wireless signal regardless of the power source or availability of a communication wire, and has the battery lifetime to make it legal as opposed to one which is only designed as a short-term battery backup when not wired.

I don't know of any smoke detectors that fit this description. Assuming it doesn't exist. Should I just buy a bunch of battery-operated interconnects or is there a compelling reason to hard-wire only a few with the hope of being able to expand the network during remodels in the future?

  • 2
    You should probably ask the inspector clarifying questions. If they’re mentioning interconnecting, it would be pretty shocking if they allowed two separate islands of alarms.
    – nobody
    Commented Mar 25 at 2:45
  • @nobody because there is currently no interconnection at all, therefore, he sees anything as an improvement, but he also understands that it isn't reasonable to demand for me to greatly expand the scope of my project for which the permit was pulled and essentially require that I rewire the entire house. Commented Mar 25 at 15:28

3 Answers 3


First Alert makes a wireless-to-wired bridge for their smoke alarms

If you use First Alert/BRK OneLink alarms for your wireless alarms and First Alert wired alarms, then you can use a First Alert SA520B at one of the hardwired locations as a "bridge" between the two setups.

  • I just did this with First Alert and I had a different company (forgot name) with the older alarms I replaced. Pretty easy to do the plug conversion for the wired and have them connect to the other non-wired.
    – DMoore
    Commented Mar 25 at 18:54

Hardwired is the optimal solution, yes.

If you can only do wireless interconnect for whatever reason then at least run a dead wire to the smoke detector location(s) during the reno; 14/3 if I'm not mistaken. Label them "DEAD" at both ends and home-run them to a central junction box that is accessible in future renos.

After you renovate enough spaces then some day "future you" will thank "present you".


In my area the main objective of hard wiring is to provide power, as some homeowners aren't very good at keeping batteries in their smoke alarms.

So it's completely acceptable to power the alarms from the lighting circuit (which is already in the ceiling in every room) and have all the alarms interconnect wirelessly.

Wired vs wireless interconnect is mostly a question of cost - wired interconnect alarms cost less, but you've got to run new cables as the interconnect needs a dedicated core. Wireless interconnect alarms cost a bit more upfront, but save on labour.

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