As always I must advise you that I am only versed...well somewhat versed....okay I know a little bit about California code. The rest of you are on your own and none of you should blindly trust anything that I come up with. I have been wrong before .... I'll be wrong again and sometimes I make stuff up.
California Residential Code
R314.2 Where required. Smoke alarms shall be provided in accordance with this section.
R314.2.1 New construction. Smoke alarms shall be provided in dwelling units.
R314.2.2 Alterations, repairs and additions. Where alterations, repairs or additions requiring a permit occur, the individual dwelling unit shall be equipped with smoke alarms located as required for new dwellings.
In the past I have been challenged with an argument against requiring alarms unless there is a building permit. In other words if the only work is a service panel replacement, the alarms are not required. When told that the residential code says "alterations, repairs or additions requiring a permit" it means a building permit. The argument is pushed further along by the fact that California did not include electrical, mechanical or plumbing sections of the Residential Code that we adopted. Worth noting is that there is no requirement for installing residential smoke alarms found in our plumbing, electrical or mechanical codes.
Then I found the verbiage in the exception to R314.8 that states that the power source can be solely battery power if the scope of work is limited to electrical, plumbing and mechanical work. Those trades would not require a building permit but clearly they would require a permit and alarms.
R314.6 Power source. Smoke alarms shall receive their primary power from the building wiring provided that such wiring is served from a commercial source and shall be equipped with a battery backup.
Exceptions:
5. Smoke alarms are permitted to be solely battery operated when work is limited to the installation, alteration or repairs of plumbing or mechanical systems or the installation, alteration or repair of electrical systems which do not result in the removal of interior wall or ceiling finishes exposing the structure.
And so you know, we don't pay much attention to the hardwired and interconnection codes except on new work. The existing portions of dwellings are off limits. And yes I understand what the code says but hey now, people will put up with just so much. There could have been a lazy tiger in the Wizard of Oz singing "If only I had a spine."
For only California jurisdictions that are still hung up on the $1000.00 valuation threshold: That applied for the years 1985 and 1986. Two years, thirty-four years ago. Get over it.