Sounds like it is allowed, since MA Amendment 210.25, exception says branch circuits [plural] and both units are on the same level.
I personally don’t like the idea of only one tenant having access to the circuit breaker supplying the smoke alarms for the entire building, even with the battery backups, but it sounds like it’s perfectly okay as far as the exception goes.
If the circuit panels were both located in a common area like the hallway, basement or laundry, I wouldn’t have any problem with it at all.
Leland: Are the CO alarms now required to be hard wired and interconnected between units in MA, or is this just because it is a single structure with no firewall separation?
Does this mean they are no longer allowing the individual 120V plug-in units with battery backup?
