joji
Member
- Location
- North east
- Occupation
- Electrician
The house was built late 1800's. It was converted to a boarding house mid/ late 1900's. There are smoke detectors in all the hallways ave they are connected together. They are hardwired in that they talk to each other, but there is no power from the service. They are running off the 9v dc battery. After investigating, I found a transformer near the panel that says low voltage smoke detectors. On the line side is 12/2 bx, On the load side is a low voltage cable - type I've never seen before. Made of metallic shealth but very flexible, not breakable, probably 16or 18awg.
So, my questions are: does the NEC require two power sources in this scenario? Does it actually require 120 v a/c or does it just require all common area smokes to be wired in tandem? Would it pass Inspection as is, powered by battery but wired in tandem?
Next, has anyone ever seen low voltage smoke detectors? Was that ever a thing? Im curious why this was constructed this way to begin with.
So, my questions are: does the NEC require two power sources in this scenario? Does it actually require 120 v a/c or does it just require all common area smokes to be wired in tandem? Would it pass Inspection as is, powered by battery but wired in tandem?
Next, has anyone ever seen low voltage smoke detectors? Was that ever a thing? Im curious why this was constructed this way to begin with.
