This was interesting - When Installing fixtures and devices while finishing an improvement project, I reinstalled an existing Smoke Detector. After connecting the unit I noticed that the Green Power indicator did not light up. I double checked for power and found that all the breakers were on, but there was no voltage found on the smoke detector circuit. The occasional Red Indicator flashed, showing that the device was working on battery and communicating to the other detectors. I held down the test button and found that all of the home detectors worked just fine - on Battery.

I notified the homeowner who stated that he has never seen a Green Light on any of the smoke detectors.

The home is seven years old, and apparently the circuit has never been energized. The homeowner instructed me not to spend any time on the problem as he would notify the builder.

The owner indicated that the steam from the shower has occasionally set off the detectors, so he knew they were working.

Wow! Thank Goodness for the code that requires that 120 Volt Smoke Detectors with battery backup be installed.