Just moved into a house. External sconce light wasn't working. I swapped it out for another bulb rated 110/120V. The light flashes on and off repeatedly.
I removed the bulb and put my multimeter leads into the screw base at the + and - terminals and read voltages hopping around between 90 and 100V.
I went upstream to the easiest access point (not the immediate next one) and measured 120V.
So I removed the sconce and measured the wires there and get 120V.
From that point, the cable runs directly into the sconce and to the bulb base.
I've repeated this multiple times and get the same thing. There's nothing else between the wall/sconce 120V and sconce/bulb 100V.
Does this just mean there's something wrong inside the sconce?
Edit Update: there might be a photocell in the fixture I was not aware of. We have two of these sconces, and the other one I turned on at night but wasn't on this morning. There's no apparent photocell anywhere, so maybe it's in the fixture itself somewhere. My understanding is a photocell changes resistance depending on lighting, so that would mean the voltage drops during the day, explaining the 100/120V discrepancy. Will update.