I have an AFCI outlet in my foyer, and the circuit continues through that outlet and out to the porch for an overhead light above the front door, and then past that to the front of the house for an overhead lamp above the steps leading up to the porch. The two outside lights are on a switch inside the foyer, and the wiring runs through the porch roof. It's 'inside' in the sense that it's not exposed to the elements, but it's 'outdoors' in the sense that it's not inside the walls of my house, the construction is old, and there is some suspicion that the porch roof may have moisture in it.
When the circuit has load (i.e. one or both of the lights are installed), flipping the switch and supplying power will immediately trip the outlet. When there is no load (no lights are installed and the wires are not connected), flipping the switch does nothing.
It was suggested that the two possibilities are:
- The AFCI outlet is not rated for this use, and a small amount of moisture may be causing the trip
- The circuit has a short in it somewhere between the outlet and the first porch light. I've attached an image of how the porch light is wired. As you can see, the neutral on one of the wires does have a tiny nick, but it doesn't seem to go through to the copper.
What are people's thoughts about the most likely explanation?