I live in a home that was built in the late 1930s with some old electrical wiring and some new wiring. As I was identifying which outlets and lights are controlled by which wires I discovered a brainteaser:
A garage outlet that my outlet tester identified as properly wired and grounded:
However, it only had 2 wires going into it: a red one and a white one:
Furthermore, for some reason, the box that holds the outlet is attached to another box with thicker gauge wires that are black, red and white which are not connected anywhere.
I suspect the other box with thicker (12AWG) wires used to have the outlet for a dryer, while the first outlet pictured used to power the washer (they have since been moved to another location).
But my question remains -- how can my tester (which has been pretty good at showing missing ground in other outlets) be showing this outlet as ALL GOOD in terms of ground even though it only has 2 wires going in?
P.S. Making sense of the source of these wires at the panel is not an option for me -- it's a mess.