My electrician friend came last weekend to do some work. He had this device
that looked like a large black crayon with a green conical end. About six
inches long, and as big around as a quarter.

He would put it close to a wire or a socket, and if it was hot, the green
light would come on, and a beep.

He said he thought they made them for 12v. automotive use. Anyone seen or
used these 12v. models?

Steve