80s townhouse had an old dimmer (looks original to the house) hooked up to red and black (no ground). Both tested as being hot, which I thought this was strange. I tried swapping it with a new LED-compatible dimmer, and it won't turn the light on at all. If I touch the wires together, it turns on.
Does it make sense to have two hots for a light dimmer? How can I make the new dimmer work?