Three white cables come into the metal mounting box. Each cable has a red wire, a green wire and a black wire. The 3 green wires are screwed onto the earth terminal in the top right-hand corner of the box. The 3 black wires are all screwed in to a connector block in the bottom right-hand corner of the box.
That leaves 2 red wires. How can I tell which ones should be connected to the three terminals at the back of the new dimmer switch: L1, L2 and the arrowed wavy line?
That leaves 2 red wires. How can I tell which ones should be connected to the three terminals at the back of the new dimmer switch: L1, L2 and the arrowed wavy line?