2 black wires on my light switch - Lutron Electrical Supplies

SOURCE: 3 way dimmer turns on and off, but does not dim

All your wiring looks good. Many times dimmer just have problems and are faulty. You should note that the dimmer can only handle 600 watts. If you have that or more on it, than you have probably fried the dimming mechanism. In either case the dimming mechanism is not working properly and you will have to take it back and get the same dimmer or a different one. Tell the store they sold you a faulty dimmer and you can get a replacement at no cost.

SOURCE: I would like to install

The circuit you are working on is a 3-location circuit - where two of the devices were 3-way switches, and the remaining device (the one you are trying to replace with a dimmer) is a 4-way switch. Standard dimmers like the one you're using CAN NOT be used to replace a 4-way location. If you wanted to use it to replace either of the 3-way switches, that's no problem - but what you're doing right now will not work.

If you absolutely want to dim the lights from that specific electrical box, my suggestion is to upgrade to a "smart dimmer" where instead of a basic dimmer and two light switches, you have three devices that talk to one another and all dim the lights together.

In terms of your ground wire questions - ground wires certainly aren't necessary to make the whole thing work - rather they're there for safety. Sometimes installers will ground the device by connecting the ground wire to the backbox (assuming its metal) and then rely on the mounting screws on the dimmer or switch to perform the grounding. There are some code rules/exceptions for allowing the device to not be grounded (usually when its in a plastic, non-combustible backbox). If you want to make sure everything is completely up to code (which are usually goverened by local municipalities), you should consult a licensed electrician - but above all else, just use good judgement. Long story short, if the devices weren't grounded before, you can't make it any worse.

SOURCE: New dimmer switch not working

Hi -

The Lutron D600P is a preset single pole dimmer. Wiring is pretty straight forward as show in this diagram. Recheck wiring and if OK, continue below.

If power is present on both wires (black / red wires), power is being passed through the switch to the lamp and the light should be on. If not, try replacing the lamp.

Minimum recommended connected load is 40 watts. This switch is ONLY for use with filament type lamps - such as traditional tungsten, halogen, etc. It is NOT to control speed of Fan Motors, nor dimming of CFL (compact fluorescent lamps) energy saving types or other ballast operated lamps such as High (or Low) Pressure Sodium, Metal Halide, Fluorescent, etc. as this would create a high heat condition and could cause a fire.

If you're still having trouble, you can contact Lutron Technical Support Center 1.800.523.9466 24 hrs / 7 days www.lutron.com

I hope this helps & good luck!