Switch – Help with bathroom timer and light switch install

No way from here to know which wire fed the light or fan, but you have a continuous hot feed into the box that fed the receptacle, light and fan. The third wire, maybe it fed the fan or maybe something something else farther down the line, if the latter that needs to be tied in 100 percent to the hot feed. All whites still tied together, blacks to the dimmer from the light and hot. All grounds tied together set with a screw to the metal box. Securing the ground to the box is not needed if the box is plastic.

Before I got too wordy, here is a sketch

Still have to learn to format better

The sketch is a little rough, it should get the idea across I hope

I'm surprised that the box or paperwork that came with the switch didn't have instructions, so here is my advice (25 years as an electrician): The black wire goes to the hot bundle, the green wire is ground, and the blue wire goes to the light that is being switched. If there is a pig-tail that acted as an individual wire to the old switch, you can either keep that and attach the black wire to it, or remove it from the bundle and connect the black wire on the switch directly to the bundle.

As a way of checking what I am telling you, on the switch itself, there may be some labels for each of the wires (the black, blue and green wires). Typical labeling for the 'hot' wire is: "Hot", "Common", and "Line" Typical labeling for the switched wire is: "Load", "Line", or "Switched"

Note that in my experience, whenever the label for the Hot wire is "Line", the switched wire is never called "Line" -it is almost always labeled "Load" (which is more accurate -but let's not argue semantics).

Good luck and happy wiring!

:) Greg