Different electrical layers

[Rooster2b]

I've started creating new layers for each item such as having a plugs layer and a separate lighting layer and it is much easier to control.

So when I want all of the plugs on one layer, recessed lighting on another, and sconces on a different one how do I go about setting them up on their own layer by default rather than opening each item up and changing it's layer assignment? How do I include the whole group on to a different layer than it's default? And can this be done retrospectively such as moving all of the recessed lighting on to its own layer after the fact?

-Thanks