In article . com, wrote:
Hi all,

Sorry if this is really trivial, or has asked before, but I can't seem
to find an answer.

I just bought a new light switch for the laundry room in the basement.
It is a Leviton brand which has a bunch of buttons to give you a
predefined amount of "on" time for the light - i.e. you hit the "10"
button for 10 minutes of light.

The switch has 4 wires: Black, white, green, blue. The old basic
switch has 2 wires - black and white. The wiring diagram from Leviton
shows multiple wires coming in from the top and bottom of the switch
box, and how to wire things appropriately.

I know exactly what you're talking about. Just put one of those in each of my
bathrooms last year.

My old switch has only the two wires: black and a white.

Short answer: you're screwed. Long answer: see below.

I assume the new switch green goes to the grounding screw on the box.

Yes, or to the bare wire that is (hopefully) present in the cable coming into
the box.

I also assume the white should be joined to the white, and the black to
the black, each through Marrs connectors.

Given your description (one black wire and one white wire connected to the
switch) this assumption is almost certainly INcorrect. That's because the
cable coming into your switch box is a switch leg, with no neutral conductor.

To wire this switch properly, you need to connect the black wire of the switch
to a wire that's always hot, the blue wire to the light you want to control
(I'm going from memory here -- I might have that backward -- check the
instructions) and the white wire to neutral.

You don't have a neutral in that box.

What do I do with the blue. I've tried a couple of things (joining it
in with the blacks)

Now wait a minute. "Blacks" *plural* ? A moment ago, it was a black and a
white. No mention of anything else.

How many cables come into the switch box, and how many wires (and of what
colors) are in each cable?

which powers the switch properly (it has LEDs that
show which timer setting is in use) but the light doesn't go on - which
is really the whole point of a switch....

What should I be doing?

Depends on the answer to my question above: how many cables, and what's in
them?

--
Regards,
Doug Miller (alphageek at milmac dot com)

It's time to throw all their damned tea in the harbor again.

By blacks, I meant the one coming into the box, and the one that is
part of the new switch. I optimistically, naively, (foolishly?) tried
joining them together along w the blue. Got pretty LED lights on the
switch, but nothing from the bulb.

So I've taken the advice given here and returned the thing for a far
less pretty manual spring timer similar to the one in the link provided
by Jeff Wisnia. After a small issue with the new unit not wanting to
fit into the existing box (persuaded with hammer, my favourite tool)
the whole thing works like a charm. And the wife somehow confuses my
for someone who is handy around the house, but this and a few low
voltage lights in the garden has been enough to earn a golfing pass for
tomorrow morning.

A satisfactory outcome all round. Thanks!

Dave