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.
My old switch has only the two wires: black and a white.
I assume the new switch green goes to the grounding screw on the box.
I also assume the white should be joined to the white, and the black to
the black, each through Marrs connectors.
What do I do with the blue. I've tried a couple of things (joining it
in with the blacks) 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?
I know exactly what you're talking about. Just put one of those in each of my
bathrooms last year.
Short answer: you're screwed. Long answer: see below.
Yes, or to the bare wire that is (hopefully) present in the cable coming into
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.
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?
Depends on the answer to my question above: how many cables, and what's in
Doug Miller (alphageek at milmac dot com)
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
A satisfactory outcome all round. Thanks!
If you only have two wires, the black and the white in the switch box, that
timer won't work. You need a mechanical timer. That timer requires a
neutral. Your current switch has a hot wire and a return, but no neutral. If
you had a neutral, you'd wire the hot to black, the neutral to white, and
the load (wire that goes to the light), to blue
You have to run another white wire to where the switch is from the light.
Some light have the black, white and green(bare) ran up to the box the
light is mounted to. The white wire goes to one side of the light socket.
The bare wire goes to the grounding screw. From the switch you run a white
and black wire toward the light. One of the wires (white) will go to the
free black wire, the other (black ) will go to the light socket. What you
need to do is get a wire from the white wire at the light socket to the new
switches white wire. Then connect the black wire at teh switch to the
black wire at the light socket box. Then run a wire form the blue wire of
the new switch to the other side of the light socket.
It sounds as if the switch itself needs power for the 'timer' function,
hence the need for a white wire (common) to attach to the whites (commons)
in the box These would not have been attached to the old switch, rather
would have probably been joined with a wirenut in the back of the box.
EXCEPT - since you say you have a white that is bare, that was probably
connected to the old switch, I'm thinking your hot came into the light and
what you have in your switch box is simply a drop down from the light. That
is, you don't really have a common to connect to - that's only available in
the box at the ceiling where it connects to the light.
Did you only have a black and a white connecting to the old switch? Did the
white have any kind of marking on it (tape or paint) to indicate it was a
hot and not a common?
My guess is that with your configuration you may not be able to use your new
As other posters indicted, you are probably screwed with that switch and
your existing wiring. You _could_ always replace the 2-conductor romex
between the switch and light with 3-conductor but that isn't trivial for
a beginner and depending on how the walls and ceiling are finished can
be a PITA for anyone.
How about this: take the timer switch back and try to get your money
back. Then buy a "warm moving body detector" switch for about half the
price. The common ones, such a Eagle that some big-box stores carry, can
be wired to work in your situation. And they work even better in my
experience than a timer since you don't have to touch anything -- you
walk into the room and the light comes on and after you leave it waits
for a pre-determined time and then switches off. Just the thing if you
have your hands full. Best of all, the Eagle probably costs half of what
your Leviton timer cost ($20 vs. $40?)
I've wired my garage bays and some entry switches with the Eagle brand
units from the Borg and they work very well.
Given that many other posters gave the same opinion, I guess I'm toast
unless I upgrade the wiring - and I'm not really keen on doing that....
So I will follow your suggestion and look for a motion detector switch.
If that gets me some $$ refunded as well, then that would be a good
As an aside - my ISP recently ditched their news server, and so I've
had to find another means to access usenet. I signed up to Google
Groups a few months back, but have ended up just lurking in my
favourite groups. Until now. So this was my first ever post from my
new account, as well as a first ever to al.home.repair. I have to say
I am mightily impressed with the speed, usefulness and general civility
of the posts I've received. Better than I had any hopes for.
Thanks to all for your replies!
Well, the Eagle Electric brand for sure does not need the neutral --
I've installed several and none of them had both hot and neutral in the
switch box. Their drawing calls for the black to go to the hot and the
red & brown to be nutted and connected to the load and the green to go
the ground. Works fine every time for me. Who knows, they might be using
the ground lead to provide the little bit of "neutral" current needed --
probably wouldn't meet code but I've not checked it out.
Nah. Seems to me the "timers" working current has to be there when the
light is ON, and that's when there should be NO voltage drop between
those two wires to run the timer with. So you couldn't ask for a very
large voltage drop there without having to put up with some significant
power wastage and heating, depending on the size of the bulb load.
Now I suppose you could put a current transformer over the current
carrying lead to the light bulbs and use the voltage developed on its
secondary, after regulation, to run the timer circuit. But that's a long
run for a short slide and transformers ain't cheap parts to make. Then
again, they do use current transformers in all GFCIs, so maybe it's not
such a whacky idea, and if a rustbucket like me could think of it, then
other engineers could easily do the same.
The OP's switch may be different, but I have two electronic timer switches
to turn lights on and off automatically at evening and morning. They are
powered by trickle current wither the load is on or off. I think they just
use such a small amount of power that it doesn't cause a significant voltage
drop. I know they use current from the light ckt because if and only if all
connected bulbs burn out, the timer loses its programming.
"Remember, an amateur built the Ark; professionals built the Titanic."
Dave - Don't despair - That switch sound pretty nice. You said this was
a utility room, right? If so, can you see the wire from the switch to
the light or does it run in a finished wall? Do you think you would be
able to fish a different, or new, wire from your light to your switch?
If you could get a different wire there then we could get that thing
working for you.
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You may not be able to use that switch as it requires a neutral
connection in the box where the switch is... many times the neutral is
at the fixture, and not at the switch at all.
The instructions are probably like this:
White - neutral
Black - hot
Blue - load
Green - ground
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