This is probably too convoluted to try and explain here but I'll try.
I have two lights that I want to control with 3-way switches: 1 light
is in the garage 60 feet away and one light is the house. I plan to
put them on the same circuit.
In the house I have two 3-way switches: H1 and H2
In the garage I have two 3-way switches: G1 and G2
I planned to share the neutral, so I put in the conduit one 14/3 and
But now it seems to be that I'm one wire short!!!
The problem is that while the garage light is wired H1-G1-light, the
house light needs to be wired H2-light-G2 and I just can't come up
with a diagram that will make it work.
Can anyone help out of my predicament?
the diagrams at
may be of help
if I understand what you are trying to do, you may need to wire the
H1G1 set as "Basic", and the H2G2 set as "Variation #3", involving a
total of 6 wires between house and garage. Note that Var 3 really does
not have a "neutral" between the house and garage !!
Assuming your existing wiring is
powerH->H1->H2->lightH (basic 3-way switch)
powerG->G1->G2->lightG (also basic 3-way switch)
Between H1 and H2 you would find 3 to 4 wires (ground, neutral, and two
traveller wires). Ground wire doesn't have to come from H1 to H2; it could
come from anywhere, I believe.
Between G1 and G2 you would find the same.
In theory, you can make it work with 4 wires between the house and the
garage (two travelers from house to garage, and two travelers from garage to
house). If you do this you'd end up with:
The only wirings you change is between H1->H2, and G1->G2.
Doing this would mean combining hot from one source with neutral from
another source. This is very unusual way to wire stuff. If one of the
sources has a GFCI or AFCI this kind of wiring would cause problem. It may
also be against electrical code. And even if it isn't, I wouldn't do it if I
To avoid mixing hot and neutral, you need 3 wires between H1 G2, and G1 H2.
So, the best solution is to replace the 14/2 in the conduit with a 14/3 so
you can have 6 wires.
If you don't want to change the conduit, you can choose to have one of the
lights (the garage or the house) works as a 3-way, and then wire the other
light as a normal one-switch light.
Assuming you have 2 two gang boxes at each location and two 3way switches at
each location. You have to have 2 wires at either location going to each
light. you need a feed brought into one of the switch locations, and you'll
need 3 wires going from each switch to it's corresponding switch location
Of course you're one wire short. A 3-way switch needs 3 wires. Two 3-way
switches requires 6 wires. "Sharing the neutral" doesn't have anything at all
to do with this. That's a completely different matter -- suggest you Google on
"shared neutral circuit" or "Edison circuit" for an explanation.
If wiring it with cables you need a 3-wire for each light. If you need
power at the garage you need another 2 wire.
If wiring with conduit and wires you need 6 wires (not including
ground). If you need power you can still use 6 wires and connect one of
the 3-ways as a "California 3-way".
If you used a 3-way at each end to control both lights at the same time
(2 switches total) you could also use a "California 3-way" (also gives
power at the garage). Requires 4 wires in conduit. Since a couple codes
ago this requires a 4 wire cable.
You can use what you have if one of the 3-ways uses an X10 control.
(You don't detail your wiring method. Cables in buried conduit have to
be UF (not Romex).)
How do those two cables reach the garage? Is the garage attached or
detached? What kind of cable did you use? What Country, State /
Province are you located in? Answer those questions and we can give
you much better answers.
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