I would like to wire three 3-ways switches for various external lights
in my new detatched garage (switches in both house and garage). I just
laid the schedule 40 with 2-2-4AL (240vac power to garage with seperate
grounding rod) and pulled six 14g THHN black wires also. It was late
and I wasn't thinking about the fact that I need more wires for three
I know there are several options for wiring 3way switches, some with
power to the light and others with power to the switch. Is one way
more preferable than the other? Also, when I pull additional 14g THHN,
should I use specific colors to meet code? Can I use one ground wire
between all 3 house switches? I need 4 wires per switch if I am
reading things right (hot, neutral, runner and ground).
Don't know why, but 3ways confuse me a bit and I want to make sure I am
doing it right.
Just looking for clarification...please don't post that I should hire
an licensed electrician.
You can do it with the existing 6 conductors.
The 3 switches in the house will be SPST type and will
feed 120V to 3 of the conductors. In the garage these
conductors connect to 3 120V AC relays which are SPDT.
The relay contacts act as the 3W switch.
To keep everyone happy, the relays will be UL-listed
for the purpose and have NEMA1 enclosure(s).
(Ask if a separate disconnecting means for each
of the live conductors will be req'd at the garage.)
So......you need these wires:
3 Signal wires to relays
Equip Ground (Green)
Just for grins, the number could be further reduced,
but 6 will do it.
Yes, there's a reliable way of controlling three external lights on the
garage from three switches in the house and three switches in the
garage, assuming the lights are reasonably sized, like not over 500
But, the amount of work and materials needed may be more trouble than
your just pulling the needed extra wires.
Buy three single pole 10A contact 120 vac coil "impulse stepping relays"
like the ones shown here:
mount them in an enclosure in the garage.
use two of the six 14 gage wires to bring a 120 volt hot, neutral and
ground to the garage. (One side of the 240 in the garage is probably
going to be at the same potential as a separate 120 volt hot, but I'd be
more comfortable using a separate wire.)
Power the three lights from that circuit, through the contacts of each
of the three relays.
Install three normally open pushbutton switches in the house and wire
them so they put 120 volts on each of the three remaining wires when
they are pushed.
Connect those three wires to the coils of the three relays, the other
ends of the coils are connected to neutral.
Install three normally open pushbutton switches in the garage and use
them to also put 120 volts on on the coils of the three relays. (They
will be electrically in parallel with the switches in the house.)
To turn a light on or off, just push the appropriate button, and the
relay will "alternate" and do the job, just like pulling on the string
of an overhead "on-off" fixture.
I'm presuming you can see the lights from both the house and the garage
switch locations, but if you can't, you're no worse off than if you
wired them with conventional three way switches, 'cause they don't give
you an indication of whether the controlled light is on or off either
unless you add more wires and pilot lamps. <G>
If you want a more expensive space age solution, I'm sure you can
accomplish the job with X-10 equipment where you'd only have to use
three of those wires to bring a 120 vac hot, neutral and ground to the
Wow, those are some creative ways. Thanks, but I think I will resort
to pulling additional wires. So now, I will need what? 1 ground that
I can share? and 3 runners? Should I pull 1 green and 3 reds? or does
it matter. I have a lot of 14g black THHN, so I could still use that
if that is ok.
Also, my schedule40 is 1.5" wide and has 2 90degree and 1 45degree
bends and is about 50ft in length (carrying 2-2-4AL URD and 6 14g
THHN). Should I try to do this with a nylon fish? or use one of the
existing 14g THHN wires to pull the additional wires...will the 14 hold
up for this?
If you're doing three "classic" sets of three-way switches (6 switches
in total switching three loads): Each pair of switches need 3 wires
that will be hot/switched hot. Plus a ground (green) and a possibly
a neutral (white, if the load is at the other end of the conduit from
the unswitched power feed you need a white wire).
All black is okay for the hot/switched hot, but one red per switch pair
may make things a little simpler to puzzle out when you're wiring.
Using one of the existing wires to pull the others would probably
work best. Especially if it's stranded.
Chris Lewis, Una confibula non set est
It\'s not just anyone who gets a Starship Cruiser class named after them.
Yes, I would agree, use X-10.
You are talking two or three control locations for under eight
lights/appliances. When you research X-10 a little bit, you will see
that it has huge advantages.
Now if you were talking about controlling 20 lights from 5 controllers
with remote control and timers and computer control, I'd say avoid X-10
like the plague, but for your installation, you will love it.
and pulled six 14g THHN black wires also. It was late
please don't post that I should hire an licensed electrician. YOU NEED ONE
"2-2-4AL (240vac power to garage with separate grounding rod)"
A separate ground rod is a violation of the electrical Code. What you need
is another conductor for the ground. What you have created is commonly
called a ground loop. Your installation will use the earth as a return path
for a fault in the garage, not good practice nor code complaint.
if all you wanted was 2 3 ways the 6 #14's would be enough to make 2-3way
Actually, a separate grounding rod IS acceptable per NEC as long as
there are no gas or metal water pipes shared between the buildings.
You don't bond the bus on the subpanel...so no loop.
"if all you wanted was 2 3 ways the 6 #14's would be enough to make
switches work. " I don't think this is right either...each switch
would require hot, switched hot, neutral and ground. even for 2
switches, that's 7 wires even if you share the ground. Thanks for
posting a response though.
In this configuration you do bond the neutral/garage-ground/ground-rod.
I would follow the advice of email@example.com if using the #14s. I
havn't looked at X-10, an interesting idea, but my understanding is it
uses signals imposed on power wires and could use the feeder wiring with
no use of the 14s. I agree with Tom Horne that you can't include #14
I'm not sure what you are asking. You can't run a #14 ground from house
to garage as this would be a "separate metalic path" which is prohibited
if you run only a neutral (without a ground) as the supply in your
feeder. A #14 ground from house to garage would appear in parallel with
the neutral. The grounds at the garage are picked up from the common
OK, let me restate, cause I think I am finally getting it.
for my light fixture in the garage, the neutral (white wire) stays in
the garage. It is the Hot/Switched Hot/Runner (3 wires) that goes to
the House 3way and then to the garage 3way. I got that.
If I run a #14green wire from the garage to the house as an EGC ground
(just for the switch which is in non-metalic switchbox)...I have
If I run the green ground wire from the house side switch to the house
EGC, and keep the garage side switch grounded to the garage, would this
allow me to keep the grounds separate and not violate code/be unsafe?
I'm trying to figure out my options short of running another #4AL
feeder cable for the ground. I can pull more #14 wires, but just need
to know how I can make this code compliant and safe.
I don't think you can. You have two mutually exclusive choices:
1: Supply power to the garage with two hot wires, and a combined
ground/nuetral connected to earth in the garage.
2: Have switches in the house that are electrically connected to
something in the garage.
I'm pretty sure you're not allowed to do both.
SO you have to either figure out how to control the
garage lights with a remote, or run a 4-wire feeder
cable to the garage, and abandon the local ground.
I don't have the NEC, but my understanding is that 225.30(d) allows an
exception for outside lighting to be controlled from multiple locations
is permitted. I'm not clear though if what I want to do falls within
that. Either way since it is detached, I must have the local ground
even with a 4 wire feeder, just would keep the neutral and EGC seperate
in that case. (i think)
No you do not "abandon the local ground"! The grounding electrode
system is required in either case whether the feeder has an Equipment
Grounding Conductor (EGC) run with it or not. In a three wire feeder
the neutral of the feeder is bonded to the grounding electrode system of
the garage at the building disconnecting means. With a four wire feeder
that includes an EGC The EGC is bonded to the grounding electrode system
at the building disconnecting means and the neutral is kept aloof from
ground in the garage so that the neutral current will not flow on the
parallel conductive pathways to the building in which the service is
Well we aren\'t no thin blue heroes and yet we aren\'t no blackguards to.
Well I be damned. They changed it to allow feeders. I was wrong, and not
more than a little surprised. Haven't had many states reference 2005 yet,
most are still on the 99 where it was referencing services. (After all
these years of it being a no, no...... grin.)
Thanks for the reference Bud.
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