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
3-way switches.
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: Neutral Hot (always)
3 Signal wires to relays Equip Ground (Green)
Total: 6
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 watts each.
But, the amount of work and materials needed may be more trouble than your just pulling the needed extra wires.
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Here goes:
Buy three single pole 10A contact 120 vac coil "impulse stepping relays" like the ones shown here:
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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.
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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.
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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 garage.
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?
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.
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.
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 switches work.
THHN isn't permitted for underground use. Article 300.5 requires that all cables & conductors installed underground in metal or plastic conduit be listed for wet locations. You should use THW or similar. Also, article
300.50 requires that the PVC conduit be protected with 3" of concrete. Also be aware that you are limited to a 40% conduit fill with these conductors. (Just guessing but you should be up around a 2" to 2-1/2" conduit.)
As for the entrance, if this is being wired into your existing service, you MUST run a 4-wire feeder to the garage, and NO grounding rod (Article
250.24(A)(5) "no grounding connections on the load side of the service). If this is wired directly to the pole with a meter base, your Ok with the
3-wire installation & grounded service. (If you are running a service entrance, your local utility will not connect this unless you have a building permit posted and the final hookup is done by a licensed electrician (usually- in most parts of the country.)
Also remember that all receptacles installed in the garage must be protected by a GFCI's.
As far as your question, if these 15 amp circuits are connected into your existing service, you have six conductors running to the garage. You need two conductors for each 3-way circuit.
Here's how to wire 3-way branch circuits. As you have 6 conductors, you can have three 3-way circuits (but you will still need to pull 3 more conductors for the grounds on these circuits (colored white). Basically, three cables of 14/3 w/ground, are what's required.
Now, not forgetting what you said, I still strongly recommend you hire a licensed electrician to AT LEAST look over the final installation and make the final connection (to power.) This would not amount to a lot of bucks and would be the best money you could spend in the entire project. The reason I harp on this is, based on the questions you are asking, I feel that you know just enough about wiring to be dangerous. Not meant to be an insult, just feel that what your doing could be dangerous in the long run.
You also need to get a building permit. I assume you didn't bother with one as the AHJ (Local Electrical Inspector) would have probably made you submit a feeder diagram and would have nixed your plans right then and there. If you don't,the AHJ could discover this construction during the next assessment and you could end up paying an electrician to re-wire it and have additional fines and fees to pay then. Also remember that if you ever sell the home, your still responsible forever should a problem develop. The new owners insurance company will come back on you (or your estate.)
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
2-3way 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.
No insult taken, I posted to learn. Your right on the THWN, and most THHN is also rated as THWN (which mine is). Interestingly I do have a building permit and the electrical inspector is the one who showed me the code on being able to run 2-2-4AL with a grounding rod at the garage. My original intent was 2-2-2-4AL, but he convinced me otherwise and showed me the code which supported it (no metal pipes shared between buildings)
I could be mistaken, but you mentioned the ground wire should be white? I thought that it should always be green if possible.?
I'm sure your inspector meant well but the prohibition against other metallic pathways between the two buildings includes those lighting switch circuits or any other wiring besides the feeder itself. If you run a ground with your switching circuits it will end up carrying neutral current in parallel with the neutral of the feeder. If you don't run a ground with the switching circuits you will have a poor fault clearing pathway for those circuits because the Equipment Grounding Conductors (EGCs) for the garage will be bonded at the building disconnecting means to the neutral of the garage feeder and the EGCs for the house are bonded to the neutral of the power company supply at the service disconnecting means for the entire premise. That may make for an excessively long fault path. You would also never be able to run an extension telephone, intercom, alarm circuit, video cable, nor any other conductive pathway between the garage and the house. In order to have a fully safe and efficient system to supply power to your garage I'd suggest that you run a separate EGC in the feeder and use it to provide the fault clearing pathway for all of the garage's wiring.
Help me understand what the risk is if I run a ground for the switches to the garage? I don't forsee any need to run phone, alarm, etc. When you say separate EGC do you mean another run of #2 AL to ground to the house ground?
If he is using the 6 wires for two 3 way switch loops he doesn't need a neutral. Feed the travellers from the garage panel and come back with the switched hot on the 3d wire. The neutral starts in the garage and never leaves. If you ground the switches from the house EGC there is no "bond" between the buildings. The 3 wire feeder is still OK. There is no parallel path for neutral current.
To have 3 switches control one circuit of lamp(s), it's easy to do with a 24 V (or other) coil bi-stable latching (or toggle) relay. The 3 switches are just pushbuttons. Momentarily pressing of a button will put the relay in the opposite state that it is in currently. In other words, If the light is on, press a button and the light will turn off. If the light is off, press a button and the light will turn on.
If you use the low voltage control circuit, you won't need 14 gauge wire. And with a relay, you can have as many buttons as you want - not just 3.
I paid $32 for that kind of relay about a year ago from
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. A quick web search didn't turn up anything that cheap currently, but you would look harder (use the phone too), or maybe pay more.
Reguardless of where you end up grounding, you can drive the switches with seven insulated conductors, and one bare/green, for a total of
8 wires between buildings.
See
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for a schematic.
If the supply line originates in the house, use the top layout, with the one nuetral(white). If the supply line originates in the garage, use the bottom layout, in which case that last conductor becomes a supply line, and should be colored.
If the three switches in the house are in different boxes, then you'll end up with a useless white wire between the three switch-boxes.
In this configuration you do bond the neutral/garage-ground/ground-rod.
I would follow the advice of snipped-for-privacy@aol.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 grounds.
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