Wiring 3 way switches for detatched garage lights

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snipped-for-privacy@yahoo.com wrote:

switch legs per switch.

house-garage ground wire is a prohibited separate metalic path.

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wrote:

X10 devices use a 121KHz signal sent over the power line. A burst is sent at each zero-crossing (so obviously, X10 requires AC power). No additional wiring is required. X10 commands are slow, about 1/3 second per command. A simple operation usually takes 2 commands. one to select the device and the other to operate the selected device.
One good thing about X10, is that it uses separate ON and OFF commands (rather than just a toggle). This is useful (or even essential) sometimes.
Wireless X10 controllers exist (with the decreased reliability of wireless). It's best to avoid them if you have (or can add) wires to the control locations (the simplest and least expensive X10 controller is an 8-device unit that can be plugged into any outlet using the same power transformer as the devices to be controlled).
Note that there will be a unit code (1-16) and house code (A-P) allowing up to 256 addressable devices. The controller can only be set to one house code (it's best to avoid A since that's the default). You could use G1, G2, G3, and G4.
--
25 days until the winter solstice celebration

Mark Lloyd
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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.
-----------------------(grounded wire - white) ------------| house garage | |---- (black) ---------| (L) --------15a------(S) (S)----------------| |---- (black) ---------| (S)- 3-way switch (L)- light
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.)
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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.?
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snipped-for-privacy@yahoo.com wrote:

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.
--
Tom Horne

"This alternating current stuff is just a fad. It is much too dangerous
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Hmmmm....interesting.
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?
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snipped-for-privacy@yahoo.com wrote:

When you run a separate EGC to the garage it will be in parallel with the neutral of the feeder because the code requires it to be bonded to the neutral at both buildings disconnecting means. That means it will carry a portion of the neutral current during normal operating conditions. If anything then happened to the continuity of the feeder neutral the EGC will carry the neutral current at a very high voltage drop until it fails open. With either a high voltage drop or an open circuit the voltage of all exposed metallic portions of the electrical system and any conductive surface in contact with it will rise to 120 volts relative to the earth or such grounded conductive surfaces as the garage floor.
I am a firefighter / EMT and I have run a call were such a condition killed the user. Yes it's rare but it does happen. Since such incidents are rarely investigated when they occur in a non work setting the number of such incidents is undoubtedly higher than is currently known.
--
Tom Horne

Well we aren\'t no thin blue heroes and yet we aren\'t no blackguards to.
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snipped-for-privacy@yahoo.com wrote:

You ran a feeder with 2 hots, a neutral and no ground. The other option is to run include a ground. The ground wire is sized from a table and would likely be smaller than #2, I'm too lazy to look it up. The ground wire from the house is connected to the ground wires in the garage (ground bar) and the grounding electrode (usually ground rod). The difference is that the neutral bar is isolated from the garage ground system. If you wired the garage this way you don't need #14 grounds from the house to the garage because the feeder ground is sufficient.
I have a very rare disagreement with Tom Horne, who puts up very good posts. The fault clearing path as you are wiring the garage is via the feeder neutral. If you ran a separate ground wire with the feeder, the fault clearing path would be through the likely smaller feeder ground wire. I don't see how that is an advantage.
I assume there is only one Tom Horne and you just changed hats?
bud--
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Bud-- wrote:

Perhaps I was not clear. If the fault clearing path is via the feeder's neutral it would be because the Equipment Grounding Conductors (EGCs) are connected to the main bonding jumper at both buildings. Between the main bonding jumper and the switch boxes the EGC would not be in the same raceway or cable as the current carrying conductors for the circuit. Such divergent pathways always have a higher impedance then one that remains with the current carrying conductors for it's entire length.
--
Tom Horne

"This alternating current stuff is just a fad. It is much too dangerous
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On Wed, 30 Nov 2005 03:59:31 GMT, "Tom Horne, Electrician"

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.
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So I am using the ground from the house instead of the garage? No issues with that?
The load is in the garage. This sounds like it might work for me...any NEC issues?
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On 30 Nov 2005 06:51:05 -0800, snipped-for-privacy@yahoo.com wrote:

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 www.goedjn.com/sketch/3x3.gif 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.
--Goedjn
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snipped-for-privacy@yahoo.com wrote:

Yes that is exactly the type of parallel pathway that the code forbids for three wire feeders. Your switching circuits do count as another metallic pathway.
If you run all portions of the garage end of the circuit in non metallic raceway, use all nonmetallic boxes and cover plates, and install only non metallic lighting fixtures it might be reasonably safe. The moment one of the non metallic switch plates or fixtures is replaced with one that has exposed metal then your single layer of safety is gone. You would also have to violate the code requirement that the EGCs in the garage should be bonded to the neutral of the feeder at the building disconnecting means.
You can use X10 controls via the feeder without violating the code. Wireless three way switches that use radio signals to control the switch at the light would also work.
--
Tom Horne

"This alternating current stuff is just a fad. It is much too dangerous
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I could be mistaken, but you mentioned the ground wire should be white?

The "grounded" conductor (mistakeningly called a neutral in a 120 volt circuit) is colored white, the "grounding" (or bonding) conductor is green.
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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 http://eskc.com/default.asp . 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.
You could use some electronics to do the job too: http://ourworld.compuserve.com/homepages/Bill_Bowden/page9.htm#4013
-- )|:(__ Nehmo __):|(
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Hire an unlicensed electrician?
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On 29 Nov 2005 11:27:50 -0800, snipped-for-privacy@yahoo.com wrote:

You do? Why7 IIUC, you don't want 3 pairs of 3-ways, you just want three switches to control some lights in the garage.
I presume you want one switch in the house and one in the garage. Where do you want the third switch?
It doesn't really matter.
When you go above two 3-way swtiches, the rest of them have to be 4-way switches. Electrically, the 4-ways have to all be between the three-ways that are at the end.
Between each pair of switches you need 2 hot wires, only one of which will be hot at any given moment. Plus a neutral wire. Plua the uninsulated ground that comes inside BX, for example.

Yes.
I don'tt know what you mean "per switch". You need 4 wires AT each switch, but in most ways of looking at things, they are the same 4 wires. Two are the neutral and ground -- two wires come in and two wires go out, usually spliced witha wire nut.
In addition, for the first 3-way switch one wire goes in and two go out. For the second 3-way, two wires go in and one wire goes out. And for all the 4-ways in between, 2 wires go in and 2 wires go out.
This may sound like 8 wires, but 4 are going back to the previous switch and 4 are going on to the next switch.. You only need four wires, and some places only 3.
No relays, no X-10 needed imo.

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