Conduits, circuits, and outlets.

[Chris Padilla]

You should check with the AHJ (authority having jurisdiction) about messing with the colors of your wiring. I really wouldn't use anything but black, red, white, and green/bare for any residential wiring.

I know zilch about 3-phase systems but that is likely a place where colors other than the ones I mentioned come into play.

I also agree to run a separate ground/ECG (bare cooper or green wire) and to not rely on the conduit. The AHJ can tell you if conduit is acceptible or not but I would use wire regardless. The EGC is no less important than any other wire and in fact, could be the most important one to safeguard YOU.

I went with 4 11/16" x 4 11/16" x 2 1/8" boxes in my garage rewire. Finding mudrings for them was a bit more challenging than visiting the BORG...I had to go to an electrical warehouse.

[Rick Moyer]

David, most of my boxes will be on a wall with two windows that will preclude me from running horizontally as you did since the windows would be in the way. I will run along the top of the wall and drop on either sides of the windows. this will still give me 7'-8' of unobstructed wall space between the windows with the 4-plug recept boxes about that far apart. That should give me enough places to plug into with having to go more than three to four feet max. I wll also run across the middle of the ceiling with conduit, placing a ceiling box for the two garage door openers to plug into and and an additional outlet for future use. This will continue across and down the opposite wall to a box. I don't really even need outlets over there as that is where the wood racks are, but thought I would put some there anyway. you never know.

Chris, since I decided to run seperate conduit I don't feel the need to use other colors as previously suggested. I'll stick to the usual blk-red-wht-grn. I also don't need mud rings as this will all be surface mounted. The AHJ doesn't know me nor I him and we'll probably keep it that way.

I believe I will use the GFCI outlets as stated and will pull a ground wire throughout the conduit. Shouldn't be any problems that way. I plan on using the larger boxes as well for the extra space.

[Rick Moyer]

Here are the three walls for reference. the fourth is two OH garage doors.

I plan to run from the panel box, up the wall , then across the top of the wall to the crnr behind the DC, across the wall to beyond the second window. there wil be drops to the right of the entry door, next to the blue board at the DC, on the right side of the left wdw, and both sides of the right wdw. Also will come across the ceiling between the wdws and put a box in the ceiling then over and down the wall between the lumber racks.

Anybody have any thoughts as to how many outlets at each of these drop locations? Or if you would do anything differently (before I get started)?

[Rick Moyer]

You can avoid leapfrogging the conduit by using J-boxes that have two openings in each side and a single opening in the bottom. This will allow two parallel runs of 3/4" conduit that share J-boxes.

Using this idea, how many ccw's can I have in a j-box?

The conduits could contain 6 ccw (three circuits)each, but when I pass thru the j-boxes and also tie into the drops I would have a lot of wires in there. For example: if there were 3 circuits in each conduit (6 ccw)coming into the box, four of which would just pass thru, and two would drop to the first outlets, that would be 12 ccw in the first box. I suspect this is not good.
I'm still struggling with being able to do this as I'd like. If I run all the 120's and all the 240's in their own conduits, I think I'd have to have them in their own j-boxes as well, but then I'm back to leapfrogging around the drops. (picture two j-boxes staggered such that there are two conduits coming in from the left and two going out to the right of each, with each box having a drop conduit. somewhere one conduit will have to jump over another). The only way around this that I can see is if I am allowed the 12 ccw's in the j-box. Any ideas???
If I have to leapfrog, would you suggest flex cable in a short span to leapfrog? Sounds like I keep making this more complicated.

[Rod Sheridan]

Rick, this is getting far more complicated and more expensive than needed.

If you are only running one machine at a time, use a 20 ampere multiwire feed, which requires a single 2 pole 20 ampere breaker.

Run a feed from the panel around the room at the ceiling, use 4 inch junction boxes at the ceiling to drop a piece of 1/2" EMT to a 4" junction box for your machines.

Put a 240V 20A receptacle, and a 120V 20A GFCI receptacle in the box. This gives you a receptacle for any machine or portable tool.

This requires qty 3 #12 AWG conductors plus a #14AWG ground wire. I never count on the conduit as a ground, the wire's cheap, and ground is the only wire that has to work.

Regards, Rod.

P.S. A seperate circuit for your dust collector and you're in business for any machine of 3 HP or less with only two circuits.

[Rick Moyer]

Rod, I appreciate your suggestion and your sensibility. I know I really only NEED what you propose. I have a tendency to over-engineer stuff. When I look into costs I MAY decide to go the route you propose. I will think on it some more. I just don't want to put it in and later regret not having more circuits.

[Rod Sheridan]

Rod, I appreciate your suggestion and your sensibility. I know I really only NEED what you propose. I have a tendency to over-engineer stuff. When I look into costs I MAY decide to go the route you propose. I will think on it some more. I just don't want to put it in and later regret not having more circuits.

Far be it from me to ever suggest that I never over do anything.

Regards, Rod.

[Dennis Ford]

I don't see a problem with 12 ccw in a "large" J-box, most of them would pass straight through with no connection. If you drop to the outlet and come back from the outlet, there would be no connections in the J-box and then it is just a pull box. You can get into trouble trying to make too many connections in a J-box and I can not promise that your inspector (if any) will be happy with your installation.

Using this idea, how many ccw's can I have in a j-box?

The conduits could contain 6 ccw (three circuits)each, but when I pass thru the j-boxes and also tie into the drops I would have a lot of wires in there. For example: if there were 3 circuits in each conduit (6 ccw)coming into the box, four of which would just pass thru, and two would drop to the first outlets, that would be 12 ccw in the first box. I suspect this is not good.
I'm still struggling with being able to do this as I'd like. If I run all the 120's and all the 240's in their own conduits, I think I'd have to have them in their own j-boxes as well, but then I'm back to leapfrogging around the drops. (picture two j-boxes staggered such that there are two conduits coming in from the left and two going out to the right of each, with each box having a drop conduit. somewhere one conduit will have to jump over another). The only way around this that I can see is if I am allowed the 12 ccw's in the j-box. Any ideas???
If I have to leapfrog, would you suggest flex cable in a short span to leapfrog? Sounds like I keep making this more complicated.

[Rick Moyer]

Dennis, I spoke with the local electrical supply place and they said basically the same thing; that all the pass-thru wires would be no problem. If I use a 4 11/16" box I could run two runs of 3/4" emt in and out and still drop from that box, with plenty of room in the box for any connections I would need. I now just have to decide if I want to go to the extra trouble and expense of that arrangement or go more simple.

Thanks to everyone for their help.

[David Parker]

From your pictures, it look like your windows are high enough to allow a horizontal conduit run beneath them. I attached a quick sketch of a possible wiring scheme in PDF format. This would consist of 4 circuits; two 120V 20amp circuits and two 240V 20amp circuits. One of the 240V circuits would be dedicated to the dust collector. I included box fill calculations on or adjacent to each of the boxes. For 12 gauge wire, you need 2.25 cubic inches for each volume unit (based on NEC 314.16). The largest count is 21, which would require 47.25 cubic inches. A 4 11/16 inch square 2 1/8 deep box with a raised Garvin type lid would accommodate this.

If you use one duplex 120V outlet in each box, you can split apart the top and bottom plugs electrically and wire a separate circuit into the top and bottom portions. Alternatively, if you use two duplex outlets in each box, you can wire each up to a different circuit. (You can use different colored outlets to indicate which circuit is which). 3/4 inch conduit will carry up to 16 12 gauge wires, so that's not a problem. On the 120V outlets closest to the door, just use two GFCI outlets and run the protected outfeeds from these back up the drop so they can continue downstream to the rest of the 120V outlets. (that actually will bump the volume units up to 11 for this box -13 if you use two duplex outlets). For about $50 more, you could instead use two GFCI circuit breakers in the panel.

You can either continue your ceiling conduit across to the wood storage wall for an outlet there, or you can run a conduit directly from the breaker panel, whichever you think would be simpler. A direct run from the panel will give you another circuit.

Good luck with your project.

[Rick Moyer]

David, the bottom of the windows is exactly 48" of the floor. I could do as you suggest but would have to tilt any 4x8 sheets, although they really wouldn't be over there anyway. I'll consider this option.
The only real problem I see is even though the 3/4 EMT would hold that many wires, I am only allowed 6 current carrying wires and still be ok with 20a. Therefore only 3 circuits, not 4.
I appreciate the suggestions and will consider some more.

[David Parker]

I agree with you. If the window bottoms are at 48 inches, I'd also do separate drops for each location just to keep the outlets above any carts, etc. The other advantage of separate drops is that you can then use smaller boxes for the outlets. I calculate 9 fill units for each box. A standard 4x4 by 1 1/4 box has a volume of 18 cubic inches. If you use a Garvin raised box cover (typically 5 to 7 cubic inches), you meet the 20.25 cubic inch volume requirements (9 x 2.25). I'd use drawn boxes rather than welded boxes. They look nicer and don't have the sharp corners. The junction boxes up high will still have to be the large 4 11/16, 2 1/8 deep ones.

I'm not sure if you're limited to 6 current carrying conductors in the EMT. According to Table 310.15(B)(2)(a), the adjustment factor goes from 80% (4-6 conductors) to 70% (7-9 conductors). Since 12 gauge THWN 90 degree wire is rated to carry 30 amps (Table 310.16), if you use the 70% adjustment factor, this still keeps you above 20 amps. Therefore, you should be able to run 9 current carrying conductors in the EMT. Maybe someone more knowledgeable could set me straight on this.

[Michael Lutz]

When I ran my outlets, I ran two 120V outlets in one conduit and 2 - 240V Outlets in another (one for DC/Air Comp., one for tools) in both directions to power three walls. If needed I can just plug into an outlet on the opposite wall to run more than one tool at a time. It was just a few more breakers since I was running the conduit to both locations anyway. I just ran the conduit between duplex boxes without putting in any extra junction boxes. In each 120V duplex box I had two outlets (1 white, 1 grey) so I could tell which circuit I had something tied into.

Mike

[bill gervais]

Hi Rick,
First my recomendation, hire a licensed qualified electrician. I have been reading many postings in regard to electrical wiring here and elseware scary stuff!!!!
I know we all mean well and want to help each other out and save a buck. So i honestly don't think anybody on this site will intentionaly give you the wrong information but there are just to many variables.

Think of this;
1. In my state we have adopted the National Electrical Code not all states or citys do.
2. Some have their on code.
3. My state requires 6 years of work experience and 576 hour of classroom instruction as well as a current 45 hour code class to qualify to sit for the Master Electrician exam. Not finished yet. Once you get to this point slightly above 50% will pass the written exam the firt time!
4. You screw up a water system sweatted joint , pipe leaks. You screw up a wiring project you loose your house and heaven forbid your family or at a minimum try explaining your loss to an insurance adjuster..

By the way i am a Master Electrican with nearly 30 years experience and also an Electrical Instructor of both high school students as well as adults for over a decade.

Wow! Sorry for being so long winded on my first post.

Bill

[Terry Brogan]

Not trying to hijack this very useful thread but I have a simpler question that's always nagged me: none of my 3 or 5 HP 1-Phase machines gets a neutral wire. They all double up two 110 conductors at the outlet to make up the 220. Why no neutral to return current? Is it the motor design? (Never mind the ground.)