? about 240V wiring; what gauge, separate circuits?

[burs0028]

I'm wiring up a converted (attached) carport that currently only has 2x120V outlets. I'm having an electrician put in a 60amp subpanel that should have room for 12 circuits this coming monday. I'm gonna run conduit (3/4" EMT) from there and want to put a couple 120V quads (i think thats what you call it, 2 gang boxes w/ 2 sockets each) along each of the 3 inner walls, two outlets in each of the inside corners up high for oscillating fans, & a total of 3 240V outlets for woodworking machines. In the future will probably add some other circuits for lighting, & possibly another 240V for a mini-split, but for now just being able to plug in the shop vac, run a small saw, & still have my cheapo Lowe's fan all running simulaneously is a stretch!

I've never used 240V machines before...

My specific questions are:
1) Is 12g wire big enough for the average dust collector, a cabinet saw, or other typical woodworking motor?

2) Do I need each 240V outlet on a separate circuit or can I run a couple in series like several of the 120V runs will be?

3) What does a "typical" 240V plug look like? Is it usually like the 120V plug with the prongs turned 90 degrees?

Thanks ahead of time for your help guys!

Competence w/o confidence : confidence w/o competence :: safe & slow : fast & dead

 

[alan_3301]

I'll try to answer, but I would wait for confirmation from someone who knows what they are talking about before you go buying materials, or doing work.
Also by a home wiring book to read through for the basics, it helped me a lot when wiring my shed.

1. 12 gauge is good for 20 amps, whether it is 120v or 240v
2. not sure, that is a good question, but I would think you could have as many outlets as you wanted, given the breaker was sized according to the wiring.
3. search for nema 6-20r for a 20amp 240v receptacle 6-20p would be the plug.
also look at 6-50r for a 50 amp variety. I'm sure there are others, but those are the ones I am familiar with.

 

[theoldwizard1]

6-20 (P for plug, R for receptacle) is common, but so is 6-30. For 12 gauge wire stick with 6-20. This is good for motors up to about 2 hp. For 3 hp you would probably need 10 gauge wire and 6-30.

You might see plugsreceptacles with an "L" prefix. That means "locking". Probably more common in industrial equipment. You swap plugs from locking to non-locking (or vice versa) with no issues.

 

[Speedy Petey]

Mine in blue:

1) Is 12g wire big enough for the average dust collector, a cabinet saw, or other typical woodworking motor?
Probably, but no way to tell until you get the machines.

2) Do I need each 240V outlet on a separate circuit or can I run a couple in series like several of the 120V runs will be?
You can have as many as you like on a circuit. You just have to use logic in figuring out the circuits; ie: what will be used simultaneously.

3) What does a "typical" 240V plug look like? Is it usually like the 120V plug with the prongs turned 90 degrees?
There is no such thing. There are many "240V" receptacles. A 15 or 20A 240V receptacle looks just like a standard 120V receptacle with the prongs twisted different ways. 30 & 50A are much larger.

 

[2ManyProjects]

I'm wiring up a converted (attached) carport that currently only has 2x120V outlets. I'm having an electrician put in a 60amp subpanel that should have room for 12 circuits this coming monday. I'm gonna run conduit (3/4" EMT) from there

I gather from this that the carport is already "converted" in the sense that the walls are up and those walls are already finished on the inside? OTOH, if the studs are open, it would be simpler, easier, and probably cheaper, to just run NM-B (a.k.a. "Romex") through appropriately sized/placed holes in the studs, rather than run conduit all over the place. And if/when you do put up drywall or similar, you'll have a much neater finished job.

and want to put a couple 120V quads (i think thats what you call it, 2 gang boxes w/ 2 sockets each) along each of the 3 inner walls, two outlets in each of the inside corners up high for oscillating fans, & a total of 3 240V outlets for woodworking machines. In the future will probably add some other circuits for lighting, & possibly another 240V for a mini-split, but for now just being able to plug in the shop vac, run a small saw, & still have my cheapo Lowe's fan all running simulaneously is a stretch!

That all sounds reasonable at first blush; but there are a few details you might want to consider...

The ideal placement for general-purpose 120V outlets will greatly depend on just what you plan on plugging into them; but typically, three or four duplexes spaced out along each of those long walls will probably be more useful & convenient than concentrating all the outlets in one or two arbitrary locations.

An oscillating fan in a wood shop means sawdust gets instantly distributed EVERYWHERE, probably including in your face & eyes at the least convenient moments (not to mention that still-drying varnish job over in the corner ). I don't know your geographic location or climate; but I'd probably urge you to go for that Mini-Split system (possibly with a reverse-cycle function, for those chilly evenings) sooner than later. Alternately, you might be better served with an appropriately-sized window air conditioner, even if you wind up mounting it through the wall; as these can also provide some degree of air-exchange functionality when desired. (I realize you mentioned a dust-collection system later in your post; but they are never anywhere near 100% effective; and constantly blowing the remaining dust around just doesn't seem like a very good plan over the long haul.)

I've never used 240V machines before...

My specific questions are:
1) Is 12g wire big enough for the average dust collector, a cabinet saw, or other typical woodworking motor?

Depends on the machine. As others have mentioned, AWG 12 is good for up to 20 Amps, regardless of the voltage. However, if the run from the sub-panel is especially long (which I'm guessing it won't be, in this case), going to a heavier wire will minimize the voltage drop imposed over that run, and make whatever tools are at the other end of the string MUCH happier (electric motors do NOT like inadequate voltage!).

Particularly given that you have apparently not as yet bought your stationary machines, my recommendation would be to go heavier, maybe MUCH heavier. This will help keep your options open when you go tool shopping. You can always run a lower-draw tool off a higher-capacity circuit; but not he other way around. And even if you do wind up with relatively light-duty tools, the reduced voltage drop will still be a benefit (albeit, possibly a minor one). At this point in the project, the difference in the materials cost is relatively trivial, at least until you get into the REALLY heavy stuff. In any event, it sure beats having to re-wire AGAIN, when you buy that King-Kong saw, or surface planer, or whatever.

2) Do I need each 240V outlet on a separate circuit or can I run a couple in series like several of the 120V runs will be?

You can daisy-chain (NOT "series-connect" -- that's very different) 240V loads just like 120V loads; but whether or not it is a good idea will again depend on the actual usage of those circuits. In a typical one-man shop, you won't normally be using more than one of your "big" machines at a time. But such things as the dust-collection system and the HVAC will presumably be running constantly whenever the shop is occupied, regardless of what tool(s) may be in use.

3) What does a "typical" 240V plug look like? Is it usually like the 120V plug with the prongs turned 90 degrees?

Depends on the specific type (and amperage rating) of the plug/receptacle. You can get a good overview of the various types at:

http://www.stayonline.com/reference-nema-straight-blade.aspx
or http://en.wikipedia.org/wiki/NEMA_connector

Bear in mind too, your really big heavy machines will probably be installed once, and left in place indefinitely. This implies that hard-wiring is likely preferable to plug-and-socket.

 

[burs0028]

Thanks for the quick replies guys! The space is already converted, but not insulated or wired. All 4 walls (2 of which are exterior) are covered with ~3/8" thick siding/panel board. I thought about pulling that off to run nomex underneath, but decided to run conduit on top instead. On the exterior walls I am pulling it off so I can throw some insulation in, but dont think i need it on the interior facing walls and didnt want to do 1/2 the room in conduit and 1/2 wired in the walls. Im confident most of the room's heat gain is from the roof, which is currently just exposed rafters/beams so i'm gonna insulate up there soon too per advice given in the HVAC threads.

Im thinking i'll go with 10g for the wiring & leave the ends capped/covered; sounds best to wait till I know exactly which outlet to buy.

Someone had asked where I'm at; sunny San antonio, TX. Yesterday house was 78 degrees, outside was 95 in the shade, & garage was 101.

 

[pattenp]

I think you will be wasting your money wiring the 240V outlet circuits with #10. Typical 240V wood working tools need 20A circuits which is #12. There are some highend cabinet saws that need 30A circuits because of having 5hp motors but I doubt that's the type of table saw you'll being using.

 

[2ManyProjects]

Thanks for the quick replies guys! The space is already converted, but not insulated or wired. All 4 walls (2 of which are exterior) are covered with ~3/8" thick siding/panel board. I thought about pulling that off to run nomex underneath, but decided to run conduit on top instead. On the exterior walls I am pulling it off so I can throw some insulation in, but dont think i need it on the interior facing walls and didnt want to do 1/2 the room in conduit and 1/2 wired in the walls.

Your call; but I would view installing a bunch of conduit as more work (and expense) than temporarily pulling the panelling off that third wall. I'm assuming that if you do it carefully, only the fasteners will need to be replaced; not the paneling itself. I'm also assuming that the fourth wall is mostly garage door (or similar) anyway.

Im confident most of the room's heat gain is from the roof, which is currently just exposed rafters/beams so i'm gonna insulate up there soon too per advice given in the HVAC threads.

Good move. The thing with insulation is, more is almost always better than less. Some will tell you that the payback period for extra insulation is too far out to justify its initial cost; but that sort of thinking presumes that energy costs will stay roughly stable over the next 5/10/20/whatever years. History has taught us otherwise (at least, assuming we were paying attention). The "Bottom Line" is, eventually, even the most extreme "overkill" insulation will pay for itself; and from there on out, it's "pure profit", so to speak. So it's really just a question of, how patient can you be for your payback?

Im thinking i'll go with 10g for the wiring & leave the ends capped/covered; sounds best to wait till I know exactly which outlet to buy.

Probably prudent.

Someone had asked where I'm at; sunny San antonio, TX. Yesterday house was 78 degrees, outside was 95 in the shade, & garage was 101.

You need that insulation yesterday!

I think you will be wasting your money wiring the 240V outlet circuits with #10.

Whereas, I see it as cheap insurance.

Consider, just for example:

http://www.homedepot.com/p/Cerrowire-100-ft-12-3-NM-B-Wire-147-1603CR/202206563
http://www.homedepot.com/p/Cerrowire-100-ft-10-3-NM-B-Wire-147-1803CR/202206569

For about thirty bucks (maybe a bit more if the runs are longer than I'm guessing), he's covered his bases.

OTOH, if he really is going to do surface-mount conduit, then there's no real need to run anything at all until he KNOWS what he needs.

 

[RickP]

Thanks for the quick replies guys! The space is already converted, but not insulated or wired. All 4 walls (2 of which are exterior) are covered with ~3/8" thick siding/panel board. I thought about pulling that off to run nomex underneath, but decided to run conduit on top instead. On the exterior walls I am pulling it off so I can throw some insulation in, but dont think i need it on the interior facing walls and didnt want to do 1/2 the room in conduit and 1/2 wired in the walls. Im confident most of the room's heat gain is from the roof, which is currently just exposed rafters/beams

Hey there - welcome to the board!

Running conduit sounds great, especially for future expansion, but it will definitely be more work than running cable. You might be able to run the cable without pulling off the wall boards, though. Have you considered running it across the ceiling? You might have to remove the section of wall board above your subpanel, but the rest of the cable could be fished through the wall from the joist pockets pretty easily, especially if there's no insulation in there. Good luck with your project.



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[burs0028]

some very good points being made; some details left out for brevity further explain why I'm not pulling down more paneling for easier & more complete wiring / insulation.

1) House was built in the 40s/50s & the original carport walls are really thick vertical tongue & groove boards w/ about a dozen coats of paint & pulling them off would dbe a bear. The only paneling that's easily removed is around the garage door (6" on one side, ~4' on the other, & ~4' above). I pulled it down this weekend and that sucked because it fit like a glove, was nailed & stapled to hurricane-proof standards, & then caulked on all sides w/ some really heavy duty stuff...Im sure you can imagine me 8' up on my ladder, cursing my 100 degree garage while the sweat runs into my eyes while struggling to get my prybar under the edges.

2) My main electrical needs are on the walls w/ the tongue & groove boards, main insulation needs are around the garage door & on one of the side walls--which is actually a double wall; old tongue & groove boards facing the inside, then a 3' space that functions as a room-length closet (perfect for storing paint, contractor saw, ladders, etc.), and the an open stud wall that forms the true exterior. I'll throw insulation up in that outer wall & then probably cover w/ peg board...easy-peasy.

3) unless its waay more &, the cost of 10g vs. 20g shouldnt affect my overall budget, but I really appreciate the efforts to keep my costs limited.