Shop Wiring Suggestions

I am in the process of applying for an electrical permit from the township. I have an existing 200 amp service which has two breaker spots available. From here I am going to run a 100 amp subpanel to support new outlets in the shop. The current drawing I am working on can be see here:

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plan on running at least 1 240v outlet for a table saw. Then I was going to run a couple more outlets to support various other shop tools.

Some questions I have:

  1. I am wondering if I should run 30 amp breakers with 10 gauge wire for everything or wether 20 amp breakers with 12 guage would suffice.

  1. The table saw that I am planning for the shop rates at 240v 13 amp. Will that pull more than 13 amp when it is first turned on? It seems like there is always a spike when a motor first turns on.

  2. At this point I don't have plans for another tool that requires 240, and I don't have a whole lot of space in the shop. I don't think I should bother running another 240, but does it make sense to run a second one just in case?

  1. The shop part of the basement is unfinished and has exposed studs which are the back of the finished part of the basement. Right now all existing recepticals are just connected to these studs with NM electrical cable running through the studs back to the existing panel. Is it OK to duplicate this practice with the new subpanel? (I wired an unfinished basement without studs some years ago and used aluminum conduit. I fealt really good about it. It doesn't sit well having all this cable exposed.)

  2. In the existing wiring there is a bunch of NM cable that runs over some ceiling beams. It isn't secured and kind of weaves in and out of each other. Is that up to code? It seems odd.

  1. What kind of wire is recommended to run between the panels? It needs to be rated to 100 amp and have 3 wires and a ground. I believe I read that the grounding is done differently on the subpanel vs the main panel because one wants the shortest path to ground. Could someone elaborate?

  2. The existing panel is Square D, but I have heard some complaints and was considering using GE for the new one. Should I use Square D for the new panel to remain consistent?

Thanks, Howard

Reply to
Howard Swope
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Sorry I've been lurking but here is my $0.02 I would run all the duplex outlets with 12 guage wire with a 20 amp breaker protecting 2 or 3.

I would think a 20 amp breaker would work but I'm not positive on this. You might even have to have a 30 amp breaker, but I would run aleast 10 guage wire to it.

If it was me I would run the extra outlet.

You can run NM cable inside walls like your describing. If you don't have a joisted wall to contain the wire you need to use conduit, but then you have to use thhn or thwn wire. You also have to staple the wire within 8 inches of the box and every 4ft there after.

It can be run like that, but I can't remember if the NEC requires it to be stapled or not. I always secure it down with a staple every other joist.

3/3 is rated for a 100 amp sub, but if you can afford it run 2/3.

I would stick to SquareD so that you don't have to buy 2 different kinds of breakers. But I've not heard of any complaints about SquareD. Here in Tennessee SquareD is one of the popular brands of electrical products.

My answers are all based on the info that I attained over the years and my recent sub panel install that I had to do for my remodel. A good book if for nothing else but for the NEC code information is "Black & Decker The Complete Guide to Home Wiring" it is sold at Lowes. I picked it up so I could see what new code changes I had to be aware of. But if your unfamiliar of how to do something, this book will explain it step by step. I don't do electrical for a living so I sometimes need a little nudge. Of course I learned all the woodworking, electrical and plumbing from the best, my father.

Reply to
Dale Miller

The spike is unimportant; it isn't for more than a second or two. However, some day you may need a larger circuit, so 10 gauge with a 20a breaker makes sense. It will also reduce voltage drop, especially on the spike.

you can always put another outlet in, where you really want it, later; can't you? Someday you will want a 240v dust collector, but maybe not where you put the outlet.

What do you mean it runs over beams? Steel beams? Normally it runs through holes in the joists; no harm in it running over beams as long as it is secured by the joists.

Reply to
Toller

Howard Swope wrote: > I am in the process of applying for an electrical permit from the > township. > I have an existing 200 amp service which has two breaker spots available. > From here I am going to run a 100 amp subpanel to support new outlets in > the > shop. The current drawing I am working on can be see here:

Some suggestions:

SRWIW, unless you are adding A/C or a heat pump to the sub panel, a

2P-60A should be adequate for shop needs.

1) Check existing panel and see if it will accept a 2P-100A sub feed c'bkr. If not, will it accept 2P-60A?

2) Locate new 100A panel in shop area fed by subfeed c'bkr above.

3) Use 1P-20A for outlets.

4) Use 2P-30A for 240V loads

BTW, a 5HP, cap start, cap run air compressor motor requires a 2P-40A c'bkr.

Remember, c'bkrs in a panel must be derated 20% per code.

IOW, a 20A c'bkr can carry 16A on a continuous basis. At higher loads, you are operating on the time portion of the curve.

Have fun.

Lew

Reply to
Lew Hodgett

If you have an air compressor and leave it on it might be worth a dedicated crcuit for it and any dust control equipment which might run when other equipment is operating

Reply to
mike hide

Just "a couple more"? Take my advice: install at least twice as many as you think you need.

I would certainly run at least one 30A 240V circuit, to support (for example) simultaneous use of a dust collector and a table saw, or an air compressor.

Yes, but you don't need to worry about that. The spike is of very short duration. It will do fine on a 20A breaker.

I think so, yes. If you're going to run only one 240V circuit, make it 30A. If you run two, you're fine with both of them 20A.

It meets Code.

If it were my shop, I'd panel the walls with something. Drywall, OSB, plywood, whatever. Protects the wires, gives you convenient places to hang things, reduces by about 99% the number of corners where dust can collect... you can probably think of a dozen other reasons, too, but perhaps the most important (and certainly the most easily overlooked) is that once you have the walls paneled and painted white, your shop will be *much* brighter.

No, that's not up to Code. NM is required to be supported every 4.5 feet. It's also not allowed to be stapled across ceiling joists. When you need to run NM across joists, you must either (a) run the cable through holes bored in the joists, or (b) attach running boards across the joists, and secure the cable to the boards.

For 100A, you need 3-ga copper (minimum). I'm not sure anybody makes NM that large. I'd use individual THHN conductors in rigid non-metallic conduit (PVC electrical conduit -- *not* PVC water pipe).

Yes, it is done differently. Not because you want the shortest path to ground, though, but because you want only *one* path to ground.

Neutral and ground are bonded together in the main panel, and, in fact, the Code does not require (AFAIK) that there even be two separate bars in the main. If there are two bars, they are required to be connected together.

In a subpanel, however, neutral and ground are required to be on two separate bars -- if your subpanel doesn't have a separate grounding bar, you'll have to buy one -- and they *must*not* be connected. Frequently, panels are supplied from the factory with a bonding screw through the neutral bar, that bonds it to the chassis of the panel. If your subpanel has one of those bonding screws, you *must* remove it. The neutral bar in a subpanel *must* be electrically insulated from the panel chassis, and the grounding bar *must* be electrically

*continuous* with the chassis.

The four-wire feed coming from the main panel to the subpanel must be connected as follows:

- two hot legs, marked red and black, to the lugs on the subpanel main breaker

- neutral, marked white or gray, to the neutral bar in the subpanel

- ground, marked green or left bare, to the ground bar in the subpanel

It doesn't really matter. What complaints have you heard about Square D?

Reply to
Doug Miller

12 inches [2005 NEC, Article 334.30]

4.5 feet [Art. 334.30]

No it cannot. Not if he means it's crossing joists, anyway. [Article

334.15(C)]

It does. No farther apart than every 4.5 feet. [Article 334.30]

But not to the bottoms of the joists. [Article 334.15(C)]

That's a Code violation.

Please familiarize yourself with the NEC before attempting to answer any further electrical questions.

Here's a start:

"Where cable is run at angles with joists in unfinished basements, it shall be permissible to secure cables not smaller than two 6 AWG or three 8 AWG conductors directly to the lower edges of the joists. Smaller cables shall be run either through bored holes in joists or on running boards." [Article

334.15(C)]

Just to clarify: 3/3 WG (with ground).

Reply to
Doug Miller

??????

The 20% rule applies only to continuous load, which is defined as a load drawing maximum current for three hours or more. There is absolutely nothing wrong with operating a 20A circuit at 19 or 20 amps for short times.

Reply to
Doug Miller

six years ago and am glad I did, it's all you need.

Reply to
Swingman

Depends on the equipment and the length of wire. Most applications the 12 ga will be fine.

Yes, there is a spike although not enough for concern.

Yes! Most likely, your shop will evolve. Putting in more 240v outlets makes sense so you can add a 240v DC, lathe or joiner. Outlets are not expensive. Put at least one 240v outlet on every wall.

It's OK. But it is better to install paneling or drywall--makes cleaning easier.

It is best to run wires through the middle of beams, rather than under and/or over.

My subpanel has its own ground. You will have to seek a local electrician's advice on this one.

Not necessary.

Reply to
Phisherman

Ok, Doug, what if the joists are 16 or 24 OC? Wouldn't that be less than 4.5 ft? Thus the ability to run the NM above the joist so long as it was stapled or secured?

I could have bought 3-ga copper in a NM but my source couldn't get me

40ft at less than the 2-ga copper NM. They were out of the 3-ga and there new shippment would cost me more per foot than the 2 ga. Of course they had 3-ga in stock but not 40 continuous feet of it. So I opted to go with the 2 ga at just over a $1.00 foot less. Plenty large enough for a 100 amp sub.
Reply to
Dale Miller

The code book I have say 8 inches.

And it also says 48 inches. I looked up both

Thanks but I read that as the bottom of the joist not the top. Here in my jurisdication all of the electrical contractors run there wire in the attic spaces above the ceiling joists and don't use any holes to run them. And no where do I read in the code that is wrong to do that. And if you had ceiling joist 24 inches OC and stapled the wire down every other joist that is within the 48 inch code.

Reply to
Dale Miller

Doesn't matter *what* the joist spacing is. The Code does not permit stapling NM cable smaller than 6-2 or 8-3 to the bottom of joists. Period. There are no exceptions.

Securing the cable *more* often than the Code requires is not a problem. Securing it to the bottom of joists *is* a problem.

*Above* the joist? How do you do that in a basement? Above the joist is the subfloor. Did you mean below the joist? Can't do that. The Code absolutely prohibits stapling NM cable smaller than 6-2 or 8-3 to the bottom of joists.
Reply to
Doug Miller

What code book are you using? Obviously not the National Electrical Code.

What code book are you using? Obviously not the National Electrical Code.

[snip]

Yes.... that was kinda the point....

Nobody was talking about "attic spaces". The original poster wanted advice on wiring for his shop in the *basement*.

You haven't read the right parts of the Code, then. While it doesn't prohibit running cables across the top of joists in an attic, it *does* prohibit doing so without installing guard strips to protect them:

"The installation of [NM] cable in accessible attics or roof spaces shall also comply with 320.23." [2005 NEC, Article 334.23]

"Where run across the top of floor joists, or within 7 feet of floor or floor joists across the face of rafters or studding, in attics and roof spaces that are accessible, the cable shall be protected by substantial guard strips that are at least as high as the cable." [ibid., Art. 320.23(A)]

Of course, as noted above, this is irrelevant to this thread anyway, since the subject of discussion is wiring in an unfinished basement. (You didn't really think the OP had his shop in the attic, did you?)

54 inches.
Reply to
Doug Miller

Thanks for the information (everyone has been very helpful). In regards to Square D, I don't remember the specifics of what I read, but it was a posting someplace. My recollection was only that this one gentlement had difficulties with Square D and was recommending moving away from their stuff. No one else seems to have responded in the negative, so I might go with it just to stay consistent with the current setup.

Reply to
Howard Swope

The only problem with Square Duck is they use bastard size c'bkrs.

If you use their panel, then you must use their c'bkrs.

Other manufacturers use a more common 1" & 1/2" c'bkrs that can often be used interchangeably.

Lew

Reply to
Lew Hodgett

Here is the problem we are having...your thinking of a solid 2x floor joist. But the way I read OP as having truss style floor joists. So if that is what he has than you could wire above the bottom of the joist.

Reply to
Dale Miller

There's nothing whatever in the original post that even suggests that might be the case. I think "the problem we are having" is that, as shown by some of your other comments, you were thinking he was wiring in an attic.

Reply to
Doug Miller

2005 NEC...for non-metallic boxes you have to staple the NM within 8 inches of the box.

For non-metallic boxes the every 48 inches. All from NEC 314.17 (C) Nonmetallic Boxes and Conduit Bodies.

This maybe irrevalent but as per NEC 334.23 (320.23) "Where this space is not accessible by permanent stairs or ladders, protection shall only be required within 1.8m (6ft) of the nearest edge of scuttle hole or attic entrance.

If you do the searching yourself you will find the code that says 48 inches. I know it's in there I just read it.

All in all your taking the NEC out of context when you only show part of it. The laymen can't understand it this way.

As for the OP if he has solid 2X framed joists, then you would be correct. But if he has truss style joists then he could run the wiring as if it was an attic space, so long as the wire doesn't run under the framing member. But I am pretty sure there is an exception somewhere in the NEC for that too.

Reply to
Dale Miller

Boy, I went back and re-read Howard Swope's original post. I think you're making quite a stretch to interpret it that way. When you hear hoofbeats, you should be thinking of horses, not zebras. Unless, of course, you're on the African plain.

One way to settle this aspect of the controversy. Howard? Do you have solid floor joists over your shop area or some sort of open truss system?

Reply to
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