Shop Wall and Electric

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Prompted by suggestions that a shop needs convenient power, I created a (pdf) SU view of my proposed outlet configuration (for one wall), and also a corresponding wiring model:
http://web.newsguy.com/MySite /
Comments or suggestions welcome. In fact, all I seek is a simple nod. Thank you again to those of you who helped me to reach this point (of understanding)!
Bill
BTW, I think I will feel better if I use 120v duplex outlets that are **GFCI protected** in addition to GFCI CB's.
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wrote:

Sorry, you won't get that "simple nod" from me.
Keep it simple. Rather than wiring your 120V outlets to opposite sides of the 240V circuits, keep them separate: run 120V circuits for your 120V outlets, and 240V circuits for your 240V outlets. It's easier to wire, gives you more flexibility in the placement of your 120V outlets, and -- most important -- doesn't limit your 240V circuits to the same 20A as your 120V circuits.
Note that you need only two-conductor cable, not three, for the 240V circuits once you've put the 120V outlets on 120V circuits.
You should install _at least_ twice as many 120V outlets as you think you need. I'm kicking myself for having installed only three 240V outlets in my 16x20 shop, but I do have enough 120V outlets (fourteen duplex receptacles).
I have found it particularly useful to have a ceiling-mounted 120V outlet with a drop cord on a retractor. It worked so well in the shop that I put another one in the garage, plugged into the other half of the duplex receptacle that powers the garage door opener.
The air compressor could be on the same circuit as either the table saw or the dust collector, since it's unlikely that you'd ever be using it at the same time as either of the others.
Run a minimum of 10ga wire, maybe even 8ga, to your 240V outlets. Using 12ga wire unnecessarily constrains you to a future of small air compressors and table saws. If you ever upgrade to a more powerful compressor or saw, you'll have to rewire. Easier to just put in heavier wire at the outset.

Why? There's no point at all in having both.
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No matter how many you put in there never seems to be enough or one in quite the right place.

I have a row of outlets running down the centre of the ceiling in my garage/workshop.
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Your point is well-taken. Unfortunatey, I'm not fully comitted on where the tools are going to be (I may decide I want the DC closer to the door to improve the sound-level). Dedicated 240v lines seems to maximize flexability, which seems appropriate. Thanks for making me think!
Bill
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wrote:

If you have the option of locating the dust collector outside the shop and having only the ducts inside, that's something to consider.
There are pluses and minuses either way. Having the DC outside the shop means less noise and dust inside the shop -- but more noise and dust outside. If you live in sufficiently rural area where the noise won't bother neighbors, think about putting the DC outdoors (protected from the weather, of course).
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Doug Miller wrote:

Wot?
I could have all my tools on the same circuit EXCEPT the dust collector and air compressor, since they are the only ones that run at the same time as my other tools.
--
Jack
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You use pneumatic tools and the table saw at the same time?
Yes, I understand the compressor could kick on even when it's not in use, but remember that "best practice" is to shut the compressor down and drain the water at the end of the day. If it cycles on, when not in use, once a day, then you have a pretty considerable air leak somewhere.
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On Jun 5, 9:45am, snipped-for-privacy@milmac.com (Doug Miller) wrote:

Or, you can dust the saw off with the airgun between cuts... or even, for heavy use, maybe direct a bolt-in air nozzle at the saw's teeth inside the table saw housing. A drill, saw, or router can benefit from airblast chip removal as well as from dust collection. If you want to be creative, consider air-powered clamps and vises, too.
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On Sat, 05 Jun 2010 16:45:41 GMT, snipped-for-privacy@milmac.com (Doug Miller) wrote:

A compressor can come on at any time.

Are you saying that you never use your compressor in the same day as your saw?
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Does using your compressor cause it to kick on at some random time *later* that day, after you're finished using it? If so, then it's time to check your air piping for leaks.
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On Sun, 06 Jun 2010 01:56:56 GMT, snipped-for-privacy@milmac.com (Doug Miller) wrote:

It can. There are *always* leaks. The pressure switch can be right on the edge of tripping. It wouldn't be nice to have it go over the edge just as you're making a that cut in 2" maple.
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snipped-for-privacy@att.bizzzzzzzzzzzz wrote:

Not really. It will only come on if the pressure drops below the cut in pressure. Quite predictable actually.

No, but his point is valid. The compressor is not going to come on just because it's sitting there. If you're not using it to drain down the pressure, it's not going to come on unless you have a leak. Best to fix the leak.
--

-Mike-
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*snip*

I don't have a big compressor, so I've got to ask... Is it probable that the drop in temperature (say of 20-30F) and resulting drop in pressure could cause the compressor to kick on?
I've had my little one down to the threshold several times, where just plugging in a nailer (usually a big one) or shooting a couple of brads causes the compressor to come on.
Puckdropper
--
Never teach your apprentice everything you know.

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<puckdropper(at)yahoo(dot)com> wrote:

Dunno... let's do the math and find out. Suppose your pressure settings are on at 90psi, off at 120. Those pressures are psig, not psia -- absolute pressures are 1 atm higher, or on at 105psia, off at 135. When volume is constant, absolute pressure is directly proportional to absolute temperature (degrees Kelvin or Rankine). So a drop in temperature from, say, 90F = 549R to 60F 519R reduces pressure by (549 - 519) / 549, or a little more than 5%. So if the pressure in the tank is below about 111psia = 96psig, then, yes, a drop in temperature from 90F to 60F *would* reduce the pressure enough to kick in the compressor. Above that, no.

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Doug Miller wrote:

Not at the exact same time, but unlike other tools, the compressor doesn't stop running when you stop sanding, or drilling or whatever.

What happens with a compressor is it doesn't run until you use a bunch of air, then it runs until the tank pressure maxes out. You can be using other tools while it is running and you are not using an air tool.
If it cycles on, when not in use, once a day,

I have significant air leaks then, but not enough for me to bother with. One thing that also happens is if a tool drops the tank pressure to just above the start up level, the thing will start up later on it's own. Even if you have no leaks, some tools if left connected can have bleed through.
At any rate, since the dust collector runs with all other tools, and the compressor starts up on it's own, sometimes when using other tools, it's good practice to have those two on their own circuit.
--
Jack
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And you can't wait to start the table saw til the compressor stops? :-)

How often, though, do you really switch back and forth that quickly?

No, it won't, unless there's a leak somewhere.

That's a leak.

I agree that it's good practice. I don't agree that it's mandatory. And it certainly isn't a Code violation, as one person appeared to suggest.
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Doug Miller wrote:

When I was young it was frequent. Now, you have a point. I can still cut a board just as fast as then, but now, by the time I decide what I want to do, find the board to cut, find a square, find the miter gage, find my tape (in my pocket) find a pencil (in my pocket) find safety glasses (on my face) and do all this w/o losing focus and start off on some other task, the compressor has filled, and in danger of starting all over again (leaks)

Code? Whats a code?
--
Jack
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wrote:

high start up currents and your asking for nuisance trips. Don't be stingy with the breakers and circuits. The retractable drop from the ceiling as recommended I've found really useful.
Mike M
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The top of my workbench overhangs the support frame by about 5 inches. I put a 120V duplex every 2.5 feet or so along the frame under the overhang, facing out into the shop.
This keeps the top of the workbench clear of cords running from the back wall (as pictured in your "garage" sketch) when using sanders, heat guns, etc.
I'm sure you already know that the lights should be on their own circuit so that no tools can take them out and plunge you into darkness.
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news:be4235af-adbc-4050-8fbe-
The top of my workbench overhangs the support frame by about 5 inches. I put a 120V duplex every 2.5 feet or so along the frame under the overhang, facing out into the shop.
This keeps the top of the workbench clear of cords running from the back wall (as pictured in your "garage" sketch) when using sanders, heat guns, etc.
DD,
This is a nice idea. Is the workbench powered using a male-male extension cord to the wall? Sorry if the answer is obvious.
Bill
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