The mechanical side of wiring the workshop

The mechanical side of wiring the workshop · 09-27-2009, 11:59 PM

Work is progressing on the shop, slowly but slowly. After several weeks of taping, mudding and sanding, I've moved to priming and painting. That means less dust but getting the gunk off my hands is now slightly more difficult (paint instead of plaster).

Once the painting is done, it's time for the electrical.

I went supply shopping this weekend, and looked among other things at 240V outlets. In my previous shop, I wired the single 240V outlet with a L6-30P receptacle. It's what my electrician recommended. It was impressive looking, for sure, but I must admit it seemed like overkill. Plus, it's pretty "fat", especially with a surface mounted outlet. And while the twist-lock is nice, I find it hard to imagine I'd accidentally unplug it by tripping. Plus, they're not cheap either.

So - what does everyone else use for their 240V/ 20A receptacles?

The second question relates to screws. When I took down the old surface-mount wiring from the previous owner, I encountered just about every type of screw that was used to mount the boxes: Wood screws flat head/ philips, wood screws flat head/ square drive (in various lengths), metal screws (pan head), button head screws, brass screws (pretty!), really long screws (3 1/2"!), undersized screws with washers, self-tapping metal screws, toggle bolts (not always easy to find the stud I suppose), screws with drywall anchors, and my personal favorite, the invisible fastener! As in a box that's just hanging loose other than some double stick tape behind it.

I was just going to use 1 1/2" #8 pan head screws, but it got me thinking. Is there a "recommended" screw for surface mounting metal boxes?

Ozzie-x · 09-28-2009, 12:32 AM

First, the screws and a couple of questions. Do you have sheetrock on wood studs? Are you going to wire everything surface mounted on top of the wall surface?

Bas · 09-28-2009, 01:47 AM

Originally Posted by Ozzie-x

First, the screws and a couple of questions. Do you have sheetrock on wood studs? Are you going to wire everything surface mounted on top of the wall surface?

Yes, sheetrock on wood studs. And yes, everything will be surface mounted.

Phil S · 09-28-2009, 06:48 AM

Nice to hear that your shop is nearing completion.

#8 x 1 1/2 pan head screws would be correct.

The 220v outlets that are most commanly used is the L6-20R which is rated for 20 amps. The 30R is for 30 amps installations such as a welder.

Just wondering are you using metal conduit or plastic?

phil

Ozzie-x · 09-28-2009, 09:22 AM

Bas, the #8 x 1 1/2" pan heads should be fine. Are you going to wire with EMT? As for the receptacles, I think you already have some existing WW equipment, so I would try to match the NEMA configuration of the existing plugs on the equipment cords provided by the manufacturer. The manufacturer should have properly sized the cords $ plugs to get the U.L. listing. Generally, the receptacles have to be sized for the ampacity of the branch circuits that they are served by. Determining the required circuit ampacity and receptacle rating is determined by the motor horsepower and ampacity. 240V motor circuit calculations are straightforward. The L6-30R receptacle is probably overkill for most things under 3HP 240V. Except for larger industrial equipment, no equipment will come with L6-30R. All of my 240V outlets are L6-20R straightblade on 240V 20 amp circuits including the 2 HP tablesaw and 3 HP planer and I've never had a breaker trip. Attached is a shortcut to Hubbell Wiring devices that shows their receptacle and plug configuration matrix, this is one of the gold standards for the electrical industry. Simply look for the voltage and ampacity on the chart and find the device you need.

https://www.hubbellnet.com/max_htm/t...EMA/front.html

Although twistlocks are well made durable devices that are often very pricey, and I do specify and use a lot of twistlocks because they are great devices for many purposes, I do not like them for my shop. The virtues of twistlocks are also their downfall. Most of the reason for the receptacle and plug at the equipment if for safety should you need to quickly disconnect the power at the equipment. In a panic situation, a twistlock may be difficult to turn and release, a straightblade will just yank out easily. Also, I have to move some of my equipment around in the shop to use it. If I forget about the power cord, the straightblade devices just pull out, twistlocks will break or jerk sometihing loose. I've never had a machine plug work out of a receptacle due to vibration, hopefully all of my equipment runs smoothly.

Travis Porter · 09-28-2009, 11:07 PM

You can get away with those cheapo 20 amp 220 volt receptacles. They look like a 110 volt outlet but I think both sets of upper pins are horizontal and not vertical. I believe that is what came with my dust collector. Perfect for single phase, 220 volt 20 amp or less scenarios.. They are cheap (compared to the L6-30 all single phase stuff is cheap) and easy to wire.

The majority of my 220V single phase stuff I have wired with the L6-30's and at around $20 a receptacle or plug, they are quite nice but pricey. You think the L6-30 stuff is high, price some 3 phase. I go into real sticker shock looking at it.

Bas · 09-29-2009, 12:45 AM

Originally Posted by Phil S

Nice to hear that your shop is nearing completion.

That's pushing it...let's say there is definite progress

Originally Posted by Phil S

Just wondering are you using metal conduit or plastic?
phil

Metal.

Originally Posted by Ozzie-x

Attached is a shortcut to Hubbell Wiring devices that shows their receptacle and plug configuration matrix, this is one of the gold standards for the electrical industry.

That's a _very_ useful chart!

Originally Posted by Ozzie-x

All of my 240V outlets are L6-20R straightblade on 240V 20 amp circuits including the 2 HP tablesaw and 3 HP planer and I've never had a breaker trip..

I am not crazy about the twist lock either, definitely going with straight blade. Right now, the only 240V tool I have is the table saw (and it also runs on 120V), so now's the time to pick my poison, since I plan to expand quite a bit

Originally Posted by Travis Porter

You can get away with those cheapo 20 amp 220 volt receptacles. They look like a 110 volt outlet but I think both sets of upper pins are horizontal and not vertical. I believe that is what came with my dust collector. Perfect for single phase, 220 volt 20 amp or less scenarios.. They are cheap (compared to the L6-30 all single phase stuff is cheap) and easy to wire.

Yes, I saw those, the price is definitely nice. But my main concern isn't really with the receptacle configuration or cost, I just don't want a big fat plug! It just seems like overkill...then again where I grew up everything was 240V and plugs were very modest, so maybe I'm biased.

Originally Posted by Travis Porter

The majority of my 220V single phase stuff I have wired with the L6-30's and at around $20 a receptacle or plug, they are quite nice but pricey. You think the L6-30 stuff is high, price some 3 phase. I go into real sticker shock looking at it.

I'll bet - but at least that's for 3 phase (insert grunt sound...). I just find it surprising that a 20A equipment plug looks like it can power a thermonuclear flux capacitor, while a 30A dryer is only marginally fatter than a 120V plug.

Thanks for all the help everyone!

Mike Wilkins · 09-29-2009, 05:08 PM

Call me mister overkill, but I installed the twist-lock plugs on 4 of my big sawdust producers (tablesaw, bandsaw, J/P and lathe) with just 2 240 outlets. I did not buy them all at once, but the cost is still a big factor. But I did use the standard outlet for my ceiling-mounted heater, which already had the funny looking plug installed (one verticle and one horiz. blade). 3 of the machines are stationary (tablesaw,lathe and J/P) while the bandsaw is on wheels. I just liked the industrial look of the things.

Alan in Little Washington · 09-29-2009, 05:30 PM

Bas,

I used 6-20R straight blade 20 amp receptacles for all but two of my 220V outlets. My Unisaw came with a 6-15P plug which fits a 6-20R receptacle (it is perfectly ok to plug a 15 amp machine into a 20 amp receptacle.)

I opted for twist lock, 30 amp L6-30R receptacles for my two big machines but now forget the rationale for that decision.

I daisy-chained 20 amp receptacles (two branch circuits). One thing I would check into, and may do myself someday, is to see if duplex 6-20 (see pic below) receptacles meet code. It is much nicer if you have a number of 220 machines close together.

Another thing to think about- if most of your machines are wired for 220 and you want to add 110V work lights to them, is to install 14-20R (4 conductor- two hot, neutral, ground) receptacles so you can safely (and code legal) obtain 110V between one of the hot leads and the neutral. You would need to change out your power cords and plugs however.

For those who are unfamiliar with NEMA plug/receptacle configurations, look here.

Leviton Duplex 6-20R:

Leviton also makes a duplex combo (125V) 5-20R / (250V) 6-20R receptacle which might work nice in some locations if you have run four conductor ROMEX to there.

McRabbet · 09-29-2009, 06:06 PM

I use 3-wire 20 Amp twist-lock plug/receptacle sets on my tablesaw and shaper (L6-20) and 30 Amp twist-lock sets on my Woodmaster Drum Sander (L6-30). They are mobile tools with cord sets that I do not want to have pull out of their floor receptacles. My 5 HP Leeson motor on my ClearVue Dust Collector is hard-wired throught a control box on a 30 Amp dedicated circuit. The lights dim in western NC when I get them up and running...

FredP · 09-29-2009, 06:56 PM

Originally Posted by McRabbet

I use 3-wire 20 Amp twist-lock plug/receptacle sets on my tablesaw and shaper (L6-20) and 30 Amp twist-lock sets on my Woodmaster Drum Sander (L6-30). They are mobile tools with cord sets that I do not want to have pull out of their floor receptacles. My 5 HP Leeson motor on my ClearVue Dust Collector is hard-wired throught a control box on a 30 Amp dedicated circuit. The lights dim in western NC when I get them up and running...

does this meen ya got it runnin?

McRabbet · 09-29-2009, 10:28 PM

Originally Posted by FredP

does this meen ya got it runnin?

R U Kiddin?

I got another three weeks to break the 2 year anniversary of my purchase date! I didn't say the 10/2 was run from the control box back to the panel, nor the ductwork hung... Gimme time man, gimme time!

Bas · 09-29-2009, 11:34 PM

Thanks Alan. Interesting, I had not seen this type of 240V outlet in duplex form. I remember seeing your post about having both 120V and 240V for your drill press. I don't have any tools (yet?

) that require that, but I can see the value there.

Maybe the problem is that my tools are all too puny for me to fully appreciate the 6-20R plugs. So I think the answer is to buy BIGGER TOOLS!

Bas · 09-29-2009, 11:36 PM

Originally Posted by McRabbet

R U Kiddin? I got another three weeks to break the 2 year anniversary of my purchase date! I didn't say the 10/2 was run from the control box back to the panel, nor the ductwork hung... Gimme time man, gimme time!

Rob, I've been thinking about asking you to join the Procrastination club, but I haven't been able to get around to it yet....