Well it looks like I'll finally be able to have a proper shop built on my property this spring. No more scrabbling around in my vertically challenged basement like the Hunchback of Notre Dame, ducking to avoid ceiling joists.
What I'd like to do is feed this detached garage with 50 amps of single phase 220 from the house and from there split it down into 110 volt and 220 volt circuits via a breaker panel. My machine tools are all 3 phase 220 volt powered and I have built a rudimentary rotary converter to run them. I'd like to run permanent 3 phase wiring with proper outlets, the idea being to install plenty of them so I can re-arrange the shop or add new machines with a minimum of hassle.
I can't seem to find information on which plugs and outlets are appropriate for the task. Home centers don't stock such items (which doesn't surprise me).
What is recommended for 3 phase 220 with a load in the range of 3 horse power or less?
I ran 3ph around my shop. I didn't use plugs and receptacles, though. I terminated the runs in 3ph 30A disconnect boxes. Most of my machines are stationary, and I mean HEAVY. So I just run flex from the machine to the disconnect box.
Before you get too far down the plug/receptacle road, go price some. The plugs are about $20 EACH, and the receptacle about $25! Plus, you have to buy a box to put the receptacle in.
In two places I have two machines connected to one 3ph disconnect switch. That's easy to do, but if I had a plug/receptacle setup it would be very hard.
Your phase converter will never be UL approved, so you aren't ever going to get a permit for the 3ph part of this job. When you build your shop, just make sure the panel is surface mount, not recessed, and make sure there is an extra 40A breaker available to feed your phase converter.
I ran 3/4" EMT everywhere. It doesn't take too long to learn to bend offsets and bends. I'm real pleased with the result.
One more thing - I suggest you plan your ceiling carefully. Know where all your light fixtures and electrical conduit and air pipe and water pipe and gas pipe (or whatever) are going to run BEFORE you start running conduit everywhere.
If I might interject here, the better approach is to leave a pigtail of S-cord on the box, that hangs down. If the machine has an S-cord connection on it, with a cord cap. Then the box pigtail can have a female cord cap.
I've found that the larger twistlock connectors just don't do very well over the long run, especially if mounted on a wall, so the receptacle is vertical.
Also the wiring inside the box goes a good deal easier if one is connecting the S-cord pigtail to, say, NM solid conductors. Trying to get a receptacle mounted to the box, once all the wiring is hooked up, has always been a bit of a chore for me.
Jim
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That's one of the reasons I pay extra and use stranded instead of solid wire. It's also one hell of a lot easier to pull through conduit. My needs are small enough that the cost difference won't break the bank. If one must use solid wire, though, I've found that a Z configuration of the pigtails makes installing the device a lot easier. Don't know what the pro's do.
Yep, but NM is not available in stranded, it's all solid. The cost differential is tiny if you are pulling the wire through conduit, and in retrospect I should have run my lines from the converter out to the shop in pipe. That was an error, not one I would be likely to repeat. But I was new in the 3~ business, and it's there now so no sense in ripping it out. But all the new drops go in with S cord pigtails, and a female twistlock cord cap. Code actually does require a disconnect means, and a plug/receptacle combination satisifies that. Not that this installation is code of course, but the reason behind it (lockout of a machine being worked on) is valid and I do feel better being able to positively take power off a machine before working on it.
Jim
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I built my shop a few years ago I did all the normal single phase wiring in conduit. I put my conduit in for the three phase but did not pull any wires. I then had my building inspected by the electrical inspector and it passed. I wouldn't run the three phase conduit or wiring until after the inspection if you have any doubts about the inspector passing the job. I hard wired all my machines because they are basically fixed machines. I put a 50 amp 4 wire outlet (welder outlet) to plug my phase convertor into, this makes it a "portable appliance". I looked into the cost of twist-locks for three phase and quickly decided I liked hard wiring them much better. I wouldn't want to make things like lathes and mills mobile because of the time required to relevel them each time. The only three phase machine I have that is portable is the horiz saw and I converted it to single phase years ago. I would go to an electrical supply house (like Graybar, they sell to anybody with money) and price plugs and recepticals but be ready for sticker shock, the 3 phase twist-locks are high dollar.
If I recall correctly, so long as the panel is in the same room as the machine, the breaker can function as the disconnect so one can safely work on a machine. A lockout device maybe required for the breaker, however.
For wiring three phase machines in my shop, which has 3 phase delta service, each machine run terminates in a 4" square box, where the machines are wired via the S cord you spoke of. All the walls are finished, so a blank trim plate is drilled for the appropriate restraint. The installation is very clean in appearance, and, as far as I know, meets code. Lots of ways to skin this cat, but I've not even considered using connectors, except for on my Bridgeport, which will have one eventually. For the moment, it is temporarily hard wired on location. I'll use a twist lock because I have a shaper head that will need to be connected on occasion, and that prevents running a second independent circuit.
My dim recollection is, there had to be a *second* disconnect, that is, one besides the breaker in the panel - even if that's in the same room.
So running hard line like conduit or greenfield, from a box on the wall, right to the machine, does not qualify for that. I think there needs to be a second knife switch someplace on the wall or on the machine to meet that requirement. Or, as I said, for smaller items a cord connector set fills the bill, below about 30 amps or something.
A lot of the used machines I find have just such a knife switch grafted onto the side of them, which implies that a lot of industrial electricans are thinking along those lines.
Jim
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A lot of the used machines I find have just such a knife switch grafted onto the side of them, which implies that a lot of industrial electricans are thinking along those lines.
Monarch 10EEs were supplied with so-called "safety switches".
There is a main contactor within the machine, but that does not actually remove all power from the machine, so a safety switch was grafted onto the back, next to where the power entrance area is. (Internally, all wiring is within EMT, from one unit to the next).
The U.K. lathe site shows an EE without a safety switch, but every schematic diagram I've seen, and every machine I've seen, has had such a safety switch.
For a machines above, I believe, 1 HP (might be 2 HP), the cordset may not be substituted as a disconnect.
And, probably not above 240 volts, either.
The disconnect must be in plain view, must be labeled, and must be within 6 feet (might be ten feet) of the machine.
For practical purposes, this restricts such "cord disconnect" means to NEMA
To answer your specific question, the "L15-20" is the right plug and receptacle, you can get them from mcmaster.com as cheap as anywhere, that is unless you find them on ebay. Some Home Depot and Lowes stores actually do stock these.
There are many other 3 phase twist lock styles but as far as I know they are all obsolete, from earlier standards and codes.
If you want a lot of outlet locations, then run 3/4" EMT conduit from box to box and pull a single long uninterrupted loop of 12 awg stranded wire conductors through it all. Leave a foot of wire coiled up in each box and cover it with a blank plate. Then where you need an outlet, open the box, cut the wires and splice in pigtails for a receptacle.
Absolutely, although switching off the phase converter which is a multi-stage two-handed op to restart (and which is located some distance from the machines) has seemed safe enough for me so far.
S cord is rubber insulated electrical cord. It is rated to 600 Volts, is waterproof, lays well on the floor, and resists abrasion. It is NOT rated for direct burial. It is most commonly used for equipment pigtails and extension cords. The outter jacket and the inner conductor insulators are both rubber. The conductors are stranded copper, color coded, and seperated, usually by paper. There's a filler contained by the outter jacket. Commercially, it's commonly available in 2-conductor with or without ground, up to 3-conductor with ground, in gauges from 16 up to 10 AWG. You can buy it at any electrical distributor, and most home centers and hardware stores. It's expensive, but works very well.
Some phase converters are wired so that turning off the phase converter does not necessarily turn off L1 and/or L2 to the distribution panel. I helped a friend cure this problem with his rotary converter. Be careful!
The National Electric Code requires a local disconnect for every piece of equipment. A plug fulfills this requirement, as does a wall-mounted disconnect switch, and, under some circumstances, I think a dedicated circuit breaker will as well.
Call me crazy, but I use lockout-tagout even in my own shop at home. For those of you who aren't familiar with it, here's an OSHA reference, it's part of the Control of Hazardous Energy:
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If you want to learn about it, there's a link to training on that page.
I actually lock stuff out. I don't tag it, because I'm the only one who ever works on the equipment itself, although several people use my shop. I'm the only one with keys to the lock. I also Try and Test: after locking out the circuit, I try to start the equipment "normally" (e.g. push the Start button) and then I put a circuit tester (I use a "wiggie" solenoid-type tester instead of a high-impedance multimeter) on the terminals and make double-sure that sucker isn't going to turn on.
I'm really careful about this stuff, partly because I want to live to at least 100, and partly because electrical burns are not the way I want to go. I work a regular job (I'm an EE in a polyethylene plant) and sometimes once I've gotten home, had some dinner, and gone out to the shop I'm a bit tired. Rigorously and automatically following lockout-tagout and try-and-test procedure is easy, and means that I probably won't kill myself.
As already mentioned, it's rubber-covered flexible 'portable cordage.' What was not mentioned yet is that it comes in different, uh, flavors.
SJ = so-called "junior" variety, with thinner jacket SO = oil resistant, I think it's neoprene etc.
I think there's about a dozen different kinds, some are low temperature (artic) and some are solvent/chemical resistant.
Look at the actual printing on an extension cord you've made, with some black flexy wire from home depot, you will see a designation like S...
Jim
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SOW wire. Rubber jacketed, not rated for outdoors/rough duty use IIRC.
Gunner
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What you said, and more. SO cord is also available, and in larger and more configurations that you mentioned, as you likely know. I have 100' of a 4 conductor #4 cable in storage. It's great stuff, but very heavy to handle when it gets this large.
Excellent advise! One can't be too careful with electricity.
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