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Old 03-23-2008, 12:11 AM   #1
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220 shop circuit conduit


Hello: I have a detached shop with a 100A subpanel fed from the house. I need to run at least three new 220 circuits for some 220 machines I just bought. The floor is concrete and I don't want to run cords across them. The walls and ceiling are covered so going behind them is out. I plan to drop the wires from the ceiling, probably attached to the dust collector hoses. My main question: is it within code or reasonable to use heavy gray PVC conduit to run the 10g wire from the panel up to the ceiling, across to a box over the machines, and then drop down with a plug? Everything else in there is metal conduit, which I don't have the tools for and have never worked with, but I can do plastic. Thanks!

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Old 03-23-2008, 10:22 AM   #2
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220 shop circuit conduit


check local codes first. pvc not to support cable, temp not more than 122F, not subject to pysical damage, suported every 3' would not use this conduit for this application my self. take longer more expensive and looks like crap. check out the price on drop cords with proper support methods and female ends. emt is not hard to bend and use.

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Old 03-23-2008, 11:44 AM   #3
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220 shop circuit conduit


Personally I would not use PVC conduit either. My choice would be EMT. You will have a minimum of bends and it is very easy to work with.
Install the EMT run from the panel up and over to the loctaion. Mount a sturdy metal box. Then you can drop a cord from the box using a strain relief connector. There are several types of strain relief connectors. For your installation I would recommend the basket type. It will look like a wire fish net that will constrict the cable when any pulling tension is apllied to the hanging cord. Install a twist lock female connector the end of the cord. Install a mating male plug to the machine cord if it has one. Or attach a connector that matches your machine.
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Old 03-23-2008, 11:45 AM   #4
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Go with EMT if you can, buy bends if needed rather than bending if you don't have or can't use a bender.
Using EMT use is much like handling copper plumbing lines (except for the sweat soldering). There are connectors either using setscrews or compression fittings to make the job easy. Cuts with a tubing cutter or hacksaw.
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Old 03-23-2008, 11:53 AM   #5
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Thanks! I guessed if PVC was a good idea I'd have seen it in that application, but I never have. I haven't priced emt fittings so I'll see if the few bends I need will be cheaper than buying a new tool. Ooh! New tool!

So now another question: Do I run each circuit in a separate conduit or one bigger one and split it later?
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Old 03-23-2008, 11:57 AM   #6
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220 shop circuit conduit


Sure you can do this. How something looks is your choice. I would prefer you use EMT but PVC is fine so long as it is not down low where it is in an area that would be considered a possible physical damage area. Out of the top of your sub-panel up to the ceiling should be fine. I am assuming your sub is surface mounted and not flush with the drywall.
Using EMT i think you will be much more satisfied with the results and about the only thing you will need is a hacksaw. You can buy all the fittings and bends. You will need to spend some time studying the types of fittings so you know what to use. that is the case with either PVC or EMT. Probably the biggest thing I see is not using offset fittings when entering a junction box or leaving the breaker box so that the conduit lays flat to the wall or ceiling and this also depends on the conduit hangers/fasteners you use. These fittings look like this this.....


When you get over head of your equipment mount your JB's and come out of those with soow cord. If you free hang the cord then you must use stain relief at the jb's.
This link shows what you would do at the ceiling using strain relief like what JV is speaking about using. You can get all this stuff at the big box strores. the only thing is you may have a cord and plug situation vs a hard wire to a motor wiring enclosure.

http://www.hubbellcatalog.com/wiring...s/page_T38.pdf

You also need the data off the equipment to properly size your branch circuits. If you have that we can help you with it.

Turn the breaker feeding the sub-panel off in the house. When you open your sub-panel to install the breakers be sure to check for the proper isolation of the neutral and ground if you have a 4 wires coming in on the feeder from the house. If only three wires coming in be sure they have the bonding means installed for the neutral bar. And as a last note please consider a main breaker in the box if it doesn't have one, all small shops require this if a lighting and appliance branch circuit panel it would be almost impossible for it not to be. If any breakers 30 amps or less using a neutral conductor are in that panel it must have a main single throw disconnect.

Last edited by Stubbie; 03-23-2008 at 12:19 PM.
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Old 03-23-2008, 12:33 PM   #7
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The two main types of fasteners/hangers look like this..

You use offset fittings with this one....



And don't with this one


Notice that one puts the conduit on the wall or ceiling surface and the other stands if off a tad. If you look at the knockouts in your metal junction boxes you will understand why. The knockouts are not flush to the wall surface they are about 3/8" to edge for the 1/2" knockout. Which brings me to another point. Junctions boxes have various knockout sizes. You need one that will be configured the way you want it for your conduit size and then you want to pay attention to what knockout you use when entering and leaving the JB.

I also meant to mention if your equipment is cord and plug then let the plug be your guide as to the size of branch circuit wiring you need and then breaker it accordingly.
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Old 03-23-2008, 01:31 PM   #8
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220 shop circuit conduit


The saw is a 5hp, 230V, 24amp (from the data plate). The jointer is a 1 1/2 hp Baldor motor, but I can't see or access the rest of the plate without disassembly. Both came with 10gauge wire (looks like big extension cord) coming from the switch box with 20A-250V plugs. The males on the cord are Levitron, also stamped is NEMA 6-20 --they look like "normal" 120V plugs with one blade turned 90 degrees. I was thinking wiring with 10ga wire and 30amp breakers would be correct?

I priced wire, and individual THNN wire would be twice the cost of some 10-3 cable (looks just like the orange cord coming from the saw switch box to the receptacle). Any reason not to use that cable?

The box in the shop has a main breaker shutoff.
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Old 03-23-2008, 01:39 PM   #9
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Quote:
Originally Posted by mikew View Post
The saw is a 5hp, 230V, 24amp (from the data plate). The jointer is a 1 1/2 hp Baldor motor, but I can't see or access the rest of the plate without disassembly. Both came with 10gauge wire (looks like big extension cord) coming from the switch box with 20A-250V plugs. The males on the cord are Levitron, also stamped is NEMA 6-20 --they look like "normal" 120V plugs with one blade turned 90 degrees. I was thinking wiring with 10ga wire and 30amp breakers would be correct?

I priced wire, and individual THNN wire would be twice the cost of some 10-3 cable (looks just like the orange cord coming from the saw switch box to the receptacle). Any reason not to use that cable?

The box in the shop has a main breaker shutoff.
You can certainly use #10 wire if you wish, but you cannot use 30 A breakers because the plugs and receptacles are rated at 20 A. Besides that, the equipment itself may be required by the manufacturer to be on 20 A circuits,

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Old 03-23-2008, 02:32 PM   #10
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220 shop circuit conduit


Is this equipment new with factory cord and plug?

I say this because this doesn't add up to the nameplate data of 24 amps.
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Old 03-23-2008, 02:42 PM   #11
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No, it was used from a one-man commercial shop going out of business. That's what he had it attached with. My guess is the cord and plug from the machine are not factory, as the cord is orange, like aftermarket extension cords. Looks like I need to contact Powermatic and ask them what their specs are.
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Old 03-23-2008, 03:00 PM   #12
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Actually Mike that's what I thought was going on with your equipment. I wouldn't be surprised if the equipment was intended to be hard wired. But a cord and plug will certainly work.
The branch circuit conductors for single motors on their own circuit are required to be 125% of the Motor Table FLC of the motor horsepower. Unless the horsepower and running amps appear on the nameplate. In this case we can use the 24 amps. So your branch circuit conductors are 1.25 x 24 = 30 amps. So 10 awg is the correct size for your branch circuit conductors. The plugs need to be 6-30p with 6-30r on the cord from the ceiling.
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Old 03-23-2008, 03:21 PM   #13
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220 shop circuit conduit


Oh...sorry the other is a jointer at 1 1/2 hp and same plug as the saw so it is also 230 volts. The saw will need a 30 amp branch circuit but the jointer will not. The jointer is probably going to need a 15 or 20 amp circuit. If you have the model# we can look over at the powermatic site and get the specs...my guess is about 10 amps at 230 volts so conductors will need to be 12.5 amps minimum. #14 awg thhn will likely work for the jointer with 6-15 plugs.

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Old 03-23-2008, 06:54 PM   #14
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Would there be a reason not to wire all the circuits with the #10, with a 20 amp breaker for the jointer for now (I will check with Powermatic to be sure) so if I got something else needing 30 amps I could just replace the breaker? Just a thought. If you'll indulge a wire question: what is the advantage/disadvantage to the THNN, the orange "extension cord" 10-3 cable, and the white, flat "romex" style 10-3? I would guess the THNN is easier to pull in the conduit, but any other reasons? I did see the THNN is way costlier.
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Old 03-23-2008, 07:24 PM   #15
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Yes you could wire with #10 if you wish and put the jointer on a 20 amp breaker. That's your choice . If the orange is really an extension cord that someone used for a power cord it really should be changed to a duty cord like soow style. Extension cords are for temporary power uses. They sell duty cord by the foot at the big box.

10/3 power cord is 2 hots and a ground (3 wires).... 10/3 romex is 2 hots, a neutral and a ground (4 wires). 230 volt power tools only need 2 hots and a ground.

You don't want to put romex in conduit. It will take a much larger conduit than using thhn to get this done and it doesn't pull well through conduit and there are other issues. And you can't run the romex exposed on the outside of the wall.

Thhn is the only way to go IMO. It is stranded wire and will easily pull though your conduit....that is its intended use. Just buy it by the foot and not by the spool. Shouldn't be all that expensive. When you run these in conduit keep track of what wire goes where so you can terminate them correctly on the breakers. run one conduit up to the ceiling from the breaker box to a jb then branch out of it to your tools. For two 230 volt loads your going to need 4 hots and one ground total of (5) to the first jb then 2 hots and a ground from it going to each jb above the tools. You can use 1/2" EMT for everything unless you think your going to pull more wires into the conduit someday if so go to 3/4.

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