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I have recently acquired a used Delta Unisaw with a 3HP 220 Volt motor and the cord on the saw ends about 10-15 feet from a new 220 Volt dedicated outlet served by a 30 amp circuit breaker. I believe the cord on the Unisaw has the original plug. How long an extension cord can I use and what wire gauge would be required to safely serve the Unisaw? Any help in setting this up safely would be appreciated.:moil:
 

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30 Amp breaker requires #10 ga wiring, John. In theory you could probably run the motor with a 12 ga cord, because it's relatively short, but if you're fortunate enough to have a 3HP/220V beast of a motor, why would you want to handicap it with inadequate wiring. Obviously you don't; that's why you're asking! :)
The motor probably draws 21+ amps?
 

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There is an old rule in electronics, which is that you can always run bigger wire, but you cannot run smaller wire. In short, it will not hurt a thing if you run "too big an extension cord" to your saw.

My 3hp Unisaw, and the one before it, will run fine on 12 gauge circuits (20 amp), but I ran 10 gauge to them because I'm just that way. I like the "extra amp room"and I believe it's a good practice.

If you are running ten gauge extension cord, you should be able to run it the same as you would hard wire 10 gauge, if not more. I suspect even twelve gauge multi-strand could run a long way. The weak point would be your connections. Simply put, if you are not generating heat in the line, you're okay.

I have a generator I run to a five conductor 8 gauge. I tied leads together and made it into a monster, 100' foot extension I'd run even the Unisaw from. Of course, the gen wouldn't appreciate it.



I have recently acquired a used Delta Unisaw with a 3HP 220 Volt motor and the cord on the saw ends about 10-15 feet from a new 220 Volt dedicated outlet served by a 30 amp circuit breaker. I believe the cord on the Unisaw has the original plug. How long an extension cord can I use and what wire gauge would be required to safely serve the Unisaw? Any help in setting this up safely would be appreciated.:moil:
 

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I also have a unisaw and would go with the 10 gauge. Your uni came with a plug? Mine didn't. In fact, I think it only came with the wire from the switch to the motor. I don't remember a power wire.
 

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I would use an RV 30 amp extension cord then install a companion wall outlet along with a plug on the saw wire. This RV extension cord is 10 ga, very robust as far as insulation and fairly flexible to get it out of the way It would probably be way too long (usually 20 to 35 feet), but can alternatively be used for a generator or a 30 amp RV if you have one.
 

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Dave has a great idea. But, if you're not going to be moving it often, why not just wire a new RV cord direct to the motor and forget the extension cord aspect.
 

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That is the best choice dont use the extension you have to make the cord anyway just go straight to the motor and 10 gage wire is more than u probably need but you loose less current on a long run with heavier wire.
 

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I have to vote with the others - a longer cord would be best, if it's a long term install where it's at. Again, each connection is a voltage drop potential.

The RV cord is fine, but you can buy the cord and plug at a big box or an electrical supply and would probably save money. The RV cord will have to have the male end chopped off and they can add a lot to cost.

Your current cord is probably only three conductor, but you can use a four conductor when you replace it, to add a frame ground. Just for reference, both my right and my left tilt Unisaws came with cords and plugs and, as noted, were three conductor.

As I mentioned, I could get by with a 12 gauge (20 amp. That is what comes on the 3hp saws and all it calls for, but ten gauge leaves room for a bigger motor or using the cord on other equipment.

_____________________________________
Comments from the Amazon pages:

From the manual: "A suitable circuit should not be less than AWG 12/3 wiring..." (for 3hp single phase). Such a circuit requires a 20 amp dbl. pole breaker.
Thomas O. answered on October 23, 2013

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220-240 volt and minimum 15 amp circuit. The plug is for a 15 amp 230 volt outlet so that's the minimum. This is for the 3HP motor.
Gauda answered on October 23, 2013

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The 3 Hp saw comes prewired with a 20 Amp 3 prong 220V plug. The saw will draw about 12.4 amps running. Use a 20 Amp 220V circuit with a minimum 12 gauge line wiring.
Mike answered on October 24, 2013

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I run it with 240v dedicated 20 amp double pole breaker. I also use a heavy duty, 10/3, 25 foot extension cord to reach the saw.
GlenT answered on October 24, 2013
 

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That type saw isn't meant to be moved and I didn't intend to move mine again once I had it set up so I wired it direct to my panel using armored BX cable. Unless you have yours set up so that the cord will never be stepped on then I would recommend that it be done that way. You'll never have to replace it or worry about a short circuit from wires rubbing together.
 

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Mine is overkill. 6 gauge wire to one of 4 240volt outlets in my garage (2 30 amp oulets and 2 50 amp outlets). The panel saw I have to a 50 amp and use the same connectors as my welders. For my welders, I have a 50 foot 2 gauge (angel hair) extension cord (600volt). (<-- I picked up the coil at a garage sale for $20!)

I have a 1300# plus saw but opted to run flexible cables that could be disconnected. Why you ask? It's not like I can drag that saw out to the end of the driveway to use, so it's not that...

Because my saw is set in the middle of the garage. There is the working room required to do different things... It moves against a wall (right side) when I need the extra space. When I have to break down sheets, I need to move it from the wall so I can get a full sheet of movement. I havew to move things from behind it if I need full movement of the table.

The much bigger factor is that I have "other" very heavy things I have to get around my saw and I would be not able to get them safety over an armored cable.
 

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John I built an extension cord for my table saw and my jointer. Both work on 220 volt circuits. I ran my wiring into a metal square D box and then enclosed the Square D box in a wooden box made from plywood.

I would recommend the twist lock connectors. These connectors are more money but it will not pull out of the wall and last a long time. If you want I can send you a few photos of mine. If your interested just PM me and I can email the photos and explained how I did it.

I have an old post which I think I posted what I did. Have a look and if you have anymore questions just PM me. http://www.routerforums.com/workshop-showroom/14498-garage-overall-shop.html
 

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It's been niggling at me since John originally posted his question...
"...from a new 220 Volt dedicated outlet served by a 30 amp circuit breaker."

The beginning and end of the discussion is the 30AMP breaker part. Everything downstream must be rated 30AMP. That's the Electrical Code.
The motor rating is a red herring.
 

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It's been niggling at me since John originally posted his question...
"...from a new 220 Volt dedicated outlet served by a 30 amp circuit breaker."

The beginning and end of the discussion is the 30AMP breaker part. Everything downstream must be rated 30AMP. That's the Electrical Code.
The motor rating is a red herring.
Dan

Is niggling a word? lol. Here is the plug I used for my table saw and jointer. It is rated for 30 amps and meets the code. Mind you this is over kill since my tablesaw only draws 7.7 amps on 220 volts but never the less it meets the code.

Leviton 2621 30 Amp, 250 Volt, NEMA L6-30P, 2P, 3W, Locking Plug, Industrial Grade, Grounding - Black-White: Amazon.ca: Tools & Home Improvement
 

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Coincidentally, I just ran into a very similar issue at our place, over the weekend. I've had a problem with our Beam built in vacuum shutting off on its own on occasion.
I replaced the whole motor unit (the machine minus the piping) last year because the old one was doing the same thing. I found the manual and went through it looking for some answers. Buried in there is the electrical instructions...the wiring must be 12/2 and the cct. breaker 20AMPS...of course the machine comes complete with a 15AMP cord and plug assembly!
When a new home is built, the Electrical Contractor is told to put in a cct. and receptacle for a b.i. vacuum, but isn't given any specs because at that point it's not likely that one has even been decided on. So what does he do? he wires in a dedicated 15 AMP cct. complete with a normal duplex receptacle. And when the vacuum arrives, the installer simply plugs it in, no questions asked.
 

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Interesting Dan. I also have a Beam which I installed myself and I didn't see that in the manual either, but I did see the 15 amp plug and it worked fine for 15 years. However, last summer when I went home it would cut out after about 30 seconds. I think it might be a bad bearing but I'll have to remember to check that. They are supposed to be warrantied for life if I remember right, did you get free replacement?
 

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I cannot imagine ever installing less than 12 gauge to an outlet. The only exception I've made is receptacles dedicated to lights and that are well marked. People shouldn't have to open an outlet or go to a fuse panel to determine its capacity. They should be able to presume them capable of twenty amps.

I see nothing wrong, in many instances, with running a 12 gauge extension cord in to a ten gauge circuit, a fourteen into a twelve gauge and so forth. Part of the reason for running a heavier gauge is to address the matter of the length of the run.

Several of my larger tools run relatively light cords. For example, my three horse Unisaw and my three horse dust collectors both run twelve gauge power cords, since they only draw about seven amps, after start up.
 
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