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View Full Version : Can I use 10/2 wire to go from the breaker box to a 220 outlet?


thowie70
Jan 6, 2013, 12:45 PM
I bought a table saw that runs on 220. Can I use 10/2 wire to run from breaker box to the outlet? Also, can I use 10/2 wire for the power cord on the saw? The current power cord has some bad spots in it so I want to replace it. Not sure what wire it is currently using yet.

stanfortyman
Jan 6, 2013, 12:47 PM
It depends on the draw of the saw. The size of the wire is determined by the amperage of the circuit.
So you can use #10 for a 30A circuit but not a 40A circuit, regardless of the voltage.

What is the draw of the saw and how far it is from the panel?

NO, you cannot use 10/2NM or UF as a cord to the saw. You need to get flexible cord for this.

stanfortyman
Jan 6, 2013, 12:49 PM
I will say, unless this is a huge commercial saw (like 5hp or more), 10/2 will likely be fine.

thowie70
Jan 6, 2013, 12:59 PM
How do I find the draw of the saw? The current plug at the end of the power cord is a 20A plug if that helps at all. I was going to look for the 10/2 flexible wire at an electrical outlet store. The outlet will be about 15' from the panel so will be using about 25-30' of wire to run to it. I was wanting to make the power cord about 20' long so I can take my saw outside the garage to use it for dust reasons.



It depends on the draw of the saw. The size of the wire is determined by the amperage of the circuit.
So you can use #10 for a 30A circuit but not a 40A circuit, regardless of the voltage.

What is the draw of the saw and how far it is from the panel?

NO, you cannot use 10/2NM or UF as a cord to the saw. You need to get flexible cord for this.

stanfortyman
Jan 6, 2013, 01:01 PM
It is probably a safe bet that the #10 is fine. #12 would probably be fine as well. It would be good to be sure though.
There should be a rating plate right on the saw motor.
If it is under 20A then #12 cord would be much easier to work with than #10.

thowie70
Jan 6, 2013, 01:07 PM
Thanks so much for the quick answers! I am going to go look at the plate on the motor and see what I can figure out. Would be nice to be able to go with 12g wire.



It is probably a safe bet that the #10 is fine. #12 would probably be fine as well. It would be good to be sure though.
There should be a rating plate right on the saw motor.
If it is under 20A then #12 cord would be much easier to work with than #10.

thowie70
Jan 6, 2013, 01:22 PM
Got some info off the plate. It's a dual voltage single rotation single phase. 1.5HP 3450RPM, 115/230 Volts, 15.0/7.5 Amps, 60 HZ, 1 PH




It is probably a safe bet that the #10 is fine. #12 would probably be fine as well. It would be good to be sure though.
There should be a rating plate right on the saw motor.
If it is under 20A then #12 cord would be much easier to work with than #10.

stanfortyman
Jan 6, 2013, 01:30 PM
Shoot. 7.5A @ 230V. You could even go with #14 wired for 230V.

You could also go with #12 and wire it for 120V if you need to save breaker space.

thowie70
Jan 6, 2013, 01:33 PM
Seriously?? That would be cool, would that affect the performance of the motor?




Shoot. 7.5A @ 230V. You could even go with #14 wired for 230V.

You could also go with #12 and wire it for 120V if you need to save breaker space.

thowie70
Jan 6, 2013, 01:35 PM
Also, do I need to use the 12/3 or 12/2 or does it matter? As you can tell, I'm not all that familiar with the wiring! :)




Shoot. 7.5A @ 230V. You could even go with #14 wired for 230V.

You could also go with #12 and wire it for 120V if you need to save breaker space.

stanfortyman
Jan 6, 2013, 01:36 PM
Not at all. Startup will be a bit hard, but you are well within the limits of a 20A breaker. For a dedicated circuit you could even up the breaker size to 25 or 30, but I don't think you'll need it and don't recommend it.

thowie70
Jan 6, 2013, 01:42 PM
So if I have a dedicated 20A breaker going to a 110 outlet, I can rewire the motor with 12/3 flexible cord and it would work fine?



Not at all. Startup will be a bit hard, but you are well within the limits of a 20A breaker. For a dedicated circuit you could even up the breaker size to 25 or 30, but I don't think you'll need it and don't recommend it.

stanfortyman
Jan 6, 2013, 02:34 PM
So if I have a dedicated 20A breaker going to a 110 outlet, I can rewire the motor with 12/3 flexible cord and it would work fine?Yes. Be sure to get the wiring right inside the motor. You'll have to change a couple of terminals.

thowie70
Jan 6, 2013, 03:18 PM
Oh, I would have to get into motor, not sure I would be able to do that





Yes. Be sure to get the wiring right inside the motor. You'll have to change a couple of terminals.

hkstroud
Jan 6, 2013, 03:37 PM
Stan
Note that thowie said 12/3.

thowie70
Jan 6, 2013, 03:55 PM
Should it not be 12/3?

hkstroud
Jan 6, 2013, 03:58 PM
Should be 12/2 with ground for either 120 or 240 volt. Wiring connections for each voltage should be on motor wiring terminal box. May be on inside of cover.

thowie70
Jan 6, 2013, 04:53 PM
Will they be marked to tell which should be attached for 120 or 240?





Should be 12/2 with ground for either 120 or 240 volt. Wiring connections for each voltage should be on motor wiring terminal box. May be on inside of cover.

donf
Jan 6, 2013, 05:07 PM
Stop for a moment Thowie, please.

You have made several statements regarding how "Unsure" you are around wiring that you are making me concerned.

You do understand that you will:

Need a special 240 AC Volt NEMA receptacle at the outlet you have chosen for this saw. You must conform to the current NEC code for your immeadite city, county or state.
That's just for starters.

The critical stuff is far more dangerous. 240 Volts at any amperage can be fatal. Bare this in mind before you start sticking tools, fingers inside of a live panelboard. You could end up toast and crispy. That is not meant to be a joke in any way!

In order to do the work properly, you will need a dual pole circuit breaker (240 Volts) at the rated "Full Load Amperage" plus the correct overcurrent protections called for in the NEC.

Now, if tou have a main disconnect or Main circuit breaker, you will have to shut down the panelboard. This alone will not kill the supply into the panelboard if it is set up with the main breaker in the panelboard. The service entry conductors will still be hot.

Once you get the panelboard cut off, you can thread the new correctly sized cable into the panelboard. Also make sure you use the correct cable clamp to prevent the cable from pulling loose of the cabinet.

Now comes the fun stuff. Connect the two conductors Black and White to the breaker. Place a small wrapping of red or black tape around the white conductor to signify that this conductor is being used as a hot conductor. Now set the breaker onto the panelboard and make certain it is in the "OFF" position. Now you can turn the panelboard back on.

At the outlet end, after properly running the cable, make the connections to the 240 volt NEMA receptacle and again wrap or use a marker the same color as you used at the panelboard.

Set the probes from a meter into the receptacle, one in each hot slot. Turn the meter on and then turn the breaker on. At the meter you should have 240 Vac (+/-) 10%.

If its good, then turn the breaker off and install the faceplate. Now turn the breaker on and call the electrical inspector for the inspection. I say that because I just know you applied for and received an electrical work permit.

If you are in any way skitish about about what needs to be done, call several licensed electricans for bids and make sure that the contractors will pull the permit, not you!

stanfortyman
Jan 6, 2013, 05:27 PM
If it is either 120V or 240V, 12/3 cord is what he needs.
Rubber SO, SJ, etc cord is rated differently than cable.
12/3 cord is black, white and green.
12/3 w/ground cable is black, white, red, bare.

hkstroud
Jan 6, 2013, 06:04 PM
Rubber SO, SJ, etc cord is rated differently than cable.

Learn something new everyday.

stanfortyman
Jan 6, 2013, 07:17 PM
Sorry, when I said rated I meant labeled/coded.

tkrussell
Jan 7, 2013, 06:42 AM
This is why flexible cord has it's own Article # 400 in the National Electric Code:






Rubber SO, SJ, etc cord is rated differently than cable.

Learn something new everyday.

And the amp capacity is different for cords that building wiring, such as THHN, MC, etc.