Do I need a 12 awg 3 wire cord to plug in a 2 hp motor via a Kbac 27 D VFD?

[LARRYZ10]

I am going to switch my 1.5 hp motor for a 2 hp one on my KMG grinder. It has a Kbac 27 d VFD. I am having a 230 volt 20 amp box installed in my garage and want to know what power cord to use. I can wire the motor to the drive but do not know much about 230 volt things. Any advice would be appreciated. Thank you, Larry Lehman

 

[Cap’n Smudge]

220-240volt is literally two 120volt wires and a neutral. Each hot wire is 120 volts but the two hots are out of phase with each other. None of this really matters.
By code 14 gauge wire is the minimum gauge wire allowable on a 15 amp circuit.
12 gauge is the minimum wire for a 20 amp circuit.
10 gauge is the minimum wire for a 30 amp circuit.
Voltage doesn't matter, only amperage.
I work with 277/480 volt power a lot.
On a 20 amp, 480 volt circuit the wire is still 12 gauge.

So - "yes" you need 12/3 wire for a 20 amp 240 volt single phase circuit.

The circuit itself will be run in 12 wire.
The cord you plug into the circuit could be sized according to actual load, but with the VFD involved it would be safer to just use 12 wire. It is best to keep circuit resistance as low as possible (bigger wire reduces resistance).

 

[Atlas Knife Company]

However, 14-3 gauge is more than plenty to run the 8 amps that the motor is using at 240v. If you're less than 25' long, technically a 16-3 cord would be adequate. I'd use 12-3 if you wanted to move up to 5HP at some point in the future.

 

[Cap’n Smudge]

I would recommend against 16/3, especially without more info. What's the FLA (full load amps) on your motor? Does it have a start capacitor? I mean we are using a single phase circuit to run a three phase load. The VFD isn't magically supplying 8 amps(or whatever) to the third phase. If it works like the "old phreak phase" transformers it would have to pull higher amps on the single phase feed to put out 8 amps per phase on the secondary side of the VFD. Also you have to account for inrush current if there is no capacitor. Without more info, 12 gauge is the way to go.

 

[zcd]

A standard 60hz 1800rpm squirrel cage 2 hp motor running on 3 phase power (load side of your VFD or between the VFD and motor) draws 6.8A (per CEC) with a minimum wire size of 14 AWG. The single phase load (line side of your VFD or between the outlet and the VFD) will be 6.8A x 1.73 = 11.764A or 12A with a minimum wire size of 14 AWG. That being said, I would absolutely recommend running #12 AWG wire - wire gauge is not the place to save pennies. I'm in Canada so your local code may differ slightly from mine, however in my experience (I work for an electrical manufacturer and deal with cross border equipment quite frequently) the Canadian code standards are typically more stringent than those south of the border

 

[Atlas Knife Company]

According to the 2002 National Electrical Code, 14 gauge is rated for 20 amps. According to NEMA(national electronics manufacturers association), 16 gauge is rated for 15 amps.

I used 10-3 on mine, just in case I move up to a bigger motor some day. 25' of 10-3 is $40 at Menards. I also use L6-30 twistlock connectors, just to keep everything uniform.