Hello all! I'm new here so please be gentle - lol.

I'm wiring up my new metal lathe and milling machine. I have a VFD for each machine (Teco JNEV-202-H1) to run the three phase motors (1hp for the mill and 2 hp for the lathe). Since I will only be operating one machine at a time, and that will always be the case, I want to share one 220v line between the two. The VFDs specs indicate 200-240v single phase input at 15.5A.

I need to add 220v to my workshop (ok, garage) wall which is on the opposite side of the garage from the main 200 amp panel. A run of about 25 feet across the floor plus excess. I plan to run #12/2 wire (Romex) from a double pole 20 amp breaker through the attic and add it to an existing electrical run. I will then come through the ceiling of the workshop and down the wall to where the machines are located. I understand that code doesn't allow using romex within conduit, so on the wall at the ceiling I will have to transition to #12 wires to run in metal conduit.

I would like to have a cutoff (CB?) to control the two circuits, and another on/off switch for each circuit.

I'm sorry for the lengthy lead-up, but I wanted to give the general layout.

I have a few questions:

1 - Do the wire and CB size sound adequate? I read elsewhere on this board that if my CB trips during startup of one of the machines, I can switch to a 30A breaker safely with #12 wire and these motor sizes.

2 - What is the best way to transition from Romex to #12 wire at the wall/ceiling transition? Metal conduit body?

3 - What size metal conduit is adequate or approved for this?

4 - Do you see anything wrong with my plan from a safety or code standpoint?

Thank you in advance for any advice you're willing to share.

Guy in Sacramento

My answers follow each of your questions:

1 - Do the wire and CB size sound adequate? I read elsewhere on this board that if my CB trips during startup of one of the machines, I can switch to a 30A breaker safely with #12 wire and these motor sizes.

The circuit should be sized according to the input rating of the VFD.

The input amps of 15.5 needs to be increased by 25% to arrive at the feeder rating, 15.5 * 1.25 = 19.4. Since a 20 amp circuit cannot be loaded more than 16 amps, this circuit must be a 30 amp circuit with #10 wire.

2 - What is the best way to transition from Romex to #12 wire at the wall/ceiling transition? Metal conduit body?

Need #10-2 cable. The cable can exit the ceiling and enter a surface mounted 4 in square junction box, splice in the box, and continue on with the surface mounted conduit. instead of splicing, you may remove the cable sheathing and pull the conductors thru the conduit

3 - What size metal conduit is adequate or approved for this?

I would use 3/4" EMT conduit.

4 - Do you see anything wrong with my plan from a safety or code standpoint?

Be sure any penetrations thru the drywall of the garage are fireproofed, as any penetrations made by electrical cable has violated the fireproofing barrier between the garage and the remaining home.

Thanks tkrussel, you're just the person that I was trying to contact. I was going to email or PM you directly, but couldn't find a link to do so.

I'll install a 30a breaker and use #10 wire then.

I want to be able to kill the circuit. I understand from one of your previous posts that code requires both legs of a 220v circuit to be broken for a proper cutoff. Lowe's sells a motor rated 30a DPST switch. I'm planning to use that. Sound good?

I will pigtail off that switch to the two circuits. I would love to be able to find a DPDT switch to use to select either circuit to ensure that only one of them will be live at a time, but in lieu of that I will switch each outlet with a proper motor rated switch like the above.

Thanks again,

Guy in Sacramento

The 30 amp motor rated DPST switch is perfect.

What your looking for is a "transfer switch", that is either Off, or in position one or position 2.

Switch, Safety, 30 Amp - Safety and Disconnect Switches - Safety Switches - 1H299 : Grainger Industrial Supply (http://www.grainger.com/Grainger/SQUARE-D-Safety-Switch-1H299)

Holy cow! That transfer switch is pricey! This is the switch that I will use as a cutoff:

Shop Cooper Wiring Devices 30-Amp Red Double Pole Switch at Lowes.com (http://www.lowes.com/ProductDisplay?partNumber=89198-334-3032PL&langId=-1&storeId=10151&productId=3568846&catalogId=10051&cmRelshp=req&rel=nofollow&cId=PDIO1)

If it'll work for that, then I'll use one on each circuit as well.

Thanks again,

Guy

Yes, I know, people think us electricians make up these prices.

The Cooper switch is fine, rated for 2 HP.

Tkrussel, you are such a valuable resource here! The fact that you take the time out of your schedule to freely answer questions from newbies speaks volumes about your character.

Thank you so much for the advice, it is well taken and appreciated.

Guy

Hello. I just finished up wiring a Teco Jnev-203-H1 to my 3 phase 14x40 grizzly lathe. I was able to use the F/R and E-Stop and Jog. The VFD works great. The manual sucks. One very important step Teco doesn't tell you to do when you change paramenters is to shut the vfd down so it will except the changes.
I have have 30 years exp. On electric forklifts and when I program today's electric trucks you shut them down! Then power them back up! It seems this VFD requires the same.
I hooked up a external 10 k pot works great. I would say this is the best of both worlds using this VFD to run a 3 phase lathe in my small shop.

forkliftman,

Thanks for the addition. I'm finally hooking up my VFD today. Essentially the same as yours, but the 2hp model. I agree, the manual leaves a lot to be desired.

What gauge wire did you use to hook up the external switches? I'm planning on 20g as I have that on hand.

Thanks,

Guy