Is There an Electrician In The House?

[rbertalotto]

Currently my milling machine is running a 1.5hp motor off 120v through a 20a circuit.

I'm converting it to a VFD, 230v single phase in / 230v three phase, 1.5Hp motor out

My shop has a 60a Sub Panel.

I have a 40A/230v breaker running #10g wire, 30 feet to a 50a receptacle where I plug in a welder occasionally. This setup has been in effect for 20+ years and has been working great.

This 30' of 10g wire runs right behind my milling machine.

Can I add another 230v receptacle to this line in parallel to the existing 50a receptacle, or do I have to run another dedicated line for the VFD?

Thanks

 

[machPete99]

I'm not an electrician =but I would run a separate 20A circuit to provide better protection. Otherwise the 50A might not blow and allow something to burn up.

 

[jbaccell]

I'm not an electrician but I believe 10 gauge wire is rated for 30 amps. I believe you can get away with higher amps for intermittent appliances like welders within reason. As I understand it, the breaker protects the wiring so a 40 amp breaker would not be appropriate for 10 gauge wire to your mill. Otherwise, tapping into the existing line would be fine but for the fact that it is connected to a 40 amp breaker.

Just my $.02.

Cheers.

Joe

 

[tq60]

The current wire is one size too small.

Suggestion is to get a replacement for the current wire of the correct size. Your welder will thank you.

Then, use old stuff for a new circuit with proper breaker.

Sent from my SM-G781V using Tapatalk

 

[Eddyde]

To answer your first questions: "Can I add another 230v receptacle to this line in parallel to the existing 50a receptacle" No
"or do I have to run another dedicated line for the VFD" Yes
That is if you want to do it properly to code. You may get away with a rigged solution but if you ever have a fire you may be in trouble with your insurance claim for the illegal set up. If someone gets hurt or killed you could face worse...
Also, the above comments are correct, the 10 gauge wire is too small for a 40 amp circuit, either decrease the breaker to 30 amp or increase the wire to 8 gauge.
12 gauge wire will be fine for the 230v 20 amp mill circuit.

 

[BGHansen]

My understanding (not an electrician) is:

14 gauge - 15 amps
12 gauge - 20 amps
10 gauge - 30 amps
8 gauge - 40 amps
6 gauge - 50 amps

You've been successful to date with undersized wiring, likely because of an infrequent duty cycle (not laying a continuous bead for hours). However. . .

I'd start by replacing your current 10 gauge line with a new 8 gauge line to the 220 40A breaker. Then, wire your current 10-gauge wire to your mill's breaker (20 or 30 amp) and dedicate that to your mill. You could run a new 12 gauge circuit to the mill (20A breaker), but the 10 gauge wire is already there. Sadly, gone are the days when 250 ft. spools of 12 gauge cost $30!

Regarding the mill's motor, 1 HP = 745 Watts. Watts = voltage x current. A 1.5 HP motor will draw up to ~1200 W. At 220 V, that's ~5 A though there is a start-up surge. You'd be rockin' with a 20-A circuit run with 12 gauge wire.

Oh, my dad's rule of thumb (also not an electrician) is if he ran aluminum wire, he upgauged one size (12 gauge aluminum for a 15 A circuit).

Bruce

 

[Eddyde]

14 gauge - 15 amps

Note: the NEC requires a minimum of 12 gauge wire for any permanent motor circuit over ¼ hp, regardless of amperage.

 

[jbaccell]

Note: the NEC requires a minimum of 12 gauge wire for any permanent motor circuit over ¼ hp, regardless of amperage.

Not to hijack the thread but a motor plugged into a receptacle would be considered a permanent motor circuit?

Thanks,

Joe

 

[rbertalotto]

Thank You!

That's what I'll do.....Run new 8g to the welder outlet and use the 10g for the VFD with 20A breakers in the main panel and quick acting 10a fuses before the VFD at the mill.

 

[verbotenwhisky]

Currently my milling machine is running a 1.5hp motor off 120v through a 20a circuit.

I'm converting it to a VFD, 230v single phase in / 230v three phase, 1.5Hp motor out

My shop has a 60a Sub Panel.

I have a 40A/230v breaker running #10g wire, 30 feet to a 50a receptacle where I plug in a welder occasionally. This setup has been in effect for 20+ years and has been working great.

This 30' of 10g wire runs right behind my milling machine.

Can I add another 230v receptacle to this line in parallel to the existing 50a receptacle, or do I have to run another dedicated line for the VFD?

Thanks

I would like to suggest Ugly's, if you do not already have a copy: https://www.amazon.com/Uglys-Electr...hvlocphy=&hvtargid=pla-4584482474666837&psc=1