Electrical requirements?

[Ben Helmich]

So I’m running some electrical. After reading another thread here, I now have some questions. I was going to do a 30a 240V for my big single phase 5HP Dewalt. The 70 year old manual specs this size. Is that still kosher? It’s set up like that now and working fine. I’m also adding a three phase 240V 3HP Dewalt on a VFD. That’s manual also specs a 30a circuit. Will that work? Lastly, I wanted to run a circuit for a future 2.2kw spindle on a CNC, also on a VFD. 30a here also? Thanks,
-Ben

[Stan Coryell]

What is the amp draw on the radial.
2.2 kw = 10 to 18 amps depending on power factor.
A 30 amp branch is good for 24 amps. You might want to up the wire size depending on start current and length of wire to prevent voltage drop.

[Bill Dufour]

sounds good to me. The cnc will have more then just the spindle load when running. Too many amps is not a problem
Bill D

[Jim Becker]

It's likely you'll be fine. For the CNC, however, you may need a four wire circuit because many CNC machines need dual 120/240 voltage arrangements. So if you want to run the wire now, assuming you know where the machine will live, be sure to use 10/3 plus ground for that particular location or just put in conduit so you can pull it later. If there's any chance you might go higher on the spindle arrangement, either do generous conduit or pull heavy wire now so you don't have to re-do things later.

BTW, my spindle is 1.7kw and it required 30 amps. The next step up for my CNC manufacturer is 3kw and the requirement is 40 amps for that HSD spindle. That's why I mention that you may need to be careful if you are pre-wiring for a CNC.

[Stan Coryell]

Jim, has a good point. The CNC should tell you min circuit size. We have to do some math to figure out what the radial will use on single phase. I would probably just run #8. It'll help keep the lights from dimming.

[Rollie Meyers]

The NEC requires that the values of Table 430.248 be used when sizing a circuit for a single phase motor, which lists a 5HP 230V motor as 28A, 125% of that is 35A which means the conductors must have a minimum a 35A rating, 10 AWG NM cable is only 30A, but 10 AWG THHN* is 35A if run in conduit, or 8 AWG if NM cable, 430.109(F) requires that any plug used as a disconnecting means be horsepower rated, and any plug that has a 5 HP rating are very expensive, Meltric® or Pin & Sleeve connectors are in that category, $$$.

*THHN is listed as a 90°C conductor, but that rating can only be used when derating.