How much power do I need

[kc10flteng]

Hey guys...after watching the paint dry on my plans built 96A table, my better half sarcastically reminded me that I have the rest of the machine to assembly. I have the the stock 96A with a 5hp spindle. The electrician comes tommorrow. My expertise with electricity is limited to pushing switches & suffering the occaisional electric shock. I have no clue what to tell the electrician to install in the garage. I've read all the threads I can but get lost quickly in the terminology. Can somebody simplify the electrical power supply requirement (30 amps, 50 amps, fuse or breaker?????) for me or at least let me know what seems to work well for most bot operators. Thanks in advance

[patricktoomey]

Ron, I have my shopbot computer and controller on a dedicated 15 amp 110V circuit although it draws only a fraction of that. I have a 5hp Colombo spindle with the single phase Delta VFD which is on a dedicated 30A 220V circuit. The spindle will not actually draw that much current but theoretically it could get close for very short spikes. The biggest power item you will probably have to worry about would be a vacuum holddown system if you go that route. I use two shopvacs each on a separate 15A circuit. Big vac systems draw TONS of current, probably on the order of 30-50A at 220. Dust collection could also factor in if you are adding a dedicated dust collector, A 2HP unit would need another 15 amp circuit.

[beacon14]

I believe that most codes require minimum 12 gauge wire for 110 receptacle or equipment circuits, which would normally be protected by a 20 amp breaker. If you tell an electrician to put in a 15 amp circuit he may think you are asking for 14 guage wire which is not allowed in some areas and allowed only for lighting circuits in other areas.

You can put a 15 amp breaker on 12 gauge wire, but I would not use 14 gauge wire at all.

Also be prepared to dig deep - copper has increased 300-400% since a year or so ago.

[patricktoomey]

David, you're right about the wire sizing, 20 amp breakers on 12 wire would make the most sense. Unfortunately you're also right about the price of copper. I hadn't bought any large cable in about 2 years. I recently went to get 100 feet of 3 conductor 2 gauge wire and just about had a heart attack when I saw the price.

[jhicks]

Patrick, I see you recommend a 30AMP/220V line for the Delta VFD. I too am approaching a move and do have it on a 30A 220V currently but only because someone told me that would be sufficient.
Can anyone tell me the formal recommended current rating/breaker for this 5HP, Delta VFD set up?
I have some onn panels with unusual breakers at the new shop and can't find 220/30A breakers for it over the counter but have several 20A /220 breakers. Would this be sufficient or a risk not worth taking?

[patricktoomey]

Jerry, Upon closer inspection it appears that 30A may be big overkill but I need to do some more investigation to be sure. It looks like based on my labels that the Colombo 5HP running on the 10HP Delta VFD wired for single phase 220 should only draw 15A. If this is correct then a 20A breaker would be better than the 30A I have mine on and I should probably change mine. I had originally gone with 30A because the guy I bought my setup from had his on a 30A. I'll dig for the manuals just to be sure. I don't want it to pop when there isn't really a problem but I REALLY don't want it to burn up while the breaker happily supplies 10 extra amps to fuel the fireworks.

[gerald_d]

Patrick, 30A (for a reasonably efficient 5HP spindle and inverter on 220V single-phase) does not sound like too much of an overkill. 20 Amp will only drive 5HP at 220V if you have about 84% efficiency or better. Jerry, I can't see the risk of using 20 Amp breakers?

(I can't find a thread where we discussed this a few weeks back?)

[handh]

Here's what ShopBot says about it in their literature. I am wiring mine right now. http://www.shopbottools.com/files/SBD122_040809PRTalpha,Wiring%20the.pdf (http://www.shopbottools.com/files/SBD122_040809PRTalpha%2CWiring%20the.pdf)

[handh]

I am using a 10 gauge wire. Hope I am not doing a overkill also but it takes a 10 gauge wire to get 30 amps. I don't think it takes this many amps but that is what they say you need, or this is what I understand. Correct me if I am wrong.

[patricktoomey]

Gerald, I keep forgetting I'm not living in a 100% efficiency world, damn electrons! You're absolutely right, the efficiency of the three phase inverter isn't the greatest. The manual does show 25A or 30A for this configuration so I'm good where I am. That's good because I don't feel like re-wiring that thing. Jeffrey, knowing all this then 10 gauge is where you want to be unless you have an unusually long run to the box.