I’m in the process of wiring up a main power shut off for my Avid 4848. I’ve got a 220V cut off box that is already up and running. Problem is, that only works for the spindle controller, not the ESS controller since it plugs into a separate 110 outlet.
Question is with 30amp slow blow fuses on each power leg, would it be feasible to wire a 110 outlet off one of the 220 legs for the ESS controller to plug into? It sure would be nice to shut everything down with a single switch! I know it CAN be done, and I’m trying to convince myself it won’t hurt anything, but that little voice in the back of my head is talking to me! 
We do get our fair share of power brown outs and lightening strikes here in SE Kansas and cutting everything completely off the wiring when not in use would improve my odds on a surge too.
Any thoughts or other ideas?
You cannot do that per most electrical codes.
If you ran 220v in a 4 wire config, I.e. with a neutral wire, a ground wire, and 2 hots, then you could put a small breaker box in and do a 220v and 110v circuits.
If you only have 3 wires, you can add a light switch on the 120v outlet you are using.
I get the code situation but i was more concerned about possibly causing a power issue with my machine. Logic tells me if there is enough amperage for both it should function just fine.
Do you have a neutral in the shut off box though? I would guess that it isnt’ there. As abakker pointed out, you need that or you can’t do 110 with one of the hots without using ground for the return and you do NOT want to do that.
Actually I am using 10-3 with ground, so yes, I do have 4 wires, but i don’t see the difference. There’s only one neutral bar in the main box and both the white wire and bare ground wire hook up in the exact same hole. They are literally connecting the exact same thing.
That’s where I’m arguing with myself. What’s the difference and can it really cause any damage? Logic tells me no. But I have been wrong before.
I certainly appreciate the feedback and friendly banter.
Steve
Neutral and ground are bonded once, in the main box and never again. If you cross them further out, you creat ground loops, which will certainly cause problems with CNC control.
Also, it is dangerous. Nobody else would expect to find 120v on a ground line and so an electrician or someone else working on your house could be injured.
Code is there for a reason, and using fuses and non standard wiring sets you up for weird, undiagnosable problems. What you do after the outlets is up to you, but I strongly recommend conforming to normal color coding and other electrical standards when wiring your shop.
Ground is only suposed to carry fault currents (like if something gets shorted on your equipment, it would carry the current back to that panel). Your machine chassis is connected to that ground wire as well. The bar in your main panel where you see your neutral and ground connected together is also bonded to the earth somehow, via a metal rod or some other means. So basically every chassis of metal equipment in your shop that your hand can touch is the same voltage that your feet are at if you are say, standing in a water puddle.
Now imagine that you return the current from your machine through the ground wire instead of the neutral. There would be current in the ground wire starting at some point (lets say at your CNC), and there is some resistance in the ground wire. The current times the resistance creates a voltage across that ground wire. So you have just put an unknown voltage on the chassis of your CNC. If you touch that and another machine at the same time, you will have current through your body equal to that difference in voltage divided by your body’s resistance. This could easily be a few volts and would only tickle (probably). However, if you have a lot of equipment on your shop wired like this, then the chassis voltage woudl be constantly changing to some degree.
But here’s the really ugly one. If you connect your return to ground instead of neutral, and say that ground connection gets broken somewhere between the equipment and the panel. Now you don’t have the ground wire carrying your current back to the panel. So not only will the equipment not work, but you will have the local ground (your machine chassis) at line voltage if the equipments power switch is on. For something simple like a high power light, or a motor winding, that would be able to kill you easily (it only takes about 15-20mA of AC current through the heart to kill you).
So all currents need to stay on the wires in your cords, and walls that nobody can touch. Ground needs to be at ground potential always, on all equipment.
Hope that makes sense.
Ok, I see what you’re both saying and I get it… safety is the main issue here. I’ll just hook a switch up to the 110 outlet for the ESS and mount it near the 220 cutoff box for simplicity and safety! I’m just trying to simplify life and make it easy to turn the machine on and off at one location. I knew my little voice was probably right, I’m glad I listened to it!
Thanks guys. 
OK so I am going to throw in my 2 cents. Yes, you can do what you are talking about. And I do think it could be done to code as long as you have all 4 wires. They even make an outlet to that will make this possible.
220 and 120 outlet
Now, with that being said, I would not do it because of the possibility of electrical noise on that circuit. Motors in general tend to be pretty noisy and I would not want that on the same circuit as my main controller. I also wouldn’t do it because I don’t think I’d want an uneven load on one side of my 220v breaker.
Another two cents on what you are trying to achieve. If you are connecting an Avid control box it will take 110 to 220 VAC input. No 110 VAC needed, just a different plug on the end of the pig-tail feeding power to the control box wired safely to L1, L2, and ground…
Love the responses guys! All great ideas and 2 cents worth that make perfect sense. I AM wiring an Avid machine. I was unaware the ESS controller could be wired either way, it comes with the 110 cable to plug in the side of the box and into an outlet. A basic power cable for anything, male/female ends. I just assumed, and you know what that means!
I think I’ll just be happy with two switches right next to each other in a convenient location, don’t need to introduce any electrical bugs in the system.
Steve
Hello! I am running the spindle and the controller off 220v. The factory has already built in that functionality into your controller!
But first, the whole frame is grounded so running neutral through the ground will run live voltage over the entire frame of your machine.
Anyways, safety first!
Talk to the factory but its a simple task of opening the controller and throwing some switches on power supplies. They will tell you the ones you need to flip to get what you want.
Then go buy this plug and enjoy;
Thanks for this info Subnoize, I just might give this a try.
I was only trying to point out that you shouldn’t use ground to make your 110V circuit. You mentioned you have a neutral, so that should be fine if you use that for return. However, as others have pointed out, the controll box can run off of either voltage, so that may be easier for you just to run both off of 220V.
I get exactly what you were saying Jim, and I appreciate your’s and everyone else’s advice on this matter. I’m kinda old school and would like to use what I already have rather than go buy new stuff. My Grandpa taught me to, “look around and see what ya got right there that will work!” And I’ve got 50 years worth of hoarding to look through! It’s time to use it.
Believe me, there are no problems here! I’m loving this group. 