What are the risks of an electrical setup like this.

The safety ground needs to sized such that it can trip the breaker that feeds it.

Neutral is a wonder...

The transformer feeding your panel is 240 VAC with a tap in the middle.

It carries unbalanced loads, plug a light bulb in both L1 and L2 there is no current there.

Turn on a 120 vac heater and now current in neutral.

The output from transformer is FLOATING, meaning the ground is provided by you. Th

If the neutral fails the voltage gets wonky.

Ground stays same, but depending on the load, the voltage reference to ground gets real interesting as voltage depends on the current.

Just get a different cord.

Use a range cord as it has 4 conductors.

Our mill has a truck trailer cord, inside are enough wires to allow for 2 plugs, the 250. Vac plug housing has room to add sub cord to plug into the 120 vac outlet next to the 240.

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As far as my current plan. I found a 6ft or so whip I had with 4 wires. The load wires are 12 gauge. It’s just a touch short. I’m going to put a plug on it and run it to a box in the middle of the back of the lathe for my 120v power and it will junction to the lathe with the lathes wiring. So 4 wire outlet>4 wire cable>outlet box>lathes 3 wire 220v wire.

Should satisfy all issues and use up some stuff I’ve been hoarding.
 
You are correct, it wouldn't compromise the rest of the house.
In the old days, clothes dryers used the neutral as ground so three wires- the timer was 110 volts. But that's not done anymore for new installs, a separate ground is always used making it 4 wires.
Be safe
It's all about redundancy, and what is likely to fail. Ignoring RFI issues, ground wiring vs neutral is a total waste of copper until there is a fault somewhere. In a 3 wire dryer, a faulted house wiring neutral leaves the dryer frame hot when the timer pulls the neutral voltage to whichever 220 line it connects through. But a dryer has to be wired on a dedicated circuit. So lower chance of a failure putting line potential on the chassis of another device. Which is why dryers and ovens were slower to require 4 wire circuits.

When you put a load onto a ground in a shared circuit you're exposing every grounded device to that potential if the ground path fails. Neutral is not connected to device frames, so while it may fail it doesn't put a live load on things. In shared circuits it is quite possible for the ground wire to go through a lot of junctions. In an outbuilding the ground bond is remote, so a problem with the ground feed from the house to the outbuilding means everything in the outbuilding could have the ground pulled to line voltage.

Now, a better question is why do we use a ground rod at all? If we disconnected the ground rod, every utility transformer would essentially be an isolation transformer, and you wouldn't need to worry about getting shocked by completing a path to earth.
 
I do believe it would jeopardize safety of the device but not of house. Inside my electrical box the ground and neutral are bonded so if the neutral failed inside the box all grounds would be energized and if the ground failed in the box it would no longer offer ground protection. Defeating the ground at the lathe makes the lathe unsafe but I don’t see how it compromises the rest of the house (in this case it’s an outbuilding with its own panel).

Keep in mind the is just an exercise of why I shouldn’t do it. My questions are curiosity’s and i am just looking for the why’s of why I can’t.
It would not compromise the house or outbuilding with everything working properly, but not everything works properly all the time, ie my example above. If you took this short cut, how do you know someone else didn’t take another short cut that together causes a problem, but each on their own doesn’t? Electricity always seeks the path of least resistance, if your ground wire is no longer providing a path back to the panel, it will try to find a way back through the ground system, and that could be through other equipment, or people using it. The chances of that may be low, but it is not zero.

The regulations were put in place so that there is a consistent standard of installation that is known to work, by doing things differently, you could be unknowingly introducing problems elsewhere. You need to think of the possibilities outside of just the equipment that you are working on.
 
I do believe it would jeopardize safety of the device but not of house. Inside my electrical box the ground and neutral are bonded so if the neutral failed inside the box all grounds would be energized and if the ground failed in the box it would no longer offer ground protection. Defeating the ground at the lathe makes the lathe unsafe but I don’t see how it compromises the rest of the house (in this case it’s an outbuilding with its own panel).
If the neutral fails at that level it is much more obvious as everything using 120v either quits working or gets fried by 220 due to imbalanced currents. A failed ground can go easily go unnoticed for long periods of time.
 
I know you don't care about most of this (and I'm not saying you should care about most of this, and I've already said my piece on how I'd recommend moving forward...), but the specifics aren't the point of this. The point of the systematic nature of the electrical code.

I do believe it would jeopardize safety of the device but not of house.

Using the ground wire as a a current path will affect EVERY ground wire in the installation, and the devices attached to them. If that doesn't make sense, and no offense is intended here, then you've either missed something in your understanding of electrical potential and current flow, OR, you've not considered the whole circuit. Even though you can see the "bond", ALL of the wires in your entire electrical installation, the hots, neutrals, and grounds, each and every one of them are eventually connected to each other at both ends.

...Inside my electrical box the ground and neutral are bonded...
...(in this case it’s an outbuilding with its own panel)...

Which electrical box? For the house, your neutrals and grounds need to be bonded ONE TIME, at the "service equipment". That's the main feed from the power company, and it's done at the first shutoff after the meter, and some specified maximum distance from the meter. That could be your "main panel", in which the panel enclosure would be where the bonding takes place or that could be a dedicated shutoff prior to your main panel. In that case, the shutoff would be bonded, and the "main panel" would not be bonded.

I'm not taking that on, as I can only assume that the separate building was done correctly. That's not something that one can realistically take on in a text based, remote discussion.

Outbuildings have some different rules. Depending on several factors, you either carry the ground AND the neutral to the outbuilding, and utilize them there (which makes the outbuilding no different than an extra bedroom within the house, everything is still connected). In that case the outbuilding's panel is NOT bonded. Or in other circumstances you'd feed the outbuilding with two hots and a neutral, omitting the ground, and the ground is reestablished at the outbuilding, and there is again ONE point that the outbuilding is bonded. That will be at the first disconnect after the entrance to the outbuilding. Those are two very different scenarios, with criteria that dictates which way it needs to be. Sometimes those decision scenerios are as simple as if you did or did not run the forth wire, other times it's more involved. But depending on the variables that set that decision in stone, either way, the wiring will be wired, and function exactly how you'd expect it to, and it will work as it should. UNTIL you start doing non-standard things. Then, honestly, all the internet advice is a shot from the hip.

If you have the ground reestablished (not carried) to the outbuilding, you can omit the house wiring from being a part of the equation for THIS question. (Other questions will still affect the house as well). If you have four wires physically run out to the separate building, the building, I'm not aware of any exceptions, I think it's already set that you can't re-establish a ground at the building, and that panel must not be bonded.

In either situation, stealing a curent path from the ground wire MAY cause something else, somewhere else to have voltage available where it shouldn't be.

This is one of the many things that the codes do for you, EVEN IF you live where there are no codes whatsoever and nobody cares... It makes a system, such that what you did sixty years ago, what you do sixty years from now, what you did yesterday, and what you do tomorrow, they'll ALL work transparently with each other. That was the basis for my suggestion above. Re-identifying the wire on the lathe's whip, making it neutral instead of ground, That's how dual voltage appliances were always done. And the fact that "cheating" will work fine in some cases... It affects things in the future. Doing the lathe "to code" even though that "three wire" code is obsolete, plus it isn't required to do so, means that even though grounding through the neutral is obsolete, the code (and non-code wiring that is done to code) will recognize it, and it will not have adverse effects (beyond an outdated appliance that isn't up to modern UL and other codes). It doesn't maintain the integrity of one circuit, it maintains the integrity of the whole entire electrical installation.

What about this idea? Say thr outlet is properly marked that it is 220v. This example actually takes place in real life. There are 12v bulbs that have the same base as their 110v counter parts. Does this seem like an okay situation? I will end up not stealing a ground so that will be intact and the light will be 220v. Assuming I can find a light, I feel like led bulbs might go up that high.

That's an awesome example of "keeping things right". These bulbs are way outside of electrical code, but it's the same thing. The NEC ended at the box upon which you screwed a bulb base. Or at the outlet where you plugged in the lamp. Those fall under a listing agency. UL, CE, etc. but t you can be assured that they all know about each other. If you screwed a 12 volt light bulb into a 120 or 240 volt outlet, one of two things is going to happen. Either the resistance is too low, so it draws way too much current, and the breaker trips, OR, the filament is unable to handle the current that's way above it's rating, and the filament melts, inside of it's enclosure, untouchable by you, and opens the circuit, eliminating the fault. That's why light bulb bases are so universal compared to other things, the bulbs can't catch fire, smolder, carry on, or stand generating any level of heat that wasn't designed in. They can act as their own fuse, and the overall design of the product is intrinsically safe, even if you screw up. Their design also negates the need for a ground wire at the bulb, even though the box that the light is plugged into still needs that ground wire. You still see such devices today, which still to this day, come without the third pin on the plug. NEC says the ground pin must be available and wired in on the receptacle, but that's where they end. The two prong appliances (and light bulbs) fall under a different system, designed to work with NEC compliant power, but the fault protection level that the ground wire would have provided, that's built in.

In contrast, a counterpoint is that the outlet that the lamp is plugged into... You don't have the same degree of universalness. Each voltage and each circuit breaker size small enough that it's plausible to use a plug connection for, each breaker size has it's own dedicated plug, that does not interchange with any other. That seemingly arbitrary wagon load of different plugs is necessary so that you can't plug ten amp things into 50 amp circuits. The device would work, and it would control it's own current draw, so long as it was in working order and all was right in the world. In a fault scenario though, it's not capable of SAFELY restraining that much power, such as the larger breaker is cable of delivering. And so it spirals into confusion with more outlets/plugs than you can shake a stick at. But they solve a real world problem. They keep both circuits AND appliances from becoming a problem.

That being said, the side of me talking myself out of it is going to come out. I “think” the unsafe scenario there would be the same reason a travelers or Chicago 3 way is illegal. Since the appliance has a single pole switch when hooked to 220v it would still have 110 voltage potential in the socket from the other leg right?

I'm not sure I understand your analysis there, but yes, the "Chicago 3 way" is a perfect example. It's a very one dimensional analogy to this ground vs neutral thing. Let me make another analogy- The Chicago 3 way issue is a very two dimensional issue which fits very beautifully on a sheet of paper, and the danger is very specific, targeted, pinpointed, and quite clear. The ground/neutral question, that's a four, arguably five dimensional issue that makes a VERY complicated drawing of multiple, simultaneous current paths and fault modes and design decisions and permutations and variables based things about the entire electrical system that were probably never written, and were no longer available after the original electrican went on to the next job. But it's the same thing. It's a perfectly good way to make the light work. It's not intrinsically unsafe, EXCEPT.... It didn't fit "the system". Unless you've used conduit as a ground circuit or something like that, where continuous current is an issue, the available issues are all very unlikely, but when you add them up, coming from every possible direction, the whole risk becomes beyond tangible to kinda real world. Had the three way circuit been a thing at the time light bulb bases were standardized, the bases would have been done (slightly) differently, and that simple Chicago 3 way circuit would have had ZERO problems. Zero. Due to the simplicity of it's installation and typically lower wiriing cost, I suspect it would have been our defacto standard. The problem is, that to standardize that would "break" too much of the rest of the system. So the Chicago 3 way circuit was rightfully outlawed, not for being dangerous, but because it is not compatible with the rest of the established system.

Trivia- It wasn't specifically outlawed. It was fine in the knob and tube days, and probably the least of anybody's worries. Time's moved on though, and the hot socket isn't allowed any more.

Before polarized and grounded plugs was there just a chance you would get zappec when changing a bulb if you made a path to ground and touched the screw base? (In this scenario the lights plug was installed into the outlet with the bulb screw base circuit on the black wire or load side)


That was real. But just like plugging the lamp in in the first place, you learned right quick to keep your fingers off of the metal parts. Most people today never had to learn to be careful of a light bulb. Forget getting electrocuted, you don't even have to grab a paper towel to unscrew a dead one because they don't get hot anymore..... But the code still recognizes those old appliances, old bulbs, and our electrical outlet situation is still designed, to this day, to accept, accommodate, and protect those old appliances just as well as they ever were, and ever could have been, using only the neutral circuit, if that's how the appliance was designed.

Honestly, this is the biggest reason I even jump into these discussions. It's not so much that I don't think someone "could do just fine" by using a non-standard installaton, or even a dangerous appliance here and there. Your light would have it. It's the standardization that makes our modern code so much better than days gone by. With a faulty (or "custom") appliance, you have a "custom" appliance. If you break the system, you've broken the system.
 
On this forum we discuss many things which are more dangerous than the average person is likely to deal with in their every day life. We do so with the confidence that we have enough expertise within the group that the correct answer will be given.

I believe the OP’s question has been answered and he should have several safe alternatives moving forward.

Collectively, we spend a lot of effort to improve our machine tools. Therefore, I think my suggestion of changing the wiring at the lathe to accommodate a ground and neutral is the best solution given that 4 wire single phase is available.

Remember, by definition electrocution is always fatal.

John
 
When I bought my lathe years ago, it also did not come with a ground. That made me nervous enough to add my own ground. The lathe is grounded from inside the metal electrical box, mounted on the lathe, all the way back to the main breaker box.
Faced with your problem, I would be tempted to run a 220V lamp from the connectors in the lather control box, and include a separate ground. This is still probably technically against code, but as previously mentioned by others, NEVER use the ground as an active current return. Strantor provided a good explanation why.
 
I will be going with a 4 wire plug to a junction box on the lathe for the outlets then continuing from that will be the original 3 wire 220v to the lathe. Satisfies all safeties and requirements.
 
I would just find a 220v bulb for the lamp. I have seen some LED bulbs that will run on 110v/220v.

"I" would not hijack the ground and use it as a neutral. Being electrocuted is not fun!


The 220v to 110v transformer is also a good idea!
The Mill/Drill I had in the 90’s was wired that way: just got a 220V bulb - cheap, easy and most importantly SAFE.
 
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