Looking at a PM 1236T, but only have 110v available.

Check out ebay they have vfd's that go up to 3hp with 110 input fairly cheap too.
I'm sure they do but that doesn't get around the physics of it.

At 115V, a perfect motor run by a perfect VFD will consume 6.5 amps per hp. Neither are perfect though, so the average conversion efficiency is probably around 85%, so figure around 7.6 amps. From there it's easy to figure based upon your breaker rating. For a 2-hp motor, you'll be using virtually all of a 15-amp breaker's capacity, and nothing else can be on the same circuit, which is unlikely. So yeah, as others have advised, running more than about 1.5hp on a 115-V powered VFD won't work out.
 
So, this is purely hypothetical. On another forum I couldn't even post something like this so what I'm really telling you is how a licensed electrician with proper permits might be able to address your issue....

If the wires running from the main breaker panel are big enough the circuit could be switched over to 220v by just changing the breaker. If there are three wires two can be hot and one neutral with a ground rod outside for grounding. Then a sub-panel that would give 220v for a lathe and 110v for lighting and outlets could be used.

An extension cord should be legal but not ideal. I've made cheap ones from Romex but it probably needs to be run inside a conduit to be legit, AFAIK as long as it can be unplugged it's considered temporary and isn't subject to code or permitting but I'm not a licensed electrician or code enforcement official so don't take my word for it, do your own research.

Regardless of the approach, calculate the loads and make sure the conductors are capable. Never install over-current protection that exceeds the amperage rating of the wire run or outlets. That said, a 20amp circuit should be plenty for a lathe and a couple of lights and it's unlikely the existing wires are too small.

If the work is done to code, and everything is inside, there is little chance of trouble. Discuss it with your landlord of course but none of this is beyond an average handyman/hobby-machinist.

This post just details how I might approach this issue and should not be considered advice or instruction. Consult a licensed and insured electrician if you have any questions about running permanent circuits in any inhabited structure.


John
 
When I was renting, I used a 10AWG extension cord that I cut the ends off of and replaced with the standard 3 wire 220V setup. It couldn't do 110, but I didn't need it to. This was made easier by the fact that we used a gas dryer there, so that 220 plug was not needed.

I didn't have equipment that could use more current than the wire could handle. Though I think the breaker was slightly oversize.

In the place I own now I got tired of the junk electrical in the garage. My brother is an electrician, so he gave me the info I needed to do it right and inspected it after I did the work. I put a 100A subpanel out there with surface mount conduit and outlets for 110 and 220 all over the place.
 
If the wires running from the main breaker panel are big enough the circuit could be switched over to 220v by just changing the breaker. If there are three wires two can be hot and one neutral with a ground rod outside for grounding. Then a sub-panel that would give 220v for a lathe and 110v for lighting and outlets could be used.

What you are getting at is to use the ground wire (bare) in 3 conductor Romex as Neutral, then Black and White as L1 and L2 (your two "hot" lines). The convention with 110v is that Black is Hot, White is Neutral, and Bare is Ground. For switching to 220v you could set Black to L1 and White to L2 (your two hots) then keep Bare as ground. Not having Neutral means you would have no 110v. Loading up the Bare wire as Neutral doesn't seem like a "hot" idea even if you use a "ground rod".

Incidentally, Neutral and Ground are bonded in most main breaker panels, however Neutral is still the line that is to complete the AC circuit for 110v power, not the bare ground wire. Sub-panels are more commonly set up with separate ground and neutral (that gets in to a complicated mess with out-buildings and tying in generators - no generator company will take the liability of separating neutral and ground (they bond neutral of the alternator to the frame) so when you feed a floating panel the ground and neutral are automatically connected at the generator. Of course, people modify stuff to get around that. But to each their own and to each their own risk.

Getting 220 isn't going to be easy. I rent, the garage is detached and the power to the garage is run under the driveway. The house has 220, but this wouldn't be a cheap project.

I rented a place that had an out-building/garage that didn't have power. It did at one point, but not when I got there. There was a 20 amp 110v circuit with its own outlet at the main breaker panel. So I ran a 12g romex "extension cord" from that outlet to the building. All said it was 225ft or so. There was a 200ft run outside plus the bit inside to get to the outlet. 12g romex was not adequate for the set up. For lights it was OK, light power tools (hand tools) it was OK past start-up, and when my 20gal air compressor tried to start up everything would shut off with the start up load but it would go - slowly. I don't recall any welding projects while I was there, but that would have been the worst idea - the voltage drop with current would cause unsteady arc power, and a light arc at that.

I would venture to guess that your out-building isn't 200ft from the house, so that is a good thing.

If I were in your position - I would do the extension cord idea. The run I had was in flex conduit outside. Pulling the wire through the conduit was a real bugger. The conduit was 2x 100ft runs. I ran small PVC pipe with a string threaded all the way through. I started at one end and pushed the PVC through, added another piece, and kept going until the PVC came out the other end. Then I used the string to pull the romex.

Use NMEA L14-30 plugs and run 4 conductors (both hots, neutral, and ground). The normal NMEA 14-30 dryer style plug doesn't twist lock like the L14-30 - it is OK to hang on the wall, but if you bump a long cord and pull on it the locking plugs are a lot better for that reason (and they are the normal 120/240v outlet on generators up to about 8000w).

I suppose if you already have 110v for lights etc out there you wouldn't need neutral in an "extension cord" - then just run both hots and ground for 220v. However, if you are doing the effort you might as well add a wire, make 4 conductors, and use a 4 pin plug for both 120/240v. I wish I did that when I made my extension cord, just to have it. At the moment its running power to an out-building at a property in the family - the same 200ft or so length - for lights and tools.

The idea of converting the circuit that is there to 220v just doesn't sit well with me no matter how I look at it. It might "work", and I can see the logic in it. Electricians (licensed) may say it will (I have no idea - I'm not a licensed electrician, just speaking in open terms here). It just doesn't sound like a good idea to me.
 
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