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A Resident? Don’t do it, no insurance company will insure you. You burn the place down, even if it’s not from the transformer, they will blame that, and drag you through the Courts till the end of time. Remember when you are paying an insurance company, they are your best friend. They pay you, you are the enemy.

Oh and before anyone says you can't do this by code. All of these projects were done according to PE stamped design and mfg. instructions and signed off by AHJ...

I have a fish processing customer that only has a 208 3ph service to their plant. I have had to install 3 transformers this year to supply new 480 V equipment and to supply shipping containers. Any 480-208 3 ph step down transformer has worked. I have had one unit that would not produce more than 430 v no matter the tap connections and I had another 150 kva xformer that would not go lower than 500 volts.

I also have fed single ph 240 to 3ph VFD's and they power 3ph motors just fine. I suppose you could feed the output of the VFD into a 3ph transformer to supply a 480 motor and it would function fine???

Please note that the NEC only permits backfeeding a transformer if the manufacturers instructions permit it, see NEC art. 450.11(B) which was added in the 2014 edition.

my friend sold his 3 phase soft serve machine and bought a water cooled unit instead

It's just a matter of pushing two buttons instead of one, or just let it run while you're working.

and dont forget- you have to start the converter every time you want to start the unit you want to use.

OR, like my friend...


Let it run 24/7/365

All you need is a 3 phase motor about twice the size of the largest motor you plan to run, a hard start kit from an a/c to start it, momentarily start-stop switch, a relay, contactor and some capacitors (I save the old good pcb oil ones). All of which you can get used.

Originally Posted by Supa-Heat

Tell me more about this simple and cheap 3 phase converter... all options I’ve seen are pricy and intensive.


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Originally Posted by Supa-Heat

Tell me more about this simple and cheap 3 phase converter... all options I’ve seen are pricy and intensive.


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There isnt one. The transformer by itself was like 9k. The rotary converter was around 3-4k.

Originally Posted by billg

Than it's not just a transformer, is it?
It would be like hooking up a drive powered off single phase to power a 3 phase transformer, or something to that effect.
Making a 3 phase converter is simple and cheap anyway, so why bother.

Tell me more about this simple and cheap 3 phase converter... all options I’ve seen are pricy and intensive.


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Originally Posted by billg

Than it's not just a transformer, is it?
It would be like hooking up a drive powered off single phase to power a 3 phase transformer, or something to that effect.

I forget exactly who it was who referenced it for me. Maybe kangaroogod. Anyway... It *looked* like a giant transformer in a box. I assume there was a a separate control board that made a phase offset for the 3rd leg. I do remember is was LARGE DOLLARS vs. a rotary 3 phase converter.

A drive changes frequency so i dont think it'll really apply to this discussion.

Than it's not just a transformer, is it?
It would be like hooking up a drive powered off single phase to power a 3 phase transformer, or something to that effect.
Making a 3 phase converter is simple and cheap anyway, so why bother.

Originally Posted by HVAC_Marc

yes you can. there's electronics involved and they are $$$$$$$ Another member here helped my friend out with finding a single phase to 3 phase transformer. They cost more than the rotary converters that are designed for the same higher loads.

Originally Posted by billg

You can't get three phase from single phase with a transformer.

yes you can. there's electronics involved and they are $$$$$$$ Another member here helped my friend out with finding a single phase to 3 phase transformer. They cost more than the rotary converters that are designed for the same higher loads.

Any R3 enclosure types. Those are indoor I need outdoor.

Originally Posted by VTP99

If you know the make and model I could look up the physical size. Existing one fits in a outdoor enclosure.

Looks about the size of a suitcase.





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If you know the make and model I could look up the physical size. Existing one fits in a outdoor enclosure.

Originally Posted by VTP99

I'm currently looking for a buck/ boost R3 transformer.
480volt primary 240 volt secondary 10kva 1phase.
I wonder if they have one like that ?
Yes with this type of transformer you can wire them either way. You can not change the phase.

Smallest they have is a 15kva 480P 240s 1ph. Would that work for you?


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I'm currently looking for a buck/ boost R3 transformer.
480volt primary 240 volt secondary 10kva 1phase.
I wonder if they have one like that ?
Yes with this type of transformer you can wire them either way. You can not change the phase.

Originally Posted by billg

You can't get three phase from single phase with a transformer.

I know, I’m referring to single. Although there’s not really anything I’d ever need 480 1ph for... I think some well pumps use it.


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You can't get three phase from single phase with a transformer.