3-Phase Electrical Service

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I’ll ask a narrow technical question; that I hope someone on the Forum has had to address…

I’m upgrading to Felder equipment, and need to provide 3-phase electric to the machines… The 3-phase will output from a Phase Perfect PT-355.

The questions is whether the Phase Perfect output needs to go to a 3-phase distribution (sub-panel) box, with individual circuits feeding the machines; or, can I go directly from the Phase Perfect to the machines – probably a 40-50amp cable run…

As I said, this is a narrow question…

Thanks for your consideration.

Going through a sub-panel is basically the same as going direct, however the sub-panel allows you to have individual breakers for each machine.

Thanks for the responses. I’ll go the extra two miles on this… really trying to do the long-term good.

I’ve installed an additional single phase sub-panel in the work shop… creating more power for a shared shop / living space (above the shop): I’ve added electric infrared heat to the shop, and will need HVAC, stove, and water heater for the living space within two years. I’ll centralize all single phase power onto a single panel at that time. From this new panel (100A), I’ll feed a Phase Perfect PT-355 (100A single-phase in, 65A 3-phase out). The output will go to a 3-phase panel… providing multiple circuits for the machines – at max. load, one machine draws 30A, the other 20A. Since these are a J/P and TS, respectively, they will not run concurrently. I’ll convert my dust collector to 3-phase, and this draws 20A. From a concurrent load perspective, I’ll have between 40A – 50A on the phase converter.

I’m not sure if this subject is of interest to the Forum Members; however, I found precious little information to help me work through this; and I hope this will help other members who are considering three-phase. This is an expensive solution, no doubt.

Thanks, again, for your comments and consideration.

With the local utility one-time charges, and requirements to trench approximately 100′ × 30″ deep, getting 3-phase ‘from the grid’ was expensive. I’d then start being charged commercial/industrial rates for the power used.

The Phase Perfect was $5,500; 3-phase panel and installation another $500: so, I’m $6k invested at this point.

It is about this time I start questioning my sanity…


From a practicality standpoint, if you think you may want to add another 3 phase machine later on, the sub panel would make more sense. But the wire and breakers are expensive so I’d avoid it if possible. The converter already has a bunch of protection built in. You don’t need another breaker in-line.

I just read a little about these things and it looks like most people use one converter per machine. Since you’ll never run your 2 machines at the same time (you couldn’t anyway), it looks ok to share the converter. You just have to locate the machines near each other. If they’re on opposite sides of the room, then go back to considering the sub panel.

So really the only things driving the decision are the location and number of machines. Otherwise, there’s no practical advantage to putting a panel between the converter and the equipment.

Losing fingers since 1969