The short answer
Three-phase power shows up in flex space listings the same way high ceilings and paved parking do, as a feature that sounds important without explaining who it is for. Most people touring a shop bay have no idea whether they need it.
Here is the short version, and it is going to talk some of you out of caring about this at all: most small trade businesses do not need three-phase power. If your shop is where you store material, park the van, and run a chop saw and a compressor, single-phase is fine and you should spend your attention on door size and ceiling height instead.
Three-phase matters if you run production equipment in the bay. That is a real but narrow group, and if you are in it, you already have a piece of equipment in mind. It is also worth cross-checking against what size shop bay a small business actually needs, since production equipment usually drives the square footage question too.
What three-phase actually is, briefly
Single-phase power delivers energy in pulses, rising and falling 60 times a second. For a light bulb or a hand tool, that is fine. For a large motor, it means the motor gets a shove, then coasts, then gets another shove.
Three-phase delivers three overlapping supplies offset from each other, so there is always one at peak. A motor running on three-phase gets continuous torque instead of pulses. It runs cooler, lasts longer, starts under load without a hard kick, and does the same work drawing less current. For a closer look at how the three legs actually work, see this technical explainer on three-phase electrical service.
That is the whole idea. Smoother power, more work per amp, longer motor life.
Who actually needs it
The rule of thumb: if you are making something in the bay, you might need it. If you are storing things and driving somewhere else to work, you do not.
Likely to need three-phase:
- Metal fabrication and welding. Plasma tables, ironworkers, large MIG and TIG machines, and press brakes are commonly three-phase only.
- Machine and equipment repair. Lathes, mills, and larger air compressors above roughly 7.5 HP are frequently three-phase.
- Powder coating and finishing. The oven is the load, and industrial ovens are usually three-phase.
- Commercial food and beverage production. Glycol chillers, large mixers, packaging lines, and walk-in refrigeration.
- Print and sign shops running large-format or industrial equipment.
- Any shop with a dust collection system above about 5 HP.
Almost certainly do not need it:
- Plumbing, electrical, HVAC, and mechanical contractors. Your shop is storage and a bench. The work happens at the customer's building.
- Roofing, siding, framing, masonry, and excavation. Same reason.
- Landscaping and snow removal. Equipment storage and repair, not production.
- Overhead door, garage door, and window installers. You need a tall door and floor space, not phases.
- Anyone whose largest tool plugs into a standard receptacle.
That second list covers most of the busiest and most profitable trade businesses in Vermont right now. Being on it is not a downgrade. It just means three-phase is not the thing you should be evaluating a space on.
How to tell, in about five minutes
Read the nameplate. Every motor and every serious machine has a metal plate on it. Look for a line reading PH or PHASE. It will say 1 or 3. That is the answer for that piece of equipment, and it is not a judgment call.
Check what you plan to buy, not just what you own. This is where people get caught. The tenant who signs a lease based on today's equipment and buys a used plasma table eight months later has a problem. If there is a machine on your someday list, look up its requirements before you sign, not after.
Look at the panel in the bay. A three-phase panel has three hot bus bars instead of two. On the label you will see a voltage pair like 208/120V or 480/277V. Single-phase will read 240/120V. If you cannot tell, ask the landlord what the service is and what is submetered to the bay specifically, because a building can have three-phase at the main and still land single-phase in your unit.
Ask what is available versus what is connected. These are different questions with different price tags. Available means the capacity is in the building and running it to your panel is a job. Connected means it is already at your panel and you are done.
What it costs to add later
If the building has three-phase service and it simply is not run to your bay, this is a moderate electrical job: a feeder from the main to your panel, a new panel, and permits. Real money but not a project.
If the building does not have three-phase at all, you are asking the utility to bring a new service to the property. In rural Vermont that can mean transformer work and line work, and the cost is not measured in hundreds. Utilities generally require the customer to contribute toward that construction. Get a written estimate before you assume it is solvable, because in some locations the answer is effectively no.
That asymmetry is the reason to settle this before signing rather than after.
What about a phase converter?
A rotary phase converter takes single-phase power and produces a usable third leg. It is a legitimate tool and plenty of shops run on one, such as the AR Pro Series from American Rotary.
What it does well: lets you run a specific three-phase machine in a single-phase building without a utility upgrade.
What it does not do: give you a three-phase shop. The converter is sized to a load, usually with a derate, so a converter chosen for your lathe will not also run a compressor and a dust collector at the same time. The generated leg is not perfectly balanced, which matters for equipment with sensitive electronics such as CNC controls and VFDs. There is a standby draw whenever it is on. And it is one more thing that can fail, in the middle of a job.
Fine for one machine. A poor substitute for a building that actually has the service.
What to ask on a tour
Five questions, in order:
- Is the building three-phase, and at what voltage?
- Is three-phase run to this specific bay, or only to the main?
- How many amps are dedicated to this bay, and is it submetered?
- What is in the panel today, and is there space in it?
- If I need more capacity later, who pays for that work?
That last one belongs in the lease conversation, not just the tour. Who owns an electrical upgrade at the end of a term is a negotiable point, and it is worth checking what is actually in a small industrial lease before you spend money improving somebody else's building.
Reducing what it costs to run
Motor efficiency and demand charges are a real line item once equipment gets serious, and Vermont has programs built around exactly that. Vermont's energy efficiency utility program covers business equipment upgrades, and it is worth a call before you buy new motors or ovens outright. Rate structure matters too: check Green Mountain Power's commercial rate schedules to see how a three-phase load gets billed compared to standard service.
What we have at 310 Innovation Drive
Since this is our building, the specifics: the service is 400A 208/120V three-phase, with 200A submetered to each bay. Three-phase is at the panel in every bay, not just at the main. Electric is billed on your own submeter reading rather than pooled across tenants, so a low-draw tenant is not subsidizing a high-draw neighbor.
If that is a requirement for you, it is worth confirming when you compare against a self-storage operator renting units described as contractor bays. Those are usually single-phase, sometimes with no dedicated panel at all. More on that distinction: contractor bay vs storage unit.
And if it is not a requirement, ignore all of it and go look at the door.
Frequently asked questions
Do I need three-phase power for my shop?
Most small trade businesses do not. If your shop is for storage, a van, a chop saw, and a compressor, single-phase is enough. Three-phase matters if you run production equipment such as welders, mills, or an industrial oven.
How can I tell if a machine needs three-phase power?
Check the nameplate. Every motor and every serious machine has a metal plate listing PH or PHASE, either 1 or 3. That is the answer for that machine, and it is not a judgment call.
What is a rotary phase converter?
A device that takes single-phase power and produces a usable third leg, letting a single-phase building run one three-phase machine. It is sized to a specific load and is not the same as a building with real three-phase service.
What does it cost to add three-phase power later?
If the building already has three-phase service and it just is not run to your bay, it is a moderate electrical job. If the building has no three-phase at all, the utility has to bring new service to the property, which in rural Vermont can mean transformer and line work well beyond a simple panel upgrade.
Does 310 Innovation Drive have three-phase power?
Yes. The service is 400A 208/120V three-phase, with 200A submetered to each bay, and three-phase is run to the panel in every bay, not only to the building's main.
About this page
Written by the owner-operator of a three-bay flex building in the Rutland Airport Business Park, North Clarendon, Vermont, current as of August 2026. Equipment and power requirements vary by manufacturer and model. Confirm nameplate ratings and utility service details directly before signing a lease or buying equipment. Nothing here is electrical or engineering advice.
Questions about the service at 310 Innovation Drive specifically? Call (802) 417-2107 or email leasing@innovationbays.com.