Every machine in your future shop is, electrically, just three numbers: volts (the kind of power it wants), amps (how much of it), and phase (how it's delivered). Every bay you'll ever tour is also three numbers: the panel's amp rating, the voltage it serves, and whether three-phase is available. Match the two sets and everything hums. Mismatch them and you're either paying five figures for an upgrade or listening to breakers trip at 4 p.m. on a Thursday. This guide teaches you to make the match in one tour.
01Read the panel like a landlord hopes you won't
Three questions settle a bay's electrical reality: What's the main? (100A is tight for real equipment; 200A runs most single-trade shops comfortably.) Is 240V single-phase there, and how many spare two-pole slots? (Each big machine wants its own.) Is three-phase in the building?, not “available from the utility,” in the building. The difference is a $0 answer versus a five-figure, multi-month answer.
02The load math, on one napkin
The metal plate on each machine states volts and amps. Write them all down, including the compressor, the heater, and the chargers everyone forgets.
You don't need capacity for every machine simultaneously, you need it for your worst real hour: compressor kicking in while the welder's running and the heat's on. That combination is your planning load.
Continuous loads should sit at or under 80% of breaker rating, it's how electricians size circuits and how you should size a bay. A 200A panel is realistically a 160A working budget.
The second lift, the bigger compressor, the mini-split you'll add the first July. If today's list already fills the panel, the bay is too small electrically, whatever the square footage says.
03Three-phase, translated
Three-phase power delivers current in three overlapping waves instead of one, motors run smoother, bigger machines become possible, and heavy equipment is often only sold in three-phase versions. The honest guidance: most detailers, contractors, gyms, and e-commerce operations never need it. Fabricators, machine shops, and anyone buying serious used industrial equipment (the auction bargains are disproportionately three-phase) should treat it as a hard requirement. If you're borderline, a rotary phase converter can run one three-phase machine in a single-phase bay for a few thousand dollars, a fine bridge, a poor foundation.
Panel capacity, service voltage, and phase are building infrastructure, the landlord's domain. Ask before signing and get it in writing, because “we can always add power” costs $5,000 to 15,000+ and months when it means a service upgrade. Ask the Welcome Team for the panel, voltage and phase of the exact bay before you sign, and if your machine list won't fit a bay, we'll tell you which of ours it will fit.
“Ask what the panel holds before you ask what the rent costs.”
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Request received.Power is chapter one of the build conversation, chapters two and three are what the rest of the fit-out costs and what your trade specifically needs.
