Real Power Out To Your Shop

Sizing the feed instead of guessing

The first question is what actually runs at the same time. A woodworking shop with a table saw, a dust collector, and lighting has a very different profile than a garage with a welder, a compressor, and a car lift. We do a load calculation from the equipment nameplates and the way you work, then size the feeder to that. Sixty amps handles a lot of home shops. A hundred amps is the common answer when a welder, a mini split, and future equipment are in the picture.

The other half of that conversation is the house panel. Feeding a shop pulls from the same service that runs the air conditioner and the range, so we check whether the existing service has the capacity before promising anything. On the older 100 amp services in Richland and central Kennewick, adding a real shop feed often means the service upgrade comes first. We say that at the estimate, with the number attached, so you can plan the project as a whole instead of in surprises.

Detached buildings play by different rules

A detached shop is treated as a separate structure, and NEC 250.32 requires its own grounding electrode system, normally ground rods driven at the building. The feeder runs four wires, two ungrounded conductors plus a neutral and an equipment grounding conductor, and the neutral and ground bars in that subpanel stay separated. This is the single most common mistake we find in owner-installed shop panels, and a bonded neutral out there puts current on the ground path where it does not belong.

The building also needs a disconnecting means, so power to the whole structure can be killed at the shop rather than only back at the house. Underground work follows NEC Table 300.5, which sets 18 inches of cover for PVC conduit and 24 inches for direct-buried cable. In this soil, trenching is usually straightforward, but we walk the route for sprinkler lines, septic, and the gas service before a shovel goes in the ground.

Outlets and lighting built around the work

Receptacle placement should follow the bench, not the wall studs. We put duplex outlets at bench height every few feet along the work wall so nothing gets daisy-chained through a power strip, and we split them across circuits so a saw and a shop vac are not fighting each other. Dedicated circuits go to the compressor and the dust collector, because both draw hard on startup and both are the reason the lights blink. Welders and plasma cutters get their own 240 volt circuits sized to the machine's nameplate.

Lighting is where a shop stops feeling like a garage. LED strips or high bays laid out in rows, positioned so the fixtures are not directly behind you at the bench, remove the shadow problem that a single center fixture creates. Cold weather rating matters for an unheated building in January. So does GFCI protection, which NEC 210.8 requires for 125 volt receptacles in garages and accessory buildings, and a freezer out there wants its own arrangement so a nuisance trip does not cost you a season of meat.

Leaving room for what comes next

Almost nobody adds shop power once. The second call is usually a mini split, because a Tri-Cities shop hits well past 100 degrees in July and becomes unusable, and after that it is an EV charger, a heater, or a lift. Every one of those is cheap to plan for and expensive to retrofit. Running a slightly larger feeder and leaving spaces open in the subpanel costs very little at install time and saves a second trench later.

That is the conversation Kyle would rather have at the estimate. Tell us what you might do out there in the next five years, even if it is a maybe. We will size the feeder and the panel with that headroom in mind and tell you plainly what the extra capacity costs today versus what adding it later would run. If the honest answer is that you do not need the bigger feed, that is what you will hear.