Shop electrical has gotten treated as an afterthought by most hobbyists — a few outlets tapped off the house circuits, maybe an extension cord or two, and then confusion about why breakers keep tripping. As someone who rewired a shop from scratch after years of improvised electrical, I learned what proper planning looks like and what it costs to skip it. Today I’ll walk through the approach that actually works.
The electrical system determines what you can run, how safely you can run it, and whether you’ll spend years dealing with tripped breakers and extension cord tangles. Plan electrical capacity before you need it — retrofitting is expensive and disruptive, and getting it right from the start costs little more than getting it wrong.
Understanding Your Loads
Every power tool has an amperage draw listed on its motor plate. Startup current typically runs 2-3 times the running current. A table saw rated at 15 amps running may pull 35-40 amps at startup. This matters for breaker sizing and wire capacity.
Add up your maximum simultaneous load. The table saw runs while the dust collector runs. The air compressor might kick on. Shop lights stay on. That simultaneous demand determines your service requirement.
A typical home shop with a cabinet saw, dust collector, compressor, and multiple circuits for portable tools needs 60-100 amps of dedicated shop capacity. That means a sub-panel fed from the main panel, not just a few outlets tapped into existing circuits. I’m apparently someone who ran four large tools on a single 20-amp circuit for too long before accepting this reality.
The Sub-Panel Approach
Install a dedicated sub-panel for the shop. This isolates shop electrical issues from the house, provides ample circuit capacity, and positions breakers where you can reach them without walking across the house.
A 100-amp sub-panel provides room for growth. Even if you only need 60 amps today, the additional capacity costs little during initial installation and avoids future panel changes. Run 4-gauge copper or 2-gauge aluminum from the main panel to the sub-panel.
Position the sub-panel at the shop entrance, waist height, with a clear 30-inch access zone in front. You’ll check breakers regularly and need easy access for emergency shutoff.
Circuit Layout Strategy
Fixed machinery gets dedicated circuits. The table saw deserves its own 20-amp circuit minimum, 30-amp for larger cabinet saws. The dust collector gets a dedicated circuit. The air compressor gets a dedicated circuit. This prevents one tool from affecting another and allows appropriate breaker sizing for each load.
General purpose outlets go on shared circuits, but don’t scrimp. Run a dedicated 20-amp circuit for every 3-4 duplex outlets. More circuits means less likelihood of overloading during intense work sessions.
Consider 240-volt circuits for large equipment. Cabinet saws, large dust collectors, and air compressors run more efficiently on 240V. The motors last longer, and you use smaller wire for the same power delivery. Probably should have run 240V for my dust collector from the start — it runs noticeably quieter and cooler now.
Outlet Placement
Outlets at 48 inches above the floor keep cords off the work surface and out of sawdust accumulation. This isn’t residential height, but it’s the right height for a shop. Install outlets every 6 feet around the perimeter minimum.
Ceiling-mounted outlet drops serve island machinery like table saws and assembly tables. The cord runs straight up instead of across the floor — cleaner, safer, and better for the cord over time. These outlets should be on dedicated circuits for their specific machinery.
Floor outlets work for machinery that never moves, but they collect debris and create tripping hazards. Ceiling drops are generally better.
Lighting Circuits
Separate lighting from power tool circuits. When a tool trips a breaker, you don’t want to be standing in the dark next to a blade. Run at least two lighting circuits so half the shop stays lit if one circuit fails.
LED fixtures draw minimal current. A full shop lighting scheme might pull only 2-3 amps total. The safety benefit of isolated lighting circuits justifies the minor additional expense.
Safety Considerations
GFCI protection on all outlets in shops with concrete floors. Concrete is conductive when damp, and the combination of power tools and moisture potential makes GFCI protection essential. Use GFCI breakers rather than GFCI outlets for cleaner installation and easier testing.
Some motors create enough transient current to trigger sensitive GFCIs, causing nuisance trips. In those cases, dedicate non-GFCI circuits for specific machinery while maintaining GFCI protection on general outlets.
Hire a licensed electrician. Shop electrical work involves significant current capacity and specialized requirements. The permit and inspection process ensures the work meets code and protects your insurance coverage.
Future-Proofing
Run conduit instead of individual cables where possible. Conduit allows adding circuits later without opening walls. Pull a few extra wires while the walls are open, even if you don’t connect them immediately. The incremental cost is minimal compared to accessing those spaces later.
Plan for 240V in locations where you might add larger equipment. Even if you’re running 120V equipment today, having the capacity available avoids future rewiring.
The electrical system is the invisible infrastructure that makes everything else work. Build it right once, and it serves for decades.
