Install Surface Mounted Wiring and Electric Conduit (DIY)
Step 1
Plan for power
Before you buy a single stick of conduit or measure for your new bench or workspace, work out a plan. Will you be running power-hungry tools like circular saws, routers or table saws? Tap into an existing 20-amp circuit, or add one at your electrical panel.
For LED lamps or light-duty tools, a 15-amp circuit should suffice. Check the circuit breaker in the main electrical panel to determine your circuit sizes. If you’re uncertain, consult a licensed electrician.
For this project, we tapped in to a 15-amp garage outlet to power our light duty workbench area. This circuit will handle lights and other continuous loads, as well as tools and other temporarily running devices. For safety, limit the electrical load on a 15-amp circuit to 1,440 watts (12 amps), and 1,920 watts (16 amps) for a 20-amp circuit.
We’re using 14-gauge THHN electrical conductors (wires). (For 20-amp circuits, go with 12-gauge wire.) You’ll need a black hot wire, white neutral wire and green ground wire, aka an equipment grounding conductor.
The EMT can serve as the equipment ground, but I recommend pulling a separate wire to be absolutely sure you have a continuous path back to the panel in the event of a short circuit or ground fault.
The metal EMT can serve as the equipment grounding conductor, but I recommend pulling a separate green wire to be absolutely sure you have a continuous electrical path back to the panel in the event of a dangerous ground-fault occurrence.
Step 2
Lay out your run
Sketch the electric conduit route from your power source to the new electrical box locations. Use a pencil and paper, a software program or just mark the wall with painter’s tape to visualize the layout of your new design.
Start from the power source (in our case, the wall receptacle) and mark where your new boxes will go. Unless you’re a skilled conduit bender, minimize bends as much as you can.
When you have the basic layout, grab a measuring tape and figure out how much conduit and wire you’ll need to buy. Measure between boxes, including the vertical rise, and add several feet to your final total so you have plenty to work with.
Buy an extra stick or two of EMT in case you mess up, and make sure you have enough excess wire length to leave six inches in every box. I like to leave eight inches or so and cut it off.
In addition to the EMT and electrical boxes, you’ll need set screw connectors to secure the EMT to the boxes, straps or hangers to hold the conduit to the wall, and couplings to connect longer runs. And, of course, various hardware and hand tools.
When you calculate the length of your run, also count the number of fittings, boxes, receptacles and industrial box covers needed for your project.
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