Garage Wiring Basics
These days, we ask more of our garages than ever before, and we need to equip them to provide the power we need to run all of our tools and gadgets. An outlet or two here and there isn't going to cut it. Too many power tools and specialized equipment can easily overload a poorly planned electrical system, which can lead to hazardous conditions such as an electrical fire.
First and foremost, determine what activities you plan to do in the garage that will require power. If the space is simply for parking cars or storage, then a few standard outlets will be enough. Most attached garages for homes built in the past couple of decades have adequate wiring and enough outlets to handle these needs. An unattached, newly built garage, or renovation of an existing freestanding garage without power, will require its own separate system.
If you're planning on adding a water heater, installing laundry appliances, or doing woodworking or heavy auto work, you'll need to make sure you allow for the proper wiring of the equipment. Many appliances, such as water heaters and clothes dryers, require a circuit voltage of 240 volts. So does some heavy-duty equipment, such as a cabinet saw (an industrial-level table saw).
If you plan on running a lot of equipment at the same time, it’s best to set up for 240 volts with higher-gauge (thickness) wiring to keep the system from overloading and tripping breakers. At 240 volts, a power tool will draw half as many amps while running as it would at 120 volts. The higher the amp draw, the closer you get to a tripped breaker, and if you're running several tools at once, that could easily happen.
Garages also are prone to moisture: rain blowing in through open doors, water dripping off vehicles, or a water heater or washing machine mishap. Therefore, Ground Fault Circuit Interrupter (GFCI) safety outlets are a must. These are the outlets you find in bathrooms and kitchens that basically prevent you from being electrocuted if you come in contact with water while operating an appliance.
Convenience is another factor for a garage electrical system. Standard outlets are spaced apart, a foot or so above the floor. If you plan on adding workbenches along the walls, you'll also want outlets at the same above-the-counter height as in a kitchen. This way, you won’t have to drop a cord behind the bench top.
For dedicated workstations, you may also want to install a drop cord outlet, which will allow you to plug in tools overhead so you aren’t running cords across the floor. If you’re adding garage door openers, you'll need outlets on the ceiling to power those. These outlets also can be used for installing a retractable power cord reel, which can also double as a drop cord and will give you power access across an entire garage, extending to the driveway if needed. For additional outside access, in mind, install an outlet or two on the outside wall of the garage or inside near the doors.
Keep in mind that when you are renovating or building and the walls are open to bare studs, that’s the best time to do the electrical work. It will be more expensive and time-consuming to come back and add wiring later.