Unless you’re considering doing “unplugged” woodworking using only hand tools, you’re going to want some power in your shop. Even if it’s just for lighting, you need to consider how much power you’re going to need.
Let me stop right here and mention that I am not an electrician. I am comfortable installing breakers and running new circuits. However, I did consult with a licensed electrical contractor and the local code enforcement officials. You should do the same. They can tell you the requirements for cable size and type, breaker sizes, burial depth, and other important information. And certainly, if you feel uncomfortable installing wiring, receptacles, and circuit breakers, please–hire a professional.
What I’m talking about below is the situation where you need to supply power to an outbuilding. If your MiniMax Workshop is in an attached garage or spare bedroom, simple talk to a licensed electrician about options for adding receptacles, if necessary.
Where electrical is required in an outbuilding, there are two solutions for supplying power. One solution is to branch off of the main breaker panel in the house and install a sub-panel in the workshop. This has the advantage of having only one higher-amperage breaker in the main panel to cut off power to the outbuilding when needed. Plus, you can install multiple circuits in the sub-panel inside the shop. This solution definitely requires the services and advice of your electrical contractor and code enforcement official to meet the necessary requirements for breaker sizes and quantity, cable size, and electrical grounding.
The second solution is to install separate breakers in the main breaker panel and run the appropriate sized cable to the workshop. This is the option I chose.
For my MiniMax Workshop, I decided that I could get by with two 20-amp circuits. This would adequately supply the receptacles I wanted to install. Plus, I could branch off of one of those circuits for the lighting.
The problem was, my MiniMax Workshop shed is several feet away from the house. What would be the best method for running these two circuits to the shed? For my situation, the only workable solution was to run the cables underground that connected the breaker box in the house to the shed.
The first step was to apply for an electrical permit. This is required since I’m adding circuits to an existing panel. I had to specify that I was doing the work myself. In some areas, this is not allowed and a licensed electrical contractor must do the work or take responsibility for it.
The next thing you need to do is to call the utility service in your area to mark any underground cables and pipes. In my city, this is a requirement before starting any work that requires digging. The service I used painted the sod and placed flags to mark underground high-voltage wires.
With permit in hand, it was time to get to work.
To run wiring to an outside wall from the main panel, I had to fish cable up into the attic and over a laundry/utility room. The exterior walls of the house are masonry, so I opted to poke through the ceiling and run conduit down to a junction box that would connect to the outside. From there, I had to drill through concrete to connect to an exterior junction box. From the junction box to a narrow trench I dug, I used PVC conduit to protect the cable from weed trimmers and mowers.
For my municipality, I had to dig a trench 18″ (45cm) deep between the house and the shed. The required depth where you live will likely be different.
When I reached the shop building, I again used conduit to run the cable up inside the wall. Then came the task of fishing the underground cable from the shed, along the trench, then up into the internal junction box in the laundry room. Inside, I completed the run using wiring rated for indoor use. Again, check with your code official and electrician for the proper cable to use outdoors and indoors.
Before I covered the cable with soil, I installed “view tubes” or sections of pipe vertically in the trench that stuck above ground. These provided inspection ports for the electrical inspector to verify that the cable was buried at the proper depth. To prevent accidentally cutting into the cable in the future when digging, I also installed a yellow caution tape about 12″ (30cm) above the cable. This way, when a shovel hits the tape, it serves as a warning that there is a cable buried underneath.
Here’s where you may ask, “Why didn’t you run conduit the entire length of the trench?” Underground cable is very stiff and difficult to work with. I had enough trouble fishing it through the short lengths of conduit at the house and shed. The cable I used is rated for burial use without conduit, so it wasn’t an issue.
After this main cable was run, I connected it to the two new breakers in the main panel box. Then it was time to install receptacle boxes and wiring in the MiniMax Workshop. You can read more about that in another post.