Step 2: I fastened my box in place. Used the 3/4” knock out and placed a 3/4” threaded wire clamp, and stripped the excess jacket off the wires. The L6-30 receptacle uses the 2 hot wires but does not use the neutral, so I capped the neutral wire with a wire nut and tucked it into the back of the box. Because the box is metal, you need to ground the box. I created a loop and used a grounding screw to ground the box.