I used the Circle tool and then drew lines from the circle up to where I wanted them to hit the top plate. Then I erased the bit of the circle I didn’t want.
As I said before, I drew the leg in place so I created a triangle between the ground and the points were I want the wire to contact the L-shaped plate. I made that triangle a component so the next bits of geometry wouldn’t stick to it. I measured up from the bottom point to located where I wanted the center of the circle. If you are drawing the center line of the wire like I did, you have to take the radius of the wire into account when locating the circle. The triangle makes it easy to orient the circle tool at the right tilt.
After the circle was placed, I switched to the Line tool to draw the rest of the centerline.
Then erase the top half of the circle and the triangle since it isn’t needed anymore.