I'm installing some lighting on the outside of my garage. It seems pretty
straightforward, but I've got a question regarding the electrical boxes...

I'm using "pancake" boxes. I knockout one of the holes in the back of the
box. Then I hold it up where I want it mounted and mark the wall. I take it
down and drill my hole. Put it back up and screw into place. Pull the wire
through.

How do I clamp the wire so it doesn't pull out of the box? I know that there
are clips that can be put into place, but the sheathing of the garage wall
precludes my using them. I guess I could put the clip in backwards, but they
are wider than the pancake box is high.

Do I just leave the wire loose and depend on the "staple" inside the garage
to hold the wire?

Just want to be sure that this will meet code here in Calgary. Don't want to
fail my inspection.

Thanks!