Additional details on my switch The switch is a Leviton T5225. The cord I am using has a grounded plug, with the green wire leading to the ground plug, and the black and white wires going to the other two blades on the plug.

Looking at the front of the plug, black wire goes to the the screw on the left side at the switch side switch end. The white wire goes to the screw on the right side at the plug end. The green wire goes to the ground on at the switch end that is green.

As I said when I tested it with a 40 watt bulb, it blew the Ground Fault interrupter on the circuit.

The cord is new and has been used before. The light bulb was in a light I use a flexible unit I use on the work bench.

Leviton 5225-W

Does it make a difference if the wide prong and the narrow plug get reversed in the circuit.

Of course it does. The larger prong is Common or white wire that runs back to Ground, while smaller prong is Hot. I would certainly think a reversal would mess up a GFI.

So, you have a single garage circuit that runs both lights and outlets? One would hope that you had AT LEAST two circuits and it would have been better that the outlets be on 12 gauge wire with 20 amp breaker. Also better to get a 20 amp toggle switch that you could mount on the saw's front panel by drilling a hole in panel.

I found the instruction were not clear as to where to put the two wires. On the Leviton combination plug the black and white wires are placed on the same side opposite side from the ground wire. It is not clear exactly how the wires are connected in the diagrams on the box. Interpreting I had connected the wires such that when the switch was thrown, it created a dead short.