What?!
I think the earth IS used as part of the circuit. Isn't that why electricians use the term "ground"?
You have a hot wire, and a ground wire....and don't give me that crap about the ground being the third prong either. That's not the ground I'm talking about.
Sorry, I stand by my statement. The earth is ground, but it is not a good conductor. The power companies keep one of their lines used for the return path close to ground (except for three phase delta circuit which uses no ground, including no earth ground. They do this by grounding a line at power poles and at user homes. But this ground is NOT used for the carrying of normal metered power.
Electricians use the term ground for the line that is kept at ground potential, and in a three prong circuit, the "ground" prong is connected to a water pipe, Etc but this "ground" circuit is for safety not carring power. Would you normally suspect that a pair of rods hammered into the ground and separated several feet would be as good a conductor of current as a copper wire? Dirt, even wet does not conduct as well as copper. Sea water even with its salt ions does not conduct as well as copper wire.
Best idea is to do a test. Take a motor and run one wire of the motor to the hot line of a plug, put the other into a good ground. (copper rod hammered four feet into soil). Now try the switch. Since the power is "grounded" to a ground in the house, the saw should run right? It won't even humm.