Will my described method allow me to achieve my objective? If so, could you recommend a rheostat that is rated for at least 20A @120VAC that will work for my application? If not, could you describe an alternate method? Objective: Determine the ampacity of various wires at 120VAC Method: Wire a rheostat in series to the wire to be tested. Attach this circuit to a power cord and plug it into the wall (120VAC power source). Use a multimeter to measure the current across the wire and adjust the dial of the rheostat until the wire fails. Thanks for reading.