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	Subject - 3 phase voltages beaverbazz Hello all: I was trouble shooting a 3-phase system at the breaker box and the power coming in struck me as odd... A phase 120V B phase 240V C phase 120V Shouldn't all of the phases match? What could be the problem? What steps to correct? Also, how are 3-phase motors continuing to run on voltages such as the above? Thanks for your help. Ryan_J It looks like you have a high leg delta. JimmyDee You need to measure the voltage from phase to phase. A - B, A -C, and B - C. I'll bet you will see 240 volts because it is an open delta system. What you found is just about right except your 240 volt reading is probably closer to 208. Jim kbsparky Those measurements are to ground and as such are irrelevant to what a 3-phase motor would require. IF you measure the voltages between phases, I'd be willing to bet the farm you will find that they all show 240 Volts nominal. And, as the others have pointed out, your "B" phase is referred to as a high-leg delta, with its nominal voltage to ground being 208. Use a digital or accurate analog meter to verify those voltages. A solenoid type tester, such as a Wiggy or Vol-Con can not tell much difference between a 208 and a 240 reading.