: An electric dryer cannot have reverse polarity and still work, (and not blow the breaker when the dryer is plugged in). And its outlet cannot be tested with that device. A standard outlet, such as for your washing machine, can have reverse polarity, (meaning the black and white wires are connected to the wrong sides of the outlet), and still operate. The problem would be if the white, neutral, connection in the unit was also connected or shorted to the ground somewhere but the outlet did not have the third, ground terminal in it, in which case the shell of the appliance would become electrified and could cause a shock or death. If the outlet did have the third terminal and this were to happen, then the circuit breaker would trip as soon as the appliance was plugged in. So, if it is really an electric dryer and it works you have no problem. If it is a gas dryer and the wall plug has reverse polarity, use it until your electrician can get it fixed. If the power is on, however, many inspectors use a device similar to yours to check polarity in the wall outlets, and if yours did so, I would doubt that the condition exists.

: : A friend tested the outlet where my electric dryer is plugged into and found out the outlet has reverse polarity. He used one of the yellow testers with the lights on the end. What does reverse polarity mean? This was something missed by the home inspector when I bought the house. Is it safe to use the dryer until I call the electrician? How big a job is it to fix? Sorry to ask this here on Terry Love's plumbing website, but plumbers do know something about electricity don't they? Plumbers know something about everything, don't they? Love this web site. Gotta have a sense of humor in life. Thanks in advance.