Quite simply, reverse polarity means that the wires in an electrical receptacle were installed incorrectly. A receptacle with reverse polarity will have the white (neutral) wire screwed to the hot side (copper screw) and the black (hot) wire screwed to the neutral side (silver screw). The bare or green wire should be connected to the green ground screw on the receptacle.
A home inspector will flag any outlets that are reversed polarity. Why should you be concerned about reversed polarity? Most electrical appliances and devices are designed so that the on/off switch interrupts electrical power at the point of entry into the appliance, device circuitry or components. If the hot and neutral wires are reversed, then it is possible that the device could be energized even if the switch is turned off. Reversed polarity on an electrical outlet should be considered an unsafe condition, as the risks include damage to the appliance, short circuit, shock or fire.
How Can I Tell if My Receptacles Have Reverse Polarity?
You can purchase a plug-in type voltage tester at your local hardware store. These are generally inexpensive. The tester will include a chart that will tell you which lights should illuminate when you plug it in to a properly wired outlet. The chart will also indicate what the other lighting combinations mean, such as an open ground condition.
How Do I Fix Reverse Polarity?
Once you find a receptacle with reversed polarity, leave the plug-in tester plugged into the receptacle and find the circuit breaker that is delivering the voltage to that line. Turn the breaker OFF. When you return to the receptacle there should be no lights lit up on the tester. If there are, then you turned off the wrong breaker. Try again.
With the power to that circuit OFF, remove the cover plate and the two screws holding the receptacle to the wall box. Gently pull the receptacle out of the box. If there are any other wires inside the box, use a touch-style voltage tester to ensure that they are also OFF. If they are hot, find the circuit breaker feeding them and turn it OFF as well.
Inspect your receptacle. A receptacle with reversed polarity will have the white (neutral) wire screwed to the hot side (copper screw) and the black (hot) wire screwed to the neutral side (silver screw). The bare or green wire should be connected to the green ground screw on the receptacle. Simply remove the white and black wires and connect them to their properly intended sides of the receptacle. To wire it properly, the black gets connected to the dark or copper-colored screw and the white wire gets connected to the silver screw. If the wire looks brittle or damaged, use wire strippers to cut the old wire away and strip off a 3/4-inch fresh section of insulation. Wrap a strip of electrical tape around the screw terminals for added safety, resecure the receptacle to the wall box and attach the cover plate.
Finally, plug the voltage tester in to the receptacle and then turn the circuit breakers back on. When you get back to the receptacle, the tester should indicate proper wiring. If, for whatever reason it still reads reverse polarity, then the problem may be in another receptacle or in a junction box somewhere. In that case, your best bet would then be to call a licensed electrician.
By Jon McCreath, NPI Franchise Owner, Emerson, Georgia