Reverse Polarity in Electrical Outlets

This photo illustrates an electrical problem which is not discernible with the naked eye. During an inspection in Aurora Colorado, my company, Magpie Property Inspections, discovered this issue with the wiring in a home.  A circuit analyzer or other suitable device can be used to check circuits and wiring for a number of potential problems. In this case, having one green bar and the center red bar lighted on the device indicates that the wiring to this outlet is incorrect; the neutral and the ungrounded or “hot” conductors have been likely installed on the wrong poles in the outlet. This condition is know as “reverse polarity.” This can often happen when amateurs or non professionals attempt electrical repair or installation in a home.

In  a standard outlet, the ungrounded conductor, or hot wire side enters the electrical appliance and the neutral is connected to the opposite end of the appliance’s electrical circuitry. What happens when the polarity is reversed in an outlet when an appliance is plugged in, is that the appliance circuitry is electrically charged all the time, but only functional when a switch closes the neutral wire connection and the current begins flowing.

 To further explain using a toaster as an example; if the appliance is plugged into an outlet with reverse polarity, the heating element wires in a toaster would shock you if you were to stick a knife in the toaster  to help remove a piece of toast.  Another example; the metal shell of the light bulb socket in a lamp would cause a shock if touched when the polarity is reversed when off. Both of them are harmless if the wiring in an outlet is correct. Although reversed polarity is usually caused by incorrect connections at the receptacle, it can also be due to wiring reversal in the electric panel or at wire connections between the panel and the receptacle. If you discover a situation similar to one of these examples in your home, have your wiring and outlets evaluated by a qualified electrician to have it corrected to ensure the safety of  the occupants of your home.