Wiring reversal in the distribution box
This reversed connection, known as reversed polarity, transforms the receptacle into a potential shock hazard, even though the appliance may still turn on. This serious wiring error requires immediate correction to prevent injury or damage to sensitive equipment. Reversed polarity can occur when conductors or terminals intended to be "hot" and "neutral" (or positive and negative in DC contexts) are swapped in the final connection. If you are damaging phone cords, radios, or other devices more frequently than you think they should, your problem may be reverse polarity in your electrical receptacle. So, first off, always turn off the power at the breaker before you start poking around any outlets.
Read More