[1]: 287 A bootleg ground connects the neutral side of the receptacle to the conductive casing of an appliance or lamp.
[2] Before 1996, in the United States it was common to ground the frames of large 120/240-volt permanently-connected appliances (such as a clothes dryer or oven) to neutral conductors.
In the less-dangerous instance of a bootleg ground, a short wire jumper is connected between the bonding screw terminal (usually colored green) on a NEMA 5-15R or 5-20R outlet to the neutral (a.k.a.
This practice is a NEC code violation, but a standard 3-lamp receptacle tester will report the outlet as correctly wired.
This hazardous connection allows people to come into contact with a deadly voltage with a current path back to the source[2] (the power transformer) that will not trip either a normal circuit breaker, a GFCI, nor an AFCI quickly enough to prevent electrocution.