Because the neutral wires carry electricity, creating a bootleg ground makes it possible for the metal housing of something that is plugged into the receptacle to become electrified. Additionally, a GFCI breaker will not trip in the event of a fault condition to a bootleg ground, nor will it protect a receptacle wired from the load side of a GFCI receptacle.
Bootleg grounds are typically found in homes that have outdated electrical systems that do not have a grounding wire. Typically this is homes that were built before the 1960s and that have not had their electrical systems updated. These homes will have been originally built with ungrounded, 2-prong receptacles. Some homeowners or contractors, especially flippers, when replacing the outdated receptacles with modern 3-prong receptacles will create a bootleg ground to give the new receptacle the appearance of being properly wired. Unfortunately, traditional outlet testers will show a receptacle with a bootleg ground as being wired correctly.
A reversed-polarity bootleg ground is when the ground is connected to the current-carrying hot wire. This will place low-impedance live voltage on all grounded parts of all equipment plugged into that outlet. This condition is extremely likely to result in electrical shock and even electrocution. Receptacles that are wired like this need to be re-wired by a qualified electrical contractor.
If you have a home that was built before the 1960s, the electrical panel looks old but you have 3-prong receptacles, it may indicate that the receptacles were replaced improperly. We recommend testing for bootleg grounds in your home.
There are two ways to check for bootleg grounds. A tester can be purchased that is able to detect this fault. These testers are expensive and typically cost around $300. The other option is to turn off power to the circuit and to visually inspect the wiring at the back of the receptacle. This is typically not something that a homeowner would feel comfortable doing.
Please note that home inspectors are not required to disassemble outlets nor test for bootleg grounds according to state law in Oregon or Washington. At their own discretion, inspectors may use specialized equipment that can test for the presence of bootleg grounds.
You can find more information about this condition in the following video: