In the course of fixing up houses, I’ve seen a lot of wiring mistakes. Common mistakes like reverse polarity or a missing ground will cause the house to not pass inspection, but a bootleg ground is a bigger problem. It’s dangerous, and many building inspectors won’t catch it.
Here’s what a bootleg ground is, why it’s dangerous and you shouldn’t do it, and what you should do instead.
What a bootleg ground is
I won’t show you how to do it, but a bootleg ground, or false ground, is connecting the ground wire in an electrical receptacle or outlet to the neutral or white wire. People do this to avoid open grounds and to allow them to use a three-prong connector in a three-prong receptacle without calling in an electrician. This setup will show on most electrical testers as a valid ground, even though it isn’t.
The thinking behind a bootleg ground is that since ground and neutral are tied together at the electrical service panel, it’s OK to tie them together at the outlet. At least that’s the justification you hear when people try to justify it. But it’s not OK. Neutrals and grounds aren’t the same thing. Tying them together at the panel allows circuit breakers to work properly and trip in the event of a ground fault.
In fact, the practice of using neutrals and grounds interchangeably is illegal and the National Electrical Code forbids it. Here’s why.
Why a bootleg ground is dangerous
There are two problems with creating a bootleg ground. The first problem is that the white wire can carry electrical current. When current flow is working properly, electrical current flows from the service panel to your outlet over the black wire, then through your device, then back to the outlet and back to the service panel via the neutral wire.
One purpose of the ground is to protect you in the event of a metal case in an electrical appliance getting energized. Grounding the case keeps you from getting shocked. But if the outlet is grounded to neutral, you don’t get the protection. Instead, the incorrectly grounded outlet increases the chances that the case might get energized.
The second problem with a bootleg ground is that if you have GFCI outlets on your circuit, the bootleg ground can interfere and keep them from working properly.
So the problem really is pretty simple. A ground is designed partially to protect you from electrical shock. Abuse it, and you greatly increase your chance of electrical shock.
How to check for a bootleg ground
To check for a bootleg or false ground, open the outlet and take out the receptacle. The ground screw terminal should connect to a bare or green wire. By convention, the grounded conductor are always be green or bare. If you find the ground screw connected to the white neutral wire or the neutral screw in some way, it’s a bootleg ground.
The correct way to wire an outlet is to put the black wire on the brass screws, the white neutral wire on the white metal screws, and the green or bare wire on the green ground screw on the frame. There is one exception that you sometimes see in older houses. If the outlet box itself is made of metal and grounded, you can leave the ground screw unconnected and let the outlet pick up ground from the outlet itself.
Note that checking for a bootleg ground is beyond the scope of normal home inspections. Some home inspectors get suspicious if they see telltale signs and spot check a couple of outlets. But don’t count on it.
The most likely telltale sign is the presence of one and only one three-prong outlet in a bedroom. Most people who set up bootleg grounds don’t seem to go to the trouble to do all of them. I also once had a house that had three-prong outlets in one bedroom but none of the others. When I checked those outlets, they all turned out to be bootleg grounds.
What to do instead of a bootleg ground
The easiest alternative is to connect a GFCI receptacle to an ungrounded outlet and put stickers on the plate saying “GFCI protected” and “No equipment ground.” The GFCI receptacle comes with these stickers when you buy one. The National Electrical Code and most local codes allow this practice.
In this case, in the event of a ground fault, the GFCI can trip and protect you. It provides minimal protection for the device plugged into the outlet. But it at least stops electrical current from flowing to a nearby human being.
If you need a properly grounded three-prong outlet, it’s usually best to call in an electrician. The cost to run new wire to a small number of outlets usually isn’t very high. There are ways to ground an outlet yourself. The traditional way is to run a wire from the nearest cold water pipe and fish it into the outlet. This worked well when we could count on water supply lines being metal, but today they often are plastic. For this reason, this and all of the other shortcuts I’ve seen violate the National Electrical Code, so you have to assume they probably violate your local code as well.