The call was supposed to be simple. Kitchen remodel, homeowner wanted two new dedicated circuits for a coffee setup and an island, and the GC asked me to “just check the existing outlets while you’re in there.” I almost didn’t. The homeowner had already run a tester on every receptacle in the house — one of those $8 three-light plug-in jobs — and proudly told me they all read “correct.”

They didn’t read correct. They read the same, which is a different thing, and on this house the same was wrong everywhere.

What the tester said

Three-light testers work by checking which slots have voltage relative to each other. Hot-to-neutral, hot-to-ground. If it sees voltage on the ground slot referenced to hot, it lights the “correct” pattern and calls it a day.

Here’s what it cannot do: tell you where that ground voltage is coming from. It assumes the ground slot is tied to an actual equipment grounding conductor running back to the panel. It has no way to know if some genius jumpered the ground screw to the neutral screw right there in the box.

That’s exactly what someone had done. Every receptacle in the original part of the house — 1983 construction, two-wire NM with no ground pulled to the device boxes — had a little jumper between the neutral terminal and the ground terminal. Bootleg ground. The tester saw voltage on the ground pin, lit three ambers, and the homeowner slept fine for two decades.

Why a bootleg ground is worse than no ground

A two-prong outlet with no ground is honest. It tells you what you’ve got. You know not to plug a grounded appliance into it without thinking, and a tester reads “open ground” so the next person knows too.

A bootleg ground lies to everyone downstream, and it’s genuinely dangerous in a way an open ground isn’t. Here’s the failure mode that matters:

The ground pin is now tied to the neutral. Under normal load, the neutral is a current-carrying conductor — it’s got voltage drop across it relative to true ground. So the chassis of anything you plug in is sitting a few volts above ground all the time. Annoying, not deadly.

But open that neutral somewhere upstream — a backed-out wire nut, a loose terminal, corrosion in a 40-year-old box — and the full circuit voltage now appears on the neutral and therefore on the ground pin, because they’re jumpered. The grounded chassis of your toaster, your fridge, your kid’s game console is now sitting at 120 volts to earth, waiting for someone to touch it and a pipe at the same time. The bootleg ground took the one conductor that’s supposed to be your safety path and wired it to the one conductor most likely to go live.

“It tested fine” is how that house ran for twenty years. It tested fine right up until it wouldn’t have.

How to actually catch it

The three-light tester isn’t useless, but it’s a screening tool, not a verdict. When I want to know if a ground is real:

• Pull the device. Two minutes. If you see a jumper from neutral to ground, or a ground screw landed on the neutral bar bootleg-style, you’re done — it’s fake.
• Check the wiring method. Two-wire NM (no bare or green conductor in the cable) feeding a three-prong receptacle is a tell. The ground had to come from somewhere, and if there’s no EGC in the cable, it came from a jumper.
• Use a tester that measures ground impedance, not just presence of voltage. A real equipment ground is a low-impedance path back to the panel; a bootleg ground through the neutral reads differently under load. The plug-in “SureTest”-style testers that load the circuit will flag it where a three-light won’t.
• When in doubt, ohm it out with the circuit dead — ground pin to a known good ground. A real EGC is near zero. A bootleg path tells on itself.

How we fixed it

You can’t make a bootleg ground legal by feeling bad about it. Two real options under the code:

1. Pull an equipment grounding conductor to the boxes — the right fix, and we did it on the kitchen circuits we were already opening up.
2. GFCI protection on the rest, labeled “GFCI Protected, No Equipment Ground” per the code. A GFCI doesn’t need a ground to protect people — it watches for current leaving on the hot and not coming back on the neutral — so it’s the legitimate retrofit for ungrounded circuits. What it is not is permission to leave the bootleg jumpers in. We removed every one of them. A GFCI on a bootleg ground is still a bootleg ground; you’ve just added a device that may or may not catch the fault the jumper creates.

The homeowner asked me why an inspector hadn’t caught it back in ‘83. Maybe they did and it got “fixed” with a jumper after. Maybe nobody pulled a device. Doesn’t matter now. The lesson isn’t about that inspector — it’s that a tester told everyone what they wanted to hear for twenty years, and the wiring didn’t care what the tester said.

That’s not to code. That’s to luck. And luck on a grounding fault runs out the day a neutral lets go.

— Mike