1.0 Introduction: The Confession of a DIY Enthusiast

I’ve posted over 50 DIY electrical videos online, and I’ve read thousands of comments from viewers. Sometimes, that feedback is pointing out something I got wrong. There’s a unique satisfaction that comes from tackling electrical work yourself, but experience doesn’t grant you immunity from mistakes. In fact, some of my most valuable lessons came from the things I got wrong.

This isn’t a story of failure, but a story of learning the hard way. The purpose of this article is to share five critical lessons I’ve learned from my own mistakes. By understanding where I went wrong, you can approach your next project more safely, confidently, and effectively, ensuring the job is done right the first time.

2.0 Five Hard-Won Lessons in Electrical Safety

2.1 Mistake #1: The Hidden Danger of Mismatched Wires

Early on, I made the mistake of mixing 12-gauge and 14-gauge wire on the same electrical circuit. I was adding a basement light and had some spare 14-gauge wire, so I used it to connect to an existing box that was wired with 12-gauge.

The rule is simple and absolute: 14-gauge wire is for 15-amp circuits, and 12-gauge wire is for 20-amp circuits. In my case, the circuit happened to have a 15-amp breaker, making it technically functional. But ‘technically functional’ isn’t the same as ‘safe’ or ‘correct.’ This is a classic DIY trap: solving an immediate problem while creating a hidden, long-term danger. If anyone (including a future me) were to see the 12-gauge wire at the breaker and swap it for a 20-amp breaker, that undersized 14-gauge wire would become a dangerous fire risk.

“when you start mixing 12 and 14 that’s very confusing for anybody coming after you doing work whether that’s repairing or maintenance or adding to that circuit.”

2.2 Mistake #2: Installing a Light Where a Fan Might Go

In a room with no overhead lighting, I decided to add a new ceiling light by tapping into a switched outlet. To mount the new fixture, I used a simple electrical box held in place by a bracket that tightens against the back of the drywall. It was quick and easy.

The problem is that these boxes have very low weight ratings, often between 10 and 15 pounds. While that was fine for my lightweight fixture, I failed to think about the future. What if the next homeowner wanted to replace that light with a ceiling fan? A standard fan far exceeds the weight limit and produces vibrations that could easily rip that box out of the ceiling. The correct solution is to use a fan-rated adjustable bracket. You push it up through the hole in the drywall, and then twist it to expand. The ends extend out and ‘bite’ into the ceiling joists, creating an incredibly strong anchor for any future fixture, no matter the weight. It’s a crucial step in future-proofing your work and keeping the next family safe.

2.3 Mistake #3: Assuming Your Wire Connections Are Solid

There have been a few times I’ve installed a fixture only to find later that a wire had come loose inside the wire nut. This is especially common with stranded wire, which can slip out if not perfectly secured. A loose connection isn’t just an annoyance that makes a light stop working; it can create dangerous electrical arcing inside the box.

The solution is two-fold. First, if you use traditional wire nuts, you must perform a “pull test” on every single wire after tightening the nut to confirm it’s securely held. Second, a far better option for most DIYers is to upgrade to Wago-style lever nuts. With these connectors, you strip your wires, insert them until they are fully seated, and snap the levers down. The connection is secure, easy to verify, and removes the guesswork.

“…this is by far a better way for di wires and honestly i’ve never heard of somebody that tried out these wagos and they were not pleasantly surprised”

A pro tip: Wago makes different sizes. I prefer the 413 series for most household wiring (up to 12-gauge) because their smaller profile fits more easily into crowded electrical boxes. For a great starting point, look for a starter kit with a variety of the two, three, and five-port connectors.

2.4 Mistake #4: Forgetting One Tiny Wire in a Metal Box

While installing a metal junction box in my attic, I connected all the circuit wires, closed it up, and moved on. My critical error was forgetting to bond the box itself to the ground wire using a grounding screw and a short “pigtail” wire.

This is a life-threatening mistake. Unlike a plastic box, a metal box is conductive. If a hot wire ever came loose and touched the inside of that ungrounded box, the entire box would become energized. Anyone who touched it would provide a path for the electricity to go to the ground, resulting in a severe shock. When properly grounded, that same loose wire creates an immediate, massive surge of current that flows safely to ground, tripping the breaker in a fraction of a second and neutralizing the threat before anyone can get hurt.

“…if the hot conductor were too short on a metal box now the metal box turns into your hot conductor if you or somebody else comes along and touches that box now you are providing the path back to source and then you could get injured or even worse”

2.5 Mistake #5: Blindly Trusting Your Voltage Tester

A non-contact voltage tester is an indispensable tool, but I got in trouble in the past using an older model, the Klein NCVT-3. The problem with this tool is that if the batteries die, it gives no signal—the exact same indication as a de-energized, safe-to-touch wire. This can create a deadly sense of false security.

Because of this, I now exclusively use the newer Klein NCVT-3P model. The critical difference is that the “3P” has a constant green “power-on” light, giving you a strong, clear indicator that the tool has power and is ready to detect voltage. This simple feature solves the dangerous ambiguity of the older model.

Regardless of which tester you use, you must adopt this non-negotiable best practice every single time:

1. Test the tool on a known live circuit (like a nearby outlet) to confirm it beeps and lights up.

2. Test the circuit you are about to work on.

3. Test the tool one last time on the known live circuit to ensure the batteries didn’t die during your test.

This three-step process is the only way to be 100% confident that a “no voltage” reading is accurate.

3.0 Conclusion: Stay Curious, Stay Cautious

Electrical work demands respect, and safety is an ongoing learning process. No matter how many projects you complete, humility is your most important tool. By learning from the mistakes of others—and your own—you can ensure that every project you tackle not only improves your home but also keeps everyone in it safe.

Now that you’ve seen what can go wrong, what’s one safety step you’ll never skip on a project again? Jump down in the comments and let me know what mistakes you’ve made. Let’s all learn from each other and make our homes safer, one project at a time.