Has anyone ever had a close call after trusting a utility company?

Stop reading this and get yourself to an emergency room imediately. Seriously. Getting knocked out for twenty minutes and experiencing a flash like that means a massive amount of current went thru you. You can feel fine now, but **cardiac arrhythmia** can kick in hours after the initial shock once your electrolyte balance shifts. Don't risk a heart attack tonight just becasue you think you're over the worst of it. I had a similar run-in years ago on a commercial renovation where we had the main disconnect pulled and locked out. The utility company swore the site was cold. I was Sawzalling through a partition wall when I hit a 277v line that someone had illegally tapped from the neighboring suite to run a server rack. The spark was enugh to weld the blade to the stud. It’s a brutal reminder that a cold panel doesn't mean a cold building, especially in older structures where DIY additions or creative wiring are buried in the walls. Whenever I'm doing demo now, I treat every single wire as live regardless of what the meter or the utility says. If you're going into a wall, use a **non-contact voltage tester** on every single piece of Romex or conduit you see before you even think about putting a tool to it. And don't just rely on the beep; check it against a known live outlet first to make sure the batteries aren't dying. If the tester doesn't light up, I still check it with a multimeter if I can get to the leads. You also need to watch out for **back-feeding** from things like solar arrays or even certain types of UPS backups. If the utility shuts off the grid but there’s a battery bank or a generator that didn’t trip its transfer switch properly, you’re still working on a live system. It's rare, but clearly, rare happened to you today. Get your heart checked out and buy a lottery ticket once they discharge you.

Man, that is terrifying. I’m just starting out with some basic DIY and I honestly thought flipping the main breaker meant the whole house was a safe zone. I didn’t even know illegal taps from neighbors were a real thing—does that actualy happen in residential neighborhoods too, or is it mostly just an old commercial building problem?

Also, for a total newbie, how do you even tell the difference between a wire that's truly dead and one that’s just not triggering the tester correctly? After reading this, I feel like I'd be too scared to even touch a wall with a hammer.

To the guy asking about residential—yeah, it absolutely happens in houses, expecially older duplexes or places with unpermitted basement suites. But what's more common and just as dangerous is a shared neutral. You might trip the breaker for the circuit you're working on, but if it’s a multi-wire branch circuit, that neutral wire can still be carrying current from a completly diferent load. I always use a clamp meter to check for current, not just a voltage probe. It only takes one 'creative' DIY job from a previous owner to turn a simple demo into a funeral. Glad you're still with us, OP.

Glad you're still upright, man. That 20-minute gap is terrifying. One thing to watch for in older houses is buried 'Knob and Tube' wiring hidden behind newer Romex. I’ve seen demo jobs where the modern stuff was dead, but an active K&T line was tucked way back under blown-in insulation or behind a header. Those old ceramic insulators get brittle and snap, leaving live copper just sitting there. I always run my NCVT again once the drywall is down and I can actualy see what’s inside the bays.

Check if your property has a second service drop you didn't notice. I’ve seen older lots where the house has one meter, but a detached garage or a well pump has its own separate drop and meter from the utility pole. If the tech only pulled the 'main' house meter, that second line is still fully energized and could be cross-connected somewhere in the framing. Also, check for any "pigtails" coming off the service side of the main lug. Some DIYers bypass the main breaker for things like exterior security lighting or alarms so they stay on even if the house power is cut. If you're demoing the back panel, those bypasses are a total deathtrap becuase they're live even when the main switch is off.