Know when to stop.
DIY is useful. Becoming the reason a fire investigator has to take notes is less useful. These are the baseline safety rules behind ChadPDChee.
Use the right level of help
General troubleshooting can help identify likely causes, but it cannot see every condition in your home, vehicle, panel, appliance, or job site. Always follow manufacturer instructions and the rules that apply where you live.
Electrical work
Turn power off at the correct breaker before opening boxes or touching conductors. Verify de-energization with an appropriate tester before relying on a label, switch position, or someone yelling “yep, that should be it.” Do not work inside service equipment, around exposed energized parts, or on systems you are not qualified to service.
Gas, fuel, and combustion
If you smell gas, suspect a fuel leak, see signs of improper combustion, or have a carbon-monoxide alarm, leave the area as appropriate and contact the responsible utility, emergency service, or qualified technician. Do not use a flame to look for leaks.
Structural work
Removing walls, cutting framing, changing supports, or modifying foundations can affect the load path of a building. Confirm whether a component is structural before altering it and obtain engineering, permits, and inspections where required.
Vehicles and machinery
Never rely on a jack alone when working under a vehicle. Use rated jack stands on a suitable surface, chock wheels, and follow lifting points in the vehicle documentation. Disconnect or isolate energy sources before servicing machinery.
PPE and hazardous materials
Use eye, hearing, respiratory, hand, and fall protection appropriate to the task. Treat unknown old building materials cautiously because asbestos, lead, silica, mold, and other hazards can require special procedures.
Local rules matter
Codes, licensing rules, permit requirements, and accepted practices vary by country, province or state, municipality, and type of building. A technique that is common in one place may not be permitted in another. When in doubt, confirm with your local authority having jurisdiction or a qualified professional.