A safe holiday display starts before the first strand goes up. Review the labels and instructions for every light set and extension cord, and use products intended for outdoor conditions where they will be exposed to weather. Do not use a strand if you are unsure it is rated for outdoor use.
Inspect lights before installing them. Look for cracked sockets, frayed or bare wires, loose connections and other damage. The U.S. Consumer Product Safety Commission advises discarding damaged light sets rather than trying to use them for another season.
Use outdoor electrical connections carefully. CPSC recommends plugging outdoor lights into a ground-fault circuit interrupter (GFCI)-protected outlet. Keep cords and connections arranged according to manufacturer instructions, and do not exceed the number of connected strands allowed by the product label.
Secure lights with clips designed for the surface instead of piercing wires with nails or staples. Avoid climbing onto a roof or ladder when surfaces are wet, icy or unstable; professional installation can keep the work off your to-do list and reduce risky roof access.
Before switching on the display, check that cords are not pinched, damaged or placed where people can trip over them. Recheck after severe weather, and turn the lights off when you leave home or go to bed. For product-specific limits, always follow the manufacturer's instructions.