Avoid fire
String lights consist of many small lamps. Small, series-connected incandescent bulbs that are common on older string lights can become flammable. If one or more bulbs stop working, the bulbs are made so that the rest glow, but with increased strength. This may cause the lamps to become too hot. Then Christmas decorations or other flammable materials nearby can catch fire. Replace old string lights with new LED lights.
Outdoor use
Electronics do not tolerate moisture and cold very well. This can lead to overheating and fire in electrical connections and wiring. Choose string lights and extension cords that are made for outdoor use.
Avoid pinched cord
If you are going to decorate with lights outside, you must use lighting that is suitable for outdoor use. Never let the cord go over the door threshold or through the window. There it can get trapped and injured.
Turn off string lights at night
Always turn off string lights and other unnecessary electrical products at night, or before you go away.