Always Choose Waterproof Lights

There is a variety of lights to choose from. First and foremost, always use waterproof or water-resistant lights with a tag marked underwriters lab (UL). This means the lights meet national industry standards with the American National Standards Institute. Also, when you're buying Christmas lights to use outside, make sure they are rated for outdoor use (just like your extension cords). Never use indoor Christmas lights outdoors.

Using C7 or C9 Bulbs

For a more traditional holiday light, you will want to use a C7 or C9. These are the cone-shape lights you'll find most often in home improvement and convenience stores. The difference in these lights is size and wattage, with C9 being a little bigger and easier to see from a distance. Both come in frosted or clear color bulbs and are great for illuminating both your house and trees.

You can buy these in strands of 25 bulbs or larger strands of 100 bulbs. The 25-bulb strands can be connected together (daisy chained) up to a maximum of three strands; 100-bulb strands should be connected separately. Don't connect them together! The C7 and C9 strands use a standard screw-in candelabra base for easy bulb replacement. The strands are connected so if one bulb fails it only affects itself. Buying light strands with inner fuses is a great idea to prevent excess current on the strands.