How many string lights can be on one outlet depends on a number of varying factors, including the total wattage of your circuit, the type of lights, the energy needs of the lights, and cord specifications. It’s better to play it safe here to protect your circuit, so figure out the max wattage of your circuit, compare that to the lights, and move on from there. Generally speaking, LED string lights require less energy than incandescent bulbs, translating to a higher number of lights per circuit. 

There are many types of Christmas lights to choose from when working with a light installer. The main types available for outdoor lighting are dome, LED, incandescent, and C9, and your lighting professional’s choice will depend on the location and overall design. 

C9 lighting is typically the most expensive option, ranging from $15 to $70 per 25-foot strand. These usually have fewer bulbs per strand, so you might need more than expected to cover a large area. Dome lighting is usually the most cost-effective option, ranging from $6 to $15 per 25-foot strand. These bulbs are smaller and rounder than other options, creating a softer look.

The cost for professional holiday light installation averages around $430, with a typical range of $220 to $675. However, prices can be as low as $100 for simple projector setups or exceed $1,200 for extensive displays. The total cost depends on factors like the display's complexity, your home's size, labor rates in your area, and the type of lights used. For example, installation on a small, one-story home may cost $250 to $600, while a multi-story home over 4,000 square feet could cost $500 to $1,800. Costs can also be broken down by location (e.g., high roofs at $3.50–$6 per linear foot) or by the type of light strand, with prices ranging from $4 for basic incandescent strands to over $60 for color-changing LED strands.

While Christmas lights are a wonderful way to light up your home during the holiday season, they don’t have a long lifespan. Most incandescent Christmas light bulbs are designed to last between 1,000 and 1,500 hours—or about one to three holiday seasons. More durable LED bulbs should last about 10 times as long.