Yes, outdoor lights and receptacles should be on a ground-fault circuit interrupter (GFCI) for safety. The outdoors is considered a wet location where GFCI protection is generally required. A GFCI enhances safety by automatically tripping and shutting off the circuit if it detects an imbalance, which protects against electrocution and reduces the risk of an electrical fire. While it is the safest approach for all outdoor electrical components, specific requirements can vary depending on the type of light (e.g., pool lights), its location, and local electrical codes. For guidance tailored to your specific situation, it's best to consult a professional electrician.

Before investing in motion sensor lights, there are a couple of disadvantages worth noting. For starters, they’re not as reliable as other forms of lighting. Motion sensor lights can be accidentally triggered by pets or wind, which can become a nuisance after a while. The opposite situation can occur, too, where they don’t turn on when you need them to. 

The average cost to install outdoor or landscape lighting is around $4,000, with most projects ranging from $2,000 to $6,000. The total cost can vary widely depending on several factors, including the number of fixtures, design complexity, and the type and quality of the lights used, such as wall sconces, pathway lights, or lamp posts. Other factors that influence the price are the square footage of the area being lit, the amount of electrical work needed, any required excavation or trenching, and local permitting costs. For specific types, you might pay around $100 for pathway or string lighting and up to $700 for lamp post lighting.

If you need to visually inspect your Christmas lights to determine which are good and which need replacement, there are a few things to look for. First, look for discoloration, such as a dark spot or two on the inside of the glass. The spot is an indication of a burnt filament. Also, look for missing filaments, cracked bulb glass, and broken sockets.