LED light bulbs are more energy efficient than using filament incandescent light bulbs because they waste considerably less energy in the form of heat. LED lights cost more than incandescent bulbs but can last as much as 50 times longer and use less electricity. Most LED bulbs require a 12 volt DC transformer. Incandescent bulbs usually require using a 12 volt AC transformer. Always check the product specifications for power type before planning your deck lighting system. LED lights must be wired in parallel not in a series and polarity must be maintained throughout the lighting system.