Aquarium equipment is usually pretty reliable, so most hobbyists just set them up and walk away assuming things will run smoothly for months on end. Unfortunately though, some equipment malfunctions and can cause a great amount of damage. Metal halides for example can heat up to the point of melting the plastic housing of the pendant or fixture. This also exposes wires and other electronic components to warm salty air that can cause corrosion and eventual equipment failure, if not a fire first. So, inspect equipment regularly and pay close attention for burning smells and damage.