IC rating is the most important factor to consider for installing recessed downlights. If you have an insulated house, IC-rated recessed lights are essential. If you install a non-IC-rated fixture, it can cause a fire to break out anytime. Recessed downlights are attached directly to the ceiling. And when these fixtures get overheated, they can catch fire coming in contact with the flammable insulation. But IC-rated lights have a thermal protection system that makes them fire hazard-free. So, to ensure your safety, always check the IC rating before installing any recessed downlights. However, you can use non-IC-rated recessed downlights if your house is not insulated.