Firstly, I want to stress that some assumptions have been made herein. We are not fire investigators, nor do we hold any formal qualifications to make the claims we do. We only offer what appears to have happened from our experiences in conducting electrical work.
While conducting an install in an educational setting recently, we noticed some foam material covering the ceiling space above a “music room”. We suspect this was added as a form of sound insulation to prevent the sound from entering the ceiling space and then into the surrounding spaces.
Unfortunately, this was layered directly on top of the existing fluorescent light fittings. As a result, directly above where the ballast sits in this fitting, the foam heated up and began to melt, dripping into the light fitting and ballast, causing a small fire within the light fitting. Thankfully (not thankfully?) the material, around the area stopped melting once it was far enough from the hot spot and self-extinguished with a lack of fuel.
The foam matting was installed covering 6 individual light fittings, and only one appeared to exhibit the signs of ignition. We think this is a great example of how easily a good idea can turn into a disaster without identifying a risk like this.