Low break

From PyroGuide

A Low Break is defined as an aerial shell's break charge igniting and breaking the shell before it was intended to. This means that the shell has not risen to a proper altitude or apogee to be safe to break. This is commonly produced by either too short of a time fuse or spolette. A time fuse or spolette with an untested burn rate that is inserted into a shell can be dangerous to both the pyrotechnician and the audience. Other causes of low breaks include not sealing up the shell securely, allowing fire to pass into the shell during the exhaustion of the lift charge. This type of low break commonly occurs in or just outside of the mortar, and is commonly referred to as a flowerpot. There are several other less common reasons for a low break, including too long of a fuse, shell kick or set back, and the time fuse powder core being loosened by cutting with anything other than razor blades.

Low breaks are a safety hazard to both pyrotechnicians and bystanders, as the stars will burn very close to the ground. These can cause severe burns, and the break charge sound wave can cause temporary deafness. If someone were too close to the mortar during a flowerpot or extremely low break, they could be killed by the high-velocity projectiles coming from the shell's break.