Although newer fluorescent fixtures have built-in starters or no starters at all, older lights have an easy-to-change, visible starter. It is a small, silvery cylinder that plugs into the tube holders. Off late starters are also available with plastic casing.

How the Starter Switch Works

  1. Starter is connected in a bypass circuit with the lamp. Initially current flows through the bypass circuit since it is path of least resistance and establishes a magnetic field in part of the ballast. This magnetic field is maintained by the flowing current.
  2. When the starter switch is opened, the current is briefly cut off from the ballast. The magnetic field collapses creating a sudden jump in current making the ballast release its stored energy.
  3. This surge in current helps build the initial voltage needed to establish the electrical arc through the gas. Instead of flowing through the bypass circuit and jumping across the gap in the starter switch, the electrical current flows through the tube