A tri-model circuit breaker for use in a rapid-start fluorescent lamp. The circuit breaker includes a glass bulb, first and second electrical leads sealed into and passing through the glass bulb, and a bimetallic element disposed within the bulb and having first and second end portions. The first end portion of the bimetallic element is affixed to the first electrical lead while the second end portion of the bimetallic element is formed to be spaced from the second electrical lead at a first elevated temperature and in contact with the second electrical lead at ambient temperature and at a second elevated temperature higher than the first elevated temperature. The contact points of the circuit breaker at ambient and at the second elevated temperature are at the same location within the breaker.