An 800-ampere circuit breaker is typically classified as which type?

• A. Molded case circuit breaker
• B. Low-voltage power circuit breaker
• C. Medium-voltage circuit breaker
• D. High-voltage circuit breaker

Answer: (B)

The key idea is that circuit breakers are categorized by the voltage level they operate at, not just by their current rating. An 800 A rating describes how much current the device can carry, but the voltage level determines the category. Breakers used in everyday electrical distribution are split into low, medium, and high voltage. An 800 A device used in typical panelboards and industrial feeders operates at low voltage (up to around 1000 V in many standards), so it falls into the low-voltage power circuit breaker category. The term molded case refers to the construction style of many low-voltage breakers, including those rated around 800 A, but the essential classification here is low-voltage. High- and medium-voltage breakers are designed for much higher voltage ranges and different service conditions, so they aren’t the typical choice for an 800 A, LV distribution scenario.