How does Circuit breakers protect your home? And Why it doesn’t trip as soon as overcurrent occurs?
Ever wondered how the circuit breaker in your electric panel protects your home from overloads and short circuits that could lead to fires?
To understand this, you need to know two things:
The Breaker:
Circuit breakers, often called "thermo-magnetic breakers" or "air breakers," have two components. The thermo part handles overcurrent by heating up as current exceeds safe levels, eventually tripping the breaker. The magnetic part deals with short circuits, where an extreme surge of current creates a magnetic field that trips the breaker instantly. This youtube video by Wrapped Perception does an excellent job of explaining how it works in slow motion.
The Trip Curve:
Each breaker has a unique trip curve, showing how long it will take to trip based on current levels. To the left of the curve, it won't trip; to the right, it definitely will. Inside the curve, trip time depends on factors like temperature. This youtube video by Schneider Electric explains it nicely.
For example, a breaker rated at 25 amps won’t trip immediately at small overcurrents. Even at 1.25x the rated current, it might take over an hour to trip, and at 1.5x, it could take 10 minutes.
Here’s the trip curve for a 25-amp breaker: If 32 amps are drawn, it may over an hour, while at 40 amps, it could trip in less than 10 minutes, depending on the overcurrent level.
Questions? Feel free to ask!
