Circuit breakers are employed to automatically switch off a circuit or a load whenever any abnormalities in current flow are detected. This functionality of the circuit breakers is known as ‘Trip’. By doing so, circuit breakers are preventing fire or other damages caused to the circuit. Here are the major reasons behind your circuit breaker trip. In this article, we discuss domestic circuit breakers such as MCB, MCCB, and residual current devices (RCD, RCCB, RCBO).
Why did your circuit breaker trip?
Circuit breakers have replaced the traditional fuses due to their re-usability. At least one of the following situations can trip your circuit breaker.
- Overload
- Short circuit
- Ground fault or Earth fault
Overload
This is one of the prominent reasons behind a circuit breaker trip. An overload is a situation in which a device or a circuit draws more current than the value it can safely handle. One such example of an overload is plugging in many appliances to a single power socket such that the loads all together draw more current than the socket can deliver.
In the above case, if the load current is higher than the rated current of the MCB (Miniature circuit breaker) for a certain period of time, the MCB trips.
Short-Circuit
Short circuits are more dangerous than overloads. These are the situations in which a live conductor comes in direct contact with the neutral conductor (Direct contact of positive and negative in case of DC) resulting in a current flow several times the normal value.
This could be the result of wrong wiring or damages inside the appliance plugged. During short circuits, the circuit breakers or MCB trips instantaneously.
Learn the key differences between a Short circuit and an overload here.
Ground Fault or Earth Fault
A ground fault or an earth fault is a situation when a live conductor comes in direct contact with the ground or the earth conductor. This can cause a circuit breaker trip if the fault current is considerably high. Residual current devices (Ground fault circuit interrupters, RCD, RCBO & RCCB) can offer better protection against earth faults.
The cause of a ground fault needs to be analyzed properly and rectified. Otherwise, it may result in electrocution and can be fatal.