How to protect the small components in the distribution box?

In order to control and protect the normal operation of the electrical lighting system, the necessary configuration of various control devices and protection devices, such as switch, contactor, thermal relay, low-voltage circuit breakers and fuses, this kind of element is often referred to as "electrical control" or simply "appliances". According to their different functions, can be divided into switch (control) and electrical appliances to protect the two categories. The function of the switch is to control the work of the lighting system, that is, the "pass" and "off"". Protective devices have two functions: one is when a system failure (such as short circuit), can automatically, rapidly and selectively disconnected from the power supply part of the fault the way, to ensure that other non fault section to resume normal operation, and the fault part from continuous damage; two is when the system is abnormal working state (such as electric current, voltage or lower voltage, lower frequency, etc.) can send a signal to the timely adjustment or treatment, to prevent the abnormal state of expansion caused by fault.