Install miniature circuit breaker or switch before SPD

Question: Recently, I saw the wiring mode of the miniature circuit breaker installed in front of the surge protector. When connected in parallel with the switch, some are connected to the upper end of the circuit breaker Lower end (actually I want to ask whether the surge protector is connected above or below the miniature circuit breaker.)
What should I ask?
Answer: In the lightning protection project, there are many disputes about the installation location and selection of power surge arresters.

1. Installation principles
Theoretically, the first-level lightning arrester (Grade B) should be installed at the front of the main circuit breaker as far as possible. If installation is not convenient, it can also be installed at the open circuit protrusion. However, if there is a dual power switching device at the front of the incoming line, it must be installed at the front of the dual power switching device to protect the switching device (the current dual power switching device is mostly mechanical and electronically controlled, and some have 232 And 485 control device and 24 volt fire power supply, once the lightning current passes, it is easy to damage). The reason is that the operating time of the circuit breaker (circuit breaker) is much longer than the operation time of the arrester. Once a lightning current (overvoltage) passes, the arrester will operate in advance before the circuit breaker operates to release the overcurrent to protect the circuit And its own electrical equipment.
2. Selection principle
B-level arresters try to choose voltage switch type arresters with large current capacity and the protection voltage UP should be as small as possible.

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Jan. 13, 2020