1. Combiner box is divided into shell and plastic shell, there are two types of open type and concealed type, the box is intact.

2. The wiring busbar in the box shall be set with neutral line, protective grounding wire and phase line respectively, and shall be intact with good insulation.

3. The mounting bracket of air switch should be smooth and free of obstruction and have enough space.

4.The door panel of combiner box shall have transparent inspection window.