Under abnormal conditions (such as short circuit), the grounding switch can carry the specified rated short-circuit current and corresponding peak current within the specified time; However, under normal operating conditions, it is not required to carry rated current.

Earthing switches and disconnectors are often combined into one device. At this time, in addition to the main contact, the disconnector also has a grounding switch for grounding one end of the disconnector after opening. The main contact and grounding switch usually realize mechanical interlocking in such a way that the grounding switch cannot be closed when the disconnector is closed, and the main contact cannot be closed when the grounding switch is closed.

The grounding switch can be divided into open type and closed type according to its structure. The conductive system of the former is exposed to the atmosphere, similar to the grounding knife switch of the disconnector, while the conductive system of the latter is enclosed in SF filled. Or oil, etc.

The grounding switch needs to close the short-circuit current and must have a certain short-circuit closing capacity and dynamic and thermal stability. However, it does not need to disconnect load current and short-circuit current, so there is no arc extinguishing device. The lower end of the knife switch is usually connected to the grounding point through a current transformer. The current transformer can give signals for relay protection.

Grounding switches of various structural forms can be divided into single pole, double pole and three pole. Single pole is only used for neutral grounded system, while double pole and three pole are used for neutral ungrounded system, which share one operating mechanism for operation.