Schutzklasse

Schutzklasse is a category used in electrical safety to describe the level of protection a device provides against electric shock. The concept is defined in European and German standards and is used to guide design, labeling, and installation. The classification helps users and professionals assess whether a device requires grounding and which safety precautions are necessary.

Schutzklasse I refers to equipment with basic insulation plus a protective earth connection. The chassis or exposed conductive parts are connected to a protective grounding conductor, so a fault current is directed to earth and a protective device can interrupt the current. Devices intended for Schutzklasse I are typically labeled accordingly and must be connected to earth in installations.

Schutzklasse II describes equipment that relies on reinforced or double insulation instead of a protective earth. Such devices do not depend on an earth connection for safety, and the insulation is designed to withstand breakdown without exposing the user to dangerous voltages. The accompanying symbol is a double square. Examples include many battery-powered or plastic-bodied consumer devices.

Schutzklasse III covers equipment that operates at safety extra-low voltage (SELV). These devices are designed so that accessible parts remain at voltages well below safe thresholds, often powered from a dedicated low-voltage supply. No protective earth is required, and the risk of shock is minimized by the voltage level alone.

In practice, the Schutzklasse of a device informs installation requirements, labeling, and risk assessment. It is distinct from Schutzart (IP protection), which describes ingress protection against solids and liquids.