Type 2 surge protection devices, or SPDs (Surge Protection Devices), are installed in power distribution networks to protect people, systems, and devices from unacceptable short, impulse-like overvoltages. They can be used in network systems between L-N and L-PEN. A defect is indicated by a red light in the viewing window. The status is provided as a potential-free switching contact via a plug included in the accessory package.