PZH III C/S, PZH III C/L are surge arresters type 3 according to EN 61643-11 and IEC 61643-1 designed for installation into electrical installation systems, e.g.: cable ducts and flush-mounted sockets as an additional protection. These devices are suitable supplements of socket distribution which are protected by PZH protector. The right function of PZH III C/L type is indicated by green LED diode. When the indicator is off, the device must be replaced or technically checked. PZH III C/S contains an acoustic fault indicator (buzzer).