This 10W volume control is designed for 100V line speaker systems. The volume control is fitted to a white Clipsal Pro Series wall plate which has been specifically designed for commercial building installations. They feature 11 position switches for fine adjustment of sound level. All circuitry is housed on a PCB with screw terminals for easy installation. They include override relay for emergency paging applications & a 22µF bipolar capacitor for line monitoring purposes. An onboard switch selects between normal and failsafe modes. With the switch in the Normal position energising the override relay (24V DC to the 24V DC terminal) bypasses the controller. Full input power is directed to the speaker load. De-energising the override relay configures the unit to normal level control function. With the switch set to the Failsafe position energising the override relay is necessary for normal level control function. De-energising the override relay bypasses the controller. That is, full power is directed to the speaker load.