The low voltage powered models is designed for operation on a 3 to 5 vb d. C. Supply capable for providing in a current of 1. 5 a. Power input is via a pair of colour coded 4mm sockets. Mains operated versions are provided with 1. 5m of three core mains cable, the earth core of the mains lead being connected to the metal structure of the apparatus. Both voltage and mains versions also have independent 4mm earth sockets with discharger 75mm dia with handle.