A three-position disconnector switch includes: an earthing contact; a power out contact; a power in contact; a first piston; and a second piston. In a connected switch position the first piston makes an electrical connection with the power out contact and the second piston makes an electrical connection with the power out contact and the power in contact. In a disconnected switch position the first piston makes an electrical connection with the power out contact and the second piston makes an electrical connection with the power out contact. In an earthed switch position the first piston makes an electrical connection with the earthing contact and with the power out contact and the second piston makes an electrical connection with the power out contact.