Spur Socket | Advice on Electrical Spur Wiring | Adding a The spur must be connected to the existing circuit using the same cable as used in the main circuit. You can see how to wire a spur to an existing socket from the images below. The first image is how the back of your double socket should look and the second is the wiring for a spur.[PDF] Technical Data - Wiring Devices, Accessories and USB Sockets 1. An outdoor location should be chosen ensuring adequate access to a mains supply circuit. The circuit MUST be protected by an appropriate fuse, circuit breaker or RCD (Residual Current Device) in accordance with current IEE wiring regulations. 2.