Operation Totem status, the British government restarted its own development effort, which was given the cover name "High Explosive Research". The first British atomic bomb was tested in Operation Hurricane at the Montebello Islands in Western Australia on 3 October 1952. The main purpose of the trial was to determine the acceptable limit on the amount of plutonium-240 which could be present in a bomb. The plutonium used in the original Hurricane device was produced in the nuclear reactor at Windscale, but the Windscale Piles did not have anything like the capacity to provide sufficient material for the British government's planned weapons
Residual-current device to the appliance. The test button (8) allows the correct operation of the device to be verified by passing a small current through the orange test wire (9). This simulates a fault by creating an imbalance in the sense coil. If the RCD does not trip when this button is pressed, then the device must be replaced. Residual-current and overcurrent protection may be combined in one device for installation into the service panel; this device is known as a GFCI (ground fault circuit interrupter) breaker in the USA and Canada, and as an RCBO (residual-current circuit breaker with overload protection)