Switchable Aluminum Wire
There is also Switchable Heavy Aluminum Wire.
Like regular Aluminum Wire, place this in any location where a wire can be placed. Wires will self-connect if placed next to another wire or electric machine.
No tool is required to break wires.
Normally this wire is connected like any wire, but supply a redstone signal and it will disconnect, and energy will now not flow. When switched off, a single red cube is drawn, apparently disconnected from everything around it. Remove the redstone signal and it will reconnect.
This is useful for switching off machines or groups of machines so that they do not draw energy when you are not using them, or generally for giving you more control in large complex bases.