A security device for an electrically powered device includes a remote location-tracking circuit for mounting in a power plug or power cable, a control means for mounting in the power plug or power cable with the remote location-tracking circuit, an immobilizing circuit which is a power shut-down circuit for immobilizing a tool positioned within the tool casing, wherein the power shut-down circuit includes a relay; and a power cable connected between the control means and power shut-down circuit, the power cable being adapted to supply power to the tool, and the power shut-down circuit being controlled by the control means, wherein if the remote location-tracking circuit is removed by severing the power cable, thereby disconnecting the control means from the power shut-down circuit, the power shut-down circuit is configured to automatically shut down the power supply to the tool via the relay until the control means is re-connected.