Patent ID: 7259647

Claim:
In a warehouse storage structure having a roll up door and a door track, a method of controlling the on/off condition of a high voltage device comprising the steps of: coupling a reed switch to the door track of the warehouse storage structure; providing a control module sense circuit having sense terminals receiving a low voltage control signal from the reed switch for controlling the high voltage device, the reed switch having an open state and a closed state; mounting a permanent magnet member having a constant magnetic field to the roll up door such that the magnetic field is exposed to the reed switch to cause the reed switch to be in one state when the roll up door is in a closed position, and the magnetic field is not exposed to the reed switch when the roll up door is in an open position to cause the reed switch to be in its other state; and controlling the on/off condition of the high voltage device by the control module circuit sense terminals receiving a low voltage control signal when the reed switch is in one state and by the low voltage control signal not being received by the control module circuit sense terminals when the reed switch is in its other state.