The present invention discloses a safety device adapted to prevent workers from going into hazardous environment, such as underground using the faulty safety device. As a safety device, typically embodied as a cap lamp, must be charged prior to each use, the device is adapted to detect when the device is removed from the charger. The device starts to blink continuously when disconnected from the charger. An automated test procedure is completed on the device. The user may also complete a manual portion of the test procedure to make the device usable. When the test procedure is completed successfully, the lamp stops blinking. If the test procedure is not successful, the lamp continues blinking to effectively prevent user from using a faulty device.