In public places, what should you do if the power goes off suddenly? This time if there is an emergency power supply installed in the lamps, there will be no panic and confusion caused by sudden power outages. Then this LED emergency backup battery driver is your best choice. Pressing the test switch turns off the light and forces the unit into emergency mode, interrupting power to the designated ac driver. After releasing the test switch, the fixture returns to normal operation after a momentary delay. This driver is not suitable for a damp location, please use it in the room.