On the back of the black control box, there is an on/off switch and the spot where the electrical cord plugs in to your incubator. In between those, you will see raised lettering and a box that sits flush. Using a flat head screw driver, you can slide the fuse box open like a DVD player. The fuse box does not come out fully. Inside there is the fuse that is being used and the spare fuse. If you are accessing the fuse box because your incubator has shut down, please contact a customer support agent at (800) 511-1369.