When a combiner box has a power supply and is connected to the network, it is not possible to open any fuse holder. Doing this would create an electrical arc which could damage the combiner box and the person handling it. It is important to highlight that the fuse holder does not have any electric arc dissipation function, this function is fulfilled by the switch-disconnector, which disconnects the combiner box from the network making its manipulation possible. You can find more detailed information of the Fuse Holder in our fact sheet.