A fuse box for a vehicle contains a base box having a housing in which a first bus bar with a battery connection terminal is disposed. The fuse box is configured according to a modular system. For this purpose, the housing is provided for the attachment of an extension box. The extension box preferably has a second bus bar that is placed in contact with the first bus bar. As a result of the modular system with the extension box, it is possible, for example, to allow for extensions in a vehicle on-board power system with little expenditure in respect of the fuse box.