The fuse box is often located in a cluster of components, as illustrated here. The box is shown with the cover off.
Current flows along a single cable from the battery to the component being powered, and back to the battery through the car metal body. The body is connected to the earth terminal of the battery by a thick cable.
The fuses are usually grouped in a box or on a panel with a cover. Ideally, the box should be fixed in an accessible place — such as the bulkhead under the bonnet.
Modern cars often need room for many wires in confined spaces. Some manufacturers now use printed circuits instead of bundles of wires, particularly at the rear of the instrument panel.