FUSE BOX

[droopsnoot]

It's usually mounted on the drivers side inner scuttle area, just in front of the door pillar and above the trim panel. The idea is the bimetallic bit will cut the circuit if the load gets too high, and then reinstate when it cools down. In that way it's much better than a fuse as it will sort itself out in time for you to see the thing you're about to hit in total darkness, but if your headlamp circuit has any additional load it can be frustrating. Though not as frustrating as that awful smell of burning loom.