Install, fix, and tweak parts of various products.
A Gaffer is the head of the electrical department on a movie or television set. At this position you are in charge of the execution and design of the lighting plan for films and television. You also oversee your staff of Lighting Technicians (with the help of your Best Boy, of course).
Overall, this is a technical position with a little bit of artistic design and a whole lot of authority. Your specific tasks will vary by the size of a production, but you are always responsible for the operating and artistic effect of all electrical components. This means that in a given day you could be laying electrical cable, designing lighting structures, or tinting windows to mimic the setting sun’s glow.
Gaffers generally own most basic lighting equipment, and only rent the pieces which vary by individual productions. In fact, in British slang the word “gaffer” means old man or boss. So think of this person as the seasoned old pro who is almost a part of their rigging.