I'd be willing to bet the EW for lights won't include what would normally wear out. Bulbs / flashtubes, obviously. And cords. And, of course, accidental damage. The internal capacitors might die prematurely, but that will be excluded by claiming over-voltage input. The finish won't be covered as that's normal wear-and-tear. Same for switches, knobs, buttons, etc.
What will be covered? If you're doing a photoshoot of Mohammed Ali wearing a pink tutu, in an abandoned ice-pick factory, between 2:15 and 2:18 AM, in the city limits of Windham, N.H., on Friday the 13th, during a stampede of giraffes...............