The answer to 'lighting installation making buzzing noise' is that a buzzing sound coming from a light fixture is usually caused by an electrical issue. This could be due to a problem with the light bulb, wiring, or the fixture itself.
Common causes include a loose connection in the wiring, a faulty light bulb, or an issue with the light fixture's ballast or transformer. The buzzing noise is often a sign of an electrical problem that needs to be addressed to prevent potential fire hazards or further damage.