A ghost light is a electric light that is left energized on the stage of a theatre when the theatre is unoccupied and when dark. They are normally placed in the centre stage and the typical types used are an exposed incandescent bulb, CFL lamp, or LED lamp mounted in a wire cage on a portable light stand.
Apart from the logical explanation’s for using a light on stage such as falling into the orchestra pit or tripping over set pieces, the ghost light have a more superstitious origin.
Over the years the ghost light as been used as a justification for a more of a supernatural kind in theatres. It is a popular theatrical superstition that every theatre is haunted, ghost stories associated to theatres go back years and in many theatres across the globe the living accommodate the dead, The Palace Theatre in London keeps two seats in their balcony permanently bolted open to provide seating for the theatre ghosts.
The superstitions surrounding the ghost light in theatres differ,some believe that ghost lights provide opportunities for ghosts to perform onstage, while others believe they help to prevent against a cursing of the theatre or sabotaging the set or production by a supernatural force. Most theatres close for at least one day, it is believed a ghost light is often placed out to scare the ghosts away and not draw them in.