Ghost Lamp Superstition

“Second, we have, much like most theatres, a ghost lamp that stays on at all times. The original purpose of a ghost lamp was to protect any from gas leaks that may have occurred throughout the night by igniting it before a stagehand had a chance to get in the building and do it in the morning (It destroyed the theatre, but no one was in it at least). Now, we just use it as a superstitious way of keeping things well within the theatre when everyone’s away.”

This superstition apparently is in practice at many theatres, as two other friends also mentioned it during their interviews. they, however, were less eloquent in their descriptions, but basically said it’s a light left on the stage  that used to be for safety and is now just superstition. In my questioning, no one was able to explain why it’s called the “ghost” lamp, since no ghost seems to be involved. Perhaps it is supposed to be a light for the ghosts in the theatre?