Got a service call last week. Westminister High School Gymnasium. Some coach thought it would be a good idea to change out the 6 hour timer switch (for the 30- 400watt MH high bays) with the Clapper (u know clap on/ clap off). Well during a game that night, when everyone applauded... (u can probally guess what happened). The contactors went bezerk! and caught fire.
