Abstract: Employee #1, age 19, was operating a 600 ton cold blend press equipped with a foot switch and a light curtain interlock. Apparently, both relays in the light curtain were stuck in the OK (green) position. When Employee #1 activated the foot pedal, the press cycled and amputated the top joints on two of his fingers. During subsequent investigation, the relays appeared to have burned and/or pitted contacts. Maintenance workers stated that when an object was placed into the light beam, the lights stayed green instead of changing to red as a warning of something in the path. When the machine was de-energized and re-started, all functions were normal. The light curtain manufacturer indicated to the employer that it was theoretically possible, but highly unlikely, that both relays could stick at the same time. In automatic machines, these relays stay closed unless an employee places something into the light paths, whereupon they open, stopping the machine. In a hand-fed press, each cycle opens and closes the relays. In some cases, an employee's hands could have caused the relays to open while current was present across the contacts thus creating a small arc that, over time and over thousands of cycles, could have pitted the contacts.