TM 10-6640-239-13 4-34 4-17.    EMERGENCY LIGHT BALLAST BOX. This task consists of: a. Remove b. Install INITIAL SET-UP Tools Required General Mechanics Tool Kit, (Appendix B, Section III, Item 1) Materials/Parts Required Lockwashers, (4) Equipment Condition Power to lights removed by positioning Main Power Panel circuit breakers; A1CB9, A1CB11, and A1CB13 to OFF. General Safety Instructions WARNING ELECTRICAL SHOCK Before performing any maintenance actions on electrical equipment, ensure all electrical power has been turned off.  Failure to comply with this warning may result in serious injury or death. REMOVE Remove Ballast Box.  See Figure 4-7. a. Tag and disconnect wires to plug connector (1) from lighting circuit. b. Remove nut (2) securing conduit elbow (3) to bracket (4). c. Remove four screws (5), lockwashers (6), and washers (7) from rivnuts mounted on Mod Lab B wall.  Discard lockwashers. d. Guide wires from lighting circuit through conduit opening while removing ballast box (8) from wall mounting. INSTALL Install Ballast Box.  See Figure 4-7. a. Guide wires from lighting circuit through conduit opening while positioning ballast box (8) to wall mounting. b. Secure ballast box (8) to rivnuts of wall mounting with four screws (5), lockwashers (6), and washers (7). c. Secure electrical conduit elbow (3) to bracket (4) with nut (2). d. Connect wires from lighting circuit as tagged to plug connector (1).  Remove tags. e. Restore power to lights by positioning Main Power Panel circuit breakers; A1CB9, A1CB11, and A1CB13 to ON.