TM 10-6640-239-13 4-30 4-15.    LIGHT BALLAST. 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, (2) Wire Nuts, (3) 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.  See Figure 4-5. a. Loosen four captive screws (1) and remove diffuser (2). NOTE There are three ballast in each light fixture.  Two are located at one end and one at the opposite end of the fixture. b. Remove two screws (3) and ballast cover (4). NOTE If wires are connected with clinched wire nuts, use side cutter to remove. c. Tag and disconnect electrical wires from ballast (7). d. Remove two nuts (5), lockwashers (6), and ballast (7).  Discard lockwashers. INSTALL Install Ballast.  See Figure 4-5. a. Install ballast (7) in light fixture and secure using two lockwashers (6) and nuts (5). b. Connect wires, as tagged, using wire nuts.  Remove tags. c. Install ballast cover (4) and secure with two screws (3). d. Install diffuser (2) and secure by tightening four captive screws (1). e. Restore power to lights by positioning Main Power Panel circuit breakers; A1CB9, A1CB11, and A1CB13 to ON.