TM 10-6640-239-13 4-45 4-21.    EXPLOSION PROOF DISTRIBUTION BOX A13 COMPONENTS. 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, (24) 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 1. Disassemble Explosion Proof Distribution Box A13.  See Figure 4-11. a. Open circuit breakers A1CB1 and A1CB2 located in Main Power Panel.  Disconnect power to Mod Lab at power distribution module. b. Remove 20 screws (1) and cover (2). 2. Remove Control Relay K1 thru K4. a. Tag and disconnect relay K1 thru K4 (3) electrical leads by loosening relay terminal screws. b. Loosen two screws (4) and remove relay K1 thru K4 (3). 3. Remove Terminal Board TBGND. a. Tag and disconnect terminal board TBGND (5) electrical leads by loosen terminal board screws. b. Remove two screws (6) and terminal board TBGND (5). 4. Remove Terminal Board TB1 thru TB4. a. Tag and disconnect terminal board TB1 or TB3 (7) electrical leads by removing terminal board screws. b. Remove four screws (8), lockwashers (9), and terminal board TB1 or TB3 (7).  Discard lockwashers. c. Tag and disconnect terminal board TB2 or TB4 (10) electrical leads by removing terminal board screws. d. Remove four screws (11), lockwashers (12), and washers (13) and carefully withdraw mounting panel (14) to gain access to terminal board TB2 or TB4 (10) mounting hardware.  Retain four standoffs (15) for reassembly.  Discard lockwashers. e. Remove four screws (16), lockwashers (17), washers (18), standoffs (19) and terminal board TB2 or TB4 (10). Discard lockwashers.