TM 10-6640-238-13 1-21 (3) Lighting System (Refer to Figures 1-5 and 1-6).  Lighting for the Petroleum Laboratory is provided by 15 fluorescent ceiling light fixtures.  Thirteen are located in the laboratory compartment and two are in the mechanical room. Power for the laboratory compartment lights is provided by circuit breakers A1CB9, A1CB11, and A1CB13 located in the MAIN POWER PANEL A1.  A1CB9 provides phase A power via rear and curbside door interlock switches S1, and rear and curbside light switches S9 and S12 to lights DS6, DS8, DS9, and DS10.  A1CB11 provides phase B power via door interlock switches S3 and light switches S10 and S13 to lights DS1, DS2, DS3, DS4 and DS5.  A1CB13 provides phase C power via door interlock switches S4 and light switches S11 and S14 to lights DS7, DS11, DS12, and DS13.  Power for lighting in the mechanical room is phase B power provided by circuit breaker A15CB10 via door interlock switch S1 and light switch S3 to lights DS14 and DS15. (a) Blackout Lighting.  The center lamp in each of the light fixtures is covered with a blue filter.  When an access door is opened, the door interlock switch is activated.  This will turn off all white lights and leave on all blue filtered lights.  When the access door is closed, the interlock switch is again activated, returning power to the white lights.  As a safety feature, when the light switches are turned off all blue filtered lights will remain on until power to Mod Lab A is removed. (b) Emergency Lighting.  Emergency lighting is provided to the laboratory compartment by light fixtures DS7 and DS13 and two emergency light ballast boxes A26 and A27.  When normal power is available, phase C power continually charges the battery device in ballast box A26 and A27.  When normal power is lost, power from ballast box A26 will be provided to DS7 via the Forward Emergency Light Switch S17 in the ON position and the rear and curbside door interlock switches S2. Power from ballast box A27 will be provided to DS13 via the Rear Emergency Light Switch S18 in the ON position and the rear and curbside door interlock switches S5. b. Purge System (Refer to Figure 1-5 and FO-1).  The purge system is used to exhaust potentially dangerous contaminated air from inside the Petroleum Laboratory.  The system consists of the following components: (1) A1K1 power control relay located in the MAIN POWER PANEL A1. (2) A3K1 time delay relay located in Purge Control Distribution Box A3. (3) A3K2, and A3K5 blower control relays located in Purge Control Distribution Box A3. (4) Two purge intake doors and two purge exhaust doors located on the outside wall of the Petroleum Laboratory. (5) Four purge door limit switches. (6) Two intake dampers and two exhaust dampers located behind the external purge doors. (7) Three ventilation dampers mounted in the ECU plenum located in the mechanical room. (8) Seven purge damper motors. (9) One purge alarm buzzer located at the POWER INPUT PANEL A34.