Provision is made for energizing the D. C. busses:
(a) From an external source of power: Close single circuit breaker and close switch No. 2 to the right—facing the board.
(b) From the casemate generator: Close single circuit breaker and close switch No. 2 to the left—facing the board.
(c) From the storage battery: With switch No. 2 open, close double circuit breaker.
Feeder switches are plainly marked. The D. C. switches supply power as follows:
No. 3. When up, supplies the operating boards (negative pole to boards, positive to earth); when down, it is spare.
No. 4. When up, supplies motor-generator No. 1; when down, motor-generator No. 2.
No. 5. When up, supplies the mine commander’s station.
No. 6. When up, supplies casemate lamps; when down, it does the same, but the power is now drawn from an external source and not from the D. C. busses.
No. 7. When up, grounds the positive bus and connects the negative bus through the protective lamp and mil-ammeter to the mil-ammeter lead.