TM 11-6780-225-35
CHAPTER 2
FUNCTIONING
the circuit breaker panel. All circuit wiring is contained in
2-1.
General
external metal wire raceways.
Each receptacle
The darkroom functions as a temperature and humidity
grounding jack is connected to ground (through the metal
controlled photographic laboratory with facilities for black,
shell of the ES82A) by a green color coded 12gauge
white, color film, and print processing.
Refer to TM
wire. The total current capacity of the electrical system
11678022512 for additional information. Refer to figure
is 305 amperes as follows:
21 for the block diagram of the darkroom photographic
PA 100 amp; OB 85 amp; PC 120 amp.
function.
CB2 (OA) is a spare unused 20amp circuit.
The
2-2.
Elecrical System
functioning of the 11 circuits of the electrical system are
The function of the electrical system is to control and
given below.
supply a path for current flow from an outside electrical
a. Circuit 1. Circuit 1, controlled by CB1 (40 amp),
source (primary power) to components in the ES82A.
is a 10gauge wire supplying power to the AIR COND. 1
The primary power may be a commercial power source
receptacle located forward, outside of the E'S82A. A
or a generator set, either one capable of supplying 12
weatherproof cable connects air conditioner No. 1 to
kw, 120/208v, 60 Hz, 3phase (OA, OB, and pC) power,
this receptacle.
with a 4wire wye connection. The ES82A is grounded
b. Circuit 2. Circuit 2 controlled by CB12 (40 amp),
by a ground rod. The rod is driven into moist earth, and
is a 10gauge wire supplying power to the AIR COND. 2
has a ground strap connected between the rod and the
receptacle located forward, outside of the E,S82A. A
ground tie point on the ES82A. The 3phase primary
weatherproof cable connects air conditioner No. 2 to
power is applied to the electric power connection of the
this receptacle. In addition, two black color coded 18
ES82A through the power cables, with appropriate
gauge wires are connected between the air conditioner
adapters. From the electric power connection power is
No.2 thermostat located in the aft compartment, and
routed through color coded 4gauge cables to an RFI
TH,ERMOSTAT AIR COND.
2 receptacle located
(radio frequency interference) filter.
The RFI filter
forward outside of the E82A.
A weatherproof cable
consists of three capacitors, one for each phase, which
connected between the thermostat connection of air
shunts all signals above 30 kHz to ground through an
conditioner No.
2 and this receptacle allows
integral bleeder resistor. From the RFI filter the power is
temperature control of the air conditioner from the aft
distributed as follows: OA (red) is distributed through
compartment.
main circuit breaker 13 (CB13) to CB1, CB12, CB7, and
c. Circuit 3. Circuit 3, controlled by CB3 (15 amp),
CB8; OB (black) through CB13 to CB3, CB4, CB9, and
is a 14gauge wire supplying power to a cable connector,
CB10; PC (green and blue) through CB13 to CB5, CB6,
which is connected to a socket on the dehumidifier.
CB11, and CB2 (spare); neutral (white) to the ground
d. Circuit 4. Circuit 4, controlled by CB4 (20 amp),
buss in the circuit breaker panel. The ground buss is
supplies power to two CIRCUIT 4 receptacles via a
connected to the ES82A ground tie point through a
12gauge wire.
Power is also supplied to the two
6gauge green color coded cable.
All components in
exhaust fan ONOFF switches and the four intercom
ES82A are operated 110volt single phase. Each circuit
ONOFF VOLUME controls via an 18gauge wire. The
is wired with a black color coded wire coming from its
voice circuits of the intercom stations are interconnected
respective circuit breaker, and a white color coded
via color coded 20gauge wires. The immersion heater
(neutral) wire as a return connected to the ground buss
line plug is connected to the CIRCUIT 4 receptacle in the
in
forward compartment.
2-1
