have a duct vented outside so that it may be used to exhaust air from the room. Incoming
air should be pumped through filters and should be sufficient in volume to change the air in
the room from 6 to 10 times each hour.
c. When ventilating ducts are absent, fans with lightproof intakes may be installed
in the wall. Doors may be equipped with lightproof louvers to permit passage of air.
a. Low-potential electrical outlets and fixtures can be hazardous to personnel.
Voltages of 110 and less may prove fatal if contact is made with moist skin. Special care
should be exercised to avoid a situation in which the body becomes part of an electrical
circuit. Hazards include the proximity of wiring to the solution tanks and plumbing, spilled
water on the floor and moisture on the hands. All exposed metal parts of both fixed and
portable equipment, such as the metal frames and exteriors of illuminators, safelight
lamps, electric timers, and foot switches should be grounded. If such equipment is
connected with an armored cable, a separate ground wire is not required because the
metallic sheathing should provide an adequate ground. However, if a two-wire cord is
used, a separate ground connection should be installed. For ease in installation, the outlet
box may be used with the third wire attached to metal on the equipment and the outlet box
by means of approved devices, but not held with solder. If a three-wire cable is not
feasible, a length of no. 16 stranded fixture wire may be taped along the outside of the
two-wire cord. The ground may be fastened to a cold water pipe, if necessary.
b. All outlets, switches, sockets, and similar devices should be insulated and
grounded. Despite safety devices, always follow the "one-hand" rule, that is, when
operating electrical apparatus with one hand, avoid grounding yourself with the other.
Foot switches eliminate the use of hands in operating electrical equipment, but special
care must be taken in grounding them because of the likelihood of moisture on the floor.
c. A safelight installed in the ceiling of the entrance lightlock should have its switch
at a convenient height on the right side of the inner entrance. The white-light circuit
switch, however, should be high on the wall above the safelight switch so it will not be
turned on inadvertently. All safelights should be on the same circuit, but should have
individual switches. In manual processing, the film dryer should be on a separate circuit of
ample capacity. As an extra precaution, it is advisable to have all three main circuits (for
white light, safelight, and dryer) controlled by a single heavy-duty disconnecting switch in
addition to their individual switches.
THE LOADING BENCH
a. General. The loading bench is the primary component of the "dry" side
(manual) and "dark side" (automatic) of the processing room. It contains an area for
loading and unloading film holders, a cassette transfer cabinet, a film bin, compartments