MIL-HDBK-1025/10
6.5.1.4 Inching. Inching is an unauthorized method of opening manually-
operated nonloadbreak disconnects in a gradual manner, when the operator believes there
is no load current. Inching is dangerous and this practice is prohibited.
6.5.2 Oil Switches. The consequences of operating a faulty oil switch or
closing into a faulted circuit with an oil switch are likely to be devastating and possibly
fatal. Switching procedures should be developed at each facility to make sure that no
energized oil switch is operated while workers are in the vicinity.
a. Unless the switch has been equipped to operate from a remote location at least
6 meters (20 feet) away, the switch should be completely de-energized before switching.
Switch position and grounding conditions should be verified before operation. Many
manufacturers recommend that no medium-voltage oil switch is to be operated unless
routine maintenance, including oil testing, has been performed within the past year.
b. Oil switches should incorporate a mechanical stop to prevent inadvertent
operation to ground. Any abnormalities or defects discovered in any oil switch should be
reported to the supervisor.
6.5.3 Similar Switching Sections. When switch bays, cells, or compartments
are similar to adjacent sections, the separation barrier between sections should be painted
an appropriate color to prevent the possibility of pulling the wrong blade.
Fusing Safety. Always remember that a fuse is a single-phase device.
6.6
Fuses can be subject to partial melting or damage by currents that may not be of sufficient
magnitude to blow the fuse.
WARNING
Fuses may fail during handling if energized, creating arc blast
hazards. Wear fire resistant clothing and/or switching suits when
changing energized fuses in accordance with Table 11 distances.
6.6.1 Fuse Handling. Fuses should normally not be handled, except when they
need to be replaced. Remove them completely and as speedily as possible. When
replacing fuses in primary fuse cutouts, do not use your free arm to shield your eyes from
possible flashes. Always use safety glasses. The person changing the fuses should stand
firmly on a level surface and, where operating in an elevated position be secured with a
safety harness to prevent a slip and fall if there is a flash. Fuse sticks should be used in all
instances.
6.6.2 Operation of Energized Fuses. Open all lines protected with energized
fuses in the same manner as for air switches. De-energize nonloadbreak installations. For
loadbreak installations provide a time delay after fuse replacement, in order to allow the
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