UFC 3-560-01
6 December 2006
Including change 1, 7 December 2006
CHAPTER 11
UNDERGROUND LINES
11-1
UNDERGROUND WORK.
11-1.1
This chapter applies to work in manholes, vaults, and handholes; work on
duct lines, trenches, and underground cables; and work on ground-mounted and
underground equipment associated with underground electrical lines.
11-1.2
Treat underground structures such as manholes and unvented vaults as
confined spaces. For the Navy, conform to the requirements of the OPNAVINST
5100.23 Series, (Confined Space Entry Program).
11-1.3
All equipment inside an underground structure (including manholes and
vaults) operating at high voltage levels should be deenergized before allowing entry into
the underground structure. This includes insulated conductors. If the equipment inside
the manhole cannot be deenergized, apply the personal protective equipment
requirements of Tables 4-1 and 4-2. If a cable in an underground structure has one or
more abnormalities that could lead to or be an indication of an impending fault, the
defective cable must be deenergized before any employee can enter the manhole.
Note: Abnormalities such as oil or compound leaking from cable or joints, broken cable
sheaths or joint sleeves, hot localized surface temperatures of cables or joints, or joints
that are swollen beyond normal tolerance are presumed to lead to or be an indication of
an impending fault.
11-1.4
Do not switch or rack energized equipment in or out of switchgear in an
underground structure. For the Navy, comply with the NAVFACINST 5100.11 Series as
follows:
11-1.4.1 All activities shall secure, whenever feasible, all electrical power prior to start
of work in electrical vaults, manholes and other confined or enclosed spaces.
11-1.4.2 When absolutely not feasible to secure the power in these locations, refer to
paragraph 1-5.1 for guidance.
11-1.5
For the Air Force, work inside underground structures, including manholes,
requires special precautions and limitations. Refer to AFI 32-1064, Electrical Safe
Practices, for additional requirements.
11-2
GENERAL PROTECTION REQUIREMENTS.
11-2.1
Protect pedestrians, motorists, facility workers, and equipment by the use of
barriers, warning signs, lights, flags, traffic cones, high-level standards, barricade rope,
and flagmen, as appropriate for the job site.
||content||
\ Use the guidance from the current
11-1
Previous Page
