Sail Method of Manhole Ventilation
Work Inside Underground Structures. Work inside underground structures
requires special attention to general safety, familiarity with the cable and equipment being worked
on, and safety aspects applying to such underground work.
8.6.1 General Inside Structure Safety. All work should be done in a manner that
observes the following precautions
a. Continuous adequate ventilation is required.
b. While work is being performed in manholes or vaults, a worker should be available on
the surface in the immediate vicinity to render emergency assistance if required.
c. A ladder will always be used when entering or leaving a manhole or vault. Climbing
into or out of manholes or vaults by stepping on cables or cable supports is forbidden. Manhole
ladders, when not in use, should be placed so as not to be a hazard to workers, pedestrians, or
d. Use only flashlights or facility approved lighting units for illumination in manholes.
e. Tool handling should be done in a manner that protects the workers and work area.
Always place tools or materials a safe distance from manhole openings, where they will not cause