(1) Guarding manholes and street openings.

(a) When covers of manholes or vaults are removed, the opening must be promptly guarded by a railing, temporary cover, or other acceptable temporary barrier to prevent an accidental fall through the opening and to protect employees working in the manhole from foreign objects entering the manhole.

(b) When work is to be performed on underground plant, the immediate foreman in charge and/or the craftsman assigned to do the work must make a complete job hazard assessment of the work location in regard to the hazards that are created or that could exist prior to beginning the work in underground plant.

(c) The immediate foreman and/or the craftsman responsible for the job completion must be in agreement of the proper method of eliminating or reducing any hazards that are present or could be caused by the location of the worksite, before the job proceeds.

(2) Requirements prior to entry of manholes and unvented vaults.

(a) The internal atmosphere must be tested for oxygen deficiency and combustible gas.

(b) Mechanical forced air ventilation must be in operation at all times when employees are required to be in the manhole.

(c) The mechanical forced air equipment provided must be of a quantity to replace the exhausted air and must be tempered when necessary.

(d) Ventilation equipment must be designed in such a manner that employees will not be subjected to excessive air velocities.