Section 125.32 - Construction of Manholes(1)Minimum Strength. The design and construction of manholes and handholes shall provide sufficient strength to sustain, with a suitable margin of safety, the loads which may reasonably be imposed on them.(2)Dimensions. Manholes should meet the following requirements where practicable: (a)Width. The least horizontal inside dimension should be not less than three feet six inches.(b)Working Space. A clear working space should be provided. The horizontal dimension should be not less than three feet. The vertical dimension should be not less than six feet except in manholes where the opening is within one foot on each side of the full size of the manhole.(3)Drainage. Where drainage is into sewers, suitable traps shall be provided to prevent entrance of sewer gas into manholes.(4)Manhole Openings. Round openings to any manhole should be not less than 24 inches in diameter. Rectangular openings should have dimensions not less than 24 by 20 inches.(5)Manhole Covers. Manholes and handholes, while not being worked in, shall be securely closed by covers of sufficient strength to sustain such loads as may reasonably be imposed upon them.(6)Supports for Cables. Cables should be adequately supported at each manhole.(7)Manhole Location. Manhole openings shall, where practicable, be located so that barriers or other suitable guards can be placed to protect the opening effectively when uncovered.