Section 1926.953 contains requirements for entry into and work in enclosed spaces. These include manholes, vaults, tunnels, or shafts that have a limited means of egress or entry, is not designed for employee entry under normal operating conditions, and under these normal operating conditions, does not have a hazardous atmosphere. However, it can contain a hazardous atmosphere under abnormal conditions.
Usually in this case, the hazardous atmosphere is caused by lack of adequate ventilation in the space. This can normally be controlled through the use of continuous forced air ventilation. These types of practices are widely recognized and are currently used in electric, telecommunications, and other underground utility industries.
