Regulations (Standards - 29 CFR) - Table of Contents Regulations (Standards - 29 CFR) - Table of Contents
• Part Number: 1926
• Part Title: Safety and Health Regulations for Construction
• Subpart: V
• Subpart Title: Power Transmission and Distribution
• Standard Number: 1926.956
• Title: Underground lines.


Guarding and ventilating street opening used for access to underground lines or equipment.


Appropriate warning signs shall be promptly placed when covers of manholes, handholes, or vaults are removed. What is an appropriate warning sign is dependent upon the nature and location of the hazards involved.


Before an employee enters a street opening, such as a manhole or an unvented vault, it shall be promptly protected with a barrier, temporary cover, or other suitable guard.


When work is to be performed in a manhole or unvented vault:


No entry shall be permitted unless forced ventilation is provided or the atmosphere is found to be safe by testing for oxygen deficiency and the presence of explosive gases or fumes;


Where unsafe conditions are detected, by testing or other means, the work area shall be ventilated and otherwise made safe before entry;


Provisions shall be made for an adequate continuous supply of air.



Work in manholes.


While work is being performed in manholes, an employee shall be available in the immediate vicinity to render emergency assistance as may be required. This shall not preclude the employee in the immediate vicinity from occasionally entering a manhole to provide assistance, other than emergency. This requirement does not preclude a qualified employee, working alone, from entering for brief periods of time, a manhole where energized cables or equipment are in service, for the purpose of inspection, housekeeping, taking readings, or similar work if such work can be performed safely.


When open flames must be used or smoking is permitted in manholes, extra precautions shall be taken to provide adequate ventilation.


Before using open flames in a manhole or excavation in an area where combustible gases or liquids may be present, such as near a gasoline service station, the atmosphere of the manhole or excavation shall be tested and found safe or cleared of the combustible gases or liquids.


Trenching and excavating.


During excavation or trenching, in order to prevent the exposure of employees to the hazards created by damage to dangerous underground facilities, efforts shall be made to determine the location of such facilities and work conducted in a manner designed to avoid damage.


Trenching and excavation operations shall comply with 1926.651 and 1926.652.


When underground facilities are exposed (electric, gas, water, telephone, etc.) they shall be protected as necessary to avoid damage.


Where multiple cables exist in an excavation, cables other than the one being worked on shall be protected as necessary.



When multiple cables exist in an excavation, the cable to be worked on shall be identified by electrical means unless its identity is obvious by reason of distinctive appearance.


Before cutting into a cable or opening a splice, the cable shall be identified and verified to be the proper cable.


When working on buried cable or on cable in manholes, metallic sheath continuity shall be maintained by bonding across the opening or by equivalent means.

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Regulations (Standards - 29 CFR) - Table of Contents Regulations (Standards - 29 CFR) - Table of Contents