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Subchapter 21. Telecommunication Safety Orders
Article 1. Telecommunications
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§8616. Underground Lines.

The provisions of this section apply to the guarding of manholes and street openings, and to the ventilation and testing for gas in manholes and unvented vaults, where telecommunications field work is performed on or with underground lines.

(a) Guarding Manholes and Street Openings.

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

(2) While work is being performed in the manhole, a person with basic first-aid training shall be immediately available to render assistance if there is cause for believing that a hazard exists, and if the requirements contained in Section 8604(a) and Subsection (a)(1) of this Section do not adequately protect the employee(s). Examples of manhole worksite hazards which shall be considered to constitute a hazard include, but are not limited to:

(A) Manhole worksites where hazards are created by traffic patterns that cannot be corrected by provisions of Section 8604(a) and Section 8616(a)(1).

(B) Manhole worksites that are subject to unusual water hazards that cannot be abated by conventional means.

(C) Manhole worksites that are occupied jointly with power utilities as described in Subsection (c) of this Section.

(D) Where combustible or explosive gas vapors have been initially detected at an explosive level.

(E) Where toxic or otherwise hazardous substances are used in such quantities that the work operations or inadvertent spills would create unsafe airborne concentrations or other bodily injury exposures.

(F) Where open flame torches are used in the work procedure.

(G) Where hazardous substances:--i.e. pesticides, herbicides, etc. are encountered.

(H) When employees are required to perform extended night work in manholes, except where constant voice communication is maintained with other person(s) who can render ready assistance. This shall not prohibit performing emergency trouble work without assistance providing the work can be performed safely.

(b) Requirements Prior to Entering Manholes and Unvented Vaults.

(1) Before an employee enters a manhole or unvented vault, the following steps shall be taken:

(A) The employer shall determine that a confined space condition as defined in General Industry Safety Orders Article 108 is non-existent. If a confined space condition exists, the requirements of Article 108 shall be followed. Otherwise, the requirements set forth herein shall be followed.

(B) The internal atmosphere shall be tested for combustible gas and, except when continuous forced ventilation is provided, the atmosphere shall also be tested for oxygen deficiency.

(C) When unsafe conditions are detected by testing or other means, the work area shall be ventilated by mechanical means and otherwise made safe before entry.

(2) An adequate continuous supply of air shall be provided while work is performed in unvented vaults and manholes under any of the following conditions:

(A) Where combustible or explosive gas vapors have been initially detected and subsequently reduced to a safe level by ventilation,

(B) Where organic solvents are used in the work procedure,

(C) Where open flame torches are used in the work procedure,

(D) Where the manhole or vault is located in that portion of a public right-of-way open to vehicular traffic and/or exposed to a seepage of gas or gases, or

(E) Where a toxic gas or oxygen deficiency is found.

EXCEPTION: Work in central office cable vaults that are adequately ventilated.

(c) Manhole Platform. A manhole platform shall consist of nominal 2-inch by 12-inch lumber of a grade no less than that of a "Structural Plank" as defined (see Lumber) in Section 1504 "Definition" of the Construction Safety Orders, or other nonconductive material of equal strength.

(d) Joint Power and Telecommunication Manholes. While work is being performed in a manhole occupied jointly by an electric utility and a telecommunication utility, an employee with basic first-aid training shall be available in the immediate vicinity to render emergency assistance as may be required. The employee whose presence is required in the immediate vicinity for the purposes of rendering emergency assistance is not to be precluded from occasionally entering a manhole to provide assistance other than in an emergency.

(e) Ladders. Metal ladders having non-skid rungs, wooden ladders or portable reinforced plastic ladders shall be used to enter and exit manholes exceeding 4 feet in depth.

(f) Flames. When open flames are used in manholes, the following precautions shall be taken to protect against the accumulation of combustible gas:

(1) A test for combustible gas shall be made immediately before using the open flame device, and at least once per hour while using the device; and

(2) A fuel tank (e.g., acetylene) may not be in the manhole unless in actual use.

NOTE: Authority and reference cited: Section 142.3, Labor Code.


1. Amendment filed 3-30-82; effective thirtieth day thereafter (Register 82, No. 14).

2. Amendment of subsections (b), (c) and (e) filed 11-3-87; operative 12-3-87 (Register 87, No. 45).

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