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Standard Interpretations - Table of Contents
• Standard Number: 1926.550(a)(15) ; 1910.269; 1910.331(b); 1910.333; 1926.952

OSHA requirements are set by statute, standards and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at

December 7, 1999

Mr. M.F. Game
13263 48th Ct. N.
Royal Palm Beach, Fl 33411

Dear Mr. Game:

Thank you for your October 24, 1996 letter to the Occupational Safety and Health Administration's (OSHA's) [Directorate of Enforcement Programs (DEP)]. You have a question regarding an unqualified crane operator contractor, who is being guided by a qualified Journeyman electrician, working in close proximity to unguarded (7,620 to 500,000) voltage. Please accept our apology for the delay in responding.

In your scenario, this qualified person has been assigned to work with the contracted crane operator (an unqualified electrical person) in a space less than you believe is safe (10 feet or greater) as specified in 29 CFR §1926.550(a)(15) construction safety standards. Additionally, your corporate safety department, in response to your concerns, referenced Table R-6, Live-Line Work Minimum Approach Distance, from 29 CFR §1910.269, on Electric Power Generation, Transmission and Distribution. This work is performed in an electrical substation.

Question: Is it permissible for an unqualified employee to work within the 10 foot minimum clear distance between the overhead lines (rated at 50 kilovolts or less) and any part of the crane even if he or she is observed by another qualified employee?

Response: No, an unqualified employee, who is operating a crane, cannot work within the 10 foot minimum clear distance between the overhead line (rated at 50 kilovolts or less) and any part of the crane even if he or she is observed by another qualified employee.

For your information, I am including an explanation of the standards that apply to construction, operation and maintenance of transmission and distribution lines and general industry work performed with a crane.

The type of work performed with the crane: OSHA's regulations define "construction work" as "construction, alteration, and/or repair, including painting and decorating" [29 CFR §1926.32(g) and 29 CFR §1910.12(b)]. Also, according to paragraph 1926.950(a)(1), construction includes the erection of new electric transmission and distribution lines and equipment, and the alteration, conversion, and improvement of existing electric transmission and distribution lines and equipment. This type of work is covered by the requirements of Subpart N and Subpart V of Part 1926. On the other hand, the 1910.269 standard applies to the operation and maintenance of transmission or distribution lines.

When the work falls under OSHA's Construction Standards, §1926.550(a)(15) provides two options where operations are closer than 10 feet from the power line. One option is to deenergize and visibly ground the line. The other option is to use insulating barriers to prevent physical contact with the line. In your scenario, the crane operator (if performing construction operations) would need to meet the minimum clearance distances and other related safety requirements as specified in §1926.550(a)(15) unless one of the two described exceptions are met. In addition, under section §1926.550(a)(15)(iv), an observer would be required for the purpose of providing timely warning for all operations of the crane where it is difficult for the crane operator to maintain the required clearance distances by visual means. The observer must be positioned so as to be able to visually monitor the clearance between the equipment and the power lines. The designated observer cannot be assigned other duties that interfere with the ability to give a timely danger warning to the crane operator.

When the work falls under the General Industry Standards and is performed by unqualified persons (as is the case in your crane operator example), working near electrical power generation, transmission, and distribution installations is covered by Subpart S [see §1910.331(b)]. The safety-related work practice requirements of Subpart S permit only qualified persons to work on electric circuit parts and equipment that have not been deenergized under the procedures of §1910.333(b). (The electric power generation, transmission and distribution standard does not cover electrical safety-related work practices for unqualified employees [see §1910.269(a)(1)(ii)]. Please be advised that the reference to the mechanical equipment provision, 1910.269(p), is not applicable in the situation described in your request since the crane operator is an unqualified employee.)

Paragraph 1910.333(c)(3) contains electrical safe work practices for overhead power lines. If work is to be performed near overhead lines, the line must be deenergized and grounded, or other protective measures must be implemented before work is started. If protective measures are provided, such as guarding, isolating, or insulating, these precautions must prevent employees from contacting such lines directly with any part of the body, or indirectly through conductive materials, tools, or equipment.

Paragraph 1910.333(c)(3)(iii) applies to the operation of mechanical equipment, such as cranes, near overhead power lines. This provision requires that equipment be operated so that a clearance of 10 feet from any energized overhead line is maintained. This clearance distance must be increased by 4 inches for every 10 kilovolts over 50 kilovolts. Exceptions for cranes are made when (1) vehicles are in transit with their structure lowered or (2) when an insulating barrier has been erected to prevent contact with the line. The barrier must be rated for the voltage of the line being guarded and must not be a part of or attachment to the vehicle or its raised structure. Maintaining these clearances protects the unqualified employee, who is not trained in the recognition and avoidance of the hazards involved, from contacting the energized lines or equipment involved.

Crane operators who are "qualified persons": The OSHA safety requirements differ for qualified [versus] unqualified persons who are mechanical equipment operators. Existing rules in Subpart V of the Construction Standards, and §1910.269(p)(4) of the General Industry Standards, require mechanical equipment to be kept away from exposed energized lines and equipment, at distances greater than or approximately equal to those set forth in Table R-6 of 1910.269. Table V-1 provisions on derrick trucks, cranes and other lifting equipment, as referenced by §1926.952, provide minimum working distances for the construction of power transmission and distribution systems. These specific requirements permit only qualified persons to operate mechanical equipment closer than the previously described 10 foot provisions.

Electrical contact with uninsulated vehicular equipment or suspended loads, such as occurs in pole setting or other similar operations, cannot simply be avoided. Therefore, additional safety requirements, as specified in §1910.269(p)(4), are necessary when operating mechanical equipment near exposed electrical lines where there is a possibility of dangerous voltages being impressed or induced on mechanical equipment. These employee protection measures include the minimum approach distances (of Tables R-6 through R-10), the use of safety observers, and supplemental protective measures if the employer knows or reasonably could know that the hazard of the mechanical equipment's becoming energized during operation exists. Some supplemental protective measures include the use of overhead line insulation, equipment insulation, equipment grounding/bonding, and the use of electrical protective equipment.

The above described general industry versus construction differences exist, but the common requirement for overhead lines is employee protection. The agency recognizes that there are "gray" areas when determining whether a contractor is engaged in construction or general industry which may involve servicing or maintenance-type work. Consequently, these decisions must be made on a case by case basis. When there is uncertainty, OSHA would encourage employers to apply the more protective standard. An employer who does this will have addressed the hazard and is not likely to be cited.

Thank you for your interest in occupational safety and health. We hope you find this information helpful. Please be aware that OSHA's enforcement guidance is subject to periodic review and clarification, amplification, or correction. Such guidance could also be affected by subsequent rulemaking. In the future, should you wish to verify that the guidance provided herein remains current, you may consult OSHA's website at If you have any questions, please feel free tocontact the [Office of General Industry Enforcement at (202) 693-1850].


Richard E. Fairfax, Director
[Directorate of Enforcement Programs]

[Corrected 5/26/2005]

Standard Interpretations - Table of Contents

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