Standard Interpretations - Table of Contents|
| Standard Number:||1910.269; 1910.333|
February 26, 1996
Mr. John Cadick
Dear Mr. Cadick:
This in response to your July 23, 1995 letter requesting an interpretation of the application of the minimum approach distances in 1910.269 of the electric power generation, transmission, and distribution standard and in 1910.333 of the electrical standard as they apply to the servicing and maintenance of several 69 kilovolt (kV) air, disconnect switches. Your workplace scenario and question and our reply follow. Please accept our apology for the delay in responding.
Scenario: The aforementioned switches are of vertical configuration with the supply (energized) side on the top and the load (de-energized) side on the bottom. The bottom side is the blade side and the top is the jaw. To de-energize the top portion of the switch would, in many cases, require that the entire facility be shut down.
With the switch open, the bottom side has a clearance distance of at least 3 feet from the top. Employees work on the bottom of the switches de-energized with the top still energized. The work consists of cleaning, lubricating, and adjusting the switches. While working on the bottom of the switches, the workers are enclosed in an equipotential, grounded zone. The workers are instructed to stay within the equipotential, grounded zone and to stay at least 3 feet away from the top of the switch. The workers are also instructed to keep all tools and equipment they use at least 3 feet away from the energized top portion of the switch.
All workers have received the training stipulated in section 1910.269 and 1910.332 and have met the requirements for qualified employee as defined in paragraph 1910.269(x) and paragraph 1910.399. A copy of the drawing included in your letter as a rough illustration of the work arrangement is enclosed to facilitate our reply.
Question: Several employees are concerned for their safety when using tools and materials which could contact the energized part of the switch when performing servicing and maintenance on the lowered, de-energized portion of an air, disconnect switch as delineated in the preceding scenario. In addition to using qualified employees who are trained, what other provisions of the 29 CFR 1910.269 or 29 CFR 1910 Subpart S - Electrical standard are applicable to the employer to provide for the safety of employees working in the workplace scenario above?
Reply: The interface between 1910.269 and 29 CFR 1910 Subpart S - Electrical is addressed in 1910.269 Appendix A. A copy of the Occupational Safety and Health Administration's (OSHA's) August 29 letter to the Aluminum Company of America (Mr. Daryld Ray Crow) which includes interface clarification applicable to the scenario above is enclosed for your use.
For the type of installation you described, 1910.269 normally would be the applicable standard. Under paragraph 1910.269(l)(2), an employer must ensure that no employee approaches or takes any conductive object closer to parts (such as the top portion of the switch) when energized and exposed unless paragraph 1910.269(l)(2)(i) (See paragraph 1910.269(l)(3)), (l)(2)(ii) or (l)(2) (iii)) is met.
As specified in Table R-6 of 1910.269 for phase to phase nominal voltages of 46.1 to 72.5 kilovolts, the minimum approach distance when phase to ground exposure is the concern is 3 feet (0.9 m) which is the clearance between the blade side on the bottom and the jaw at the top of the switch. To comply with this requirement, the employer must ensure that employees position themselves so that the minimum approach distance is maintained over the full range of anticipated movements. These include movements planned as part of the job and other movements that the employee could reasonably be expected to take, such as adjusting a hard hat or reaching for a tool. In short, employees must be positioned so that the employees and any conductive objects they handle, over the full range of their anticipated movements, are outside the minimum approach distance.
Under paragraph 1910.269(l)(1)(i)(C), at least two employees must be present while performing servicing and maintenance of a 69 kV air, disconnect switch (as described in the preceding scenario) if an employee is exposed to contact with the energized top portion. The exception to the requirement is when the work is performed with live-line tools if the employee is positioned so that he or she is neither within reach of nor otherwise exposed to contact with energized parts as required under paragraph 1910.269(l)(1)(ii)(B).
No matter how many employees are used, the employer must ensure safe working position for the servicing and maintenance employees an required under paragraph 1910.269 (l)(4). Also, the employer must comply with the job briefing requirements under paragraph 1910.269(c) before his or her employee(s) start each job.
We appreciate your interest in occupational safety and health. If we can be of further assistance, please contact the Office of General Compliance Assistance, Mr. Ronald Davies, telephone (202) 219-8031, extension 110.
Standard Interpretations - Table of Contents|