January 3, 2002

Mr. Tommy P. Lucas
Program ManagerA
Tennessee Valley Authority (TVA)
400 West Summit Hill Drive
Knoxville, TN 37902-1401

Dear Mr. Lucas:

Thank you for your December 27, 2000 letter to the Occupational Safety and Health Administrations's (OSHA's) Directorate of Compliance Programs (DCP). This letter constitutes OSHA's interpretation only of the requirements discussed and may not be applicable to any situation- not delineated within your original correspondence. You had specific questions regarding the Electric Power Generation, Transmission, and Distribution standard (29 C.F.R. §1910.269). Please accept our apology for the delay in responding. Your scenario, questions, and our replies follow.

Scenario:  TVA nuclear plants use waxed cotton string to attach tagout devices. The string has a break strength greater than 50 pounds, which is substantial enough to prevent inadvertent or accidental removal.

Waxed string, which is secured to a clearance card, remains attached to the clearance card when cut loose from the energy isolating device. This provides a high level of confidence that the card and string will be removed from the area and disposed of properly. In contrast, nylon cable ties are not easily attached to the clearance card in a manner that ensures the cable tie will remain attached to the card when it is cut loose from the energy isolation device. As a result, there is a high probability that the wire tie can separate from the clearance card and be lost, thus causing an increase in radioactive waste or clogging floor drain lines.

Some of the equipment at the nuclear plants is not designed to accept the nylon wire ties and the cost of modifying the equipment is expensive.⁽¹⁾ TVA's equipment clearance (tagout) process is very rigorous and thoroughly documented, and a “Problem Event Report” would be issued when a clearance card is inadvertently or accidentally removed from a clearance isolation device. The lack of events and near miss experience, from 1994 to present, shows TVA's high level of confidence in the clearance card and waxed string method.

Question #1:  Will the use of waxed cotton string in lieu of nylon cable ties for attaching clearance tags to energy isolating devices be considered in compliance with 29 CFR 1910.269(d)?

Reply:  Please be aware that a Memorandum of Understanding (OSHA Instruction CPL 2.86, which is enclosed with this letter) between the U.S. Nuclear Regulatory Commission (NRC) and OSHA delineates areas of responsibility for each agency in nuclear power plants. For example, the OSHA standard does not apply to servicing and maintenance on machines or equipment that affect the safety of licensed radioactive material and thus present an increased radiation hazard to workers. This letter addresses only plant machinery or equipment for which OSHA has authority to inspect pursuant to the Occupational Safety and Health Act.

With respect to the isolation of hazardous energy associated with equipment and machines that are within the scope of OSHA's authority, the waxed cotton string, by itself, is unacceptable because it is neither non-reusable nor self-locking. Paragraph 1910.269(d)(3)(ii)(D) contains these additional tagout device features to ensure that tags do not become disconnected or lost during use, thereby negating their effectiveness. Tagout devices having reusable, non-locking, easily detachable means of attachment (such as string, cord, or adhesive) are not permitted pursuant to the standard.

You have asserted that using a nylon cable tie, in lieu of waxed cotton string, to attach a tagout device and clearance card may produce an increased risk of radioactive waste or a clogging of drain lines. Other means, such as threading the tie through the tag's hole twice or using tight-fitting cable ties, can be used to secure the cable ties so that they will not come off the tag after being cut.

However, nothing inherent to the tie, or the manner in which the tie is used, makes it likely that the tie will be misplaced, potentially clogging a drain line or producing radioactive waste. Like all materials used in this work environment, care should be taken, and effective housekeeping procedures followed, to ensure that materials are not misplaced or left behind in a manner that could produce such adverse consequences.

Question #2:  If the answer to question #1 is “No,” are there exceptions to the requirement where waxed cotton string or some other attachment means would be acceptable? Please provide examples.

Reply:  No.

Question #3:  Does the means of attachment need to be self-locking?

Reply:  Yes.

Thank you for your interest in occupational safety and health. We hope you find this information helpful. 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 appraised of such developments, you can consult OSHA's website at http://www.osha.gov. If you have any further questions, please feel free to contact the Office of General Industry Compliance Assistance at (202) 693-1850.

Sincerely,



Richard E. Fairfax, Director
Directorate of Compliance Programs

Enclosure

Footnote 1 - Where a tag cannot be affixed directly to the i solating device (because it is not capable of being locked out), the tag must be securely affixed as close as safely possible to the isolating device, in a position that will be immediately obvious to anyone attempting to operate the device. Where tagout devices are used with energy isolating devices capable of being locked out, the tag attachment must be fastened at the same point at which the lock would have been attached. Please note that after November 1, 1994, whenever major replacement, repair, renovation, or modification of machines or equipment is performed, and whenever new machines or equipment are installed, energy isolating devices must be designed to accept a lock. See §§1910.269(d)(2)(ii)(C) and 1910.269(d)(6)(iv)(B). [Back to text]