Resetting circuit breakers after a protective trip

November 19, 2001

Mr. Edward M. Corcoran

Consultant

EMC Code Consultants

[Recipient address omitted]

Dear Mr. Corcoran:

Thank you for your May 24, 2001, letter to the Occupational Safety and Health Administration's (OSHA's) Office of General Industry Compliance Assistance (GICA). This letter constitutes OSHA's interpretation only with respect to the requirements discussed and may not be applicable to any scenario not delineated within your original correspondence. You made specific statements regarding your understanding of 29 CFR 1910.334(b)(2) and asked for our comments on your interpretation. Your statements have been paraphrased into questions in this response.

1910.334(b)(2), Reclosing circuits after protective device operation. After a circuit is de-energized by a circuit protective device, the circuit may not be manually reenergized until it has been determined that the equipment and circuit can be safely energized. The repetitive manual reclosing of circuit breakers or re-energizing circuits through replaced fuses is prohibited.

Note: When it can be determined from the design of the circuit and the over current devices involved that the automatic operation of a device was caused by an overload rather than a fault condition, no examination of the circuit or connected equipment is needed before the circuit is reenergized.

Question 1: May unqualified personnel reset a circuit breaker or replace fuses without having a qualified person investigate why the breaker tripped or the fuse blew?

Reply: Paragraph (b)(2) requires an evaluation to determine whether equipment and circuits can be safely reenergized prior to operating a manual circuit protective device. However, as the "Note" advises, if employees can verify an overload condition from the de-energized circuit, then no examination is needed before the circuit is reenergized. In this situation, an unqualified employee could reset the breaker or replace the fuse once, if doing so would not expose the employee to electrical parts that are energized above 50 volts.

Question 2: Should an unqualified employee be allowed to reset a circuit breaker more than once without determining the cause of the circuit malfunction?

Reply: If the breaker referenced in question #1 tripped again, then the circuit and/or equipment must be examined and repaired by a qualified person before it could be reenergized. Paragraph (b)(2) prohibits the repetitive manual reclosing of circuit breakers or reenergizing circuits through replacement fuses.

Question 3: Are equipment operators and foremen considered electrically unqualified to evaluate and reset circuit breakers?

Reply: According to subsection 1910.332(a), employees exposed to electric shock or other electrical hazards that are not reduced to a safe level by the electrical installation requirements of sections 1910.303 - 308 must be trained in the electrical safety-related work practices contained in sections 1910.331 - 335. Paragraph 1910.333(c)(2) states that only qualified persons may work on electric circuit parts or equipment that has not been de-energized under the lockout/tagout provisions of subsection 1910.333(b). Additionally, paragraph 1910.334(c)(1) stipulates that only qualified persons, i.e., those familiar with the construction and operation of the equipment and the hazards involved, may perform testing work on electric circuits or equipment.

Therefore, qualified persons must have electrical-related training sufficient to effectively avoid the electrical hazards associated with work on, or near, exposed energized parts. These qualified persons must be capable of working safely on energized circuits. This capability includes familiarity with the proper use of: special precautionary techniques, personal protective equipment, insulating or shielding materials, and insulated tools. The operator or foreman would have to meet the qualifications referenced above (and fully detailed in Subpart S) before examining or troubleshooting a circuit that is energized above 50 volts.

Question 4: Are operators and foremen allowed to reset circuit breakers where the operator or foreman must open a piece of electrical equipment and become exposed to parts energized above 50 volts?

Reply: See reply to Question 3.

Question 5: Would resetting circuit breakers with the manufacturer's metal enclosure door opened on 480-volt equipment be allowed if the exposed energized parts are covered by a plexiglass barrier as a substitute for the protection normally afforded by the metal enclosure when the breaker is tripped?

Reply: Employees may only use electrical equipment that has been tested and determined to be safe for use in a specified configuration by a nationally recognized testing laboratory (NRTL). The electrical equipment must be used in accordance with the manufacturer's instructions or any instructions included with the listing or labeling. Therefore, the only approved use of the referenced enclosure would be that prescribed by the manufacturer whose instructions must concur with NRTL test results, i.e., metal door attached and in its operating position during breaker manipulations.

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 apprised 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