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.

March 12, 1998

Mr. John Wilson
Alcan Rolled Products Company
Box 32850
Louisville, KY 40232-0850

Dear Mr. Wilson:

This is response to your January 13 letter request for interpretation of 29 CFR General Industry Standards covering electrical safety in the workplace. Your letter, addressed to Mr. Steven F. Witt, Director of the Directorate of Technical Support, was forwarded to this office for reply. Please accept our apology for the delay in responding. Your scenario and questions along with our replies follow.


According to Table S-4 of 29 CFR 1910.332, welders are among those employees who are required to be trained because they face a risk of electrical shock that is not reduced to a safe level. Footnote (1) at the bottom of the table exempts certain employees from requiring the training if they do not work in close proximity to exposed parts of electric circuits operating at 50 volts or more to ground. However, the application of the footnote is not indicated for the occupation of welders. Since the secondary voltage on the majority of arc welding machines is less than 50 volts, it is quite possible that the job requirements for certain welders would not cause them to be exposed to energized parts of more than 50 volts.

Question 1:

In the scenario above, is it permissible to exempt the employee or employees from the requirement of training?


No. Welder training is covered by 29 CFR 1910 Subpart Q - Welding, Cutting, and Brazing. Under paragraph 1910.252(a)(2)(xiii) of Subpart Q, management must recognize its responsibility for the safe usage of cutting and welding equipment on its property and under paragraph 1910.252(a)(2)(xiii)(C), insist that cutters and welders and their supervisors are suitably trained in the safe operations of their equipment and the safe use of the process. Welding electrical safety and welder training requirements are covered under §1910.254 Arc welding and cutting and under §1910.255 Resistance welding.

Question 2:

Section 1910.332(c)(1) [sic] makes reference to electrical transmission and distribution systems. These terms are also used throughout §1910.269. What is the formal definition of "transmission,"what is the formal definition of "distribution," and what is the difference between the two types of systems?


Generally, the electric power system is delineated by generation, transmission, distribution and utilization.

"Transmission" means the part of the system used to transport bulk supplies of electric power from one or more generating sites to a market load center. An electric power generating site may be remotely located or nearby. When supplied via transmission lines from a remote generating station, the load center is a bulk power substation. When supplied from a nearby generating station, the load center is the generating station.

Also, transmission includes the interconnections used to supply electric power from more than one source. These interconnections provide diversity to ensure electrical power in an emergency and to respond to fluctuating, for example, unusually high, market demands.

"Distribution" means the part of the system between the market load center and the consumer's services. Distribution systems can be divided into the following six parts: subtransmission circuits, distribution substations, distribution or primary feeders, distribution transformers, secondary circuits (or secondaries), and consumers' service connections and meters (or consumers' services). See the enclosed diagram.

From the standpoint of a utility system, distribution is between the generating source, or intervening substations, and the customer's entrance equipment. From the standpoint of the customer's internal system, distribution is between a source or receiving station within the customer's plant and the points of utilization.

The source of this reply and of the enclosure is the "Electrical Transmission and Distribution Reference Book" published by Westinghouse Electric & Manufacturing Company, Third Edition, 1944.

We appreciate your interest in worker safety and health. If we can be of further assistance, please contact the Office of General Industry Compliance Assistance, Mr. Ronald J. Davies, telephone #(202) 219-8031, extension 110.


John B. Miles, Jr., Director
Directorate of Compliance Programs