Common Violations of a Vague OSHA Electrical Standard

Misuse of Power Strips and Outlet Boxes Net Citations

February 1, 2016 - The OSHA electrical standard I am about to discuss sounds very vague when you first read it, to the point it is very easy to ignore the deeper meaning. But beware - this particular OSHA standard can be violated in so many different ways. So I felt compelled to give examples of the two most common ways I see this OSHA electrical standard violated in this month’s blog.

The standard I am referring to is 1910.303(b)(2) in the OSHA general industry standards for electrical safety. The same requirement appears in its twin, 1926.403(b)(2), which is located in the electrical safety standards for construction. These standards both state that “listed or labeled equipment shall be installed and used in accordance with any instructions included in the listing or labeling.” So first you must understand what is meant by “listing or labeling”.

Manufacturers of electrical equipment used in the United States (and most other countries) have their product evaluated and/or tested by an independent evaluating agent to demonstrate it complies with appropriate requirements regarding reasonably foreseeable risks associated with the product. That product is then listed and labeled by the independent evaluating agent for a specific use or purpose. The most commonly used independent company performing this evaluation service in the United States is Underwriters Laboratory (UL). So when you pick up any electrical tool, appliance, or component, it usually will be stamped or labeled with the UL certification mark (or something similar), and it will be listed in their documentation for a specific approved purpose (or purposes). But many times, people never bother to look up the listing which describes the specific purpose. As a result, we often use the tool or piece of equipment for purposes for which it was not listed or approved. And that, in turn, nets us an OSHA citation.

So how do you know the listed purpose of an electrical tool, piece of equipment or electrical component?  Often times that information is provided by the manufacturer in their product information. But of course we usually throw that type of information into the trash can as soon as we have opened the box!  So another source of this information that can be readily accessed is the UL White Book (click here to access this document). There you can look up a specific type of electrical equipment or components and, if it has been evaluated by UL, you will find the approved purpose(s), and in many cases, specific prohibitions. Now, with that background information in mind; here, based on my experience conducting inspections for clients, are two common ways employers violate the OSHA regulations cited above, based on the misuse of equipment according to its listed purpose in the UL White Book:

Power Strips: You see them used all the time in offices with printers, computers and space heaters plugged into them; or, they are permanently attached to portable carts or work benches and plugged into an extension cord so we can plug other stuff into the power strip; or, they are plugged into the end of extension cords being used out in shops and on construction sites to provide power to all sorts of tools or appliances. According to the UL listing for power strips, some of these uses are acceptable, and some are not.

power strip daisy chained osha violation                    power strip overload osha violation

These devices are actually called “relocatable power taps” in the UL book, and are referenced by the UL product category code XBYS. Sometimes power strips are equipped with an internal breaker and called a surge protector. Listing information about power strips / surge protectors is found on page 569 of the UP White Book at the link provided above. There we can see that power strips are only intended for indoor use, and never for use on construction sites and similar locations. They are intended to be directly connected to a permanently installed branch-circuit receptacle outlet only, and not intended to be series connected (daisy chained) to other relocatable power taps or to extension cords. In addition, they are not intended to be permanently secured to building structures, tables, work benches or similar structures, nor are they intended to be used as a substitute for fixed wiring. Last but not least, they are only rated for 20 amps or less of power in total, meaning they are typically intended for use only with a few smaller appliances (such as computers and printers) and not for connecting to higher amperage tools or appliances like microwave ovens and heaters (or refrigerators, or hammer drills, or grinders, or hoists . . .). And if this UL listing information is not evidence convincing enough to discourage misuse of power strips, OSHA has also issued a letter of interpretation regarding use (or misuse) of power strips at this link.

Standard Metallic Outlet Boxes: Information about standard metallic receptacle outlet boxes can be found under UL product category code QCIT, which appears on page 402 of the UL White Book.  There we see that standard metal boxes are usually mounted indoors, inside of or onto the face of the wall of a structure. They usually contain one or two dual electrical outlets for plugging things in to them, and have “knockouts” so they can be connected to metal conduits to enclose the conductor wires.  The boxes are also designed to be provided with an approved cover plate. But I commonly find these standard metallic outlet boxes attached to the end of a shop-fabricated extension cord running along the ground on construction sites, as well as across the floor in manufacturing shops (and even in some office and warehouse environments). And therein lies the problem.

Outlet Box OSHA Violation 1                                  Outlet Box OSHA Violation 2

According to the listing information in the UL White Book, standard metallic outlet boxes must be installed in accordance with Article 314 of ANSI/NFPA 70, which is The National Electrical Code. And that code describes how standard metallic outlet boxes are to be mounted onto solid structures and similar surfaces (like walls and electrical chase-ways), or as part of an approved pendant system. But nowhere does the code discuss installing a standard metallic outlet box so it dangles from the end of a portable extension cord being used out in the shop or on a construction site as a temporary power supply.

These are not the only situations where I see violations of the OSHA electrical standards requiring listed or labeled electrical equipment only be installed and used in accordance with any instructions included in the listing or labeling. But they are the most common. Have you seen these same misuses of power strips and standard metallic outlet boxes in the workplace? Can you think of other common misuses of equipment and components that would be violations of this standard? If you do, please comment on this topic (or read comments submitted by others) by clicking here to be directed to the “Comments” box for this blog post. And last but not least, I would like to encourage you to Share this Blog post with others in your Network who might benefit from reading this information. 


Curtis Chambers is a Certified Safety Professional (CSP) and holds a Master of Science degree in Occupational Safety and Health. He has held numerous leadership positions managing and evaluating health and safety programs and providing training on workplace safety and health topics at various public organizations and private corporations. Mr. Chambers is currently the President of OSHA Training Services Inc. Visit their website at  
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