11 2024 4hr Warning Labels & Boundaries 3 of 6

Reading an Electrical Hazard Warning Label

The video explains how to interpret an electrical hazard warning label and use its information to protect workers and others nearby.

Signal word and intended audience

The example label begins with “Warning” and “Qualified persons only.” Qualified workers are expected to understand and act on the hazard information that follows.

Arc-flash energy and working distance

The example lists an incident energy of 7.84 cal/cm² at a working distance of 18 inches. These values come from an engineering analysis and describe the hazard under the assumptions used in that study.

Arc-flash boundary

The label gives an arc-flash boundary of 57 inches. This boundary describes a zone around the equipment, not just a point directly in front of it. Consider all relevant sides—including behind, above, and below the equipment—and control access in open or elevated areas.

PPE requirements

The label’s recommended PPE is a minimum. Workers should reassess the risk if conditions have changed or the equipment may not operate as expected, since the actual hazard could be greater than the study indicates.

The task or environment may also require additional, non-electrical PPE, such as fall protection or high-visibility clothing. These requirements may not appear on the electrical hazard label.

Some sites use PPE kits identified as Levels 1–4. Match the assigned level to the ratings marked by the PPE supplier, and check that the equipment is inspected, in good condition, free of stains or tears, and suitable for use. The video says Level 2 may cover Levels 1 and 2, while Level 4 may cover Levels 3 and 4.

Danger labels

A Danger label signals a more severe hazard for which ordinary site-specific PPE may not be adequate. The discussion notes that commonly used PPE often tops out around 40 calories; higher-rated suits may require specialized personnel or contracted work. The Danger signal uses white lettering on a red background.

Shock protection and boundaries

The label includes the nominal voltage and the minimum glove class required for shock protection. Compare the arc-flash and shock boundaries, and use whichever extends farther when protecting people and restricting access.

Equipment and study information

The label also identifies the equipment and lists the available short-circuit current, which helps confirm that the equipment is rated to withstand a fault.

Check when the label was prepared. If it is more than five years old, have the study reviewed and update the label if needed. Review it sooner if the equipment or site has changed—for example, after a refeed, renovation, or equipment relocation.

Speakers and sources featured

The primary presenter is unnamed and explains the warning-label information and safety considerations. Caitlyn is addressed by name and appears to participate with brief acknowledgments or responses.

The sources referenced include an engineering analysis or study and PPE suppliers’ equipment ratings.