14 2024 4hr Warning Labels & Boundaries 6 of 6

Barricades and Attendants

Use barricades together with safety signs when access to areas containing exposed energized parts must be limited or prevented. A barricade should provide a physical warning while still allowing workers to leave the area in an emergency. Cones and danger tape are appropriate examples; improvised obstacles such as stacked tables or pallets are not.

Assign an attendant to control access if people ignore signs or barriers, or if the area cannot be effectively barricaded. In busy locations such as hallways, more than one attendant may be needed. The presenters describe stopping work and placing attendants at both ends of an aisle, with another person watching the worker performing the task.

Arc-Flash Labels

Electrical equipment that may need to be opened for servicing, maintenance, adjustment, or troubleshooting should have an arc-flash label when an arc-flash hazard is possible. Labels provide hazard information, including the arc-flash boundary and the PPE required for work within that boundary.

Equipment that may require labels includes:

• Panelboards and disconnects
• Control cabinets
• Switchboards and switchgear
• Motor control centers
• Overhead bus duct

Labels should be easy to find and read, generally around eye level. Large or multi-section equipment may need multiple labels. For overhead bus duct, larger labels should be visible from the ground and placed every 25–30 feet. Each section of a motor control center should also be labeled.

Reviewing and Updating Studies and Labels

Arc-flash labels are not permanent. Review them at least every five years, and update the analysis and labels whenever a change could affect the study results. Examples include changing a breaker or its settings, installing different fuses, refeeding equipment, or adding or removing equipment.

Keep the one-line diagram accurate. It serves as a map of how equipment is connected upstream and downstream; the analysis and labels are reliable only if that information is current.

Speakers and Sources

Two unnamed presenters discuss requirements and practical examples. One presenter shares a personal example from conducting an arc-flash assessment in a busy hallway.