Arc Flash Labeling Requirements

What Needs to be Labeled, By Whom?
The NEC states that any of the following types of electrical equipment located in manufacturing and commercial establishments (other than dwelling occupancies) must be field marked with a warning label if subject to examination, adjustment, service or maintenance while energized:

The labeling requirement is the responsibility of the employer, not the manufacturer or installer of the equipment.

Since the provision took effect in 2002, equipment installed before then technically does not need to be labeled. However, labeling does need to be applied if the equipment is ever modified or upgraded in any way. At least one OSHA representative has stated that he considers changing a use or a breaker to be a modification that would require labeling. More importantly, from a safety standpoint, the hazard is the same regardless of when the equipment was installed. Consequently, most employers are simply labeling all the appropriate equipment, regardless of when it was installed.

Many employers are also labeling bus ducts and other electrical equipment not specifically called out in 110.16. Again, the logic is the same. If live electrical work may be performed on these systems, the risk of accident and injury exists. Clearly it is better to properly warn workers of the hazard.

The NEC requirement states that the marking must be located so that it’s clearly visible to qualified persons before they begin work. Typically, the label is placed outside the panel or enclosure door. In some cases, however, companies choose to put the label inside the door (e.g., to protect it from harsh environments), but this should only be done if the door must first be opened (allowing the label to be seen) before the panel face or enclosure can be removed. The key point is that the label be easily noticeable by workers before they may be exposed to any potentially dangerous live parts.