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What's Wrong Here?

Feb 4, 2010 5:06 PM, By Brian J. McPartland, NEC Consultant

Although not completely clear in this photo, this installation is at a commercial occupancy. As a result, it shows a clear violation of 110.16, which calls for the field marking of certain pieces of equipment to alert operations/maintenance personnel of a potential arc flash hazard.

The requirement of 110.16 says, "Electrical equipment, such as switchboards, panelboards, industrial control panels, meter socket enclosures, and motor control centers, that are in other than dwelling occupancies — and are likely to require examination, adjustment, servicing, or maintenance while energized — shall be field marked to warn qualified persons of potential electric arc flash hazards. The marking shall be located so as to be clearly visible to qualified persons before examination, adjustment, servicing, or maintenance of the equipment."

There is no question that this meter can would be required to have an arc flash "warning label" to satisfy 110.16, but what about the disconnects? Are they required to be marked? It doesn't appear so, as disconnects are not specifically mentioned in the first sentence of this Code section.

Here's another question that comes to mind with regard to satisfying this rule. If, for example, there were two panelboards (one on either side of the inverter) at this location, would all three pieces of equipment have to be marked with an arc flash warning label, or would a single label on the meter can be enough to satisfy this labeling requirement? My interpretation is that all three pieces of equipment would have to be marked. Even though "qualified persons" should be knowledgeable enough to understand that if the meter can is marked, then the equipment on either side of it has the same potential for such a hazard.

Field markings are critical elements for safety. There are a good number of field markings required by the Code — from circuit directories to series combination rated overcurrent protection to warning labels. It has also been adjudicated that for every Code-required warning label, the label must identify the hazard and give direction with regard to the action that must be taken. For example, with an arc-flash warning label, the sign should say something like, "Arc Flash Hazard. Proper Personnel Protective Equipment Required." This type of warning sign would serve to completely satisfy both the Code rule and the legal criteria that have been established for any Code-required warning label.

Lastly, it should be noted the courts have established that if more than one language is spoken by operations/maintenance personnel at the occupancy in question, then the warning label(s) must be provided in all of the languages spoken. The courts have indicated that failure to provide warning signs in the languages(s) spoken by operations and maintenance persons on the premises is the same as not providing a sign.

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