How far do you take the arc flash labeling?

• Typically all major equipment: Panels, MCCs, Switchboards etc.
• We often include equipment such as motors, process equipment, J-boxes etc.
• Something else

There are usually a lot of varied opinions about this one. Let us hear yours.

The intent of NEC 110.16 and NFPA 70E is that any equipment over 50 volts that is likely to be opened while energized for examination, adjustment, servicing, or maintenance must be evaluated for arc flash hazards to warn qualified workers and be labeled with the Arc Flash boundary, Voltage, and at least one of the following: (1) Possible incident energy and working distance; (2) Highest Hazard Risk Category; (3) Minimum Arc Rating of PPE: or (4) Required Level of PPE

How many guys work on motor terminal boxes while the motor is running? That is why we generally stop the labels at the MCC. I am aware of one agency that IR scans motor terminals and is interested in labelling the terminal boxes, but that is an exception.

Oftentimes, the Arc Flash incident energy is greater at the motor terminals than at the MCC. The added impedance of the cables lowers the arcing current and slows down the opening time of the breaker or fuse, increasing the possible Arc Flash incident energy at the motor terminals.