Do you need an arc flash label for equipment that is powered by a 480v drop cord?

If permanently attached...I would say yes. To aid the evaluation/calculation side: you could do a sensitivity analysis if you have multiple drops of equipment. In other words, adjust your disconnect sizing, etc. and see where your incident energy excursions are. From there, you can decide if you need to evaluate further or stick with a generic arc flash label. Hopefully that makes sense.

Mike

I often check these just to understand the hazard. This connection would be best represented by an HCB orientation. Many times I find these plugs energized in their normal state. The plug then is considered a movable conductor so the approach boundary increases. I have found a somewhat elevated arc flash hazard at plugs which is not ideal. When personnel then make/break this connection while the plug is energized their hands are directly on each end and the connection is likely near their body, possibly face. An arcing fault in this situation would not be good.

I am a fan of keeping these de-energized. Once the connection is made or broken, the upstream disconnect switch can more safely be used to energize the circuit.