120.5 Process for Establishing and Verifying an Electrically Safe Work Condition
(3) Wherever possible, visually verify that all blades of the disconnecting devices are fully open..�

Viewing the disconnect blades is easy if the switches have viewing windows. However most switches do not have windows. In a recent discussion, the subject came up regarding opening disconnect switch covers to view the blades - it was an interesting exchange. An obvious issue is the line side would likely be energized and exposed. Also, remember most equipment is old/legacy equipment.

Here is the question:

Do you believe switches should be open to view the blades even when the line side is energized?
Yes
No
It Depends