"Sufficient access and working space shall be provided and maintained about all electric equipment to permit ready and safe operation and maintenance of such equipment."
Is what it says first, and later lists the parameters....
"Working space for equipment operating at 600 volts, nominal, or less to ground and likely to require examination, adjustment, servicing, or maintenance while energized..." - You can shut off a box, and it very unlikely that you would need to do all of those things hot, like you might for a panel, especially a main panel. As far as "F" goes, I (Can't) think of anything else...
[This message has been edited by e57 (edited 07-14-2006).]
"Well - I oughta....." -Jackie Gleason