The 30 in wide rule has been used since the 1971 nec.
Electrical panel clearance door swing.
The width of panel or 0 762 meter which is greater.
Clear height in front of panel 480v.
Headroom clearance has been required since the 1965 nec.
0 9 meter 3 ft clearance when facing other electrical panels 480v.
Graphically originally from mike holt.
But then if the panel is 3 from the door the door would not block the panel.
A clearance of at least 3 feet is required for equipment using 120 to 250 volts.
Updates to working space clearance around electrical equipment according to nec 2017.
The width of working space in front of the electric equipment shall be the width of the equipment or 762 mm 30 in whichever is greater.
Clearance to ensure that an electrical panel can be accessed at all times during inspection maintenance or emergency osha has determined that the working space in front of the equipment must be at least 30 inches wide or the width of the equipment.
0 9 meter 3 ft the width of the workingspace in front of the panel.
There are specific clearance requirements in the code.
Not sure if a door that is movable qualifies as a blockage.
The clearance is 36 in front and 30 side to side but that side to side clearance does not have to be centered on the panel as long as both edges are accessible.
Installations built before the 1978 nec only require a minimum clearance of 2 ft in front of electrical equipment.