110.26(A)(3) Height of Working Space. The work space shall be
clear and extend from the grade, floor, or platform to a
height of 2.0 m (61⁄2 ft) or the height of the equipment,
whichever is greater. Within the height requirements of this
section, other equipment that is associated with the electrical
installation and is located above or below the electrical
equipment shall be permitted to extend not more than 150 mm
(6 in.) beyond the front of the electrical equipment.
Exception No. 1: In existing dwelling units, service equipment
or panelboards that do not exceed 200 amperes shall
be permitted in spaces where the height of the working
space is less than 2.0 m (61⁄2 ft).
Exception No. 2: Meters that are installed in meter sockets
shall be permitted to extend beyond the other equipment.
The meter socket shall be required to follow the rules
of this section.