Electrical Contractor - September 2016

66 ELECTRICALCONTRACTOR | SEP. 16 | WWW.ECMAG.COM
requirements, other equipment located
above or below the electrical equipment
can extend beyond the front of the equip-
ment, but the difference in depth shall
not be more than 6 inches. It is impor-
tant to note that the other equipment
has to be associated with the electrical
installation.

For example, two panelboards are mounted above a trough (wireway). Since the trough contains conductors for the panelboards, it is associated with the electrical installation. Each panelboard is 6 inches deep, and the depth of the trough is 12 inches. Since the depth difference is not more than 6 inches, this installation is permitted (see Figure 2).

There is no limit to the number of items permitted above or below the electrical equipment within the height requirements of 110. 26(A)( 3) as long as the other equipment is associated with the electrical installation and does not extend beyond the front of the equipment by more than 6 inches. Note that no requirement restricts the electrical equipment within the height requirements of 110. 26(A)( 3) from extending more than 6 inches beyond the front of other associated equipment unless the other equipment also requires working space.

For example, a trough is installed
above a switchboard. It is associated with
the electrical installation and, therefore,
The actual depth of the electrical
equipment and the associated equip-
ment can have a difference of more than
6 inches, as long as the depth differ-
ence after installation is not more than
6 inches. For example, a 4-inch-deep
panelboard needs to be installed above
a 12-inch-deep trough. The trough con-
tains conductors for the panelboard;
therefore, it is associated with the elec-
trical installation. If the panelboard
were mounted directly to the wall above
the trough, the installation would be in
violation of 110. 26(A)( 3) because the
trough would extend 8 inches beyond
the front of the panelboard. The maxi-
mum distance it can extend beyond the
panelboard is 6 inches. In this installa-
tion, 2-inch-square steel tubing will be
mounted to the wall and the panelboard
will be mounted to the tubing. After the
panelboard is installed 2 inches off the
wall, the depth difference is not more
than 6 inches. Since the trough, after
installation, does not extend more than
6 inches beyond the front of the panel-
board, this installation is permitted (see
Figure 4).

An old common practice was to install a transformer on the floor in front of a panelboard. In the 1996 NEC, a sentence was added in Section 110-16(a), pertaining to working clearances, and it permitted other equipment within the work space; however all of the equipment in the work space had to be of equal depth. Besides a number of revisions to this section in the 1999 edition, the section was renumbered from 110-16 to 110-26.

In the 1999 NEC, a new subsection covered working space height. The requirement was changed to permit other equipment associated with the electrical installation to be installed above or below the electrical equip-

CODE IN FOCUS
FIGURE 3 MORE THAN 6
INCHES BACK

No requirement restricts the electrical equipment within

110. 26(A)( 3) height requirements from extending more than 6 inches beyond the front of other associated equipment, unless the other equipment also requires working space.

Troughs do not require 110. 26(A) working space.

The front of this
switchboard
extends more than
6 inches beyond the
front of the trough,
but this is not a
violation.

The switchboard
is electrical
equipment that
requires 110. 26(A)
working space.
24
in.

12 in.

FIGURE 4 EQUIPMENT MOUNTED SO DEPTH
COMPLIES WITH 110. 26(A)( 3)

The actual depth of the electrical equipment and the actual depth of the associated equipment can have a difference of more than 6 inches as long as the depth difference after installation is not more than 6 inches.

2-inch-square
steel tubing
This
panelboard has
been mounted
2 inches away
from the wall,
so the trough
does not
extend more
than 6 inches
beyond the
panelboard
This
panelboard has
been mounted
on the wall.