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.
This trough
extends more
than 6 inches
beyond the
front of the
panelboard. This
is a violation of
110. 26(A)( 3).
VIOLATION PERMITTED
This trough
extends exactly
6 inches beyond
the front of the
panelboard. This
is permitted.
4
in.
4
in.
12
in.
12
in.
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