The first provision states, where
equipment is installed above a lay-in
ceiling, there has to be an opening that is
at least 22 inches by 22 inches. This first
part does not specify the width or depth
of the working space, just the opening to
be able to get to the equipment.
For example, a 208V heating, ventilating and air conditioning (HVAC)
unit is installed above a 2-foot-by-2-foot
lay-in ceiling. Inside this unit, behind
the access door, is equipment likely to
require examination, adjustment, service
or maintenance while energized. There
is a full-size, 2-foot-by-2-foot ceiling tile
located below and in front of the access
door. The opening for a full-size 2-foot-
by-2-foot ceiling tile is at least 22 inches
by 22 inches. Therefore, the opening to
be able to examine, adjust, service or
maintain this HVAC unit while it is energized meets the stipulation in 110.26(A)
( 4)(a) (see Figure 1).
The provision in 110.26(A)( 4)(a) also
states, where equipment is installed in a
crawl space, there has to be an accessible
opening that is at least 22 inches by 30
inches. Like equipment above a lay-in
ceiling, this provision does not specify
the width and depth of the working
space; it specifies the opening to be able
to get to the equipment in a crawl space.
The next requirement in this section
applies to working-space width for the
equipment. The width of the working
space shall be the width of the equipment enclosure or a minimum of 30
inches, whichever is greater [110.26(A)
( 4)(b)]. This width is not the total width
of the equipment, such as an HVAC unit.
It is the width of the enclosure housing
the electrical components.
For example, an HVAC unit has been
installed in a crawl space. The unit con-
tains equipment that is likely to require
examination, adjustment, service or
maintenance while energized. The access
door for entering and exiting the crawl
space is 24 inches by 32 inches. The
access door to the electrical components
in the HVAC unit is 16 inches wide. One
of this HVAC unit’s ducts is directly to the
right of the access door, but there is no
obstruction to the left.
Since the width of the equipment
enclosure is less than 30 inches, the
minimum width in front of the equipment enclosure is 30 inches. Because of
the size of the access door to the crawl
space, this installation meets the stipulation in 110.26(A)( 4)(a). This installation
also meets the requirement in 110.26(A)
( 4)(b) because there are at least 30 inches
of working space width (see Figure 2).
Where equipment, located in a space
with limited access, has hinged doors
or panels, the doors or panels must be
able to open a minimum of 90 degrees
[110.26(A)( 4)(c)]. This requirement is
just like the requirement in 110.26(A)( 2),
which states, in all cases, the work space
shall permit at least a 90-degree opening
of equipment doors or hinged panels.
Depth and height requirements for
equipment located in a space with limited access is in 110.26(A)( 4)(d). The
space in front of the enclosure shall comply with the depth requirements of Table
110.26(A)( 1). The minimum depth of
working space depends on the nominal
voltage to ground and one of the three
conditions. The three conditions are
described under Table 110.26(A)( 1).
A height requirement is in the same
subsection with the depth requirement,
but it is different from the height requirement in 110.26(A)( 3). In accordance with
110.26(A)( 4)(d), the maximum height of
the working space shall be the height
necessary to install the equipment in the
limited space. The minimum height of
working space required by 110.26(A)( 3)
is 6½ feet. There is no specific minimum
dimension for working space height in
110.26(A)( 4)(d); the minimum height is
only the height necessary to install the
equipment in the limited space. The
last sentence in this subsection states a
horizontal ceiling structural member or
access panel shall be permitted in this
FIGURE 2 EQUIPMENT INSTALLED IN A CRAWL SPACE
Equipment located in a space with limited access includes equipment installed above a
lay-in ceiling and equipment installed in a crawl space.
Where equipment operating at 1,000V, nominal or less to ground and likely to require
examination, adjustment, service or maintenance while energized is located in a crawl
space, there shall be an accessible opening not smaller than 22 inches by 30 inches.
[110.26(A)( 4)(a)].
The width of that working space shall be the width of the equipment enclosure or a
minimum of 30 inches, whichever is greater [110.26(A)( 4)(b)].
The enclosure door to this HVAC equipment is 16 inches wide.
The opening to gain access
to the HVAC equipment is 24
inches by 32 inches. Therefore,
this installation is permitted.
The minimum working space
width for this HVAC equipment
enclosure is 30 inches.