Electrical Contractor - February 2017

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)].