3.3 Working Space, Access, Egress & Illumination — 110.26(A) through (D)

The Purpose Statement

110.26 opens by stating that access and working space shall be provided and maintained about all electrical equipment to permit ready and safe operation and maintenance. The word maintained is deliberate — a compliant installation that later becomes a storage area is a violation.

110.26(A) applies where equipment is likely to require examination, adjustment, servicing, or maintenance while energized. A junction box does not require working space; a panelboard does.

Depth — Table 110.26(A)(1) and the Three Conditions

Depth is measured from the exposed live parts, or from the enclosure front or opening if the live parts are enclosed. The required depth depends on the nominal voltage to ground and on what is on the opposite side of the working space:

The critical detail is the Condition 2 definition: concrete, brick, or tile walls are considered grounded. A 480Y/277 V panelboard across a corridor from a concrete wall is Condition 2 at 151–600 V, requiring 3.5 feet, not 3 feet. Change the wall to painted gypsum board over wood studs and it becomes Condition 1 at 3 feet. Put a second energized panel opposite and it becomes Condition 3 at 4 feet.

Remember that the table is indexed on voltage to ground, not phase-to-phase voltage. A 480Y/277 V system is 277 V to ground and therefore sits in the 151–600 V row. A 480 V corner-grounded or ungrounded delta is 480 V to ground and also sits in that row. A 208Y/120 V panel is 120 V to ground and falls in the 0–150 V row, where all three conditions require 3 feet.

110.26(A)(1)(a) Dead-Front Assemblies. Working space is not required in the back or sides of assemblies such as dead-front switchboards or motor control centers where all connections and renewable or adjustable parts are accessible from locations other than the back or sides. Where rear access is required to work on de-energized parts on the back of enclosed equipment, a minimum horizontal working space of 30 inches shall be provided.

110.26(A)(1)(b) Low Voltage. By special permission, smaller spaces are permitted where all uninsulated parts operate at not greater than 30 V RMS, 42 V peak, or 60 V DC.

Width and Height

110.26(A)(2) Width. The width of the working space shall be the width of the equipment or 30 inches, whichever is greater. In all cases the working space shall permit at least a 90-degree opening of equipment doors or hinged panels. The space may be measured from left to right, from right to left, or be centered on the equipment — it does not need to be centered.

A 20-inch-wide panelboard requires 30 inches of clear width. A 42-inch-wide switchboard requires 42 inches.

110.26(A)(3) Height. The work space shall be clear and extend from the grade, floor, or platform to a height of 6.5 feet (2.0 m) or the height of the equipment, whichever is greater. Within the height and width of the working space, other equipment located above or below the electrical equipment shall be permitted to extend not more than 6 inches beyond the front of the equipment.

110.26(A)(4) Limited Access. Where equipment is installed in a space with limited access — above a suspended ceiling or in a crawl space — additional rules apply, including a minimum 22-inch-wide horizontal opening path and a 30-inch by 30-inch working space at the equipment where the equipment is installed with the face parallel to the access opening.

Clear Spaces, Grade Level and Headroom

110.26(B) Clear Spaces. Working space required by this section shall not be used for storage. When normally enclosed live parts are exposed for inspection or servicing, the working space, if in a passageway or general open space, shall be suitably guarded.

110.26(E)(2) Outdoor. Outdoor electrical equipment shall be installed in identified enclosures and protected from vehicular traffic, and the working space shall be adequate to permit safe operation and maintenance.

110.26(F) Locked Electrical Equipment Rooms or Enclosures. Rooms or enclosures containing exposed live parts or exposed conductors operating at over 1000 V shall be kept locked unless under the observation of a qualified person at all times. Electrical equipment rooms controlled by a lock are considered accessible to qualified persons.

Entrance and Egress — 110.26(C)

This subsection produces very consistent exam questions, and the two thresholds are different numbers. Learn them separately.

110.26(C)(1) Minimum Required. At least one entrance of sufficient area shall be provided to give access to and egress from the working space.

110.26(C)(2) Large Equipment. For equipment rated 1200 A or more and over 6 feet (1.8 m) wide containing overcurrent devices, switching devices, or control devices, there shall be one entrance to and egress from the required working space not less than 24 inches wide and 6.5 feet high at each end. There are two exceptions: where the location permits a continuous and unobstructed way of egress travel, one means is permitted; and where the required working space depth is doubled, only one entrance is required, and it must be located so that the edge of the entrance nearest the equipment is the minimum clear distance away.

110.26(C)(3) Personnel Doors. Where equipment rated 800 A or more that contains overcurrent devices, switching devices, or control devices is installed and there is a personnel door intended for entrance to and egress from the working space less than 25 feet (7.6 m) from the nearest edge of the working space, the door shall open in the direction of egress and be equipped with listed panic hardware or listed fire exit hardware.

So: 1200 A and over 6 ft wide triggers the two-entrance rule; 800 A within 25 ft triggers the panic-hardware rule. Mixing these two thresholds is the most common error on this topic.

Illumination — 110.26(D)

Illumination shall be provided for all working spaces about service equipment, switchboards, switchgear, panelboards, and motor control centers installed indoors, and shall not be controlled by automatic means only. In electrical equipment rooms, additional lighting outlets shall not be required where the working space is illuminated by an adjacent light source.

The phrase "not controlled by automatic means only" is the tested point: an occupancy sensor may be present, but there must be a manual override or a manually operable switch. Nobody should be plunged into darkness with a panel cover off.