10.5 Working Space and Equipment Access (NEC 110.26)

Why This Rule Earns Its Own Section

The PSI content outline lists Workspace Clearance as a named sub-topic inside Electrical Equipment and Devices, the 10-item block on the NEC Knowledge portion. It is one of the few Chapter 1 rules on the blueprint, and it is heavily tested because the answer is a table lookup that punishes anyone who reads the wrong row.

110.26 requires access and working space about all electrical equipment 1000 V nominal or less that is likely to require examination, adjustment, servicing, or maintenance while energized. The trigger is the word energized: a junction box that is only ever opened dead does not need 110.26 working space, but a panelboard, disconnect, motor controller, or switchboard does.

Depth — Table 110.26(A)(1)

The depth is measured from the exposed live parts, or from the enclosure or opening if the live parts are enclosed, straight out in the direction a worker would stand.

The three conditions describe what is on the opposite side of the working space:

• Condition 1 — live parts on one side, and no live or grounded parts on the other side. Also applies where the opposite side is effectively guarded by wood or other insulating materials.
• Condition 2 — live parts on one side and grounded parts on the other. Concrete, brick, tile walls and grade are all treated as grounded.
• Condition 3 — live parts on both sides of the working space with the worker in between.

The trap almost everyone falls into

The left column says voltage to ground, not system voltage. A 208Y/120 V panelboard is 120 V to ground; a 120/240 V residential panel is 120 V to ground. Both live on the 0-150 V row, where all three conditions require the same 3 ft. Facing a concrete wall does not push a 120 V-to-ground panel to 3.5 ft — that number belongs to the 151-1000 V row.

Where the numbers actually change is 277/480 V. A 480Y/277 V motor control center is 277 V to ground. Facing a grounded masonry wall it is Condition 2 and needs 3.5 ft; facing a second energized lineup across the aisle it is Condition 3 and needs 4 ft.

Depth exceptions

• 110.26(A)(1)(a) — working space is not required behind assemblies such as dead-front switchboards or motor control centers where there are no renewable or adjustable parts on the back and all connections are accessible from other locations.
• 110.26(A)(1)(b) — where rear access is required to work on de-energized parts, a 30 in. horizontal working space is required.

Width and Height

• 110.26(A)(2) Width — 30 in. or the width of the equipment, whichever is greater. The space may be measured from either side of the equipment (it does not have to be centered), and in all cases every door or hinged panel must open at least 90 degrees.
• 110.26(A)(3) Height — 6.5 ft measured from the floor, grade, or platform, or the height of the equipment, whichever is greater. Other equipment or support structures associated with the installation may not project more than 6 in. beyond the front of the equipment inside that space.
• 110.26(B) Clear Spaces — the working space may not be used for storage. This is the citation for the "boxes stacked in front of the panel" violation.

Entrance, Egress, and Illumination

• 110.26(C)(1) — at least one entrance of sufficient area gives access to and egress from the working space.
• 110.26(C)(2) — for equipment rated 1200 A or more and over 6 ft wide that contains overcurrent, switching, or control devices, there must be an entrance not less than 24 in. wide by 6.5 ft high at each end of the working space. One entrance is permitted if unobstructed egress exists, or if the working space depth is twice the value required by Table 110.26(A)(1).
• 110.26(C)(3) — personnel doors within 25 ft of the nearest edge of that working space must open in the direction of egress and be equipped with listed panic hardware or listed fire exit hardware.
• 110.26(D) — illumination is required for working spaces about service equipment, switchboards, switchgear, panelboards, and motor control centers installed indoors, and it shall not be controlled by automatic means only (an occupancy sensor alone does not satisfy it).

110.26(E) Dedicated Equipment Space

Working space is for the worker. Dedicated equipment space is for the equipment — room to bring conduits and cables in.

All service equipment, switchboards, switchgear, panelboards, and motor control centers must sit in a dedicated space. Indoors that space is the width and depth of the equipment, extending from the floor to a height of 6 ft above the equipment or to the structural ceiling, whichever is lower. No piping, ducts, leak-protection systems, or other foreign systems may occupy it. A suspended ceiling with removable panels is permitted within the 6 ft zone, and sprinkler protection is permitted where the piping complies with the space rules.

The 2023 NEC added "service equipment" to that opening list, which closed a gap for service-rated disconnect switches that were not panelboards or switchgear.

110.26(F) confirms that electrical equipment rooms controlled by a lock are still considered accessible to qualified persons.

Do Not Confuse 110.26 With 240.24

110.26 governs the space; 240.24 governs where the overcurrent device may be placed:

• 240.24(A) — readily accessible, with the center of the grip of the operating handle not more than 6 ft 7 in. above the floor or working platform.
• 240.24(D) — not located near easily ignitible material, such as in clothes closets.
• 240.24(E) — not in the bathrooms of dwelling units, dormitories, or guest rooms.
• 240.24(F) — not located over the steps of a stairway.

A panel can satisfy 240.24 and still violate 110.26, and vice versa. Read the stem for which one is being asked.