6.3 Service Equipment & Working Space

Working Space Is a Service Topic on Prov

Article 230 tells you what service equipment is and where disconnects go. 110.26 tells you whether a human can safely stand in front of that equipment. Arkansas’s outline includes both Services/OCP (8) and Safety (3) — working-space items can be scored under either framing. For service gear (meter-main combinations, service disconnect enclosures, service panelboards), treat 110.26 as mandatory companion reading to Article 230.

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Scope — 110.26 Opening Paragraph

Working space is required about electrical equipment likely to require examination, adjustment, servicing, or maintenance while energized. Service equipment clearly qualifies. The space is for operation and maintenance access, not for storage of paint, lumber, or water heaters.

If a stem says materials are stored in front of a service panel, the violation is 110.26 clearance/access — not an ampacity table problem.

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Depth of Working Space — Table 110.26(A)(1)

110.26(A)(1) sends you to Table 110.26(A)(1). Depth depends on the nominal voltage to ground and on the Condition (1, 2, or 3) that describes what faces the worker across the space. §19.1 drills the Condition definitions and the full table under the Safety outline block; this section applies them to service equipment.

High-frequency dwelling/service fact: a 120/240 V single-phase service is 120 V to ground, so it is read on the 0–150 V row — and on that row all three Conditions require 3 ft. A meter-main mounted on a garage wall directly across an aisle from a grounded concrete wall is Condition 2 thinking, but the required depth is still 3 ft. Depth only grows when voltage to ground grows.

A 480Y/277 V service is 277 V to ground, which lands on the 151–600 V row: 3 ft (Condition 1), 3½ ft (Condition 2), and 4 ft (Condition 3). That is the row where an aisle between two open switchboard sections becomes a 4 ft measurement, not a 3 ft one.

Exam workflow for service stems:

1. Convert the service description to volts to ground (120/240 V → 120 V; 208Y/120 V → 120 V; 480Y/277 V → 277 V).
2. Classify Condition 1/2/3 from what faces the worker.
3. Read the one cell in Table 110.26(A)(1) — remembering that on the 0–150 V row the Condition does not change the answer.

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Width of Working Space — 110.26(A)(2)

The width of the working space in front of the electrical equipment must be the width of the equipment or 30 inches, whichever is greater. In all cases, the working space must permit at least a 90-degree opening of equipment doors or hinged panels.

Traps:

• A 20-inch-wide panel still needs 30 inches of working-space width.
• A 36-inch-wide switchboard needs at least 36 inches of width (equipment width governs when larger than 30 inches).
• Depth from Table 110.26(A)(1) and width from 110.26(A)(2) are different measurements — do not answer a width question with a depth number.

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Height (Headroom) — 110.26(A)(3)

The height of the working space must be clear and extend from the grade, floor, or platform to a height of 6½ feet (6 ft 6 in) or the height of the equipment, whichever is greater. Limited exceptions exist for service equipment or panelboards in existing dwelling units that do not exceed 200 A — open the exception text when the stem screams “existing dwelling.”

Prov favorite: minimum headroom 6 feet 6 inches for equipment rated 1000 V or less (unless the equipment is taller).

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Entrance to Working Space — 110.26(C)

For large equipment (generally 1200 A or more and over 6 ft wide), 110.26(C)(2) requires special entrance/egress arrangements (doors at each end, or the exception paths). Smaller service equipment in dwellings usually does not trigger the large-equipment dual-entrance rule — but commercial service gear might. If the stem gives 1200 A and width over 6 ft, open 110.26(C).

Personnel doors within 25 ft of the working space edge for large equipment may need to open in the direction of egress and be equipped with listed panic hardware under the conditions in 110.26(C)(3).

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Illumination — 110.26(D)

110.26(D) requires illumination for working spaces about service equipment, switchboards, switchgear, panelboards, or motor control centers installed indoors. Additional lighting outlet controls and automatic control limitations appear in the section — for exam purposes, know that working spaces need lighting, and control of that lighting generally must not place you in darkness while standing in the working space in a way the section prohibits.

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Dedicated Equipment Space — 110.26(E)

Do not confuse working space (in front) with dedicated equipment space (typically above and in the footprint of the equipment).

For indoor installations, 110.26(E)(1) generally requires a dedicated space equal to 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. Foreign systems (ducts, pipes) are restricted in that zone unless protection/foreign-system rules in the section are met. Outdoor installations have related dedicated-space rules in 110.26(E)(2).

Teaching distinction:

A sprinkler pipe dripping into the top of a service panel can be a dedicated-space problem even if the aisle in front meets Table 110.26(A)(1).

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Guarding, Enclosures, and Service Equipment Marking

Service equipment must be enclosed or guarded per Article 230 Part V and general 110.27 guarding rules. Combine:

• 230.66 suitability marking for service equipment
• 110.21 / equipment labeling for ratings and warnings
• Working-space compliance so the marked disconnect can actually be operated

On exam day, if the stem mentions both “clearance in front of the service disconnect” and “pipes above the panel,” you may need both 110.26(A) and 110.26(E).

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Practical Service-Equipment Layout Checks

Use this field/exam checklist:

1. Is the disconnect location legal under 230.70?
2. Can a worker stand in Condition-correct depth per Table 110.26(A)(1)?
3. Is width ≥ 30 in / equipment width?
4. Is headroom ≥ 6½ ft (or equipment height)?
5. Is the space used for storage? (Should be no.)
6. Is indoor working space illuminated per 110.26(D)?
7. Is dedicated space above clear per 110.26(E)?

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Timed Open-Book Tips for §6.3

• Permanent-tab 110.26 and Table 110.26(A)(1) next to Article 230.
• Always convert the stem to volts to ground before opening the table.
• Width answers are usually 30 inches; depth answers are usually 3 / 3.5 / 4 feet depending on condition/voltage — do not swap units.
• Dedicated space “6 ft above equipment” is not the same number as working-space headroom “6½ ft.”