Working Space Clearance Calculator
Size the clear working space in front of a panel, switchboard, or motor controller under NEC 110.26(A). Enter the nominal voltage to ground and the Condition and the tool returns the minimum depth from Table 110.26(A)(1) plus the 30 in width and 6.5 ft headroom.
How to use this calculator
- Enter the nominal voltage to ground. For a 120/240 V single-phase or 208Y/120 V system it is 120 V; for 480Y/277 V it is 277 V; for a 480 V delta it is 480 V.
- Select the Condition: nothing live or grounded opposite (1), a grounded surface such as a concrete or brick wall opposite (2), or exposed live parts on both sides (3).
- Optionally enter the equipment width and height in inches, so the tool can tell you whether a wide switchboard or a tall enclosure governs the width or headroom instead of the code minimum.
- Read the minimum depth in front, the minimum width, and the minimum headroom. The depth comes straight from Table 110.26(A)(1); width and headroom are the greater of the code floor and the equipment size.
- Keep the full depth clear from the floor to the required headroom, and confirm the space still lets every door and hinged panel swing to at least 90 degrees.
NEC reference
This calculator implements NEC 2020 110.26(A) for equipment operating at 600 V nominal or less. The depth of working space comes from Table 110.26(A)(1) by Condition and nominal voltage to ground; the width is 30 in or the equipment width per 110.26(A)(2) (with a 90-degree door swing required in all cases); and the headroom is 6.5 ft or the equipment height per 110.26(A)(3). The 601 V and higher rows of the table, 110.34 over 1000 V, the 110.26(C) entrance and egress rule, and the 110.26(E) dedicated equipment space are out of scope for this tool.
Results are for reference only. Verify against the applicable adopted edition of the NEC and consult a licensed electrician for code compliance.
Table 110.26(A)(1) depth, 600 V or less
The depth of the working space in front of the equipment depends only on the nominal voltage to ground and the Condition. For systems 600 V or less there are two voltage rows. The width and headroom are fixed minimums that only grow when the equipment itself is wider or taller.
| Nominal voltage to ground | Condition 1 | Condition 2 | Condition 3 |
|---|---|---|---|
| 0-150 V | 3 ft | 3 ft | 3 ft |
| 151-600 V | 3 ft | 3.5 ft | 4 ft |
Width (110.26(A)(2)): the greater of 30 in and the equipment width, and always enough to open doors and hinged panels to 90 degrees. Headroom (110.26(A)(3)): the greater of 6.5 ft (about 78 in) and the equipment height.
The three Conditions
- Condition 1. Exposed live parts on one side and no live or grounded parts on the other side of the working space, or exposed live parts on both sides effectively guarded by insulating material. This is the smallest required depth.
- Condition 2. Exposed live parts on one side and grounded parts on the other. Concrete, brick, and tile walls are considered grounded, so a panel facing a masonry wall is usually Condition 2.
- Condition 3. Exposed live parts on both sides of the working space, not guarded, with the worker between them. Two facing lineups of equipment in the same aisle are the classic Condition 3.
Worked example: a 480 V lineup facing a panel
Take a 480 V, 3-phase panel (480 V to ground on an ungrounded delta) that faces another section of live gear across the aisle. The voltage to ground falls in the 151-600 V row and live parts on both sides make it Condition 3, so the required depth is 4 ft of clear space, floor to 6.5 ft headroom. If instead the panel faced a concrete wall it would be Condition 2 and the depth would drop to 3.5 ft; if it faced an empty drywall partition with nothing live or grounded, Condition 1 and 3 ft.
A 42 in wide switchboard raises the width from the 30 in minimum to 42 in, and an 84 in tall enclosure raises the headroom from 78 in to 84 in. A standard 120/240 V load center (120 V to ground) is 3 ft deep in every Condition because the whole 0-150 V row is 3 ft.
Common mistakes
- Reading the depth off the system voltage. The table is indexed by voltage to ground. A 480 V delta is 480 V to ground and needs the 151-600 V row, not a 277 V reading.
- Letting storage creep into the depth. The working space must stay clear for its full depth and up to the headroom; it is not a place for stored material even temporarily.
- Forgetting the door swing. A 30 in width is only the floor. If a dead-front door or hinged panel swings wider than 30 in, that swing sets the required width.
- Confusing working space with dedicated space. The 110.26(A) working space is the clear space a worker stands in. The 110.26(E) dedicated equipment space above the equipment is a separate rule this tool does not compute.
Frequently asked questions
How much working space is required in front of an electrical panel?
NEC 110.26(A)(1) sets the minimum depth by Condition. For 0 to 150 V to ground it is 3 ft in all three Conditions. For 151 to 600 V to ground it is 3 ft in Condition 1, 3.5 ft in Condition 2, and 4 ft in Condition 3, measured as clear space from the live parts or enclosure front.
What do Condition 1, 2, and 3 mean?
Condition 1 is nothing live or grounded on the far side (or both sides guarded by insulation). Condition 2 is a grounded surface opposite, and concrete, brick, and tile walls count as grounded. Condition 3 is exposed live parts on both sides with the worker between them. The Condition selects the depth column.
What is the minimum width and height of the working space?
The width is the greater of 30 in and the equipment width (110.26(A)(2)), and the space must permit a 90-degree opening of doors and hinged panels. The headroom is the greater of 6.5 ft (about 78 in) and the equipment height (110.26(A)(3)).
Do I use the system voltage or the voltage to ground?
Voltage to ground. A 120/240 V single-phase or 208Y/120 V system is 120 V to ground (the 0 to 150 row); 480Y/277 V is 277 V and a 480 V delta is 480 V (the 151 to 600 row). Keying on voltage to ground avoids under-clearing a 480 V delta system.
Does this cover working space over 600 V?
No. It covers equipment 600 V nominal or less. Over 600 V to ground the higher rows of Table 110.26(A)(1) and NEC 110.34 apply and are out of scope, and the 110.26(C) egress and 110.26(E) dedicated-space rules are separate from this depth, width, and headroom.
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- Service Size Calculator: size the service disconnect, conductors, and grounding electrode conductor for the equipment in that space.
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- Pull Box Size Calculator: minimum pull and junction box dimensions per NEC 314.28.
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