Spot the Violation

ElectricalPanels, breakers & overcurrentLevel 12023 NEC

Basement storage wall

Unfinished basement with a concrete block foundation wall. A gray residential load center with its door closed is mounted on a plywood backboard, with NM cables and a service cable running down into its top from the joists. A freestanding wire shelving unit stands on the floor a short distance out from the wall, directly in front of the panel, loaded with paint cans, a box of holiday lights, plastic totes, cardboard boxes, and bags of water softener salt. A gas water heater sits to the left, and at the right a dehumidifier on the floor drains through a hose to a floor drain in the slab. XMAS lights SALT SALT
Unfinished basement, utility wall

What's wrong here?

  1. Storage shelving sits in the required working space in front of the panel
  2. The water heater must be at least 3 ft from the side of the panel
  3. A panel may not be mounted on a concrete block foundation wall
  4. Nothing. This installation is compliant
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Show the answer and the code reference

The answer

A loaded storage shelf has been placed in the working space directly in front of the panelboard.

Correct choice: 1. Storage shelving sits in the required working space in front of the panel

A 120/240 V residential panel needs a clear working space in front of it at least 3 ft deep (Table 110.26(A)(1); at 0-150 V to ground the depth is 3 ft under all three conditions), at least 30 in wide or the width of the equipment, and 6 1/2 ft high, and 110.26(B) says that space shall not be used for storage. The rule exists so someone can get to the main and the branch breakers fast, stand square in front of the panel with the dead front off, and back away from an arc flash without tripping over paint cans. Shelving in front of the panel is one of the most common basement correction items.

How to fix it

Move the shelving and stored items out of a 30 in wide by 3 ft deep by 6 1/2 ft high zone in front of the panel and keep that zone clear. Marking the floor in front of the panel helps keep it that way.

Code references

  • NEC 2023 110.26(B) — Clear Spaces

    Working space required by 110.26 shall not be used for storage. When normally enclosed live parts are exposed for inspection or servicing, the working space in a passageway or open area must be suitably guarded.

    Drills citing 110.26(B)

  • NEC 2023 110.26(A) — Working Space

    Working space for equipment likely to require examination, adjustment, servicing, or maintenance while energized must meet 110.26(A)(1) through (A)(4): depth per Table 110.26(A)(1) (3 ft at 0-150 V to ground under every condition), width of 30 in or the width of the equipment, whichever is greater, with room for equipment doors to open at least 90 degrees, and height of 6 1/2 ft or the height of the equipment, whichever is greater.

    Drills citing 110.26(A)

2026 NEC:same rule and number. 110.26 was revised in 2026 (equipment doors open to 90 degrees may not cut the egress path below 24 in by 6 1/2 ft, depth measured from the enclosure front rather than exposed live parts, dc voltages added), but 110.26(B) still says working space shall not be used for storage, so this answer and fix stand. Confidence: medium

Minnesota

MN adopts the NEC rule as writtenConfidence: high

Minnesota adopts the NEC by reference without amendment (Minn. Rules 1315.0200; Minn. Stat. 326B.35), so 110.26(B) applies as published. The 2023 NEC governs permits filed July 1, 2023 through Aug. 16, 2026; the 2026 NEC governs permits filed on or after Aug. 17, 2026 (exams moved to the 2026 NEC on Sept. 8, 2026). See the 2026 NEC note on this drill.

How Minnesota adopts the NEC

Why the other choices are wrong

  • The water heater must be at least 3 ft from the side of the panel. The 3 ft in Table 110.26(A)(1) is the depth of clear space measured out from the front of the panel, not side clearance to other equipment. The water heater just has to stay out of the 30-in-wide working space, which does not have to be centered on the panel.
  • A panel may not be mounted on a concrete block foundation wall. Mounting on masonry, usually on a plywood backboard, is normal. In damp or wet locations the enclosure needs 1/4-in airspace from the wall (312.2), but nothing prohibits a block wall.
  • Nothing. This installation is compliant. A panel needs a clear working space at least 30 in wide, 3 ft deep and 6 1/2 ft high in front of it, and that space may not be used for storage (110.26(A), 110.26(B)).
Safety hazardLevel 1 · Apprentice#panel#working space#clearance#basement#storage

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