Panelboard Working Space and Dedicated Space in a Remodeled Mechanical Room
A restaurant remodel installs a new 400 A, 208Y/120 V, 42-space panelboard in a 12 ft by 14 ft mechanical room. The enclosure is 36 in wide and 39 in tall, mounted with its bottom 30 in above the finished floor (top at 69 in) on a wall with a plain gypsum board surface opposite, 4 ft 2 in away. During rough-in the inspector writes up three items: (1) a 4 in sprinkler main crosses the room horizontally 18 in in front of the panel face at 5 ft 6 in above finish floor; (2) a 2 in black steel gas line runs across the wall at 7 ft 0 in, directly above the panel; (3) a 6 in concrete equipment curb sits under the panel, which the electrician says he will stand on to work. The electrician asks whether nailed-on pipe guards would let the sprinkler main stay and whether lowering the panel a foot would clear the gas line.
1. Evaluate the working space in front of the panel. Is the 4 ft 2 in room dimension adequate, and what does the sprinkler main do to the required space?
Read the worked answer
Depth is fine on paper, but not as built.
- 120 V to ground (208Y/120) with no live or grounded parts on the opposite side puts this in Condition 1 of Table 110.26(A)(1): 36 in minimum clear depth.
- The wall-to-wall distance is 50 in, so the room dimension itself is not the problem.
- The sprinkler main sits 18 in off the panel face. That leaves 18 in of clear depth inside a space that must be 36 in, measured from the enclosure front. The pipe also falls inside the required width (30 in minimum, or the 36 in equipment width, whichever is greater) and inside the 6 ft 6 in height of the working space.
- Guards do not cure this. 110.26(A) requires the space to be clear, not merely protected; a permanent foreign object inside the working space is a violation regardless of guarding.
- The 6 in curb is also a problem: the floor of the working space is required to be at equal level. Standing on a curb to work live parts is not an acceptable substitute.
Conclusion: the sprinkler main must be rerouted (or the panel relocated). This is a rough-in rejection, and it must be corrected before the walls close.
2. Does the gas line above the panel comply? Would lowering the panel 12 in help, and what limits how high the panel can go instead?
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No, and lowering it makes things worse.
110.26(E)(1) requires a dedicated electrical space: the space equal to the width and depth of the equipment, extending from the floor to 6 ft above the top of the equipment or to the structural ceiling, whichever is lower. No piping, ducts, or equipment foreign to the electrical installation is permitted in that zone.
- Panel top is at 69 in; the dedicated space extends to 69 + 72 = 141 in (11 ft 9 in). The gas line at 84 in is well inside it.
- Lowering the panel 12 in moves the top to 57 in and extends the dedicated space to 129 in; the gas line is still inside.
- The "foreign systems above the dedicated space with drip/leak protection" allowance applies only above that zone, so it is not available here.
- Raising the panel is not a practical fix: the dedicated space above the equipment is always 6 ft, so the pipe would have to be above the panel top plus 6 ft, and the top breaker handle may not exceed 6 ft 7 in above the floor (404.8(A)). There is no compliant elevation.
Conclusion: the gas line must be rerouted around the electrical room. Many jurisdictions also prohibit gas piping in an electrical room outright, so confirm the local amendment before proposing an alternative.
3. What is the correct procedural sequence for resolving these findings, and who decides? Can the electrician simply field-modify and cover the walls?
Read the worked answer
No field-modification-and-cover.
- Stop and document. Rough-in must be inspected and approved before concealment; covering rejected work creates a rework problem and an inspection liability.
- Submit the fix, don't improvise it. Pipe relocation, panel relocation, or any deviation from the approved plans goes back through plan review as a revised drawing or RFI.
- The AHJ decides. Under 90.4 the authority having jurisdiction interprets the Code and may grant limited exceptions for new materials or installations equivalent in safety - that authority does not extend to waiving working-space dimensions, and an inspector's field approval of one item does not waive the rest.
- Equipment must be installed per its listing and labeling (110.2, 110.3(B)); a field-built guard or a relocated gas line that conflicts with the manufacturer's clearances is not acceptable without written direction.
- Re-inspect, then close up. Get the corrected rough-in signed off before insulation and drywall, and keep the RFI response with the job file so the next inspector sees the reasoning, not just the result.