Electrical room clearance starts with three minimums: a working-space depth of 3 to 5 feet depending on voltage and conditions under NEC Table 110.26(A)(1), a width of at least 30 inches or the equipment width, and 6.5 feet of clear height. The space must stay unobstructed. Look up NEC 110.26 (110.32 and 110.34 above 1,000 V), NFPA 70E and OSHA 1910.303, then confirm with your AHJ.
TL;DR:
- Measure depth from exposed live parts, or from the enclosure face when parts are enclosed; Table 110.26(A)(1) sets it by voltage and opposing conditions.
- Reserve the area from the floor to 6 feet above equipment or the structural ceiling, whichever is lower, and keep pipes, ducts, and storage out.
- Provide 24 inch by 6.5 foot entrances at both ends of equipment rated 1,200 A or more and wider than 6 feet, unless an exception applies.
- Above 1,000 V nominal, NEC Part III adds stricter width and depth rules, plus guarding, warning signs, and controlled entry; a locked room does not waive clearances.
- Draw clearances before trades coordinate layouts, including 90 degree door swings; designers often add 10% to 20% beyond minimums for maintenance and thermal management.
Table of Contents
- What working space and dedicated space mean under NEC 110.26
- Minimum depth by condition and voltage: using Table 110.26(A)(1)
- Width, height, doors and egress
- Special cases: vaults, ceiling spaces and installations over 1,000 V
- Designing beyond the code minimum
- Quick compliance checklist for site walks and plan review
- Why early clearance planning pays off
- How we help with electrical room layout, code review and permit filing
- FAQ
- Sources
What working space and dedicated space mean under NEC 110.26
Working space is the zone in front of equipment where a qualified person can operate, inspect and service it safely. Dedicated space is the footprint above and below the equipment reserved for electrical use, running from the floor to 6 feet above the equipment or to the structural ceiling, whichever is lower. Pipes, ducts and sprinkler mains do not belong there.
Measurement starts from the right reference point:
- Measure from exposed live parts when they are exposed, or from the enclosure face when they are enclosed.
- Keep the zone free of storage, including temporary pallets and "just for now" carts.
- Provide lighting and a level floor or platform so the work area is safe.
The reasoning goes beyond convenience. NFPA commentary notes that clear space also gives personnel a path to retreat or maneuver if an arc flash occurs. OSHA 1910.303 imposes matching access and working-space duties in workplaces, so an inspector or compliance officer can cite the same conditions from either side.
Minimum depth by condition and voltage: using Table 110.26(A)(1)
Depth is the dimension most often misjudged, because it depends on the voltage to ground and on what sits across from the equipment. The three conditions work like this:
- Condition 1: exposed live parts on one side and no live or grounded parts on the other, or only insulated wire or grounded parts behind guards.
- Condition 2: exposed live parts on one side and grounded parts on the other, such as a concrete or masonry wall.
- Condition 3: exposed live parts on both sides of the working space.
The trend is simple: higher voltage and more exposed parts across the aisle mean more depth. Equipment doors must also swing open to 90 degrees within the working space, as IAEI Magazine explains, so depth is measured with doors in mind. Inspectors often cite the "36 × 30 × 78" shorthand for working space in front of a panel, but it is only a baseline, since actual depth depends on voltage and conditions.
Width, height, doors and egress
Width must be at least 30 inches or the width of the equipment, whichever is greater. The space does not have to be centered on the equipment, but it cannot be narrower than the gear. Where doors or hinged panels open, the width must still clear them.
Height is the other fixed dimension. The headroom must stay clear from the floor, grade or platform to at least 6.5 feet (78 inches) or the equipment height, whichever is greater, per NEC 110.26(A)(3).
Entrance and egress rules add the following:
- One entrance of sufficient area must give access to and egress from the working space.
- For large equipment rated 1,200 A or more and wider than 6 feet, an entrance of 24 inches by 6.5 feet is required at each end unless an exception applies, such as doubled working space or continuous unobstructed egress.
- Personnel doors near the working space must meet applicable egress and hardware requirements.
Plan these dimensions on the drawings, not in the field. A door that swings into the aisle can quietly cut the depth you thought you had.
Special cases: vaults, ceiling spaces and installations over 1,000 V
Above 1,000 V nominal, the rules shift to NEC Part III. NFPA's electrical room series points out that 110.31 through 110.34 add larger working-space dimensions, guarding, signage and locked-room provisions. Minimum width, for instance, is stricter under 110.32 than under 110.26, and NFPA also covers how depth follows Table 110.34(A).
- Dedicated rooms and vaults: a locked room may limit access to qualified persons, but the measurements still apply. Assuming a dedicated room removes clearance duties is a common pitfall that AHJs enforce against.
- Above suspended ceilings and in crawl spaces: equipment needs an access opening, commonly 22 by 22 inches or 22 by 30 inches depending on the arrangement, and the working-space depth and width still hold.
- High-voltage areas: expect guarding, warning signs and controlled entry in the design.
Designing beyond the code minimum
The NEC is a floor, not a target. As EC&M notes, designers often exceed minimum clearances by about 10 to 20 percent to ease maintenance and improve thermal management. We follow that approach on our electrical room layouts, because a few extra inches cost little on paper and a great deal after steel is set.
Our coordination habits:
- Settle clearances early, before HVAC, sprinkler and architectural layouts harden.
- Protect airflow paths around convection-cooled gear and keep foreign equipment out of the dedicated space.
- Check door swings, lighting and ceiling grids against the same dimensions.
- For heat-dense enclosures, thermal analysis guidance helps decide when simple spacing is not enough.
- Where generators are involved, fuel truck access planning belongs in the same coordination pass as the electrical room.
Pro Tip: Dimension every working space and dedicated space on the drawings and call them out at permit review, so the AHJ sees compliance before it becomes a comment.
Quick compliance checklist for site walks and plan review
- Measure depth from the applicable reference point and compare it to Table 110.26(A)(1).
- Confirm width is at least 30 inches or the equipment width, per NEC 110.26(A)(2).
- Verify clear height of 6.5 feet or the equipment height, per NEC 110.26(A)(3).
- Check entrance sizes, door swing and the egress path, including applicable panic-hardware requirements.
- Confirm dedicated space is clear from the floor to 6 feet above the equipment or to the structural ceiling.
- Check lighting and a level floor or platform at the work area.
- Make sure nothing is stored in the working space, a point OSHA 1910.303 reinforces.
- For systems over 1,000 V, verify signage, guarding and locked-room provisions under 110.32 through 110.34.
Why early clearance planning pays off
Most clearance trouble shows up late: a panel pushed against a column, a duct run through the dedicated space, a door that cannot swing 90 degrees. Each one means rework and a stalled permit. Planning conservatively from day one is cheaper than fixing it in the field. We review codes and coordinate permits for exactly this reason, and we recommend bringing us in before drawings are final.
— Joseph
How we help with electrical room layout, code review and permit filing
If you need to confirm or correct electrical room clearances before submitting plans, we can help. Our team handles code compliance reviews, MEP layout coordination across mechanical, plumbing, fire protection and electrical trades, and permit filing support for NYC. We work with building owners, property managers, architects and contractors, and you have direct access to our senior engineers.
Send us your plans and we will verify clearances before permit submission. See everything we offer on our services page and request a plan review or consultation.
FAQ
What is the working clearance in front of an electrical panel?
Working clearance in front of a panel is at least 3 feet deep, 30 inches wide, and 6.5 feet high. Depth increases to 3.5 feet or 4 feet at 151–600 V when grounded or live parts face the panel, per NEC Table 110.26(A)(1).
What is the 6 12 rule in electrical?
Taken as 6.5 feet, it is the minimum clear headroom for the working space, or the equipment height if greater. Dedicated space, by contrast, extends 6 feet above the equipment or to the structural ceiling.
What are the NEC door requirements for an electrical room?
At least one entrance of sufficient area must give access to the working space. Large equipment of 1,200 A or more and over 6 feet wide needs a 24 inch by 6.5 foot entrance at each end unless an exception applies. Nearby doors must meet applicable egress requirements.
What are the OSHA electrical panel safety requirements?
OSHA requires sufficient access and working space around electrical equipment, with tabled depths and entry dimensions, under 1910.303. The space must remain clear so workers can operate and maintain equipment safely.