110.26 — the rule everything gets stacked in front of.
Working space is required so that a person can operate and maintain equipment safely. It is also the single most convenient empty rectangle in a crowded electrical room, and it fills up within a year of occupancy.
Access and working space must be provided and maintained about all electrical equipment to permit ready and safe operation and maintenance. The word that gets ignored is maintained — the clearance is not satisfied by having been drawn on the plans.
§ Depth of working space — the three conditions
| 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 ft 6 in | 4 ft |
| 601–2500 V | 3 ft | 4 ft | 5 ft |
| 2501–9000 V | 4 ft | 5 ft | 6 ft |
- Condition 1 — exposed live parts on one side, no live or grounded parts on the other side; or exposed live parts on both sides effectively guarded by suitable insulating material.
- Condition 2 — exposed live parts on one side and grounded parts on the other. Concrete, brick and tile walls count as grounded.
- Condition 3 — exposed live parts on both sides of the working space, not guarded.
A panel on a wall is Condition 2, not Condition 1, because the concrete wall counts as a grounded surface. At 480 V that is 3 ft 6 in, not 3 ft. Electrical rooms designed to 3 ft flat are non-compliant for most of what is in them.
§ Width, headroom and access
- Width — 30 in, or the width of the equipment, whichever is greater. The space must permit at least a 90-degree opening of equipment doors or hinged panels.
- Headroom — 6 ft 6 in, or the height of the equipment, whichever is greater.
- Entrance to and egress from working space — at least one entrance of sufficient area. For equipment rated 1200 A or more and over 6 ft wide, one entrance at each end is required, with exceptions where the working space is doubled or unobstructed egress exists.
- Personnel doors within 25 ft of the working space of equipment rated 800 A or more must open in the direction of egress and be equipped with panic hardware or listed fire exit hardware.
- Illumination is required for working spaces about service equipment, switchboards, switchgear, panelboards and motor control centers installed indoors. It may not be controlled solely by automatic means.
§ Dedicated equipment space — 110.26(E)
- The space equal to the width and depth of the equipment and extending from the floor to 6 ft above the equipment, or to the structural ceiling, whichever is lower, is dedicated to the electrical installation.
- No piping, ducts, leak protection apparatus or other equipment foreign to the electrical installation may be installed in that zone.
- Sprinkler protection is permitted where the piping complies with the dedicated-space rules — the exception exists specifically for sprinklers.
- Equipment must be protected from damage from condensation or leaks from foreign systems located above.
§ Why data center electrical rooms fail this
Four pressures, all of them predictable. Cable tray and containment get routed through the dedicated space above the gear because that is where the room is. Spare parts, ladders and staging land in the working space because it is the only clear floor. Capacity expansions add gear into rooms sized for the original build. And mechanical piping gets routed overhead because the electrical room is on the way to somewhere else.
The consequence is not paperwork. Working space exists so a person can get out of the way of an arc flash and so a second person can pull them clear. Blocked egress from a switchgear working space is a fatality mechanism, not a code technicality.
The 130.2(A)(2) additional person requirement makes this sharper: there now has to be room for a second person to be positioned outside the boundary and still reach the worker.
Working space blocked by the arc flash PPE cabinet. It happens constantly, and the irony is complete.
Housekeeping, clear spaces and 130.8
Classes cover the work-practice side — clear spaces, alerting techniques, and what "maintained" actually requires.
See the schedule Bring it onsite