Switchgear

Front Working Space Depth

Provide the working-space depth required by NEC Table 110.26(A)(1), based on the system voltage-to-ground and the condition opposite the switchgear.

For typical systems rated 151–600 V to ground:

Condition 1: Minimum 3 ft (0.91 m)

Condition 2: Minimum 3.5 ft (1.07 m)

Condition 3: Minimum 4 ft (1.22 m)

For systems rated 150 V or less to ground, the minimum depth is generally 3 ft. Final clearance must be verified against the locally adopted NEC edition and site conditions.

Width and Height of Working Space

The working-space width must be at least 30 inches (762 mm) or the width of the switchgear, whichever is greater. Equipment doors and hinged panels must be capable of opening at least 90 degrees.

The clear working-space height must be at least 6 ft 6 in (1.98 m) or the height of the switchgear, whichever is greater.

Access and Egress for Large Equipment

Where switchgear rated 1200 A or more and wider than 6 ft (1.83 m) meets the conditions of NEC 110.26(C)(2), an entrance to and egress from the working space is generally required at each end.

Applicable NEC exceptions may permit a single entrance where the working-space depth is increased or where an unobstructed exit path is provided. Final room layout must be approved according to the locally adopted code.

Personnel Doors and Panic Hardware

Where the applicable conditions of NEC 110.26(C)(3) are met for equipment rated 800 A or more, personnel doors located within the specified distance of the working space must:

Open in the direction of egress;

Be equipped with listed panic hardware or listed fire-exit hardware;

Provide a clear and unobstructed escape path.

This requirement is conditional and should not be described as mandatory for every UL 1558 installation.

Dedicated Electrical Space

For indoor installations, provide dedicated electrical space equal to the width and depth of the switchgear, extending from the floor to 6 ft (1.83 m) above the equipment or to the structural ceiling, whichever is lower.

Foreign systems such as water piping, drainage piping, and HVAC ducts should not be installed within this dedicated zone. Code-compliant sprinkler protection may be permitted when installed in accordance with the applicable NEC requirements.

Rear Access, Foundation, and Anchorage

For rear-access switchgear, provide the rear working space required for the actual maintenance activity:

If examination, adjustment, servicing, or maintenance may expose energized parts, apply the working-space requirements of NEC 110.26;

If rear access is required only for nonelectrical parts, provide at least 30 inches (762 mm) of horizontal working space where required;

Follow the manufacturer’s drawings for escape aisles, cable access, ventilation, and door clearances.

Front-access-only switchgear may be installed closer to a wall only when permitted by the listed equipment design and manufacturer’s instructions. Install the lineup on a level concrete pad and anchor it according to the approved seismic and structural requirements.