Dedicating Space for Electrical Equipment in New Buildings: What You Need to Know

When designing a new building, allocating proper space for electrical equipment is critical to ensure both safety and long-term serviceability. Improper planning can result in code violations, costly redesigns, or unsafe working conditions for maintenance personnel. The National Electrical Code (NEC) provides specific requirements for working clearances and dedicated space around electrical equipment. In this post, we’ll walk through key considerations for transformers, switchboards, panelboards, and disconnects—helping you get it right the first time.

Transformers

Transformers, especially those installed indoors, require careful consideration for ventilation and clearance. While the NEC does not provide dedicated working clearances for dry-type transformers specifically (except where they’re part of an assembly like a switchboard), the manufacturer’s installation instructions must be followed per NEC 110.3(B). These instructions typically include minimum clearance for cooling.

If the transformer includes overcurrent protection or disconnecting means, NEC 110.26 applies, which requires:

• 36 inches of clear working space in front of the equipment (depending on conditions)
• Width of the equipment or 30 inches, whichever is greater
• 6.5 feet headroom clearance

For transformers rated over 112.5 kVA, consider mechanical ventilation due to potential heat buildup.

Exterior transformers can take up an even larger footprint and are also governed by the rules and restrictions of the utility provider. It is important to review the Electric Service Requirements of the utility provider and coordinate locations with other affected disciplines (civil, plumbing, mechanical, etc.). The total area needed for this gear can extend much larger than the size of the gear itself.

Switchboards

Switchboards, which consolidate multiple power distribution elements, are substantial pieces of gear that require clear, accessible work zones.

Per NEC 110.26(A):

• Provide working space in front: minimum 36 inches for 0–150V to ground, 42 inches for 151–600V to ground (depending on conditions)
• Width: At least 30 inches or width of the equipment, whichever is greater
• Height: Clear headroom of at least 6.5 feet

Additionally, NEC 110.26(E) requires dedicated space above switchboards and panelboards:

• Space equal to the width and depth of the equipment extending up to 6 feet above the equipment (or to the structural ceiling)
• This space must be kept clear of ducts, piping, or other foreign systems, except for suspended ceilings with removable panels

Switchboards can require front and rear access depending on the design—check with the manufacturer and account for that in the layout. Be mindful that the swing of the equipment doors does not impede the required access/egress space of 24 inches wide and 6.5 feet high to the working space of the equipment.

Panelboards

Panelboards are frequently installed in electrical rooms, closets, and other dedicated electrical spaces. Despite their smaller footprint compared to switchboards, they must meet the same NEC 110.26 working space requirements:

• 36 inches minimum depth
• 30 inches wide (or width of equipment)
• 6.5 feet vertical clearance

If installed in commercial or multi-occupancy buildings, consider NEC 240.24, which restricts panelboards to readily accessible locations and not in bathrooms or over steps of a stairway.

Disconnect Switches

Disconnect switches are used to safely isolate circuits or equipment. Even though they can be compact, NEC requires clear space for operation and maintenance.

NEC 110.26(A) again governs the working clearances:

• Minimum 36-inch clearance in front (may vary based on voltage and condition)
• 30-inch width or width of equipment
• 6.5 feet headroom

Disconnects serving mechanical equipment must be within sight of and accessible from the equipment served, per NEC 440.14 (for HVAC units) or 430.102(B) (for motors).

Additionally, if the disconnect is likely to be serviced while energized, clearance rules become even more critical.

Conclusion

Dedicating appropriate space for electrical equipment is not just good design—it’s a code requirement and a safety imperative. Every new building project should account for the NEC’s clearance and dedicated space rules to ensure code compliance, operational safety, and future maintainability.

Whether you’re placing transformers, switchboards, panelboards, or disconnect switches, the NEC can guide your layout and spacing strategy. At Royal Engineering, we have the experience and expertise to help ensure that your project runs smoothly. Work closely with your design team and AHJ (Authority Having Jurisdiction) to confirm local interpretations and ensure smooth inspections down the line.