Let's break down the NEC 2017 Article 110.26(C)(2) Large Equipment requirements and how they apply to your described situation.

NEC 2017 110.26(C)(2) Large Equipment

This section of the NEC addresses working space and access for large equipment that is likely to require examination, adjustment, servicing, or maintenance while energized. The key aspects are: Equipment Likely to Require Work While Energized

This is often interpreted as equipment containing overcurrent protective devices (OCPDs) or switching mechanisms that might need troubleshooting or resetting. Switchboards, ATSs, and panelboards certainly fall under this category.

Entrance to and Egress from the Working Space

Specifically, if the depth of the working space (the distance from the front of the equipment to the opposite wall or obstruction) is 6 feet or more, then two entrances and egresses are required. Moreover, these entrances/egresses must be located at opposite ends of the working space.

Exception

A single entrance/egress is permitted if the location provides a continuous and unobstructed way of travel.

Analysis of Your Sketch

Here's the breakdown based on the information you provided:1. Existing Switchboard

The existing 2000A switchboard is over 6 feet wide. This is a critical piece of information.2.

New Switchboard Behind

The addition of the new switchboard behind the existing one is relevant to the overall arrangement of equipment.3.

New ATSs in Front

This is the crucial part for 110.26(C)(2) compliance. The ATSs require working space in front of them.
4.

One Exit

You've indicated only one exit is provided from the working space in front of the ATSs and switchboard.5.

Distance Between ATS and Existing Switchboard: 4.5 feet This dimension is the depth of the working space.

The Problem & Potential Non-Compliance

Here's why you likely have a problem with 110.26(C)(2): The working space depth is less than 6 feet (4.5 feet). Therefore, the two entrance/egress rule in 110.26(C)(2) does not apply. The fact that the switchboard is longer than 6 feet is irrelevant. However, NEC 110.26(A) still applies! You must have sufficient working space depth (4.5 feet in your case) and width (the width of the equipment or 30 inches, whichever is greater). You must also have sufficient height to access the equipment (usually 6.5 feet, or the height of the equipment, whichever is greater).

NEC 110.26(C)(2) Conclusion

Based on the information provided, you don't need a second door for the working space in front of the ATS.

Important Considerations & Recommendations Local AHJ is the Final Authority

The interpretation and enforcement of the NEC are ultimately up to the local Authority Having Jurisdiction (AHJ). Consult with them directly. Show them your sketch and get their opinion. This is the most important step.*

Documentation

Keep thorough documentation of your design and any AHJ interpretations.

Disclaimer: I am an AI chatbot and cannot provide legal or professional engineering advice. This analysis is for informational purposes only and should not be substituted for consultation with qualified professionals. You MUST consult with licensed engineers and your local AHJ to ensure full compliance with all applicable codes and regulations. Flag for review