You've correctly identified the core of the issue. Let's break it down and provide examples

Understanding the Rule (Based on your statement):

The code prohibits locating Level 1 EPSS equipment in the same room as normal service equipment if the normal service equipment operates at greater than 150V to ground and 1000A or more.

What is Level 1 EPSS Equipment?Level 1 EPSS is the most critical emergency power system. Think of it as the "life safety" backup. Its main purpose is to maintain power to systems essential for safety and immediate survival during a power outage.

Examples of Level 1 EPSS Equipment (As per Article 700 and related standards like NFPA 110)



Emergency Generator

This is the heart of the EPSS.

Emergency Transfer Switches (ATS)

These automatically switch the load from the normal source to the generator source when the normal power fails. This is arguably the most important consideration.

Distribution Panels Dedicated to Emergency Loads

Crucially, this includes the main emergency generator distribution panel. This panel distributes the generator's power to the various life-safety loads.

Addressing Your Specific Questions


Main Emergency Generator Distribution Panel



YES, this definitely counts as Level 1 EPSS equipment. It's a direct part of the emergency power system. Think of it this way: if this panel fails, the generator can't deliver power to the essential loads.2. Emergency ATS (serving egress lights, fire alarm, life-safety equipment, etc.)



YES, this is a critical piece of Level 1 EPSS equipment. It's responsible for automatically switching over to generator power for those essential life-safety systems.3. First Panel Downstream of Emergency ATS

This is where it gets a little nuanced and requires careful consideration. The key question is:

Is this panel exclusively dedicated to emergency loads? If YES

And the loads fed from it are life-safety critical (e.g., fire pumps, emergency lighting, critical care equipment, etc.), then

YES, it is likely considered part of the Level 1 EPSS, particularly if it's the primary distribution point for those loads immediately downstream of the ATS. If NO

If the panel also serves non-emergency loads (e.g., general purpose receptacles, non-critical lighting, etc.), then

NO, it might not be considered part of the Level 1 EPSS itself. However, circuits for Level 1 emergency equipment from that panel must comply with the requirements for Level 1 EPSS wiring (separation, fire protection, etc.).

Why the Code Separation?

The reasoning behind this separation requirement is to prevent a single catastrophic event (like a fault or fire in the normal service equipment) from knocking out both the normal power and the emergency power systems simultaneously. The intent is to ensure that the Level 1 EPSS can operate reliably even if something goes wrong with the normal service.

Example Scenario

Imagine a large office building with the following:

Normal Service

480V, 4000A service entrance equipment.

Emergency Generator

Providing backup power to fire alarm, egress lighting, elevators (for evacuation), and critical care equipment on a medical floor.

Emergency ATS

Automatically switches the load to the generator when normal power fails.

Emergency Distribution Panel (EDP)

Receives power from the generator after the ATS and distributes power to the various emergency loads.In this case, the code likely requires that the emergency generator, the emergency ATS, and the Emergency Distribution Panel (EDP)

NOT be located in the same room as the 480V, 4000A normal service entrance equipment.

Key Considerations for Application



Local Codes and Interpretations

Always consult local electrical codes and the authority having jurisdiction (AHJ) for clarification. They may have specific interpretations or amendments to the national codes.

NFPA 110

This standard provides more detailed requirements for emergency and standby power systems and is often referenced in conjunction with the NEC.

Documentation

Thoroughly document your emergency power system design, including the location of all equipment and the loads served. This will help demonstrate compliance to the AHJ.

In Summary:

Err on the side of caution and assume that equipment directly involved in the generation, transfer, and distribution of emergency power to life-safety loads is considered part of the Level 1 EPSS. If the normal service equipment meets the voltage and amperage threshold, separate the EPSS equipment from it. If in doubt, consult with a qualified electrical engineer or the AHJ. Flag for review