Okay, Dan, let's break down the requirement for ground fault protection on those 2000A, 3-pole disconnects on your MSB-1 and MSB-2.

The Code Requirement: NEC 230.95

NEC 230.95 is the section that governs ground fault protection of equipment (GFPE). The key excerpt is below, emphasis added:"230.95 Ground-Fault Protection of Equipment. Ground-fault protection of equipment shall be provided for each grounded wye electrical service of more than 150 volts to ground, but not exceeding 1000 volts phase-to-phase, for each service disconnect rated 1000 amperes or more."Analysis for Your Situation

Based on NEC 230.95 and the information you've provided, the following questions need to be answered:1. Service Equipment: Are MSB-1 and MSB-2 considered service equipment?2. Voltage: Is the voltage of the system more than 150 volts to ground and less than 1000 phase-to-phase? For example, is this a 480Y/277V system?3. Rated Amperage: Do the disconnects individually have a rating of 1000 amperes or more?Likely Answer (Based on Common High-Rise Design)

Given the information and assumptions below, I'm going to say the following, but it's very important to verify these assumptions before making any critical design decisions: Most likely, the disconnects on MSB-1 and MSB-2 DO require ground fault protection of equipment (GFPE).Why? Assumption

This is a large, high-rise building. Therefore, it's very common (and likely) that MSB-1 and MSB-2 are part of the building's service entrance. This would make them "service equipment".

Assumption

Most high-rise buildings use 480Y/277V for much of their power distribution. 480Y/277V does fall within the voltage range specified in 230.95 (more than 150V to ground (277V) and less than 1000V phase-to-phase). You've stated that the disconnects are rated 2000A, which is over the 1000A threshold.

Therefore, if the above assumptions are correct, NEC 230.95 applies and GFPE is required.Important Considerations and Clarifications Service vs. Feeder

The distinction between service equipment and feeder equipment is critical. NEC 230.95 only applies to service equipment. If MSB-1 and MSB-2 are fed from another main service panel (i.e., they are not the first point of disconnect after the utility), then 230.95 might not apply to these specific disconnects (GFPE may have been provided upstream). You would need to follow the system back to where the service entrance is located.

Qualified Person(s)

This kind of determination should always be made by a qualified electrical engineer who can review the entire system design, local codes, and project specifications.

Exceptions

There are a couple of exceptions to 230.95 (like fire pumps), but they are unlikely to be relevant in this general scenario.

Selective Coordination

If you do need GFPE, you must also consider selective coordination. If there are downstream overcurrent protection devices with ground fault protection, the upstream GFPE must coordinate so that the downstream device trips first for a ground fault close to the downstream device.

Testing

GFPE systems have to be tested per manufacturer's instructions, and records of testing need to be maintained.

What to Do Next


VERIFY ASSUMPTIONS

Most importantly, confirm whether MSB-1 and MSB-2 are service* equipment. Trace the source of the power. Are they directly fed from the utility transformer(s)?2.

Check Local Codes

Local jurisdictions may have amendments or additional requirements to NEC 230.95.
3.

Consult with an Electrical Engineer

If you're unsure, the best course of action is to consult with a licensed and experienced electrical engineer familiar with high-rise construction and the NEC. They can perform a thorough review of your one-line diagram and project specifications and provide a definitive answer.4.

Consult with an electrical inspector: Check with the local inspector. If an inspection has already happened, discuss with them about the changes and required updates.I hope this helps! Let me know if you have any other questions. Flag for review