You've hit a common point of confusion with SCCR. Here's a breakdown and some options for responding to the plan reviewer

Understanding SCCR & Subfeed Lug Kits
SCCR applies to the _entire assembly_

SCCR (Short-Circuit Current Rating) is about the ability of an entire electrical panel, enclosure, or system to withstand a short circuit until the overcurrent protective device (OCPD) clears the fault. It's NOT typically applied to individual components like a subfeed lug kit in isolation.

Subfeed lugs are connectors

Subfeed lug kits are essentially just connectors. Their job is to reliably carry current. They don't have any inherent short-circuit protection characteristics on their own. They simply provide a means of connecting conductors.

Key is the upstream OCPD

The SCCR of the protected equipment (downstream of the subfeed lugs) is determined by the upstream overcurrent protective device (usually a breaker in your 400A CSED). The upstream OCPD limits the available fault current at the downstream equipment.

Series Rating

You mentioned series rating. That means the downstream panel (in your CSED) is rated to withstand 10kA of fault current, provided a specific upstream breaker is used that is rated to interrupt 22kA.

Why You Got the Comment (and What to Do About It)

The plan reviewer is likely looking for assurance that the installation as a whole is properly protected. Here's why they might have asked, and how to address their concern:1. Misunderstanding

The plan reviewer may be mistakenly looking for an SCCR on the lug kit itself. This is common because SCCR requirements are relatively new, and some reviewers may not be fully familiar with how they apply to all types of components.2.

Missing Information

They might be concerned about whether the downstream equipment connected to those lugs is properly protected given the available fault current at the subfeed lugs.

How to Respond to the Plan Review Comment

Here are several approaches, from simplest to most detailed

Option 1: (Simple Explanation - If you know the reviewer is reasonable)

> "The subfeed lug kit (HOML2225, ECSK2225, or BRPSF225) is a passive connection component and does not have an SCCR rating. The SCCR of the downstream equipment connected to these lugs is determined by the upstream overcurrent protective device in the 400A combination service entrance device (CSED). The CSED's integral panel is series-rated 22K/10K. The downstream equipment must have an SCCR of at least 10kA to be protected by the series rated overcurrent protective device."Option 2: (More Detailed Explanation with Code Reference)> "The subfeed lug kit (HOML2225, ECSK2225, or BRPSF225) is a passive connection component and does not have an SCCR rating. SCCR applies to the entire electrical equipment assembly, not individual connectors.> Per NEC 110.10, the available fault current at the point of supply to the downstream equipment connected to the subfeed lugs must be considered. The upstream overcurrent protective device in the 400A combination service entrance device (CSED) will limit the available fault current. The CSED's integral panel is series-rated 22K/10K. Therefore, the downstream equipment connected to the subfeed lugs must have an SCCR of at least 10kA to be adequately protected."Option 3: (Detailed Documentation - Best if you want to be very thorough)

This is the most work, but demonstrates a comprehensive approach:1. Available Fault Current Calculation

Perform (or have an engineer perform) a short-circuit study to determine the available fault current at the subfeed lugs within the CSED. You'll need utility fault current data for this. While the series rating gives you a good idea, actually calculating it removes any doubt.2.

Downstream Equipment SCCR

Ensure that any equipment connected to those subfeed lugs has an SCCR rating at least equal to the calculated available fault current (but not less than 10kA based on the series rating). This could involve specifying specific panels, breakers, or other devices with appropriate SCCR ratings.3.

Provide the Documentation

Include the following with your response to the plan review: A copy of the short-circuit study showing the available fault current at the subfeed lugs. Documentation (cut sheets, specifications) showing the SCCR ratings of all equipment connected to the subfeed lugs. A one-line diagram showing the entire system configuration from the service entrance to the downstream equipment.Your response should state something like this:> "Per the attached short circuit calculation, the available fault current at the subfeed lugs in the 400A CSED is X kA. All downstream equipment connected to the subfeed lugs has an SCCR of Y kA, which meets or exceeds the calculated available fault current."

Important Considerations AHJ Ruling

Ultimately, the Authority Having Jurisdiction (AHJ) makes the final determination. If they insist on seeing an SCCR for the lugs themselves, you may need to contact the manufacturer of the lug kit and ask them for a letter confirming that the lugs are suitable for use with the given upstream overcurrent protection and available fault current. (They will likely say the same thing you are saying - the lug kit is not rated on its own).

Downstream Equipment

You need to know what is going to be connected to the subfeed lugs. Is it a panelboard? A motor starter? A transformer? The plan reviewer needs to know that equipment has an adequate SCCR.

NEC 110.9 and 110.10

Familiarize yourself with these sections of the National Electrical Code. 110.9 deals with interrupting rating (the OCPD's ability to clear a fault). 110.10 deals with SCCR (the equipment's ability to withstand a fault until cleared).

In summary: Focus on demonstrating that the entire system is properly protected based on the available fault current and the SCCR ratings of the equipment downstream of the subfeed lugs. The lugs themselves are not the issue. Be clear, concise, and provide supporting documentation. Flag for review