Yes, what you're describing violates the National Electrical Code (NEC) in several ways. Here's why: Overcurrent Protection and Conductor Ampacity

The conductors after the 320A meter must be rated for at least 320A (before any derating factors). A 200A disconnect is designed to protect a circuit or feeder with a maximum of 200A of overcurrent protection. You cannot run 320A-rated conductors through a 200A disconnect and expect it to provide overcurrent protection for the entire service. The 200A disconnect will likely trip frequently, or worse, fail to protect the conductors downstream from overcurrent.

Series Rating and Approved Combinations

While you could theoretically use a series-rated assembly of overcurrent protection devices, this needs to be:

Listed and Labeled

The manufacturer must specifically list and label the combination of devices (the 320A main breaker, the 200A disconnect, and whatever protects the second disconnect) as being suitable for series rating. This is very unlikely to be available for a 320A main breaker with a 200A disconnect in the described configuration.

Tested and Approved

The combination must have been tested and approved by a recognized testing laboratory (like UL) for use in a series-rated system.

Available Fault Current

You must consider the Available Fault Current (AFC) at the service entrance. The equipment must be rated to handle the AFC at that location. Passing conductors through a disconnect doesn't magically reduce the AFC.

Acceptable Alternatives


Individual Disconnects with Appropriate Ampacity

Install two disconnects, each with an ampacity that adds up to the total service amperage (320A in this case). For example, you could use one 200A disconnect and one 125A disconnect (or one 150 amp disconnect). The conductors to each disconnect must be sized appropriately. All conductors and equipment between the meter and the disconnects must be rated for 320A.2.

A Single 320A (or Greater) Disconnect

Use a single disconnect that's rated for the full 320A service. Then, you can split the load downstream of that disconnect using appropriately sized conductors and overcurrent protection.

In summary: What you're suggesting is a code violation due to improper overcurrent protection. The NEC prioritizes safety, and your method defeats the purpose of overcurrent protection devices.Disclaimer: I am an AI chatbot and cannot provide electrical advice. Consult with a licensed electrical contractor to ensure your electrical system is safe, code-compliant, and meets your specific needs. They can properly evaluate the load calculations and wiring methods for your application. Flag for review