EXTERIOR/INTERIOR - LOAD SIDE BREAKER - NEW SUB PANEL MAIN

Design

1 | WHAT THE SETUP LOOKS LIKE

SUPPLY SIDE VS LOAD SIDE REMINDER

CRITERIA NEEDED FOR THIS INTERCONNECTION

The example to below shows what your setup might look like for this type of interconnection. Depicted is an exterior MSP with the bottom lugs feeding the interior panel. As you can see, there is plenty of space for a PV breaker in the MSP, however, the designer will need to give extra attention to ensure the sub panel feeders are protected.

This interconnection has the following requirements that need to be met before it can be considered:

1. Sub Panel feeding from the bottom lugs of the MSP can accept a main breaker:

   • Look for a knock out at the top/bottom of the deadfront for a main position

   • Check the panel labeling for compatible main disconnects:

     • If no knockout for a main is present, it is still sometimes possible to install a 2P breaker rated for service on the bus.

       • This is sometimes referred to as a "sidefed" main breaker. It would require a hold down kit.

2. There are 2 available stabs to accommodate our PV breaker in the MSP.

   • If you the panel is full but the load center allows tandems you can consider this condition met.

3. There must be no code violations present in and around the MSP. 

   • If there is a plan in place to resolve code violations, then  you can consider this condition met.

4. There must be sufficient available backfeed for the amount of PV we will be landing in this load center.

Here is how this sub panel was protected at install. The designer called out a main breaker that is compatible with this panel.

2 | DESIGN

BASELINE DT

Below is an example of what this interconnection design will look like in BASELINE DT.

• Ratings will vary based on what the set up is. 

  • It will be custom for every site; do not use these exact ratings if you are referring to this page to help choose your interconnection.

BASELINE CAD

Below is an example of what this interconnection design will look like in BASELINE CAD.

• Always use the exact verbiage that populates in the "Interconnection Block" on the Utility Requirements of the BASELINE DT.