To model a sub-panel (Panel B) fed directly from the lugs of another panel (Panel A), two conditions are essential. First, both panels must be assigned to the same "Distribution System" to ensure electrical compatibility. Second, after setting Panel B's "Supply From" parameter to Panel A, the connection method must be specified. In Panel B's instance properties, the "Connection Type" must be changed from the default "Breaker" to "Feed-Through Lugs." This correctly models the connection without an overcurrent protection device in Panel A and ensures Panel B's load is passed through to Panel A's bus.

A. Both panels are assigned to the same switchboard, and the subfeed lug breaker option is selected.: The connection is not limited to switchboards, and the "Distribution System" requirement is missing, which is a more fundamental prerequisite.

B. Both panels are assigned to the same distribution system, and the circuit subfeed panel type option is selected.: "Circuit subfeed panel type option" is not a standard or accurate term for the required Revit parameter or setting.

D. Both panels are connected via a transformer, and the connection type is set to feed through lugs.: A transformer is used for changing voltage levels and is not required for a direct, same-voltage feed-through connection.

1. Autodesk, Inc. "Instance Properties for Electrical Equipment." Autodesk Knowledge Network, Revit 2023 Help, 2022. Accessed October 2023. (This document defines the "Connection Type" parameter, specifying its options as "Breaker" or "Feed-Through Lugs").

2. Autodesk, Inc. "Connect a Panel." Autodesk Knowledge Network, Revit 2023 Help, 2022. Accessed October 2023. (This guide outlines the workflow, including the need for a common Distribution System and setting the "Supply From" parameter).