I have installed a #2/2/2/4 SER Cable from my main panel in a residence to supply a subpanel (mounted on the exterior wall of the house) that will feed branch circuits for a swimming pool. The inspector will not allow it and said I would have to install the circuit in conduit or run a separate insulated ground with the SER. I know that the ground should be insulated from the subpanel, but cannot find where an insulated ground from the main to the subpanel is required.