I recently reconfigured a main service with 2 sub panels. One of the (main lug) sub panels can take 24 slim breakers, freeing up a lot space in the main panel. It's on a 100A breaker with #4s and a #8 ground. As is always the problem, the branch circuit wires aren't long enough so I'm setting a jbox and about a an 8" nipple into the sub. To make the sub panel less crowded, I put a ground bar in the jbox. That made for a nice install, with 23 fewer ground wires.
As I was working on it, I got to wondering if I could have put an isolated neutral bar kit in the jbox and run a #4 from the neutral bar in sub to the iso neutral bar in the jbox. I've looked in the code (408) but I'm the blind squirrel, I didn't find the nut that would either allow or disallow this. I'm sure the answer is gonna be a head smacker.
As I was working on it, I got to wondering if I could have put an isolated neutral bar kit in the jbox and run a #4 from the neutral bar in sub to the iso neutral bar in the jbox. I've looked in the code (408) but I'm the blind squirrel, I didn't find the nut that would either allow or disallow this. I'm sure the answer is gonna be a head smacker.