Sub-Panel disconnect grounded to main bldg disconnect

[Skim61]

I came across the following and am wondering if I should have the homeowner call an electrician, or not:

A sub-panel for separate building has 4 wire feed from disconnect switch, with both grounded to 2 rods. The sub-panel has neutral isolated and ground to box. The disconnect and sub-panel have 4 wires between.

Here's the questionable:
The feed from main panel to sub-disconnect is 2-2-4. A separate ground wire is run between this disconnect and the main house system, but it does not run to the panel where the 100A breaker is, it runs to the main building disconnect/meter box ground. In other words, ground runs from main building disconnect to sub-building disconnect.

Since current runs back to source, this IS the original source. But, is it a problem that it bypasses the box where the hot/neutral are coming from via the 100A breaker?

 

[tom baker]

Maybe. See 300.3.B, its a very important rule to follow. Otherwise the EGC may not clear a line to case fault

 

[Skim61]

OK. So a bit more details, the 3 wire feed is 2-2-4 SEU. The ground is 2ga THWX, and does NOT use the same path as feeder. It looks like they took the easy path on the outside of the house with the ground to the meter box. The 3 wire feeder goes through the wall.