Wiring my shipping container workshop, I'm running a 30- or 40-amp feeder from main breaker panel in house, to a main lug subpanel in the workshop. Wiring within the workshop using THHN in PVC conduit and metal boxes.
For the main row of outlets along my workbench, I'm adopting a cute plan (I may have heard here). Run a multiwire branch circuit (MWBC), so four 12awg wires (green, white, black, red). Each outlet box will have one outlet driven from the black ungrounded conductor and one outlet driven from the red ungrounded conductor (either two separate duplex outlets or a split duplex outlet). Neutral will be pigtailed, and circuit will be protected by two-pole 20amp breaker. One box will have a 240v outlet using both ungrounded conductors. So far so good.
But I realize GFCI protection is probably a good idea, at least for the workbench outlets, given it's a big steel box sitting on the ground (though the floor is wood). I don't have room in the main panel to have a GFCI breaker driving the feeder (need space-saver type), and I'm not using a main breaker subpanel. One scheme might be to simply put use a GFCI breaker for the two-pole breaker protecting the outlet MWBC. Or I could simply put two GFCI outlets at the box nearest the door, which will be where I plug in extension cords for outdoor use, and such.
I'd appreciate folks' thoughts on my best solution.