Great idea - one big problem though, hopefully you can solve it for me…
I found this topic and tried it - and it worked perfectly! I needed a 20 amp 220 GFCI for a jacuzzi in a new bathroom. Such a device was $350. I found a new sub panel that came with a 220 50 amp GFCI in it for $35. Put the 50 gfci in my main panel to feed the new sub panel and put a $10 20A in the sub panel to run the tub.
Tub works great.
Later, I needed a new 110 circuit and thought I would use one of the extra slots in the new sub panel. No joy. The new circuit trips the 50A GFCI.
I suspect it may be because the 220 20A for the tub users 2 rails and the new circuit is 110 using only one rail.
Could this cause a return I’m balance that is causing the trip?
Any way to fix it?