It's not too bad - I run 6x RTX 3090s on a 2nd-gen Threadripper with PCIe bifurcation cards. The energy usage is only really bad if you're training models constantly, but inference is light enough.
I use 208V power but 120V can indeed be a challenge. The USA has split phase wiring; every house has 220-240V if they need it. Bit of a misunderstanding of how our power works - we have 220-240V on tap, but typical outlets are 110-120V.