You could run 2 L3+ on a 20amp 120v circuit, but you could only run one on a regular 15amp circuit. Well you could run 2, but you will likely end up serving drinks and food to a bunch of guys with a big red truck, sirens, and some spotted dogs... LOL
I am also looking at building out some 220v circuits and trying to figure out the plug, and PDU configurations etc for this.
If you have 15 awg breaker and 15 awg plug (120v) on a 12 awg wire 20 amp wire (look you should be able to tell the diff between 12 awg wire and 14 awg wire..the 12 awg 20 amp
wire is bigger more robust)
anyway if THAT is the case (be sure if not leave it 14 awg or 15 amp wire that would be bad) you can then make the neutral on that run ..the white wire a black wire with some black
electrician's tape (you'd have to change all 120 plugs to 220 on that circuit also) on both ends ...thus two marked black wires to a 20amp double pole breaker
on the panel (you'll need an extra slot) and 2 marked black wires to your choice of 220v outlet. Again all other outlets between have to be changed to a 220 plug
or simply wire nut bypassed and a blank cover put on those former 120v extra outlets. Then when you are DONE mining you can switch the whole works back
on a 120v 1 pole 20 amp breaker and swap back to the regular 120v outlet.
AGAIN ONLY CATCH this is if you are SURE the wire that exists on your 15 amp circuit is 12awg and 20 amp rated.
You can also if it is a small run or something get 12 awg wire and perhaps replace 15awg wire by just connecting old wire 14awg to new wire 12awg and pull and replace
and do above ..or use a piece of conduit and when done mining get rid of the conduit. If in a garage...just run the conduit where you wish...easy peasy..
anyway youtube has lots of videos.....on this....the bigger problem if in-house proper (not garage or basement) would be the noise and loudness of an L3+
the stuff above I mention have tons of youtube videos on the workarounds above
and heck your making money hand over fist now right? (or will be at least for a bit) just get an electrician and all you got to do is say where and point