Hey Echd, hey all,
Test to drive your VFD/spindle to its limit
just in case if someone wants to test under which mechanical load the circuit breaker blows with a 120 V spindle on a 30 A circuit (or simply when your VFD will correctly trip due to mechanical overload), here someone¹ shows the ampères in the VFD display at the output (=spindle) side, and how their 220 V 2.5 kW spindle is driven to draw up to 10 A current from the output of the VFD (video): The test consists of driving a 10 mm 3-flute aluminium end mill through an 6061 aluminium block with 1000 mm/min feedrate, 10 mm depth of cut and 8 mm width of cut (for US customary users: 13/32" 3-flute end mill through an 6061 aluminium block with 40 IPM, 13/32" DOC, 5/16" WOC).
Usually a 2.2 kW 230 V spindle is rated 8 A (in S1 duty cycle), the 2.5 kW Jianken ATC spindle in the video even only rated 6.6 A (for explanation see here). A 200-V-class VFD for 2.2 kW spindles can deliver up to 11 A (in CT mode) and is rated to draw up to 22 A at its input in this mode then.
So, now assuming a VFD/spindle with half the voltage, which means, with 120 V, where you have half the voltage thus double the currents, you should be able to make the spindle draw 20 A with this test, and thus make the VFD to draw over 40 A on the input, thereby using this test in the video to blow a 30 A circuit breaker 
Seriously, I would better limit the output current inside the VFD and make that in case of high mechanical load rather the VFD trips than the circuit breaker blows, as already explained above. But just in case…
Another test possibly could be to rough with a 8 mm roughing bit in black locust, one of the hardest woods in Northern America, 1/2" deep at 110 ipm, as shown here (they use a 6.6 kW HSD spindle on a Hitachi WJ200 VFD…)