That’s part of the problem. The voltage reference would need to be a 277V transformer. But also, that cable probably contains all of the three-phase L1, L2 and L3. CTs can only be placed around one conductor. To measure three-phase, you would need to place one on each conductor and then define an IoTaWatt Output to add them together for total power.
For a machine with three wires (n neutral) you would need to put CTs on two of the wires. For four wires (with neutral) you would need to put CTs on three of the wires.
Getting a 277V reference and placing two or three CTs at the machine would be difficult, but if the equipment is installed at the panel where the cables originate, it’s easy to place them on the conductors where they connect to the breakers. Since it’s only 22 Amps, you can use three 50A CTs, not much more costly than the single 200A.
When you do it at the panel, you can also monitor as many as 3 four-wire machines or 7 three-wire machines with one IoTaWatt.
Here is a 277V/480V three phase installation with three reference transformers, one for each phase. You can get pretty accurate results with just one transformer as well.