If the electrical system that you are trying to meter has 480V line to line, and 277V line to neutral, then we have meters that will work.
For this setup we recommend one of our Omnimeters with two Current Transformers for the two hot wires. (be aware that the UL Listed Omnimeters are only certified to 240 volts)
If you do not have a true Neutral to bring to the meter, and only have the 2 hot lines, then unfortunately we do not have a meter that will work.