The eGauge can monitor 480V delta systems, provided it is installed with the proper stepdown transformers. Never attempt to connect the eGauge directly to a 480V delta service. eGauge Systems has tested and recommends the 'Functional Devices TR50VA008' stepdown transformer. These transformers provides a minimal amount of phase shift (leading to a minimal loss of accuracy), although transformers of a similar VA rating can be substituted. Two transformers are required for monitoring a delta service. 

The document below outlines the wiring of the transformers and placement of CTs. Note that the images are intended to illustrate the wiring relationship and do not represent proper installation practices.