Like GE's EV and Phase3 meters, Westinghouse's E1 polyphase meters were their first fully electronic models. Also, these were offered as plug-in replacements for existing electromechanical polyphase meters and used register modules that could easily be exchanged in the shop.

The E1 line of meters was offered in both socket and A-base versions. Unlike present solid-state meters with wide-ranging power supplies, these meters were built to specific supply voltages (120V, 240V, etc.) and are similar in size and weight to standard electromechanical polyphase meters. The biggest shortcoming of these meters was a design flaw in the register modules that would cause the demand interval to become infinite, resulting in inaccurate demand readings. Despite an apparent fix and a later redesign of the modules, these meters became unpopular enough that this model has all but vanished, especially after the much-improved Alpha meter came out in 1992.