What does the term "EUSERC" mean?

EUSERC is : Electric Utility Service Equipment Requirements Committee 

Conformance to these specifications is usually required in California and a some other areas in the western United States. Below is a definition from their website:

The purpose of the organization is to promote uniform electric service requirements among the member utilities, publish existing utility service requirements for electric service equipment and provide direction for development of future metering technology. EUSERC's goal is to support the development of metering and service equipment that is safe and cost effective to the serving agencies and their customers, and to establish manufacturing and installation requirements for metering and service equipment that are acceptable to all member utilities.

You local utility should be contacted to determine if these requirements are necessary in your area.