Historical
NEMA ANSI C12.10:2004
Physical aspects of watthour meters - safety standard
Covers the physical aspects of both detachable and bottom-connected watthour meters and associated registers. These include ratings, internal wiring arrangements, pertinent dimensions, markings and other general specifications. Refer to the latest version of ANSI C12.1 and ANSI C12.20 for performance requirements.
NEMA: National Electrical Manufacturers Association [nema]