Wiring diagrams of electrical apparatus and installations (1913)
McGraw-Hill · New York, McGraw-Hill Book Company · leaf 203
Load &—= 4> Fig. 327.—Connections for a two-phasewatt-hour meter. … Fig. 328.—Connections for a two-phasewatt-hour meter using series transformers.
Electric wiring
Internet Archive · Public Domain Mark 1.0. Free to use for anything.