The first edition of the Electrical Meterman’s Handbook, now the Handbook for Electricity Metering, was first published in 1912. Nine revisions have since been published; the ninth edition appeared in 1992. As in the previous editions, the emphasis has been on fulfilling the needs of the metering practitioner. In the tenth edition each chapter includes updated text and new graphics. The following major updates have been made to the 10th edition: new examples on complex numbers; addition of current measurement technology from basic to advance meters; expansion of information on optical voltage and current sensors; inclusion of new meter diagrams; current metering testing practices; updates on standard metering laboratory and related standards; and new electronic data collection information. To make the Handbook convenient either as a reference or textbook, a great deal of duplications has been permitted.