The Standard Electrical Dictionary

1. Unit of Supply

   A commercial unit for the sale of electric energy, as defined provisionally by the English Board of Trade; 1,000 amperes flowing for one hour under an E. M. F. of 1 volt; 3,600,000 volt-coulombs, or 1,000 watt-hours, are its equivalent. It is equal to 1000/746 = 1.34 electric horse power. Synonym--Board of Trade Unit. [Transcriber's note: Now called a kilowatt-hour.]