Electrical formulas in inch units of length

ELECTRICAL formulas in textbooks and periodicals are usually expressed in metric units of length (centimeters or meters). In many countries, including the United States, dimensions on shop drawings must be reduced to inches. In the past, the inconvenience and possibility of error in converting from metric to inch units have created at least a minor barrier between electrical theory and practical application. In addition, it has appeared that an engineer starting in industry must familiarize himself with a group of electrical equations which, usually being expressed in inch units of length, differed slightly from those learned in college.