Model D (ca.1905 to ca.1911) Up
Up
Next
Next
 
Although this was a DC meter by design, many units were calibrated and sold for use on AC circuits. This was likely an attempt to get around a patent lawsuit brought by Westinghouse that prevented Duncan and Sangamo from selling induction-type meters (GE had a license agreement and was unaffected) until Tesla's patent expired at the end of 1910. This is also the only known North American model with a carrying handle built in, and the method of fastening the sheet zinc cover from the bottom is also unique to this model. Model D
Electrical Meterman's Handbook