Westinghouse Style 35241 Precision Wattmeter  
Written by Accutron on 2018-07-22  

Introduced in the early 1900s, The Westinghouse Style 35421 Precision Wattmeter is a measuring instrument used by early power companies to calibrate watthour meters. The Style 35421 has a maximum capacity of 5, 20 or 100 amperes, and requires the use of a large Westinghouse-manufactured external precision resistor. As of 1923, the list price for the Style 35421 was $515.00, equivalent to nearly $8000 in 2018 dollars.

This particular wattmeter was once owned by Dewey Electric Light & Power Co., a small electric company which supplied power to Nampa, Idaho in the early 1900s. In 1912, Dewey Electric was acquired by the Idaho Railway, Light & Power Co., suggesting that this instrument dates to 1912 or earlier.


Westinghouse Style 35241 Precision Wattmeter.


Style 35241, enlargement of dial.


Style 35241, identification placard.


Style 35241 with lid in place.


Style 35241 certificate of standardization, attached to the underside of the lid. This unit was last certified in 1923.

This article is part of the [Electronic Test Equipment] exhibit.

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