Electric meter

The invention of the light bulb quickly created the need to track people's electricity usage. In 1872, Samuel Gardiner built the first simple power meter: a lamp with an attached clock that recorded the time the light was on.

A decade later, Thomas Edison opened his own electric company and invented his own chemical-based meter. It was a container with zinc plates attached to the consumer's electrical connection. At the end of the billing period, the plates were weighed and the bill calculated by the change in weight. Even though he would later build a more accurate meter, Edison favored the zinc meter because of his love of chemistry.

The first effective electric meter came about by a lucky accident. In 1888, Westinghouse researcher O.B. Shallenberger was adjusting an arc lamp when a spring popped loose. He noticed that the spring had rotated, then figured out that it was the lamp's rotating electric fields that caused the spring to rotate.

Shallenberger realized he could use the effect to turn wheels in a meter to track power usage. He invented an AC ampere-hour meter in less than a month, and marketed it in just 12 weeks. Over the next decade, more than 120,000 of his meters were sold.

By the end of the twentieth-century, high-tech advances made it possible for manufacturers to produce fully electronic meters with LCD screens

Related Electricity & Magnetism Pages

• Timeline: 1870 – 1879