During the second year in an accident he dislocated his wrist, broke an arm, and suffered vision impairment.

Among the electricians and inventors that attended the Naval Academy around this same time were Frank J. Sprague, Dr. Louis Duncan, W. F. C. Hasson, and Gilbert Wilkes.

Shallenberger then joined the Union Switch and Signal Company of Pittsburgh in 1884 under the management of George Westinghouse.

Shallenberger ran the experiments of an alternating current apparatus which had been imported from Europe by Westinghouse.

He also was the first in the United States to innovate a method of connecting alternating current generators in a parallel circuit.

[12] Shallenberger, through a research laboratory accident, innovated a device that led to the invention in 1888 of an induction meter,[13] a paramount apparatus of the Westinghouse alternating current system.

Before it got replaced by a co-worker Shallenberger observed that the spring rotated by some sort of electromagnetic force.

He then conceived the idea that perhaps this force field could be used to turn some small wheels in such a way that they could measure electricity.

Shallenberger developed that force field concept into a mechanical device that could measure alternating current usage.

This gave way to a meter that used electrolytic jars that chemically measured zinc transfers and inferred electric usage.

In 1888, Elihu Thomson patented a walking-beam meter which was later disparagingly labeled as a Rube Goldberg-styled device.

[17] Shallenberger's simple AC motor (as it was later identified by Nikola Tesla) revolutionized electric meters.

[21] Shallenberger traveled through several major European cities in 1889 to observe their electrical systems.