In 1886, William Stanley lit a Massachusetts Main Street with a new AC system; his transformer proved electricity could travel farther and still be used safely

On 20 March 1886, offices and shops along Main Street in Great Barrington, Massachusetts, were lit by an electrical system that helped shape power distribution. Engineer William Stanley Jr. had developed a practical transformer system that allowed electricity to travel at a higher voltage and then be reduced to a level suitable for lighting buildings. The demonstration showed how alternating current (AC) could serve several businesses from a central generating station.

According to the National Inventors Hall of Fame, Stanley's achievement addressed one of the major obstacles facing the early electricity industry: how to distribute power efficiently without delivering dangerously high voltages directly to lamps and other equipment. His transformer design became a model for later systems and helped establish a principle that remains central to electricity networks today.

The experiment did not invent alternating current, and Stanley was not the first person to investigate transformers. Its significance was that he demonstrated a workable system that combined generation, transmission, and local voltage reduction. That practical achievement helped turn AC from a promising technology into a credible alternative for supplying electricity to businesses and communities.


The problem with delivering electricity over distance

By the 1880s, electricity transmission technology was still limited, and engineers were looking for ways to deliver power beyond the immediate neighbourhood of the generating plant. Direct current systems had one drawback. Delivering relatively low-voltage electricity over long distances required thicker cables, which caused significant energy loss. Increasing the voltage level could reduce the loss, but electricity then had to be transformed to low voltage. Alternating current became an option because transformers could raise or lower voltage. But a more practical method was still needed to distribute electricity to multiple clients without each building depending on the rest of the circuit.

Stanley had been working for George Westinghouse, the inventor and industrialist, since 1885. George Westinghouse hired him as chief engineer at his Pittsburgh plant. Stanley was developing a transformer capable of working efficiently within a parallel AC distribution network. Later, he relocated to Great Barrington, where he continued the project and built the system. The Stanley Transformer History by the National MagLab recognises this parallel connection as one of its key features.

How the Great Barrington experiment worked

Stanley’s installation used a Siemens alternator driven by a steam engine in an old rubber factory near Cottage Street. Electricity from the central station was distributed to buildings through wiring strung along the elms on Main Street. The installation supplied electricity to several businesses, allowing them to use incandescent lamps without generating their own power. The voltage could then be reduced at the receiving end to a level suitable for lighting. According to the Engineering and Technology History Wiki account of the IEEE milestone, Stanley raised the generator's 500-volt output to 3,000 volts during a demonstration, then used another transformer to reduce it again. Transformers installed in the basements of buildings lowered the supply to approximately 100 volts for incandescent lighting. Around 20 businesses received illumination through the system.

The demonstration took place on March 20, 1886, after initial experiments earlier that month. The significance of the demonstration lay not in any single component but in combining them into a viable distribution system. High-voltage transmission lowered the current needed to transmit power, reducing losses in the lines. Reducing the voltage at the consumer end made the power usable for the light bulbs available at the time. However, high-voltage transmission does not automatically guarantee safety in the use of electricity.

From a Massachusetts street to modern power networks

The Great Barrington trial helped Westinghouse conclude that Stanley’s method was commercially viable. Stanley received a patent for his induction coil in 1886, and his work helped lead to AC systems that were later adopted more widely. The Institute of Electrical and Electronics Engineers recognised the Great Barrington installation as significant in electrical engineering. Stanley established the Stanley Electric Manufacturing Company in Pittsfield, Massachusetts, in 1890. The company manufactured transformers and other electrical apparatus until its acquisition by General Electric in 1903.

The importance of the 1886 experiment lay in the distribution method it used. Modern power systems use the same principles: transformers step up voltage for transmission and step it down in substations and consumer areas. The equipment and methods have changed, but the overall process remains recognisable. Stanley’s work in Great Barrington did not solve all the technical problems associated with alternating current electricity, and it was only one part of a broader era of invention. However, by lighting businesses on a street in Massachusetts, he showed that alternating current electricity could be used in practice outside the lab.