Electric Utility Glossary
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
AC/DC and the Current Wars
Published: November 17, 2025
It takes thousands of electrical components and specialized equipment to make a reliable electric distribution system. The earliest electric utility systems suffered from power quality and supply reliability.
The result was electric power that would only be supplied for a limited time each day or electric power that would brown out or black out during peak capacity. The electricity brown outs and black outs damaged things like lighting, electrical components and machines. Electricity was also known to be dangerous if used improperly, resulting in fire or death.
Developing Electrical Standards
As a result, heavy emphasis was placed on creating electric standards. Standards for planning and construction. Standards for equipment and maintenance. Standards for electrical machines and appliances. However, since electricity was still a new field of discovery, there were many competing interests for what the standards should be.
Thomas Edison's team was renowned and they promoted a system standardized around one-way direct current (DC) to more reliably supply steady current. Many electric devices in the early era were also built for DC current as a result, creating a loose system of DC electricity delivery to devices that ran from the same DC current. There was a major constraint with this system though, which was distance.
DC could only transmit power for about one mile. In order to use Edison’s system, it implied creating thousands of central power generation facilities, which ultimately wasn’t realistic.
At the same time Edison's team promoted DC power, Nikola Tesla's team introduced the practical use of alternating current (AC) which could be modulated more easily to different usable voltages and it could be reliably transmitted much farther distances. AC could be converted to DC for customers as well. The AC system could reliably supply more electricity over longer distances at less cost than a DC system.
In the early years of electricity, some homes and businesses actually had two different electrical systems in their building structure and it led to many problems. Those competing and conflicting electrical systems led to what is referred to as the “Current Wars” where a scientific fight, a business fight and a political fight ensued to make DC power the primary system everyone should use.
Edison's investors and partners were building out a DC-based system with DC-based products and it made sense to promote it and defend it. This included infamously electrocuting stray animals and even an elephant for public relations displays to scare the general public on the dangers of AC current.
Edison’s team and Tesla’s team competed on many projects but Tesla had a string of high profile wins, often because he could do more with less and at less cost. By the late 1890s the “Current Wars” shifted to favor AC and AC became the current of choice because it was more practical for the needs of the time. The vast majority of electric systems around the world today operate AC current systems.
Notably, DC current didn’t just vanish. The electrical engineering field began to discover that AC and DC are better suited for certain needs. DC current technology in modern times can actually be used for longer distances now using high volume direct current (HVDC). Low voltage DC is also used frequently for almost all small consumer electronics, LED lighting and computers.
While the "Current Wars" ended with AC rising to the top, both currents are heavily used today but for very specific applications. This includes applications where the current is converted between AC and DC when needed and then further converted to specific voltages based on the electrical requirements of the end product.
Electric Utility Glossary Navigation