February 2008 Volume 8     http://www.zotzelectrical.com/     Zotz Electrical     612-501-2012, 320-983-2500

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LED Downlight Retrofit Module

Electrical Technical

Thomas Edison Built The First American Power Grid

We associate Thomas Alva Edison with the invention of the light bulb (among many other inventions), this is not totally true though, there had been previous attempts at making the light bulb. He perfected it and made it a viable and usable product for all to use. What most people do not know is that Edison also invented the first American power grid to use these light bulbs. Edison was excellent at marketing his inventions to make a profit from them. So the next step was to devise a system to use these light bulbs. But to replace the gas lighting system, he needed to invent everything from the power generation plant to the power distribution system to the building wiring system (wiring, safety fuses, lampholders, wall switches, et. al.) in a cost efficient manner.

Edison patented an electric distribution system in 1880. On December 17, 1880, Edison founded the Edison Electric Illuminating Company. The company established the first investor-owned electric utility in 1882 on Pearl Street Station, New York City. Wires had been run overhead on poles for telephone, telegraph and arc-lights in the city but were considered unsightly and a nuisance, so Edison decided to install his power conductors underground. There were problems with the wires shorting out and the inconvenience of digging up the streets that he had to overcome. Edison had proclaimed that he would shortly light up the city but with the delays of the problems, it took longer than he had thought. It was on September 4, 1882, that Edison switched on his Pearl Street generating station's electrical power distribution system, which provided 110 volts direct current (DC) to 59 customers in lower Manhattan, an area of approximately one square mile.

Earlier in the year, in January 1882 he had switched on the first steam generating power station at Holborn Viaduct in London. The DC supply system provided electricity supplies to street lamps and several private dwellings within a short distance of the station. On January 19, 1883, the first standardized incandescent electric lighting system employing overhead wires began service in Roselle, New Jersey. By 1886, orders from cities around the world were coming in to establish power and light systems.

The drawback to Edison's power system was that it operated on DC current, which can be transmitted only a short distance. George Westinghouse by this time had started selling alternating current (AC) electricity. AC electricity could be sent hundreds of miles in a distribution grid. In 1887, there were 121 Edison power stations in the United States that delivered DC electricity to customers. When the limitations of DC were discussed by the public, Edison launched a propaganda campaign to convince people that AC was far too dangerous to use. The problem with DC was that the power plants could only economically deliver DC electricity to customers up to one and a half miles from the generating station, so it was only suitable for central business districts. When George Westinghouse suggested using high-voltage AC instead, as it could carry electricity hundreds of miles with marginal loss of power, Edison waged a "War of Currents" to prevent AC from being adopted.

During this time, only DC could power an electric motor, which was crucial to manufacturing plants and street cars. Edison was reluctant to embrace AC electricity for this reason. But previously, Nikola Tesla had come to Edison to show his invention of the AC system and the AC motor. Edison was often an opponent to technological innovation and change, perhaps because they threatened his business model. This dampened the success of less profitable work by others who were focused on inventing longer lasting high-efficiency technology. When Westinghouse found out about Tesla and AC power, he promoted Tesla's invention. And over time, AC became the standard for America's power grid system.

Westinghouse's AC systems were being bought and installed more than Edison's DC systems. The "War of Currents" was stepped up by Edison. Edison went on to carry out a brief but intense campaign to ban the use of AC or to limit the allowable voltage for safety purposes. As part of this campaign, Edison's employees publicly electrocuted animals to demonstrate the dangers of AC, even though protection from electrocution by AC or DC is essentially the same. One of the more notable occasions when Edison electrocuted animals was when in 1903, his workers electrocuted Topsy the elephant at Luna Park, near Coney Island, after she had killed several men and her owners wanted her put to death. And despite Edison's contempt for capital punishment, the war against AC led Edison to become involved in the development and promotion of the electric chair as a demonstration of AC's greater lethal potential versus the "safer" DC. Edison had termed death by the electric chair as being "Westinghoused" and the term stuck for many years.

AC replaced DC in most instances of generation and power distribution, enormously extending the range and improving the efficiency of power distribution. Though widespread use of DC ultimately lost favor for distribution, it exists today primarily in long-distance high-voltage direct current (HVDC) transmission systems. Low voltage DC distribution continued to be used in high density downtown areas for many years and was replaced by AC low voltage network distribution in many central business districts. DC had the advantage that large battery banks could maintain continuous power through brief interruptions of the electric supply from generators and the transmission system. Utilities such as Commonwealth Edison in Chicago had rotary converters, also known as motor-generator sets , which could change DC to AC and AC to various frequencies in the early to mid 20th century. Utilities supplied rectifiers to convert the low voltage AC to DC for such DC loads as elevators, fans and pumps. There were still 1,600 DC customers in downtown New York City as of 2005, and service was only finally discontinued on November 14, 2007. The New York City Subway system is still run by DC power to this day.

Current News

New Electric Code Changes

Zotz Electrical Wires Boilers

In the past couple months, Zotz Electrical has wired quite a few electric boilers and one ground source heat pump. All but one on Off-Peak controlled systems. With the price of LP Gas now, it is actually more economical to heat your house with an electric boiler, forced air electric plenum heater or heat pump if it is controlled by an Off-Peak system. East Central Energy told me that with their rates as of now, if LP Gas reaches $2.51, you may as well plug in electric space heaters, the cost is the same with standard rate electricity versus LP. With the Off-Peak programs that the electric companies have, there is a big savings in using electricity to heat your homes. Payback on a completely new installed system should be easily recovered in 3 to 5 years.

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