Copper Facts: Electrical

Copper is the standard benchmark for electrical conductivity. It conducts electrical current better than any other metal except silver.

Copper is routinely refined to 99.98% purity (even more pure than Ivory Soap) before it is acceptable for many electrical applications.

Number 12 (AWG) copper wire is the most common size used for branch circuit wiring in buildings. The amount of copper products consumed in the USA in a typical year would make a size 12 wire that could encircle the Earth 2,250 times or make 120 round trips to the Moon.

CDA's Electrical Energy Efficiency program illustrates how a simple upsizing of copper conductors used for electrical distribution can earn significant paybacks to building owners, usually within one to two years or less.

Installing #10 AWG wire instead of #12 AWG for feeding a 15-amp lighting load running half time (4,000 hours per year) can pay back the difference for its higher cost in only 9 months, at $0.075 per kilowatt-hour (kWh). The higher the cost per kilowatt-hour, the quicker the payback.

Because 70% of the electricity generated in the USA is consumed by motor-driven systems, the most significant energy savings are realized by upgrading systems with high-efficiency motors.

A high-efficiency 3-hp motor operating full time at $0.08 per kWh would repay its cost premium in less than 5 months, and from then on save money and electricity.

Premium motors are not only more efficient (mostly because they are made with more copper), they also last much longer and generate less heat.

Cummins Inc., a Columbus, Indiana, engine manufacturer replaced 296 motors ranging from 1-125 hp with high-efficient copper-wound motors based on an analysis using the U.S. Department of Energy's MotorMaster+ software. The improved efficiency reduces Cummins' power costs by some $200,000 per year. According to DOE, if every plant in the United States were to upgrade their motor systems to the extent that Cummins did, "American industry would save $1 billion annually in energy costs. This would be the equivalent of the amount of electricity supplied to the State of New York for three months."

Wherever electricity flows, connectors are required. Copper in its many varieties is the dominant and favored material whether conductors are used for high-current power distribution or "signal" level currents used for data and telecommunications.

Electric power generators employ electromagnetic principles to convert mechanical energy into electric current through the use of massive copper-wound stators and rotors. Newer and smaller power generators use turbines that are either submerged to capture strong river or tidal currents or elevated to capture the flow of prevailing winds.

Copper plays a crucial role in the delivery of wind energy, based on its high-conductivity, low electrical resistance and resistance to corrosion. Some wind farms contain more than 300,000 feet of copper wire. Electricity generated through wind power flows through insulated copper cables to a copper-wound transformer. Underground copper cables collect the electricity from the base of each tower and deliver it to a substation that transmits it to the utility grid.

Some high-power connectors weigh in at 20 pounds or more, while tiny electronic connectors may weigh as little as a few milligrams with spacing between pins less than half a millimeter. The United States is the world's leader in the multibillion-dollar connector industry.

A practical die-cast copper rotor for electric motors has been the "holy grail" for motor manufacturers for many years. In the late 1990s, a consortium assembled by the Copper Development Association began developing a motor design and suitable die materials for use in casting copper motor rotors.

In 2005, Siemens AG, Munich, Germany, optimized the revolutionary rotor design and introduced new product lines, first in Europe and later in North America. Germany's SEW Eurodrive also offers a series of high-efficiency motors with copper rotors. FAVI S.A., Hallencourt, France, produces die-cast copper rotors for use by other motor manufacturers. Copper-rotor motors have a dramatic increase in motor efficiency.

The new motor rotor die-casting technology reduces heat loss and increases motor efficiency by 1.2-1.7 percentage points over motors using traditional aluminum rotors. That's significant because even a 1% increase in motor efficiency can save $1.1 billion in energy costs annually, according to the U.S. Dept. of Energy. Expressed another way, that could save over 20 billion kilowatt hours of electricity per year, equivalent to 3.5 million barrels of oil annually in the USA, alone. Other benefits are longer motor life, more lightweight motors and a reduction of carbon dioxide and other harmful emissions.

Hybrid cars and SUVs use copper-wound induction motors that draw their power from batteries. To help brake the vehicle, the induction motors act as generators, delivering power to be stored in the batteries. Manufacturers claim such hybrids can be up to 60% more fuel efficient that their standard versions.

Larger hybrid trucks and buses can be equipped with motors using highly efficient copper rotors. One company, which has road tested such vehicles says they perform exceptionally well, decreasing particulate emissions by 96% and traveling 57% farther on a gallon of fuel, thus reducing fuel costs by more than a third.

The Oshkosh Corporations manufactures the ProPulse® diesel-electric hybrid drive system that uses copper rotor motors, providing unmatched power to thunder through the most challenging environments. The system, employed in both commercial and military heavy-equipment vehicles improves fuel efficiency up to 40% and can deliver up to 200 kW of AC power, enough to run a field hospital or an airstrip. As a single-unit, power-generating solution, these vehicles eliminate the need for additional trucks or trailers to transport external equipment.

Copper rotor motors are used in the world-renowned Tesla vehicles. The company's all-electric roadster can do 0-60 mph in an incredible 3.7 seconds. Its sedan sister (a comparative slowpoke) takes 5.6 seconds. The vehicles go run 245 miles or 300 miles, respectively, on a single charge. Now that's efficiency!

Researchers at the Swiss Federal Institute of Technology have built a drill motor that spins at a 1,000,000 rpm, that's nearly 17,000 revolutions per second, at least twice as fast as any motor currently in existence. The matchbox-sized device uses ultra-thin copper wires for its windings, which are inserted into a cylinder of a "special iron previously unused for machines." The assembly is encased in a titanium shell to keep it from flying apart. The new motor will allow the drilling of holes narrower than the width of a human hair for use in the electronics industry.

Power quality problems that plague many modern offices and factories are largely preventable. Copper-intensive solutions include using larger neutral conductors to handle harmonic loads, better grounding systems to dissipate transients and lightning, and fewer outlets per circuit to lessen interaction between office equipment and computers.

Scores of lives and billions of dollars in property could be saved each year if buildings were properly protected against lightning. A single lighting strike at a commercial facility could cause thousands of dollars per hour in lost production.

Copper and its alloys are the most common and most effective materials used in lightning protection.

Nearly 50 tons of high conductivity, oxygen-free copper wire was used to make 1,700 superconducting electromagnets for a collider (atomic particle accelerator) at the Brookhaven National Laboratory in New York. The magnets are used in the 2.4-mile diameter underground collider to study subatomic particles.

The 3.9 mile Tevatron particle accelerator ring at the Fermilab, in Batavia, Illinois, is the second largest in the world and uses 50 tons of copper wire for its 1,000 electromagnets.

In one of its most spectacular and futuristic applications, copper provides the matrix in the superconductors used in the CERN Large Hadron Collider, the largest in the world, in Switzerland.

Copper has long been used as the heat exchange medium in solar heating and hot water systems. Now, it promises to become equally valuable in photovoltaic (PV) systems. These systems produce electricity through the action of sunshine on certain semiconductors. Currently, the most promising material for lower costs and ease of manufacture is copper-indium-gallium-diselenide, or CIGS for short. A number of U.S. and foreign manufacturers are now producing commercial CIGS panels.