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An Explanation of Third Harmonics for the Non-Technical
By David McCarthy
President Electri-Cable Assemblies
Web: www.electri-cable.com

Third harmonics is like the flu, it has been around for many years, and is here to stay. Third harmonics is a condition created when non-linear devices are plugged into an electrical system.
A non-linear device is anything except an incandescent light bulb or an electric heater. Fluorescent lighting creates third harmonics, computers, printers, calculators, typewriters, all contribute to the increasing level of third harmonics.
Use of non-linear devices are being used at an ever-increasing rate, thereby raising the level of problems associated with third harmonics. Third harmonics, like the flu, will always be with us. And like the flu, how we deal with this condition determines our ability to survive this problem.
Remember, third harmonics is only a problem when the electrical system is not dealt with properly, third harmonics becomes a problem when the electrical system that supplies power for the non-linear devices has an insufficient neutral conductor which acts as a return for the circuit wire.
Using water as an analogy is an excellent way to demonstrate this since there are similarities between electricity and water. Just don’t try to mix them.
Imagine a sink with three faucets (faucets equal circuits/hot wires). The sink has one drain (drain equal neutral wire). The faucets are 1 inch in diameter (#12 gauge wire), and the drain (neutral) is 1 ½ (#10 gauge wire) in diameter. If all three faucets are opened slightly, a small amount of water (water equals amps/current) will flow. This small amount of water flow will drain off easily. As each of the faucets are opened further, and water flow (amp) increase, the drain will have difficulty in handling the increase in water flow (amps), since the drain size is capable of handling only 50 percent or one-half of the total amount of water available. Similarly as non-linear devices are added to the circuits, the amperage (water flow) increases. Eventually, the drain, which is unable to handle the increased water flow (amps), will overflow. In electrical terms, the neutral wire will overheat, and create a neutral overload, burnout, or a fire. This in a nutshell is what third harmonics problems are all about.
In the above example, a 1 inch faucet equals a #12 gauge wire which is rated by the national electric code and underwriters laboratories at 20 amps. The 1 ½ inch drain equals a #10 gauge wire, and they share a #10 gauge neutral. Please refer to the aforementioned example for the results of the four circuit systems.
As previously stated, third harmonics are here to stay and how they are dealt with determines the problems we will have to face.
The Electri-Pak 8, system 83 is the solution for the elimination of third harmonics problems. How is the accomplished? Each of the three circuits #12 gauge wire is rated at 20 amps each. And the three neutral wires (#12 gauge) are each rated at 20 amps. Back to the water analogy. Electri-Pak system 83 has three 1 inch faucets, and three 1 inch drains. Go ahead, open the faucets all the way (load the circuits). As the fast water (amps) goes in the sink, it goes down the drain. Electri-Pak system 83 is the flu shot to eliminate third harmonic problems. Why take chances with your customers operations.
There are volumes of supporting documentation written by recognized and respected research engineers on this subject, and they all concur as to the cause and effects of third harmonics.