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I have spend the past 20 years researching and testing the concepts of what others have written as it relates to Grounding. I have found that much of what I learned about grounding is not really accurate, at least not in relationship to premises wiring within the scope of the National Electrical Code.
This weekend I made lots of new discoveries based on some old historical papers that I received. I think I found the origination of the 25 ohm resistance for a ground rod, why a 6 AWG wire is used for a ground rod, and about where this concept of zero reference might have originated. By the way, the resistance of 8 AWG run seven miles at 25C is 24.64 ohms.
Click here to download [PDF 960KB ] "Transactions of the American Institute of Electrical Engineers", "EARTH WIRES OR THE EARTH AS AN ELECTRIC COMPLETER."
Oh yea, Thomas A. Edison was heavily involved with the telegraphic system (before the light bulb), and he invented the fire alarm mechanism and signaling apparatus http://invention.smithsonian.org/resources/fa_wu_container12.aspx.
Now the plot thickens the Telegraphic industry uses the earth as a return conductor and Edison is involved in the Telegraphic industry. According to a good buddy of mine (Don Zipse), when Thomas Alva Edison started his electric illuminating company and began the electrical distribution system, he used the earth for the return conductor. This uncontrolled flow of electric current over the earth resulted in shocking horses and his employees as they dug along side of the underground distribution system. Horse pulled traction companies' employees working on the tracks received electric shocks, especially when separating the track joints.
In addition, based on original Ralph Lee (great engineer) writing, I figured out what the Code means about 'stabilize system voltage to earth during normal operation [250.4(A)(1)]. I'm so glad because nobody I know what this mean anyway. By the way it has to do with electric utilities and ungrounded systems, with miles and miles of overhead conductors, not premises wiring! So basically it's irrelevant.
Then in the middle of the night, I figured out how placing a ground wire (connected to a ground rod) in a plastic animal water trough could be used to reduce voltage in the water so that the animals would drink it!
I'm currently working on a new book that probably will be titled Grounding Theory and the Real History of Grounding. It will be out in time for my Grounding versus Bonding seminars this fall http://www.mikeholt.com/seminarnew.php?id=2005#October.
Oh what a great week of discovery.
HELP: I need some help to understand the wiring of the telegraph system in the 1800's. What voltage did they transmit? What was the local system voltage? What was a typical distance of transmission? What was the transmission load (watts) required needed to operate the telegraph? Do you know of any wiring diagrams?
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