US3582531A

US3582531A - Electrochemical grounding rod

Info

Publication number: US3582531A
Application number: US886417A
Authority: US
Inventors: Albert P Sheelor
Original assignee: ALBERT P SHEELOR
Current assignee: ALBERT P SHEELOR
Priority date: 1969-12-18
Filing date: 1969-12-18
Publication date: 1971-06-01
Anticipated expiration: 1988-06-01

Abstract

An electrical grounding device comprising a metal pipe capped and perforated at both ends and filled with deliquescent salts which dissolve to form an electrolyte. The pipe is buried vertically in the ground with only the perforated upper end protruding above the surface, to which electrical circuits are connected. Atmospheric air enters and leaves the pipe through the exposed perforations, and moisture is continually taken out of the air by the deliquescent material, dissolving some of the salts. The resultant solution leaks out through the perforations in the bottom of the pipe, penetrating and moistening the soil with electrolyte to provide a low resistance electrical path to ground.

Description

United States Patent H 13,5s2,s31

[72] Inventor Albert P. Sheelor 110 South Barraneo, Covina, Calif. 91722 [21 Appl. No, 886,417 [22] Filed Dec. 18,1969 [45] Patented June 1, 1971 Continuation-impart of application Ser. No. 756,194, Aug. 29, 1968, now abandoned. This application Dec. 18, 1969, Ser. No. 886,417

[54] ELECTROCHEMICAL GROUNDING ROD 7 Claims, 1 Drawing Fig.

[52] US. Cl 174/6 {51] Int. Cl.. H01r 3/06 [50] Field of Search 174/6, 7; 204/196; 343/846, 849

[56] References Cited UNITED STATES PATENTS 984,175 2/1911 Yarian 174/7 1,177,180 3/1916 Garton 174/7 1,783,035 11/1930 Borden 174/7 1,856,506 5/1932 Preston H 174/6 2,068,545 1/1937 Haig 174/7 FOREIGN PATENTS 785,188 5/1935 France 6/ 264,349 l/l927 Great Britain 7/ 400,739 11/1933 Great Britain; 6/ 413,914 7/1934 Great Britain 7/ Primary Examiner-Laramie E. Askin Attorney-Herbert E. Kidder ABSTRACT: An electrical grounding device comprising a metal pipe capped and perforated at both ends and filled with deliquescent salts which dissolve to form an electrolyte. The pipe is buried vertically in the ground with only the perforated upper end protruding above the surface, to which electrical circuits are connected. Atmospheric air enters and leaves the pipe through the exposed perforations, and moisture is continually taken out of the air by the deliquescent material, dissolving some of the salts. The resultant solution leaks out through the perforations in the bottom of the pipe, penetrating and moistening the soil with electrolyte to provide a low resistance electrical path to ground.

7 SPUN GLASS OR GLASS WOOL WADS 1;,

\ YO/x 4 8HYGROSCOPIC AND OR DELIQUESCENT SA TS 7-sPuN GLASS OR GLASS WOOL WADS PATENT ED- lm -1 Ian spun GLASS OR euxss 7/ WOOL WADS 8HYGROSCOPIC ANDKOR TS DELIQUESCENT SA 7-sPuN GLASS OR GLASS WOOL WADS INVENTOR.

ALBERT P. SHEELOR ELECTROCHEMICAL GROUNDING ROD CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation-in-part of my pending application Ser. N01 756,194, filed Aug. 29, l968, now abandoned.

BACKGROUND OF THE INVENTION The present invention relates to electrical grounding devices, and more specifically to a grounding device for use on building sites to provide a secure, low resistance return ground path for the complete electrical service circuits installed in the buildings.

Heretofore, the grounding of such circuits has been accomplished by the use of water pipes, which has long been recommended by Building and Safety authorities and-their approved codes. In recent years, however, serious difficulties have been encountered in some localities with galvanic interaction in such water and plumbing systems, and consequently those concerned with the problem in this field have begun to act to change the codes to alleviate the situation by changing the present grounding practices.

Another important factor complicating the problem is the growing use of plastic pipe, fittings, and even water meter housings, which makesit impossible to utilize the water lines as a service grounding medium without usingjumpers or other alternate equipment,

In addition to these practicalproblems, there is another factor that has long been recognized as an undesirable hazard of the water pipe grounding system, and that isthe danger of accidental electrocution. Many lives have been lost where victims have inadvertently touched a water pipe while in contact with a hot" wire. Such accidents can be prevented by isolating the electrical ground circuit from the water pipes and, instead, connecting the ground (i.e., neutral) wire of'the electrical service to a separate grounding device buried in the soil at some distance from the nearest water pipe. The relatively high resistance of the soil separating the grounding device from the water pipes has a current-limiting effect, so that the total electrical current going into the victims body is reduced to a less than lethalamount. This is an important safety factor which cannot be ignored.

In view of the above factors, building and code officials are now considering alternative electrical service grounding systems, withthe view of establishing new approved codes to specify the minimum practical requirements for maximum safety and efficiency.

In the United States there are many soils and climatic conditions, and any service grounding device, to be universally acceptable, must be sufficiently versatile for use in a wide range of soil conditions. For example, a high, dry desert in the Mojave region of California would require a different grounding device capability than a service ground on the edge of a salt marsh in Hoboken, New Jersey.

SUMMARY OF THE INVENTION The primary object of the present invention is to provide a new and improved electrical grounding device of the character described which isisolated from the water pipes, so that the pipes form no part of the electrical system and therefore cannot cause accidental electrocution of a person who is in contact with both a "hot" wire and the water pipes. One advantage of isolating the electrical ground from the water pipes is that it permits the use of plastic pipes without the necessity of usingjumpers.

Another important object of theinvention is to provide a very low resistance electrical path to ground, considerably better than the average resistance values obtained with conventional grounding systems using water pipes. Typically, the resistance ofthepresent invention averages about 4.5 ohms, whereas the water pipe grounding system usually ranges from to 25 ohms.

A further object of the invention is to provide a grounding device that maintains its low resistance over a very long period of time, and which is relatively unaffected by the moisture content of the soil.

These objects are achieved by providing a metal pipe, preferably of copper, which is capped and perforated at both ends and filled with a quantity of metallic salts which are deliquescent or hygroscopic in nature, and which dissolve to form a highly conductive, noncorrosive electrolyte. The pipe is buried vertically in the ground, with one end projecting slightly above the surface so that the holes in that end are exposed. The neutral ground wire of the electrical service is then connected to the protruding end of the pipe. Atmospheric air flows into and out of the pipe through the exposed holes in the top end of the pipe, and the deliquescent salt takes up moisture from the air, which accumulates and then runs out through the holes in the bottom end of the pipe. The moisture dissolves some of the salt, forming an electrolyte solution that permeates the soil both vertically and horizontally to provide an extensive area oflow resistance conductivity. An important feature of the invention is that it continues to form this electrolyte over a long period of time, so that the device maintains its effectiveness undiminished over many years.

The foregoing and other objects and advantages of the invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, with reference to the accompanying drawing.

The single FIGURE of the drawing is a partially cut away, clevational view of an electrical grounding device embodying the principles of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the drawing, the reference numeral 1 designates a terminal screw that passes through a hole formed in the flattened top end of a relatively small diameter metal tube 2, preferably of copper. The terminal screw l forms the point of attachment for the grounding wire (not shown) of the electrical service. The bottom end of the tube 2 is threaded, and screwed into the small end of a bell reducer 3. The internally threaded large end of the reducer 3 is screwed onto the top end of a metal pipe 4, which forms the main body of the device. The pipe 4is preferably made of copper, and is typically about 8 feet long, with an outside diameter of 2 inches. The bottom end of the pipe 4 is closed by a cap 5, and holes 6 are drilled through the sidewalls of the pipe closely adjacent the cap 5 and top closure 3.

Contained within the pipe 4 at each end thereof are wads 7 of spun glass or glass wool, which serve to prevent the contents of the pipe from spilling out of the holes 6. The pipe is filled with a quantity of moisture-absorbing material 8 consisting of deliquescent or hygroscopic salts such as calcium chloride, magnesium chloride, sodium hydroxide, sodium chloride, copper sulfate, or other salts which, alone or in combination, act to extract moisture from atmospheric air and to dissolve some of the salt to form an electrolyte. This electrolyte solution then bleeds out of the holes 6 in the bottom of the pipe and spreads out by capillary action until it is dispersed throughout the soil for a considerable distance in all directions, forming a low resistance path of electrical conductivity into the soil. Moreover, by greatly extending the effective size and depth function of the grounding device, the invention reduces the current density per unit area thereby eliminating or minimizing overheating of the unit during momentary current overloads, as in the case of a short circuit.

The choice of salt used to fill the pipe 4 is governed by the type of soil in which the pipe is to be buried. For example, in a wet soil the choice might be copper sulfate of one-half inch aggregate size; selected because of its slow dissolving rate and the fact that it is hygroscopic instead of deliquescent.

Deliquescence is not needed in a wet soil. On the other hand,

chloride in the form of coarse rock salt. The deliquescent property of the calcium chloride or sodium hydroxide causes it to take up moisture from the atmospheric air contained within the pipe, which then dissolves part of its own substance, or the sodium chloride mixed therewith, to form the liquid electrolyte which then leaks out into the soil and becomes dispersed therein. Mixtures of calcium sulfate and calcium chloride, or calcium chloride and sodium chloride in various proportions have produced good results.

The installation of the device at a building site is accomplished by digging a hole in the ground at the selected spot to a depth of about 7% feet, using a soil auger or water drill. The pipe 4 is then lowered into the hole which, if it has been dug to the correct depth, will leave only about 6 inches of the top end of the pipe protruding above the surface of the ground. It is essential only that the holes in the top end of the pipe be open to the atmosphere, Before back filling the hole, it is advisable to provide some dampness or moisture at depth, by pouring a few gallons of water into the hole around the pipe. After back filling the hole, the service ground wire is connected to the terminal screw 1, and the device is ready for use.

Almost immediately, the deliquescent or hydroscopic salt 8 within the pipe will begin to absorb moisture from the atmospheric air within the pipe. This absorption of moisture goes on day and night, through periods of low relative humidity as well as high. However, maximum moisture absorption takes place when the relative humidity is high, which is often in the cool of the night, or during and after a shower. The atmospheric air within the pipe is being constantly brcathed" in and out through the open holes 6 in the top end of the pipe, due to changing temperature and atmospheric pressure. Thus, the supply of moisture is constantly replenished, and the electrolyte inside the pipe and dispersed throughout the soil surrounding the pipe never dries out.

A grounding device of the type described above has been in use for over 5% years at the time of filing this application, and its resistance to ground has remained unchanged at 4.5 ohms for the entire time. The National Electrical Code calls for a maximum of ohms resistance (impedance), at the time of installation, but his not uncommon for the resistance values of prior grounding devices to increase to many hundreds of ohms over a period of years, owing to drying out of the soil, or corrosion of-the grounding element. The grounding device of the present invention has been dug up after being buried in the soil for 6 or 8 months, with no appreciable evidence of corrosion. Nor was there any apparent loss of chemical salts 8, although both the contents of the pipe and the soil surrounding it were damp. It is believed that, in time, both the inner and outer surfaces of the pipe would become somewhat corroded. However, the corrosion products are governed, to a large extent, by the salts 8 contained within the pipe, and such corrosion products are therefore of relatively low resistance. Galvanic corrosion is a relatively minor problem, owing to the fact that the electric current is AC, which means that the pipe 4 is alternately charged with positive and negative electricity.

With the neutral (ground) line of the electrical service connected to the grounding device of the present invention, there is no electrical connection between the service lines and the water pipes of the building. Thus, the water pipes are isolated from the electrical system, and it is virtually impossible for a person to be electrocuted by touching a water pipe while in contact with a hot" wire.

While I have shown and described in considerable detail what I believe to be the preferred form of my invention, it will be understood by those skilled in the art that the invention is not limited to such details, but might take various other forms within the scope ofthe following claims.

I claim:

1. An electrochemical grounding rod for connecting the neutral ground wire of an electrical service line to the soil, comprising:

a metal pipe having openings at both ends thereof and filled with moisture-absorbing metallic salts that are soluble in water to form a highl conductive electrolyte;

means for retaining sai salts within said pipe;

said pipe being buried in the ground with one end thereof protruding above the surface of the ground so that said openings at that end are exposed to the atmosphere, thereby allowing air to flow freely into and out of the P p said moisture-absorbing salts taking moisture out of the air, which dissolves some of said salts and runs out of said openings at the bottom end of the pipe, permeating the soil to make a good electrical contact between the pipe and the soil; and

means for connecting said pipe to said neutral groundwire of said electrical service line.

2. An electrochemical grounding rod as in claim 1, wherein said means for retaining salts within said pipe comprises caps mounted on each end of the pipe, and wads of porous material packed within the pipe adjacent said caps, said pipe being perforated in the ends thereof where said wads are contained.

3. An electrochemical grounding rod as in claim 2, wherein said metallic salt comprises copper sulfate.

4. An electrochemical grounding rod as in claim 2, wherein said cap on the protruding top end of said pipe has a terminal screw for attachment of said neutral ground wire of said service line.

5. An electrochemical grounding rod as in claim 2, wherein said metallic salt comprises a mixture of calcium chloride and copper sulfate.

6. An electrochemical grounding rod as in claim 2, wherein said metallic salt comprises a mixture of sodium chloride and a deliquescent material.

7. An electrochemical grounding rod as in claim 1, wherein said metallic salts comprise one or more salts selected from the group consisting of copper sulfate, calcium chloride, magnesium chloride, sodium chloride, and sodium hydroxide.

Claims

2. An electrochemical grounding rod as in claim 1, wherein said means for retaining salts within said pipe comprises caps mounted on each end of the pipe, and wads of porous material packed within the pipe adjacent said caps, said pipe being perforated in the ends thereof where said wads are contained.
3. An electrochemical grounding rod as in claim 2, wherein said metallic salt comprises copper sulfate.
4. An electrochemical grounding rod as in claim 2, wherein said cap on the protruding top end of said pipe has a terminal screw for attachment of said neutral ground wire of said service line.
5. An electrochemical grounding rod as in claim 2, wherein said metallic salt comprises a mixture of calcium chloride and copper sulfate.
6. An electrochemical grounding rod as in claim 2, wherein said metallic salt comprises a mixture of sodium chloride and a deliquescent material.
7. An electrochemical grounding rod as in claim 1, wherein said metallic salts comprise one or more salts selected from the group consisting of copper sulfate, calcium chloride, magnesium chloride, sodium chloride, and sodium hydroxide.