AU2020201180A1

AU2020201180A1 - Connectors for Electrical Earth Rods

Info

Publication number: AU2020201180A1
Application number: AU2020201180A
Authority: AU
Inventors: Ian William Cullimore; Samuel John Cullimore
Original assignee: Cullimore Engineering Ltd
Current assignee: Cullimore Engineering Ltd
Priority date: 2019-02-20
Filing date: 2020-02-19
Publication date: 2020-09-03

Abstract

A connector for electrical earth rods designed to make it easier to connect sections of earth rods together and to provide a good electrical contact through any join; the connector includes a collar having a cylindrical body which provides a socket at each 5 end, with the difference between the maximum outer diameter of the collar and the diameter of a rod to be held in the collar less than approximately 35% of the rod diameter; each end of the cylindrical body is tapered to reduce the outer diameter of the collar at each end. 6 1/2 xix --- ------- ----------- CDo 000

Description

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CONNECTORS FOR ELECTRICAL EARTH RODS

Technical Field The present invention relates to connectors for electrical earth rods (also referred to as "ground rods").

Background Art Electrical earth rods are metal rods which are driven 10 to 15 metres into the ground to provide electrical earthing. Typically, the rods are steel or copper coated steel and are circular in cross-section, with a diameter typically 30 to 40 millimetres. To install the rods, they are driven into the ground using an impact driver such as a hydraulic hammer; a range of suitable known driving tools can be used.

For ease of handling and driving, earth rods are produced in 2 to 3 metre length sections, and to form the completed earth rod, the sections must be joined together such that the completed structure withstands the impact of driving and also provides an excellent electrical connection.

It is known to provide connectors in the form of collars or couplers to join the sections of earth rod, but existing collars are bulky, with a much wider diameter than the rods. This frequently leads to difficulties in driving the rods plus collar assembly, because the larger diameter collar provides a substantially greater resistance to driving than the rod, and this can lead to the collar jamming in the ground, with a consequent risk of buckling of the rods.

At present, each section of rod is cut flat across each end i.e. the plane of each end of a rod is perpendicular to the longitudinal axis of the rod. This makes it more difficult to insert the end of the rod into a collar, and can result in the end of the rod jamming in the collar.

Disclosure of Invention An object of the present invention is the provision of an improved collar, to reduce the risk of jamming when the rod plus collar assembly is driven.

The present invention provides a collar for an electrical earth rod, said collar having a cylindrical body which provides a socket at each end, the difference between the maximum outer diameter of the collar and the rod diameter being less than approximately 35 percent of the rod diameter; each end of the cylindrical body is tapered to reduce the outer diameter of the collar at each end.

Preferably, the difference between the maximum outer diameter of the collar and the rod diameter is less than approximately 22 percent of the rod diameter, and the taper at each end of the cylindrical body is about 10°.

Each socket may be open-ended, but preferably the sockets are separated from each other by a portion of solid electrically conductive material which provides an end for each socket.

In a preferred embodiment, the present invention also provides an electrical earth rod wherein each end of each section of rod is formed with a shallow taper and the edge between each end of the rod and the adjacent side of the rod is bevelled.

Preferably, the taper is approximately 2 degrees, and the bevel is approximately 30 degrees.

Brief Description of Drawings By way of example only, a preferred embodiment of the present invention is described in detail with reference to the accompanying drawings, in which:

Figure 1 is a side view of a collar in accordance with the present invention;

Figure 2a is a side view of part of a rod in accordance with the present invention;

Figure 2 is a side view of part of a rod in accordance with a preferred embodiment of the present invention; and

Figure 3 is a view of part of the end of the rod of figure 2, on a larger scale.

Best Mode for Carrying Out the Invention Referring to the drawings, a collar 10 for earth rod is shown in Figure 1. The collar 10 is generally cylindrical, but with a taper at each end 11, 12 to provide a smoother transition between a rod held in the collar and the adjacent end of the collar. Preferably, the taper

(angle X on Figure 1) is about 10°. The interior of the collar provides two end-to-end sockets 13, 14 each having a diameter slightly greater than the average diameter of an earth rod, so that the earth rod is an easy sliding fit in the corresponding socket. The area 15 between the ends of the two sockets 13, 14 is solid metal, so that when each socket 13, 14 is occupied by one end of an earth rod, there is an unimpeded electrical path from a rod in socket 13, through the area 15, to the rod in socket 14. It also is possible to omit the area 15, so that each socket 13, 14 is open-ended, and earth rods placed in these sockets are in direct contact with each other.

The collar 10 is made of a low alloy steel, preferably a chromium/molybdenum/manganese steel such as 4140; steel of this type has good fatigue resistance properties, is tough, has good torsional strength, resists abrasion and has excellent impact resistance. The use of this grade of steel means that the overall diameter of the collar can be closer to the overall diameter of the rod. Preferably, the difference between the maximum collar diameter and the rod diameter is in the range 22 - 35 percent of the rod diameter.

It will be appreciated that minimising the increase in diameter between each length of rod and the corresponding collars greatly reduces the risk of the collar jamming when driven through tightly packed earth, and also reduces the resistance of the rods plus collar to driving.

Referring to Figure 2a, part of a length of rod 16 is shown. The rod is a smooth surfaced cylinder, typically about 37 millimetres in diameter and made of steel or copper coated steel.

Each end 17a of the rod 16 is cut straight across:- the plane of each end 17a is substantially perpendicular to the longitudinal axis A - A of the rod 16.

It is essential to the correct functioning of the earth rod that the rod sections and the corresponding collars are tightly connected together:- if a section of rod fails to make good contact with the base of the corresponding socket in the collar (or with the other rod, if the area 15 is not present), a poor electrical connection will result and the earth rod assembly will not function satisfactorily.

It has been found that the collar 10 of the present invention will work satisfactorily with straight cut rods as shown in Figure 2a, but to ensure that there is the best possible electrical contact between the end of each length of rod and the corresponding collar, the design shown in Figures 2 and 3 is preferred.

Referring to Figures 2 and 3, each end 17 of the rod 16 is formed with a shallow taper 18 of the order of about 20, and also is formed with a bevel 19 of about 30°.

The taper 18 and bevel 19 together provide a smooth, rounded and slightly reduced diameter at each end of the rod, and this greatly facilitates the smooth sliding fit into one of the sockets 13, 14 in the collar 10.

The above described rods and collars are used in known manner i.e. a first rod section is driven into the ground using a known driver; when the rod is nearly fully driven, a collar is dropped onto the top of the rod, with the end of the rod engaged with the collar. A second rod section is then dropped into the collar and the end of the second rod is driven. This is continued until the required length of earth rod has been driven into the ground.

Claims

1. A connector for electrical earth rods, said connector including a collar having a cylindrical body which provides a socket at each end, wherein the difference between the maximum outer diameter of the collar and the diameter of a rod to be held in the collar is less than approximately 35% of the rod diameter; and wherein each end of the cylindrical body is tapered to reduce the outer diameter of the collar at each end.

2. The connector as claimed in Claim 1, wherein the difference between the maximum outer diameter of the collar and the diameter of a rod to be held in the collar is less than approximately 22% of the rod diameter.

3. The connector as claimed in Claim 1 or Claim 2, wherein the sockets at each end of the collar are spaced apart by an area of solid metal so as to provide a good electrical connection in use between rods held in adjacent sockets.

4. The socket as claimed in Claim 1 or Claim 2 wherein each socket is open-ended.

5. The socket as claimed in any one of Claims 1-4 wherein each end of said cylindrical body is tapered by about 10°.

6. The combination of a connector as claimed in any one of Claims 1-5, and two earth rods, each located in one of the sockets of the collar.

7. The combination as claimed in Claim 6, wherein the end of each earth rod located in the corresponding socket is straight cut.

8. The combination as claimed in Claim 6, wherein the end of each earth rod located in the corresponding socket is bevelled and tapered.

9. The combination as claimed in Claim 8, wherein said taper is approximately 2, and said bevel is approximately 30°.