US3317650A

US3317650A - Electrical ground net

Info

Publication number: US3317650A
Application number: US443492A
Authority: US
Inventors: Ralph M Padellford
Original assignee: Iowa State University Research Foundation ISURF
Current assignee: Iowa State University Research Foundation ISURF
Priority date: 1965-03-29
Filing date: 1965-03-29
Publication date: 1967-05-02
Anticipated expiration: 1984-05-02

Description

United States Patent 3,317,650 ELECTRICAL GROUND NET Ralph M. Padellford, Nevada, Iowa, assignor to Iowa State University Research Foundation, Ames, Iowa, a corporation of Iowa Filed Mar. 29, 1965, Ser. No. 443,492 Claims. (Cl. 174-5) The invention described herein was made or conceived in the course of or under a contract with the United States Atomic Energy Commission.

Many people must work in the close proximity of high electrical voltages, and others are actually required in their work to handle hot lines. As a consequence, many persons are accidentally electrocuted when they inadvertently become grounded while they are at the same time in contact with a source of electrical energy. Devices have been created to ground persons who accidentally become in contact with electricity to carry the electrical current away from the vital organs of the body, but these devices often unnecessarily create injury and are totally unsatisfactory for a person who must handle hot wires.

Therefore, a principal object of this invention is to provide an electrical ground net that will permit the wearer thereof to safely handle electrically energized circuits if he is not otherwise grounded, and which will come into play to direct current away from the body if the wearer accidentally becomes grounded.

A further object of this invention is to provide an electrical ground net that will activate a visible or audible signal if the wearer thereof does become grounded so that the plight of the wearer can be quickly discovered by others.

A further object of this invention is to provide a ground net that will be easily adapted for use in conjunction with garments to be worn by the electrical worker.

A still further object of this invention is to provide a ground net that can be easily put on and taken off by the wearer thereof.

A still further object of this invention is to provide a ground net that will not interfere with the work or movements of the wearer.

A still further object of this invention is to provide a ground net that is economical of manufacture.

These and other objects will be apparent to those skilled in the art.

This invention consists in the construction, arrangements, and combination of the various parts of the device, whereby the objects contemplated are attained as hereinafter more fully set forth, specifically pointed out in the claims, and illustrated in the accompanying drawings, in which:

FIG. 1 is a schematic diagram of the electrical components of the device of the invention;

FIG. 2 is a perspective view of how an electrical worker might utilize the device of this invention;

FIG. 3 is a partial perspective view of the cuff and sleeve of a garment incorporating the device of this invention;

FIG. 4 is a perspective view of a coverall type garment utilizing the device of this invention with the electrical leads being shown in dotted lines;

FIG. 5 is a view of a jacket-type garment utilizing the device of this invention with the electrical leads being shown in dotted lines; and

FIG. 6 is a shoulder harness utilizing the device of this invention.

The numeral 10 generally designates a terminal plate of any suitable insulative material. Terminal 12 is secured thereto by any convenient means, and one end of insulated

electrical leads

14, 16, 18, 20 and 22 are electrically secured in any suitable manner to terminal 12. The other ends of

leads

14, 16, 18, 20 and 22 are electrically connected to

flexible metal bands

24, 26, 28, 30 and 32, respectively. These bands may be made of copper, flexible aluminum wire, or flexible woven metal mesh. Each of the bands has at least one conventional metal snap means 33 secured to its opposite ends (Fig. 3) to permit the ends thereof to be selectively secured together. The

bands

24 and 26 are adapted to be secured to the ankles of the worker, the

bands

28 and 30 are adapted to be secured to the wrists of the wearer, and the band 32 is suitable for attachment around the neck of the person involved.

An insulated electrical cable 34 has one of its ends electrically secured to terminal 12 and the other end is elec trically secured to relay switch 36 contained in housing 38. A ground cable 40 extends from terminal 42 in housing 38 and is adapted to have its outer end connected to a suitable electrical ground.

The relay switch 36 includes switch or shorting bar 44 that is normally in spaced or open condition with respect to terminal 42. An electrical lead 46 connects cable 34 with the coil of solenoid 48. Solenoid 48 serves to close bar 44 on terminal 42 when the coils of the solenoid are electrically excited. Lead 50 connects the solenoid coil to a conventional transducer 52 which has points that will close to pass current in the amount of ten milliamperes or more. The points will remain open at lesser values and this serves to prevent closing of the transducer points by static electricity. Lead 54 connects the transducer to signal light 56 and bell means 58 which are connected in parallel to each other and which are both connected to ground line 40. The relay switch and the aforementioned components can be placed in either a single housing 38 or a plurality of containers.

The

bands

24, 26, 28, 30 and 32 can be included in a variety of garments such as coveralls 60 or jacket 62. In each case, the outer surface of the bands is covered with an insulating material 64 but the inner surfaces thereof are exposed to the skin of the wearer. In FIG. 6, the terminal plate 10 is secured to a shoulder harness 66 which utilizes supporting shoulder straps 68 and waist belt 70 of conventional webbing material. It is preferred that the outer surfaces of the bands also be insulated in this embodiment of the invention.

The normal operation of the device of this invention is I as follows: The electrical worker puts on any one of the devices shown in FIGS. 4-6- and adjusts each of the

bands

24, 26, 28, 30 and 32 tightly against the skin on the respective parts of his body. The ground cable 40 is connected to any convenient ground (see ground 40A in FIG. 2), and the worker then proceeds to work in the electrical area. Since the points of the transducer are open, as is the shorting bar 44, the worker is not grounded even though the cable 40 is grounded. If the worker is not otherwise grounded, such as by working in an insulated basket, he can actually handle high voltage circuits with no ill effects, because current will not pass through his body until at least some portion of his body becomes grounded.

In the event that the worker accidentally touches a neutral wire while handling hot wires, or if he inadvertently touches a hot wire while being grounded (as by standing on wet ground or the like), the electrical current will enter the body at the point of contact and tend to rush through the body to the most accessible ground. Thus, if the left hand touches the hot wire and the right hand inadvertently touches a ground, the current will enter the left hand, and in the absence of the ground net, would move through the left arm and chest of the worker towards the right arm and right hand. Even nominal voltages can be fatal under such circumstances. However,

with the ground net herein described being worn by the electrical worker, the band 28 would immediately pick up the onrush of current and the current would pass through insulated lead 18 to terminal 12. The current would take the path of least resistance and enter the band 28 and lead 18 rather than pass through the left arm and body of the worker, for the lead 18 is a much better conductor of electricity than is the body of the worker.

Even though the right hand is grounded, the onrush of current will continue to seek the path of least resistance to ground, and this path is presented by ground cable 34 and not the lead 20- which extends towards the right hand, for the right hand itself insulatesthe band 30 from the inadvertent ground to some small degree. The initial impulse of current causes the points of transducer 52 to close and an electrical circuit is completed through lead 46 and the coil of solenoid 48, thence through lead 50 and transducer -2, thence through lead 54 and through signal light 56 and bell means 58 to ground cable 40. This completed circuit through the switching circuit of relay 36 energizes the coil of solenoid 48 and closes shorting bar 44 on terminal 42 to permit the heavy load of current to pass directly through bar 44 from cable 34 to cable 40. The light 56 and bell means 58 will be actuated by the switching circuit of the relay 38, which will serve to notify others that the electrical worker is in trouble. The ground net will serve to detour the fatal charge of the electricity through the electrical conductors to ground rather than following a path through the workers body. But most important of all, the worker will be able to actually handle hot lines and the relay 36 will never be actuated (or closed) unless the worker becomes accidentally grounded, such as by touching a neutral line, and in that event, the relay will function to close the bar 44, whereupon the current will be grounded through the net rather than through the workers body as described above. This phenomenon will protect the heart, respiratory and nervous systems of the worker.

The insulation on the outer surface of the bands serves to minimize the accidental grounding of the net through the bands themselves. Obviously, all of the two types of garments in FIGS. 4 and 5 will work equally as well, and the shoulder harness in FIG. 6 can be donned by those workers who do not have available garments in which the ground net is an integral part.

Thus, from the foregoing, it is seen that the device of this invention will accomplish at least all of its stated objectives.

Some changes may be made in the construction and arrangement of my electrical ground net without departing from the real spirit and purpose of my invention, and it is my intention to cover by my claims, any mofiided forms of structure or use of mechanical equivalents which may be reasonably included within their scope.

I claim:

1. In an electrical ground net device,

a first pair of electrical conducting elements adapted for connection to a wearers wrist,

a second pair of electrical conducting elements adapted for connection to a wearers ankles,

a centrally positioned terminal means located between said pairs of electrical conducting elements, only a single insulated electrical conducting lead on each said electrical conducting elements, said leads interconnecting said terminal means with each of said respective electrical conducting elements,

a single electrical ground circuit interconnecting said terminal means and an electrical ground,

and a normally open relay switch imposed in said electrical ground so that when said relay switch is closed,

said single electrical ground circuit will be the only means for grounding an electrical potential imposed upon one of said electrical conducting elements.

2. The device of claim 1 wherein said electrical conducting elements are bands of electro-conducting material having an inner surface and an outer surface, the inner surface of said bands being exposed to make electrical contact with the body of said wearer, and insulation means on the outer surface of said bands to prevent the inadvertent electrical contact of said band with a source of electrical potential.

3. The device of claim 1 wherein said device is mounted on a shoulder harness whereupon said device can be secured to the upper torso of a persons body.

4. The device of claim 1 wherein said electrical conducting elements are flexible metallic members that are adapted to be wrapped tightly around the limbs and neck of a persons body.

5. The device of claim 4 wherein said device includes a garment having sleeve and cuff portions, and one of said flexible metallic members is secured to each of said cuff portions.

6. The device of claim 4 wherein said relay switch includes a control means to maintain said relay switch in an open condition until a predetermined amount of electrical potential is imposed on said switch.

7. The device of claim 4 wherein said flexible metallic members include means to detachably hold said members in tight contact with the portion of the body upon which they are secured.

8. The device of claim 4 wherein said flexible metallic members are flat metallic bands.

9. The device of claim 4 wherein an electrical signal device is imposed in said electrical ground circuit.

10. The device of claim 4 wherein said flexible metallic members include insulation means on only a portion of the outer surface thereof which normally would be opposite to the portion thereof adjacent the persons body.

References Cited by the Examiner UNITED STATES PATENTS 318,172 5/1885 Delaney 174-5 1,940,491 12/1933 Freitag 174-5 2,131,386 9/1938 Mishelevich 340-255 2,999,189 9/1961 Gerrard 317-18 LARAMIE E. ASKIN, Primary Examiner.

J. F. RUGGERIO, Assistant Examiner.

Claims

1. IN AN ELECTRICAL GROUND NET DEVICE, A FIRST PAIR OF ELECTRICAL CONDUCTING ELEMENTS ADAPTED FOR CONNECTION TO A WEARER''S WRIST, A SECOND PAIR OF ELECTRICAL CONDUCTING ELEMENTS ADAPTED FOR CONNECTION TO A WEARER''S ANKLES, A CENTRALLY POSITIONED TERMINAL MEANS LOCATED BETWEEN SAID PAIRS OF ELECTRICAL CONDUCTING ELEMENTS, ONLY A SINGLE INSULATED ELECTRICAL CONDUCTING LEAD ON EACH SAID ELECTRICAL CONDUCTING ELEMENTS, SAID LEADS INTERCONNECTING SAID TERMINAL MEANS WITH EACH OF SAID RESPECTIVE ELECTRICAL CONDUCTING ELEMENTS, A SINGLE ELECTRICAL GROUND CIRCUIT INTERCONNECTING SAID TERMINAL MEANS AND AN ELECTRICAL GROUND, AND A NORMALLY OPEN RELAY SWITCH IMPOSED IN SAID ELECTRICAL GROUND SO THAT WHEN SAID RELAY SWITCH IS CLOSED, SAID SINGLE ELECTRICAL GROUND CIRCUIT WILL BE THE ONLY MEANS FOR GROUNDING AN ELECTRICAL POTENTIAL IMPOSED UPON ONE OF SAID ELECTRICAL CONDUCTING ELEMENTS.