US2147828A - Tubular electrical grounding rod - Google Patents

Description

2 Sheets-Sme L nulllunll u.

H, C, DNIELS Feb. 21, 1939.

TUBULAR ELECTRICAL GROUNDING RO* Filed June 29, 1957 Feb. 21, 1939. H. c. DANlL-:Ls

TUBULAR ELECTRICAL GROUNDING ROD Filed June 29, 1937 2 Sheets-Sheet 2 Patented Feb. 21, 1939 UNITED STATES FTENT OFFIQE TUBULAR ELECTRICAL GROUNDING ROD Application June 29, 1937, Serial No. 150,988

Claims.

This invention relates to an improvement in grounding-rods for electrical installations, and more particularly to grounding-rods which are of tubular form and adapted to be inserted into the soil to a considerable depth.

One ol the objects of the present invention is to provide a superior tubular electrical grounding-rod combining maximum surface area and electro-conductivity with minimum weight.

A further object is to provide a superior driving-plunger and grounding-rod combination whereby tubular grounding-rods of relatively-soft high electro-conductive material may be eiectively inserted into hard ground without ruinous bending or distortion of such tubular rods.

Another object of the present invention is to provide a tubular grounding-rod structure having means whereby a highly effective electrical connection may be made between the same and a grounding-wire.

With the above and other objects in View, as will appear to those skilled in the art from the present disclosure, this invention includes all features in the said disclosure which are novel g5 over the prior art.

In the accompanying drawings:

Fig. l .is a perspective View illustrating a mode of installing a tubular electrical grounding-rod of the present invention, adjacent a telegraph pole or the like;

Fig. 2 is a view mainly in vertical central longitudinal section illustrating a tubular grounding-rod as embedded in the earth and showing a driving-plunger therein;

Fig. 3 is a broken view in vertical section showing the tubular grounding-rod as having been driven into the earth to the desired limit, the driving-plunger being removed and the sustaining-plug installed in place and the groundingclamp attached to the exterior of the projecting end of the tube member of the grounding-rod;

Fig. 4 is a horizontal sectional View taken on the line @-4 of Fig. 3;

Fig. 5 is a view in side elevation of the drivingplunger;

Fig. 6 is a similar view of the tube member of the grounding-rod;

Fig. I is a view in side elevation of the leadingpoint, detached; and

Fig. 8 is a similar view of the tube-sustaining plug. a

The tubular grounding-rod herein chosen for illustration includes in the main a tube member, generally designated by the reference character I0, and a leading-point rigidly attached to the lower portion of the said tube and generally designated by the reference character II. The tube member I 0 is preferably formed of thin-walled copper tubing which may vary greatly with respect to length, diameter and wall-thickness, ac- 5 cording to the conditions. For instance, the tube member may vary in length from about two feet to eight or more feet and may vary in external diameter from about one-half inch to about one and one-quarter inch. The wall-thickness of the tube member I0 is preferably within the range of .025 to .035 approximately, to afford maximum surface area for contact with the ground, and at the same time minimize the amount of copper, or the like, which is required.

The leading-point II may be made of iron and includes a conical head I2 and an axial shank i3 which latter is proportioned to be driven into the lower end of the tube member I0 so as to slightly expand the same and secure a couplinggrip thereupon. The upper surface of the said shank i3 constitutes an anvil-surface i3d and the external diameter of the said shank may, for instance, exceed the internal diameter of the tube member Ill by about .005. At the junction point of the shank I3 with the head I2, the leading-point II is formed with an upwardlyfacing shoulder Id against which the lower edge of the tube member I0 rests. Preferably, the largest diameter of the conical head I2 exceeds the external diameter of the tube member I0 by a slight amount sufficient to insure that the said head shall form a complete passage in the soil for the said tube member IU, to thus minimize the friction upon the exterior surface of the said tube member l0 as the same is being driven into the earth in a manner as will hereinafter appear.

ln conjunction with the tubular grounding-rod above described, I employ a driving-plunger, which driving-plunger is generally designated by the reference character I5 and includes a relatively-heavy cylindrical hammer-head I 6 providing a hand-grip and from which rigidly projects a long rod-like driving-shank I'l freely reciprocatable in the tube member I0 and having a length slightly in excess of the distance from the anvil-surface I3a of the shank I3 of the leading-point II to the upper edge of the tube member I0, as is shown in Fig. 2.

After the leading-point II has been pressed into the ground by the workman as illustrated in Fig. l, the driving-plunger I5 is grasped by its hammer-head I6 and is reciprocated up and down in the tube member I0, to thus cause the lower end of its shank II to hammer against the upper face or anvil-surface Isa of the shank I3 of the leading-point Ii. The action just described will drive the leading-point VI I into the soil and since the said leading-point is coupled by a tight frictional t with the lower end of the tube member III, said tube member I will in eifect be drawn downwardly into the soil rather than driven thereinto.

After the tubular grounding-rod has been projected into the soil to the desired extent in the manner described, the driving-plunger I5 is withdrawn and a sustaining-plug I8 is installed in the upper end of the said tube member, Vas illustrated in Figs. 3 and 4. The said sustaining member I8 includes a downwardly-extending cylindrical body I and a relatively-narrow head which overlaps the upper edge of the tube member I Il. After the sustaining-member I8 has been installed in the upper end of the tube member I0, a suitable grounding-clamp such as V 2|, shown in Figs. 3 and 4, is placed upon the exterior surface of the projecting portion of the tube member IU and tightened thereupon. The grounding-clamp 2l may be firmly tightened upon the tube member I0 without fear of crushing the same and losing the proper electrical contact therewith, owing to the presence in the interior of the said tube of the cylindrical body I9 of the sustaining member i8, which latter member not only serves to prevent collapse of Vthe portion of the tube upon which the grounding-clamp 2l is installed, but the said grounding-clamp also serves to hold the said sustaining member in place in the tube member l0 against withdrawal therefrom. A grounding-wire 22 is connected in any approved manner to the grounding-clamp 2l and is thereafter in thorough electrical connection with the tube member I0.

By so proportioning the driving-plunger I5 and the tubular grounding-rod so that the lower end of the shank I'I of the driving-plunger imv pinges upon the anvil-surface of the shank I3 of the leading-head II before the under face of the cylindrical hammer-head I6 of the said driving-plunger contacts the upper edge of the tube member I8, it is possible to project thin-walled tubing such as Ii! deeply into the soil solely by draft imposed thereon. It will be appreciated in this connection that if an effort were made to drive the thin-walled tube member IQ into the soil by hammering and pounding the upper edge thereof, such tube member I0 would collapse and buckle Aafter but very slight penetration into the soil. As before indicated, the sustaining-member or plug I8 not only serves to sustain the ull'- per portion of the tube member I0 from collapsing under the clamping action of the grounding-clamp 2i but the said grounding-clamp 2l serves to compress the adjacent portion of the saidtube member against the shank I9 of the sustaining-plug I8 and thus prevents the inadvertent withdrawal of the same from the member I0. v

By means of the present invention it has been made possible to employ copper or similar relatively-expensive grounding-rod material in place of the heavier and bulkier iron grounding-rods now most generally in use. Not only are such iron grounding-rods of relatively-low conductivity but they yare very apt to corrode and disintegrate in the moist soil in which they are usually employed.

If, during the operation of inserting the tubular grounding-rod into the soil, the frictional grip of the soil upon the tube member Ill should be so severe as to cause the driving-plunger to drive the leading-point I I slightly out of the tube member IG, the under face o-f the hammer-head I will then come into engagement with the upper edge of the tube member I0 and under these conditions the continued reciprocation of the driving-plunger I5 will act both upon the anvilsurface Ilia as well as the upper edge of the tube member I0.

The invention may be carried out in other specific ways than those herein set forth without departing from the spirit and essential characteristics of the invention, and the present embodiments are, therefore, to be considered in al1 Vrespects as illustrative and not restrictive, and

all changes coming within the meaning and equivalency range of the appended vclaims are intended to be embraced therein.

I claim:

l. A grounding-device comprising in combination: an elongated tube; a leading-point; and interconnecting-arrangements therefor; the said leading-point being arranged to close the lower end of the tube and having an upwardly extending shank, the said shank terminating in an impact-receiving surface for receiving impact from a driving-element to Vdrive the leading-point axially under all conditions of ground encountered; the said tube and the said shank having such relative diameters as to provide force-fit interconnection thereof; the said force-rit interconnection acting Vagainst resistance to impact on the leading-point of the magnitude of ordinary ground-resistance, to cause the said tube to be drawn axially with the driven leading-point to enter ground jointly therewith, and 'the said force-lit connection being yieldable to force exceeding said ordinary ground-resistance in magnitude, whereby under impact the said leadingpoint is driven axially forward relatively to the tube and 'penetration-lag of the tube with respect to the leading-point, is effected.

2. A grounding-device comprising in combination: an elongated tube; a leading-point; and interconnecting-arrangements therefor; the said leading-point'being arranged to close the lower end of the tube and having an upwardly extending shank, the said shank terminating in an impact-receiving surface for receiving impact from a driving-element to drive the leading-point axially under all conditions of ground encountered; the said tube and the said shank having such relative diameters as to provide force-lit interconnection thereof; the said force-lit interconnection acting against resistance to impact on the leading-point of the magnitude of ordinary ground-resistance, to cause the said tube to be drawn axially with the driven leadingpoint to enter ground jointly therewith, and the said force-nt connection being yieldable to force exceeding said ordinary ground-resistance in magnitude, whereby under impact the said leading-point is driven axially forward relatively to the tube and penetration-lag of the tube with respect to the leading-point, is effected; the said tube being arranged to also receive impact-force whenretarded, and the said force-fit interconnection being yieldable to permit movement of the tube with respect to its leading-point to counteract penetration-lag of the tube.

3, A grounding-device comprising in combination: an elongated tube; a leading-point; and interconnecting-arrangements therefor; the said tube being open at least initially at its upper end for reciprocation of a driving-element therein; the said leading-point being arranged to close the lower end of the tube and having a shank extending upwardly therein, the said shank terminating in an impact-receiving surface for receiving impact from a driving-element to drive the leading-point axially under all conditions of ground encountered; the inside diameter of the tube being less than the outside diameter of the said shank, and the said shank being forcibly inserted in the said tube to provide force-fit interconnection thereof; the said force-nt interconnection acting against resistance to impact on the leading-point of the magnitude of ordinary ground-resistance, to cause the said tube to be drawn axially with the driven leading-point to enter ground jointly therewith, and the said force-t connection being yieldable to force eX- ceeding said ordinary ground-resistance in magnitude, whereby under impact the said leadingpoint is driven axially forward relatively to the tube and penetration-lag of the tube with respect to the leading-"point, is eiected; and means for limiting the penetration-lag of the said tube.

4. A grounding-device comprising in combination: an elongated tube; a leading-point; and interconnecting-arrangements therefor; the said tube being open at least initially at its upper end for reciprocation of a driving-element therein; the said leading-point being arranged to close the lower end of the tube and having an abutment-shoulder and also having a shank extending upwardly therein, the said shank terminating in an impact-receiving surface for receiving impact from a driving-element to drive the leading-point axially under all conditions of ground encountered; the inside diameter of the tube being less than the outside diameter of the said shank, and the said shank being forcibly inserted in the said tube to provide force-t interconnection thereof; the said force-fit interconnection acting against resistance to impact on the leading-point of the magnitude of ordinary ground-resistance, to cause the said tube to be drawn axially with the driven leading-point to enter ground jointly therewith, and the said force-fit connection being yieldable to force exceeding said ordinary ground-resistance in magnitude, whereby under impact the said leading-point is driven axially forward relatively to the tube and penetration-lag of the tube with respect to thev leading-point, is effected; means for limiting the penetration-lag of the said tube; the said tube being arranged to also receive impact-force when retarded, and the said force-fit interconnection being yieldable to permit movement of the tube with respect to its leading-point to counteract penetration-lag of the tube; and means comprising the abutment-shoulder of the leading-point for limiting the counteracting movement of the said tube.

5. A grounding-device including in combination: an elongated tube provided with an impact-receiving surface; a leading-point having a shank terminating in an impact-receiving surface; a force-fit connection between the said shank and the said tube; and a reciprocatable driving-element provided with an impact-surface at its lower end and at its upper end, the distance between the lower and upper impact-surfaces of the driving-element being shorter than the length of the said tube and longer than the distance normally between the respective impactsurfaces of the leading-point and the tube, whereby impact is normally delivered only to the impact-surface of the leading-point; the said forcet connection acting against resistance to irnpact on the leading-point of the magnitude of ordinary ground-resistance, to cause the said tube to be drawn axially with the driven leading-point, whereby the leading-point and tube jointly enter the ground, and the said force-fit connection being yieldable to force exceeding ordinary groundresistance whereby the leading-point is driven axially forward relatively to the tube and penetration-lag of the tube is effected to expose the impact-surface of the tube to impact of the upper impact-surface of the driving-element.

HAROLD C. DANIELS.

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