US2993084A - Service entrance head - Google Patents

Description

July 18, 1961 1.. M. CURTISS 2,993,084

SERVICE ENTRANCE HEAD Filed June 5, 1958 2 Sheets-Sheet 1 A TTIIPNE Y July 18, 1961 cu T ss 2,993,084

SERVICE ENTRANCE HEAD Filed June 5, 1958 2 Sheets-Sheet 2 I'IIII II INVENTOR. [AW/FENCE M (027/55 @,4 m4; &

United States Patent '6) 2,993,084 SERVICE ENTRANCE HEAD Lawrence M. Curtiss, Mountainside, N.J., assignor to The Thomas & Betts Co., Elizabeth, N.J., a corporation of New Jersey Filed June 5, 1958, Ser. No. 740,141 2 Claims. (Cl. 174-81) The invention relates to electric service entrance fittings, and more particularly to improvements in a service entrance head of the type exemplified in Gill Patent No. 2,739,999.

More specifically, the invention has particular reference to a service entrance head which is adapted to be utilized, in each size thereof, with either thin wall tubing E.M.T. or a rigid metallic conduit of relatively larger outside diameter, or with a conventional non-rigid service entrance cable, without the use of separate spacers or shims, in the installation thereof for leading outside electric power lines into a building or to points within a building, the service entrance head being provided with means including a detachable bracket for securing the service head to a building wall, when a non-rigid service entrance cable is to be connected thereto, and a reversible clamp for securing either the aforesaid conduit, the tubing or a non-rigid service entrance cable in and to the service entrance head.

Devices of this character, as known heretofore, were not adapted, in each size thereof, for selectively accommodating either a thin-wall tubing, rigid conduit, or a non-rigid service entrance cable without the use of separate spacers or shims.

Accordingly, it is an object of the invention to provide a service entrance head as specified which is adapted, in any one size thereof, for the selective bearing reception therein of either thin-Wall tubing, rigid conduit or a non-rigid service entrance cable without the use of sep arate spacers or shims.

Another object of the invention is to provide an improved service entrance head of the character described which is adapted to be selectively supported either by thin-wall tubing or rigid conduit, or secured to a building wall by means of a detachable bracket when used in conjunction with a non-rigid service entrance cable.

A further object of the invention is to provide an improved service entrance head which afiords protection against the elements in outside installations thereof, and which is adapted to accommodate either (E.M.T.) thinwall tubing conduit or rigid metallic conduit in separately journalled relation thereto.

Another object of the invention is to provide an electric service entrance head wherein a mounting frame is provided with a pair of counterbores in-eccentric relation to each other with one of said counterbores occupying a plane inclined at an acute angle to the plane occupied by the other of said counterbores, whereby when an end por tion of thin-wall rigid tubing is seated in said inclined counterbore the outer periphery thereof will intersect the lowermost inner peripheral edges of said other counterbore to provide a point of support for clam-ping said tubing laterally thereagainst without disturbing the seating of the end face of said tubing in said inclined counterbore. 2

Another object of the invention is to provide an improved service entrance head which is adapted to receive an end portion of either thin-wall tubing or rigid conduit in axial alignment with the axial center of the throat opening therein, whereby the extension of cable conductors from either conduit or tubing through the proved service entrance head adapted to be secured on an upstanding end portion of a rigid conduit in a plane acute angle thereto, whereby multi-point contact between the tubing and the frame of the service entrance head is established and relative rocking thereof on the tubing thus precluded.

With the above and other objects in view, the invention resides in the novel construction, combination and arrangement of parts, the novel features of which are set forth with particularity in the appended claims, the invention itself, however, both as to its organization and its method of operation, together with additional objects and advantages thereof, being best understood from the following description of a specific embodiment thereof when taken in connection with the accompanying drawing, in which FIG. 1 is an exploded view in perspective showing the component parts of the improved service entrance head;

FIG. 2 is a side view in elevation showing the improved service entrance head assembly as mounted on an upstanding end portion of a rigid conduit, having a normal wall thickness, square therewith;

FIG. 3 is a fragmentary bottom plan view of the annular socket portion of the mounting frame, showing the respective counterbores and the annular throat opening as formed on different axial centers;

FIG. 4 is a detail sectional view showing the manner in which an upstanding end portion of a rigid conduit is journalled and secured in the frame of the improved service head;

FIG. 5 is a similar detail sectional view showing the manner in which an upstanding end portion of a thinwall E.M.T. rigid tubing is journalled and secured in the frame of the improved service entrance head;

FIG. 6 is a bottom plan view of the service entrance head assembly looking through the annular socket por tion of the mounting frame into the hood;

FIG. 7 is a detail fragmentary sectional view of the annular socket portion of the mounting frame showing the respective counterbores in eccentric relation to each other and the annular throat and the adjacent intermediate counterbore inclined at an acute angle to the axial center of the outer counterbore; and

FIG. 8 is a side view in elevation showing the improved service entrance head as secured on an upstanding end portion of a non-rigid, service entrance cable in grounded relation thereto and as supported by a bracket secured to a suitable fixed support.

Referring to the drawings and to FIG. 1, in particular, the improved service entrance head, generally indicated at 10, comprises a mounting base or frame 12, a detachable cap or hood 14 therefor, each comprising a casting of suitable metal, an annularly flanged bushing 16, of suitable insulation material, a sheet metal clamping plate '18 adapted to be adjustably secured to the frame 12, and a bracket 20 of stamped metal adapted for hanging the service entrance head assembly 10 on a building wall or other fixed support 22, in certain applications thereof, as when used with conventional non-rigid service entrance cable 24.

In accordance with the invention, the mounting base or frame member '12 comprises an annular socket portion 26, including a semi-circular skirt 28 depending from the rear half thereof in coaxial relation, the outer periphery of the semi-circular skirt 28 being provided with an integral boss 30 of keystone configuration cent-rally between its diametrically opposite ends and in alignment with the axial center of the annular socket portion 26, for a purpose presently to be described. The diametrically op- Patented July 18, 1961 3. posite ends of the semi-circular skirt 28, each terminates in a radially extending car 32, provided with a screwthreaded opening 34 therethrough for securing the clamping plate 18 thereacross by means of suitable machine screws '36, and also for a purpose to be described.

As clearly shown in FIG. 1, the opposite front half of the annular socket portion 26 includes a pair of arcuate tines 38 integral therewith and extending upwardly at an angle of approximately 45 degrees to the axial center of the annular socket portion 26, and diametrically opposite the boss 30 on its semicircular skirt 28, the arcuate tines 38 forming an interruped circular opening 40 for receiving the flanged insulating bushing 16, in spaced angular relation with the annular socket portion 26 of the mounting frame 12.

\AS also best shown in FIG. 1, the outer side of each of the arcuate tines 36, at a point adjacent the annular socket portion 26, is provided with an inverted, open-ended recess 42 for receiving the inner end of a screw or rivet 44 fixed through one side of the hood 1'4, and the inner end of a screw 46 adjustably threaded through the opposite side of the hood 14, whereby the hood is detachably secured on the mounting frame 12, as shown in FIG. 2.

Further in accordance with the invention and as best shown in FIG. 7, the annular socket portion 26 of the mounting frame 12 is provided with a counterbore 48, from which depends the semi-circular skirt 28 having an inner periphery of corresponding radius and adapted for receiving therein an end portion of a rigid metallic conduit 50 having a corresponding external diameter in bearing relation square therewith, the counterbore 48 terminating at its upper annular end in a square shoulder 52, in abutment with the end face of the conduit 50, which is subsequently secured in parallel engagement with the inner periphery of the depending semi-circular skirt 28, by means of the clamping plate 18 disposed across the conduit 50, with its opposite ends secured to the ears 32 on the depending skirt 28 by means of the screws 36.

The annular socket 26 of the mounting frame 12 also includes a shallow intermediate annular counterbore 54, of relatively smaller diameter and in substantially eccentric relation with the axial center of the counterbore 48, in spite of its slight inclination toward the arcuate tines 38, at an acute angle to the axial center of the counterbore 48, and adapted for receiving an end portion of electric metallic tubing 56, having a smaller external diameter than that of the rigid conduit 48, whereby when the end face of the conduit 56 is in abutment with the annular shoulder 58, formed by the counterbore 54, the smaller outer diameter thereof will bear against the bottom inner peripheral edge of the depending semi-circular skirt 28, as indicated at 60, whereby the mounting frame 12 is supported against relative rocking movement on the journaled end of the conduit 56, and lateral thrust of the clamping plate 118 thereon opposed, as in FIGS. 2 and 5, when secured thereon.

Further in accordance with the invention, the intermediate counterbore 54 opens into a reduced annular throat 62, presenting a rounded peripheral surface 64 having a diameter smaller than the internal diameter of either the conduit 50 or the metallic tubing 56, and constituting the uppermost or opposite open end of the annular socket portion 26 of the mounting frame 12, and providing a cable protecting outlet for the conductors C, from either conduit 50, or tubing 56, into the hood 14 and through the openings 66 provided therefor in the insulating bushing 16, outwardly of the service entrance head It}, in depending relation.

As best shown in FIG. 7, the rounded annular throat opening 62 is formed in parallelism with and in coaxial alignment with the axial center of the inclined counterbore '54, but in substantially eccentric relation with the axial center of the counterbore 48, the axial center of the throat opening 62 and the intermediate counterbore 54 being inclined toward the insulating bushing 16 to facilitate drawing the insulated cable conductors C therethrough. Moreover, the diameter of the throat opening 62 is such as to prevent contact of the insulated conductors C with the inner peripheral edge of either the conduit 50 or tubing 56, and thus prevent abrasion of the insulation thereon when drawn through the annular socket portion 26 of the mounting frame 12, into and outwardly of the hood 14, as will be understood.

It is to be noted that the service entrance head 10, as exemplified throughout the drawings, is intended to show a size adapted for use with two types of one and one-halt inch metallic tubing, viz., rigid metallic conduit and rigid E.M.T. (electric metallic tubing), as indicated respectively at 50 and 56. Larger sizes of service entrance heads involve variations in the diameter and angle of inclination between the axial centers of the respective counterbores 48 and '54, and the annular throat opening 62. In FIG. 3 there is shown a fragmentary bottom plan view of the annular socket portion 26 of the mounting frame 12, to illustrate the radius of the respective counter-bores 48 and 54, and the annular throat opening 62, by means of the arrows A, B and C. The arrow A indicates the radius of the counterbore 48; arrow B, the radius of the counterbore 54; and arrow C, the radius of the annular throat opening 62. The angle of inclination of the axial center of the shallow counterbore 54, relative to the axial center of the counterbore 48, is such that the inner periphery of the rigid conduit 50, or the electric metallic tubing 56, when seated in its respective counterbore 48 or 54, will be substantially eccentric with the rounded periphery 64, defining the annular throat opening 62. Thus, the formation of the counterbore 54 at an acute angle to the axial center of the counterbore without substantial loss of concentricity therebetween, and the diameter of the counterbore 54 relative to the diameter of the counterbore 48, compensates for the difference between the external diameter of the rigid conduit 50 and the electric metallic tubing "56 whereby, when the tubing 56 is seated in the shallow counterbore 54, its outer periphery will bear against the bottom inner peripheral edge 60 of the depending semi-circular skirt 28, as clearly shown in FIG. 5, and thereby preclude the conventional practice of employing separate shims or spacing material to provide such bearing contact therebetween to maintain the mounting frame 12 in proper position on the plain end portion of the tubing 56, upon seeming the clamping plate 18 thereon.

As will be understood by those skilled in the art, use of the improved service entrance head 10, with a thin-wall rigid conduit 56 and a rigid conduit 5!), having a normal wall thickness, does not require the use of the bracket 20, since the service entrance head is supported solely by either one of the conduits 50 and 56, and thus may be positioned in closer proximity to a wall surface, as indicated at 22, than in the example shown in FIG. 8.

Referring now to FIG. 8, the service entrance head 10 is shown as utilized with non-rigid service entrance cables 24, in which case it is detachably secured to a fixed wall support 22 by means of the off-set bracket 24) adapted to receive the tapered, keystone boss 38 formed on the outer periphery of the depending skirt portion 28, with an end portion of the non-metallic service entrance cable 24 suitably intruded into the annular socket portion 26, and secured therein by the clamping plate 18, when disposed in reversed position, the head 10 being grounded by clamping the grounding conductor G of the cable 24 under the clamping plate 18, as shown.

While the invention has been illustrated and described with respect to a preferred embodiment thereof, it is to be expressly understood that various changes and modifi'cations may be made therein without departing from the inventive concept underlying the same. Therefore, the invention is not to be limited except as is necessitated by the prior art and the scope of the appended claims.

I claim:

1. In an electric service entrance head having a hood and a frame and complementary means connecting the hood and frame, said frame comprising an annular open socket portion and a semi-circular skirt portion depending from the socket portion, said skirt portion being provided with a counterbore for receiving therein an end portion of an electric conduit, said counterbore terminating in a shoulder in the frame concentric with the axial center of the skirt counterbore, for reception of the conduit within said counterbore of the skirt portion and against said shoulder, said socket portion being provided with a second counterbore formed in eccentric and inclined relation to and smaller than the said axial center of the skirt counterbore forming a shoulder inclined with duit therein and against the lower end of the skirt portion, and means engaging the socket portion and conduit to hold the conduit in the socket portion.

2. In an electric service entrance head as set forth in claim 1, said eccentric counterbore being spaced from and opening into the end of the socket remote from the skirt portion, said socket being formed rounded from the said eccentric counterbore to said end of the socket.

References Cited in the file of this patent UNITED STATES PATENTS 1,774,357 Cooper Aug. 26, 1930 1,839,945 Boyton Ian. 5, 1932 2,739,999 Gill Mar. 27, 1956 2,771,263 Boho Nov. 20, 1956 2,908,745 Appleton Oct. 13, 1959

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