US 3250957 A
Description (OCR text may contain errors)
May 10, 1966 R. E. BRISTOL CIRCUIT BREAKER PANELBOARD 2 Sheets-Sheet 1 Filed May 8, 1961 FIG. 5
INVENTOR. ROBERT E. BRISTOL BY WMTQMV A TTORNEY May 10, 1966 R. E. BRISTOL CIRCUIT BREAKER PANELBOARD 2 Sheets-Sheet 2 Filed May 8, 1961 FIG. 6
INVENTOR. ROBERT E. BRISTOL BY ATTORNEY United States Patent 3,250,957 CIRCUIT BREAKER PANELBOARD Robert E. Bristol, Bristol, Conn, assignor to General Electric Company, a corporation of New York Filed May 8, 1961, Ser. No. 198,440 3 Claims. (Cl. 317-119) This invention relates to circuit breaker panelboards and more particularly to means for preventing the im-- proper replacement of circuit breakers in such panelboards.
In electric wiring installations, a number of circuit breakers, for protecting a number of circuits having wide- 1y differing ampere requirements, are frequently mounted in side-by-side relation in the same circuit breaker panelboard. Since the ampere requirements of the circuits may vary, it is necessary to also provide circuit breakers in variety of ratings, such as 15, 20, 30 and 50 amperes, in order to efiectively protect the circuits. The selection of a proper circuit breaker for the protection of any particular circuit is, of course, dictated by the requirements of that circuit. The original selection and installation of circuit breakers is generally made at the time of wiring the circuits and is ordinarily made by qualified workmen, thus practically assuring that a circuit breaker having a correct rating will be placed in each circuit. As added assurance that the initial installation will be correctly done, it is frequently the practice that such original installations are inspected and approved by proper civil authorities.
It sometimes occurs in practice that a circuit is overloaded and, as a result, repeated opening or continual tripping of the associated circuit breaker occurs. Because of such continuing tripping of the circuit breaker, a user may attempt to replace a correctly rated circuit breaker with one of a greater rating in order to stop the tripping. This, of course, defeats the protective function of the circuit breaker. It is also possible that, in attempting to replace a faulty circuit breaker the user may accidentally insert a breaker of an'improper rating into the panelboard because of the general similarity of circiut breakers of different ratings. Regardless of the reason for the insertion of a breaker having a greater than required rating, the insertion of such a breaker will defeat the protective function of the circuit breaker and thus create a danger of fire or injury.
It is an object of this invention to provide a panelboar assembly containing circuit breakers of different ratings which avoids the problem of improper breaker substitution by the user by preventing the removal and replacemerit of such circuit breakers by all except authorized personnel.
elboard is provided including a support plate on which a plurality of circuit breakers having different ratings may be removably mounted. In order to prevent the removal and replacement of the circuit breakers by unauthorized personnel, a releasable locking means is provided which engages the casing of each circuit breaker and is releasably secured to the support plate. According to one 3,250,957 Patented May 10, 1966 embodiment of the invention, the locking means is secured to the support plate by means of special fasteners which can only be removed from the support plate by means of a special tool, to which access is limited to only authorized personnel. In accordance with another embodiment, the locking means is secured to the support plate by conventional fastening means in an area to which unauthorized personnel ordinarily have no access.
While the specification concludes with claims particularly pointing out and distinctly claiming the subject matter. of the invention, it is believed that the invention will be understood from the following description taken in connection with the accompanying drawings in which:
FIGURE 1 is a perspective view of a panelboard assembly including a frame locking member for preventing the unauthorized removal and replacement of circuit breakers;
FIGURE 2 is a partial section view of a circuit breaker in a mounted position on the support plate;
FIGURE 3 is a perspective view of a special fastener for securing the frame locking member shown in FIG- URE l to the support plate;
FIGURE 4 is a perspective view of another embodiment of the invention;
FIGURE 5 is a side view of the embodiment of the invention shown in FIGURE 4; and
FIGURE 6 is a cross-sectional view of the strap locking member shown in FIGURES 4 and 5 'taken along the 'line 6-6 of FIGURE 4.
Referring to the drawings, a panelboard is shown comprising a channel-shaped support plate 10 having a generally flat central support surface 11 and two offset circuit breaker supporting flanges 12 and 13 disposed in a plane parallel to that of the support surface 11. Arranged along the length of each of the circuit breaker supporting flanges 12 and 13 in a spaced relation are a number of hook-shaped circuit breaker retaining elements 14, one retaining element being provided for each of the circuit breakers to be mounted on the supporting flanges.
A number of relatively stationary line terminal contact blades 15 are provided for delivering power to the electric circuit breakers which are to be mounted on the support plate 10. The stationary contact blades 15 are electrically connected to bus bars 16 and 17 which are supported on a suitable insulating support such as, for example, insulating block 18. A power cable or wire is connected to each of the bus bars 16 and 17 by means of connectors 20 and 21, respectively.
The panelboard assembly is adapted to receive a number of electric circuit breakers such as 25, 26, 27 and 28. As best shown in FIGURE 2, each of the circuit breakers such as circuit breaker 26 is provided at one end with a lug 3t) integral with the casing of the circuit breaker. The lug 30 on the circuit breaker casing is adapted to be received under one of the hook-shaped retaining elements 14, the circuit breaker 26 is rotated about the engagement into a fully mounted position in which a bladereceiving contact or socket (notv shown) adjacent the other end of the circuit breaker casing is moved into a connected engagement with one of the contact blades 15. The design of the casings of the circuit breakers is conventional and no modification of the casings is necessary for use with the locking means of this invention.
In actual practice, a number of circuits having various ampere requirements may be wired into the same panelboard, thus making necessary the use of circuit breakers having various ratings in conjunction with the various circuits. In order to provide for maximum flexibility of the panelboard assembly, circuit breakers having different ratings have identical casing structures so that a circuit breaker having any desired rating may be mounted in engagement with any selected retaining accordance with the invention for securing the correctcircuit breakers in engagement Withthe proper contact blades and for holding the breakers in' the correct engagement until the locking means is removed by an authorized person.
Referring now to FIGURE 1, a locking frame 31 is provided comprising strip portions 32 and depending leg portions 33. After the desired number of circuit breakers are mounted in plug-in engagement with the stationary contact blades 15 on thesupport plate 10, the locking frame 31 is positioned over the circuit breakers so that the strips 3-2 contact the ends of the circuit breakers. In order to prevent the removal of the circuit breakers from the support plate by pivoting the breakers about the hook-shaped retaining elements 14,
the lower ends of the depending legs 33 are securely fastened to the supporting flanges 12 and 13. The lower end of each of the depending legs is preferably bent outwardly at a right angle to the remainder of the leg and a special fastener 34 is applied to secure the bent-out portion to one of the supporting flanges l2 and 13. The fastener 34 as'shown in FIGURE 3 is provided with a special head which is designed so as to be removable only by the use of a special tool.v The head 35 of the special fastener 34 is provided with a slot 36 for receiving a conventional screwdriver. Portions 37 of the walls of the slot 36 are cut away so that the fastener can not be removed from the support plate with the screwdriver. Flats 38 on the sides of the head 35 may be engaged by a special removal tool in order to remove the depending legs 33 from the supporting flanges 12 and 13 and thus make possible removal and replacement of the circuit breakers. By limiting access to the special removal tool to only authorized personnel, it is possible to prevent the removal and replacement of the circuit breakers by unauthorized personnel.
Another embodiment of the invention is shown in FIGURES 4 and 5 in which a single locking strip or strap 40 is provided for contacting each of the circuit breakers at the same end as that at which engagement between the breakers and the stationary contact blades takes place. By securing the strap 40 to the support plate 10,
the contact between the strap 40 and the circuit breakers prevents the pivoting of the breakers about the retaining elements 14 to remove the breakers from the support plate It), thus effectively preventing the unauthorized removal of the circuit breakers from the support plate. The strap 40 is preferably secured to the back surface of the support plate 10 in an area to which unauthorized personnel ordinarily would have no access. As partic-' ularly shown in FIGURE 5, one end of the strap 40 is so as to prevent their removal from the support plate 10. The other end of the strap is then preferably secured to the back side of the support plate 10 by means of a convention-a1 fastener designed to be removed by a convventional tool. If desired, both ends of the strap 40 may be secured to the front of the support plate 10 by fastening means removable only by the use of a special tool such as the fastening means 34 described in connection with FIGURE 1, thus also effectively preventing the removal and replacement of circuit breakers by unauthorized personnel. If the single strap 40 is subjected to sizable forces during use, there is a possibility that it may flex along its length, thus allowing the circuit breakers to slip out from under it. In order to prevent this, a reinforcing portion 43 is provided, as shown in FIGURE 6, along the under surface of the strap 4% The reinforcing portion 43 is thin enough to fit down in between the rows of circuit breakers which are disposed on each side of the row of contact blades 15. As shown in FIG- URE 4 of the drawings, the circuit breakers 27 and 28 include generally rectangular insulating casings having a front, back, and end Walls, 27A, 27B, and 27C and 28A,
23B, and 2C, respectively. Likewise, as shown in FIG- URE 2, the circuit breaker 26 has front, back, and end walls 26A, 26B, and 260 respectively. The circuit breakers are mounted in the panel assembly with the ends 27C, 28C, etc. in. juxtaposed relation, and the locking strap 40 overlies portions of the front walls 27A, 28A, etc.
Also, if desired, it is possible to secure the locking frame 31 shown by FIGURE 1 to the back sides of supporting flanges 12 and 1-3 by conventional fastening means similar to the means described with respect to the embodiment of the invention shown by FIGURES 4 and 5.
It can be seen that the invention provides locking means for'elfectively preventing the removal and replacement of circuit breakers by unauthorized .personnel, the locking means being usable with circuit breakers having casings of conventional design. Additionally, the locking means of the invention may be easily removed by qualified personnel to provide for fast and easy removal and replacement of the circuit breakers. It is likewise obvious that both forms of the invention may be easily and inexpensively manufactured.
The term electric circuit breaker as used herein denotes an electric circuit protective device adapted to be mounted in a panel assembly, and includes circuit protective devices operating by fusible means as well as those operating by means of separable contacts.
. While only two embodiments of the invention have been shown, it will be readily apparent that various modilications thereof may be made, and it is intended tocover by the appended claims all such modifications as fall within the true spirit and scope of the invention.
What isclaimed'as new and desired to secure by Letters Patent of the Unite-d States isi 1. An electrical panel-board comprising a support having front and back surfaces, a plurality of stationary electrical contacts aligned in a row generally centrally on said front surface of said support, circuit breaker retaining means adjacent opposite edge portions of said support on either side of said row of contacts, a plurality of electric circuit controlling devices disposed in two rows on said front surface of said support, the devices in each of said rows being disposed in end to end juxtaposed relation to corresponding devices in the other row, each of said devices having one end thereof in pivotal releasable engagement with said retaining means adjacent one of said edge portions and having a plug-in type electrical engagement with one of said stationary cont-acts at the other end thereof, whereby each of said devices is removable from said front surface of said support by pivotal movement of said device about said retaining means to disengage said device from said stationary contact and to release it from said pivotal engagement, and locking means preventing said pivotal movement of at least some of said devices, said locking means comprising an elongated locking strap extending generally centrally of said support and over-lying portions of the casings of circuit breakers of each of said rows, and fastening means at the ends of said locking strap connecting said locking strap to said support, said fastening means being not readily releasable from said front surface of said support but being readily releasable from said back surface of said support.
2. An electrical panelboard as set forth in claim 1 wherein said circuit controlling devices each comprise a generally rectangular insulating casing'having aback wall and a front wall and first and second end walls, said devices being mounted on said support with said back walls adjacent said support and with said first end wall of each of said devices in juxtaposed relation to the first end wall of a correspondingly positioned device, said plug-in electrical engagement being made adjacent the corner of said casing adjacent said back wall and said first end wall and said locking strap overlying the corner of said casing adjacent said front wall and said first end Wall.
3. An electrical panelboard comprising a support having front and back surfaces, a plurality of stationary electrical contacts aligned in a row generally centrally on said front surface of said support, circuit breaker retaining means adjacent opposite edge portions of said support on either side of said row of contacts, a plurality of elect-ric circuit controlling devices disposed in two rows on said front surface of said support, the devices in each of said rows being disposed in end to end juxtaposed relation to corresponding devices in the other row, each of 'said devices having one end thereof in' pivotal releasable engagement with said retaining means adjacent one of said edge portions and having electrical engagement with one of said stationary contacts at the other end thereof, whereby each of said devices is removable from said front surface of said support by pivotal movement of said device about said retaining means, and locking means preventing said pivotal movement of at least some of said devices, said locking means comprising an elongated locking strap extending generally centrally of said support and over-lying portions of the casings of circuit breakers of each of said rows, and fastening means at the ends of said locking strap connecting said locking strap to said support, said fastening means .being not readily releasable from said front surface of said support but being readily releasable from said back surface of said support.
References Cited by the Examiner UNITED STATES PATENTS 2,428,322 9/1947 Robertson et a1. 317119 2,647,191 7/1953 Humpage 200168 2,883,587 4/1959 Dorfman et al. 317-119 2,910,630 10/1959 Hammerly 317119 2,943,244 6/1960 Platz et al. 339-254 2,945,162 7/1960 Flour 317101 3,173,063 3/1965 Kussy et al. 317-119 3,174,078 3/1965 Koen-ig 317-119 KATHLEEN H. CLAFFY, Primary Examiner.
JOHN F. BURNS, Examiner.
J. G. COBB, W. C. GARVERT, Assistant Examiners.