Terminal connector securing wire with a wide range of diameters to a conductor of an electric power switch and an electric power switch incorporating the terminal connector

A terminal connector connects wire with a range of diameters to the conductor of an electrical power switch. The connector includes a collar with a laterally extending slot sized and shaped to receive the switch conductor. An aperture adjacent the slot is sized to accommodate the full range of wire diameters. A screw is threaded into a longitudinal tapped bore in the collar to clamp the wire to the conductor. The collar is reversible on the conductor for access to the screw for panel and DIN rail mounting of the power switch. A telescoping screw extends the range of wire sizes accommodated. The aperture is shaped to funnel wire diameters in the lower end of the range of diameters under an inner screw of the telescoping screw and into engagement with the switch conductor.

BACKGROUND OF THE INVENTION
 1. Field of the Invention
 This invention relates to a terminal connector for connecting wiring to
 switches used in electric power circuits, and particularly to such a
 terminal connector which can accommodate a wide range of wire sizes and
 alternate mounting configurations of the switches.
 2. Background Information
 Where electric power switches such as circuit breakers, transfer switches,
 contactors and the like are used in distribution systems having wires as
 the conductors, terminal connectors are needed to connect the wiring to
 the rigid, generally flat conductors of the switches. A common type of
 connector has a collar with a transverse slot engaging the flat conductor
 of the switch. An adjacent aperture receives the wire which is clamped
 against the flat conductor by a screw threaded into a longitudinal bore in
 the collar.
 Depending upon the installation, or section of an installation, the size of
 the wire may vary over a wide range, e.g., from 14 AWG to 1/0. With wire
 at the lower end of the range of sizes, the installer must be careful to
 ensure that the wire is directly in line with the screw. Otherwise, a poor
 connection can result, such as where the smaller diameter wire lodges
 between the side of the screw and the edge of the aperture. Such a
 connection will not pass the required pull test in which the connection
 must support a designated weight for a prescribed time period.
 For electric power switches with molded casings, the terminal connectors
 are typically disposed in pockets formed in the ends of the molded casing
 with the wires inserted laterally into the aperture in the terminal collar
 and with the screw accessible from the top face of the casing. Where the
 switches are mounted with the bottom face engaging rails, the screws are
 easily accessible for connecting and disconnecting the wiring. Currently,
 different terminal connectors are required when the switches are front
 mounted, that is, with the front face facing a panel so that the terminal
 screws are accessible from the bottom face of the switch. Otherwise, the
 switch cannot be wired while installed on the panel.
 SUMMARY OF THE INVENTION
 This invention is directed to an improved terminal connector and an
 electric power switch incorporating the improved terminal connector. The
 terminal connector, for use in connecting wire with a range of sizes to a
 flat conductor of an electric power switch, comprises a collar with a
 lateral slot sized and shaped for receiving the conductor of the switch.
 An aperture adjacent to and intersecting the slot is sized for receiving
 the full range of sizes of the wire. The collar also has a longitudinally
 extending tapped hole transverse to and intersecting the aperture. The
 terminal connector further includes a telescoping screw comprising an
 outer screw with an external thread threaded into the tapped hole of the
 collar and a tapped longitudinal bore. The telescoping screw also includes
 an inner screw threaded into the tapped longitudinal bore of the outer
 screw. The outer screw is advanced in the threaded hole in the collar to
 clamp the wire against the conductor of the switch with the inner screw
 being advanced toward the switch conductor beyond the outer screw when the
 wire is in the lower end of the range of diameters.
 The aperture is shaped to cam the wire in the lower range of diameters into
 engagement with the flat conductor as the inner screw is advanced toward
 the flat conductor. Preferably, the aperture is at least partially
 circular, having a diameter complementary to that of the wire at the upper
 end of the range of diameters. More particularly, the aperture can have a
 circular section not intersecting the slot and a transition section
 extending between the circular section and the slot. This transition
 section can be a cylindrical passage axially aligned with the threaded
 bore in the collar and with a diameter complementary to the diameter of
 the inner screw. The inner screw may be provided with a beveled end
 extending toward the slot in the collar to form an annular gap with the
 cylindrical passage and the flat conductor having a cross section smaller
 than the diameter of the wire. The circular section of the aperture in the
 collar can be sized, for example, to receive a 1/0 wire at the upper end
 of the wire diameters and the annular gap can be sized smaller than a #14
 wire at the lower end of the range of wire diameters. In addition, the
 collar can have a longitudinal hole extending to the slot and a fastener
 extending through this hole to secure the flat conductor in the slot of
 the collar.
 The invention also embraces an electric power switch having a molded casing
 with a top face, a bottom face and an end face between the top and bottom
 faces with the end face having an elongated recess. A conductor of the
 switch projects from the molded case into the elongated recess. A
 reversible terminal for securing a wire to the switch conductor in the
 recess comprises a collar having a first aperture extending laterally in
 the collar and sized and shaped to receive the switch conductor. A second
 aperture extends laterally in the collar substantially parallel to and
 intersecting the first aperture. The first aperture is adjacent a first
 end of the collar through which a first axial bore extends to the first
 aperture. A first fastener extends through this first bore and engages the
 switch conductor to clamp the collar to the switch conductor. A second
 axial bore extends from the second end of the collar to the second
 aperture. A second fastener in the form of a screw threads into the second
 bore and clamps the wire inserted into the second aperture against the
 switch conductor to effect an electrical connection between the wire and
 the switch conductor. The collar and the recess in the molded housing are
 shaped for reversible mounting of the collar on the switch conductor with
 the second fastener selectively accessible through the recess from the top
 face of the molded casing and alternatively from the lower face. For
 installations where the wire can have a range of diameters, the screw can
 be the telescoping screw described above.

DESCRIPTION OF THE PREFERRED EMBODIMENTS
 The invention will be described as applied to an electric power switch in a
 form of a two pole miniature circuit breaker. However, it will be clear to
 those skilled in the art that the invention has application to other types
 of electric power switches.
 Referring to FIG. 1, the exemplary electric power switch 1 is a two pole
 circuit breaker 1 comprising two single pole circuit breakers 3 secured
 together. Each single pole breaker has a molded case 5 which includes a
 raised escutcheon 7 with an opening 9 through which a handle 11 protrudes.
 The two handles are operated together by a handle tie 12. The molded cases
 5 include extensions 13 at each end face 17 of the molded case 5 forming
 elongated recesses 15 extending between an upper face 19 and a lower face
 21. Switch conductors 23, forming the main electrical path through the
 circuit breaker, project laterally into the recesses 15. In the exemplary
 circuit breakers 3, these conductors are flat, rigid conductors.
 The two pole circuit breaker 1 can be mounted in two configurations as will
 be seen. For mounting inside a panel, a pair of nuts 25 are recessed in
 the upper face 19 of the casing 5 (see FIG. 5). The molded casing also
 includes a transverse groove 27 in the lower face 21 for mounting the two
 pole circuit breaker 1 to a standard DIN rail, as is well known.
 Terminal connectors 29 are provided for connecting external wiring to the
 flat conductors 23. Referring also to FIG. 2, the terminal connectors 29
 each comprise a collar 31 having a slot 33 extending laterally there
 through. This slot 33 is sized and shaped to receive the switch conductor
 23. An aperture 35 extends laterally in the collar adjacent to and
 intersecting the slot 33. This aperture is sized to receive the full range
 of diameters of wire to be connected to the switch conductor 23.
 The collar has a first longitudinal hole 37 extending from a first end 39
 of the collar and extending into the slot 33. The collar also has a second
 longitudinal tapped hole 41 extending from the second end 43 of the collar
 to the aperture 35. A fastener in the form of a screw 45 extends through
 the longitudinal hole 37 and engages a tapped hole 47 in the switch
 conductor 23. A second fastener in the form of telescoping screw 49 is
 threaded into the tapped longitudinal hole 41. In the embodiment of the
 invention illustrated in FIG. 2, the fastener 49 is a telescoping screw
 which includes an outer screw 51 having an external thread 53 which
 threads into the tapped hole 41. The outer screw 51 has a longitudinal
 bore 55 which is tapped at the lower end 57. The outer screw has a
 hexagonal socket 59 in its upper end concentric with the longitudinal bore
 for receiving an Allen wrench.
 The telescoping screw 49 further includes an inner screw 61 having an
 external thread 63 which is threaded into the tapped section 57 of the
 longitudinal bore 55 in the outer screw 51 using an Allen wrench seated in
 hexagonal socket 62. The outer screw 51 and inner screw 61 are both
 chamfered 64 and 65, respectively at their lower ends.
 The terminal connector 29 is sized and shaped to accommodate wire within a
 range of diameters. It is shaped to cam wires near the lower end of the
 range of diameters into engagement with the switch conductor which is
 received in the slot 33. The exemplary terminal connector is sized to
 accommodate wire diameters from 14 AWG to 1/0. Thus, the aperture 35
 includes a circular section 67 having a diameter complementary to that of
 a 1/0 wire. The circular section 67 of the aperture 35 does not intersect
 the slot 33. Therefore, an intermediate or transition section 69 is
 included in the aperture 35 to connect the circular section 67 with the
 slot 33. This intermediate section 69 is cylindrical and has a diameter
 complementary to the diameter of the diameter of the inner screw 61.
 As can be seen from FIGS. 3 and 4, a wire 71 having a diameter at the upper
 range of diameters accommodated by the connector, substantially fills the
 circular section 67 of the aperture 35. The outer screw 51 is threaded
 into the tapped longitudinal hole 41 in the collar 31 to clamp the wire 71
 against the switch conductor 23. The 1/0 wire is a braided wire which is
 easily deformed through the intermediate section 69 of the aperture 35 and
 spreads out to make substantial surface contact with the switch conductor
 23.
 The collar 31 is secured on the switch conductor 23 by engaging the slot 33
 with the switch conductor 23 and then passing the fastener 45 through the
 longitudinal hole 37 in the bottom of the collar and threading it into the
 tapped hole 47 in the switch conductor 23.
 As shown in FIGS. 5 and 6, when the wire 71' is at the lower end of the
 range of wire diameters, the outer screw is threaded down in the threaded
 longitudinal hole 41 in the collar and then the inner screw 61 is threaded
 down in the tapped bore 55 in the outer screw to extend toward the
 terminal connector 29. The dimensions of the circular section 67 and the
 intermediate section 69 of the aperture 35 are such that as the
 telescoping screw 49 is threaded inward, the wire 71' is cammed toward the
 switch conductor 23. As can be seen in FIG. 6, the chamfer 65 on the inner
 screw 61 forms an annular gap 73 which has a cross section smaller than
 the diameter of the wire 71' so that whether the wire 71' is centered
 under the inner screw 61, or becomes clamped in the annular gap 73 and
 makes good electrical contact with the terminal connector 29. While the
 range of wire diameters in the exemplary connector was 14 AWG to 1/0,
 other ranges of wire diameters can be similarly accommodated.
 As another aspect of the invention, the terminal connector 29 can be
 reversibly mounted on the switch conductor 23. For instance, as shown in
 FIG. 3, where the circuit breaker 1 is mounted on a DIN rail 75, the
 terminal connector can be inserted in the recess 15 with the telescoping
 screw 49 facing upward and therefore accessible from the upper face 19 of
 the circuit breaker 1 while the circuit breaker is mounted on the rail 75
 received in slot 27 in the molded housing. In this instance, the connector
 would be mounted on the switch conductor 23 using the fastener 45 before
 the circuit breaker is mounted on the rail.
 In an alternate arrangement, as shown in FIG. 5 where the circuit breaker
 is panel mounted behind a panel 79 having an opening 81 through which the
 escutcheon 7 and handle 11 protrude by screws 83 which extend through the
 panel and gauge the nuts 25 in the molded case 5. It can be appreciated,
 that when so mounted, wiring could not be connected or disconnected using
 the terminal connector 29 if it were mounted in the same orientation as in
 FIG. 3. Therefore, for panel mounted circuit breakers the position of the
 terminal connector 29 is reversed so that the wire 71' is connected below
 the switch conductor 23 and the telescoping screw 49 faces downward for
 access from the lower face or rear face 21 of the circuit breaker.
 To assist in aligning the slot 33 in the terminal connector 29 with the
 switch conductor 23, the collar 31 and the recess 15 in the molded case 5
 are keyed. For this purpose, the collar 29 is provided with a pair of
 transverse grooves 85 which engage either of two pairs 87 and 89 of ribs
 molded into the recesses 15. When the grooves 85 in the collar 31 are
 aligned with the first pair of ribs 87, the terminal connector 29 is
 positioned as shown in FIG. 3 with the telescoping screw accessible from
 the upper face 19 of the circuit breaker 1. On the other hand, the
 terminal connector 29 must be turned upside down to align the slot 33 with
 the switch conductor 23 when the grooves 85 are aligned with the second
 pair of ribs 89 to mount the terminal connector as shown in FIG. 5. A
 chamfer 91 on the collar accommodates the rib 87 or 89 not engaged by the
 groove 85. Alternatively, ribs can be provided on the collar and grooves
 can be molded into the recesses.
 While specific embodiments of the invention have been described in detail,
 it will be appreciated by those skilled in the art that various
 modifications and alternatives to those details could be developed in
 light of the overall teachings of the disclosure. Accordingly, the
 particular arrangements disclosed are meant to be illustrative only and
 not limiting as to the scope of the invention which is to be given the
 full breadth of the claims appended and any and all equivalents thereof.