GB2050079A - Insulation piercing contact element - Google Patents

Abstract

Prior art contacts for automatic insertion without stripping of insulation have been fabricated of a good electrical conductor material which also has high strength and is resistant to creep relaxation. The prior art contacts have been expensive because of the cost of material, because available materials require designs which employ excessive amounts of material, and because the resulting designs are difficult to fabricate. The present invention provides a two-piece contact element in which the contacting function and the mechanical functions are provided by separate members. A contacting member 103, which comprises two insulation piercing slots, 101, 102, is formed of material selected only for electrical conductivity, and does not require as much of this relatively expensive material as do the prior art contact elements. Because less material is used, the design also permits savings in fabrication. Spring and retaining functions are provided by a member 100, which maintains the gripping action of the slots 101, 102, and is of a material chosen only for mechanical properties, typically steel. The design of both members provides for economical fabrication and assembly. <IMAGE>

Description

SPECIFICATION Contact element Technical field The present invention relates to a contact element for electrical connection of wire conductors in a terminal strip without stripping of insulation.

Background of the prior art Automatic striping of wires to make connections is increasingly used in the art of joining electric wires to electrical components or other wires. This new technique permits considerable savings of wiring time by elimination of the step of stripping insulation from conductors, such as is required for connections by tin soldering, by crimping, or by some wire wrap techniques.

The first applications of automatic wire stripping connections were permanent connections, i.e. not rewirable, made by crimping lugs where protrusions perforate the insulation before contacting the conductor. An improvement of this system gave birth to the slot contact that perforates the insulation of wires and pinches the conductor on diametrically opposite sides. These slot contacts are arranged for solid or stranded wire conductors, of individual wires, or wires connected in harnesses, according to particular uses or needs, and are obtained by cutting, folding, rolling, shearing, etc., presenting two or more contact points to the wire conductor.

The development of automatic stripping connection techniques has required that inexpensive contact elements, for maintaining the price of the joined point at a relatively low level, must be made of a good electrical conductor, while providing a mechanical contact pressure sufficient after numerous rewiring operations for safeguarding an efficient and reliable connection.

The known contact elements with stripping contacts are therefore confronted with apparently contradictory requirements. For assuring good electrical characteristics, the contact element must be made of a good electric conductor material, such as a gold plated cuproberyllium alloy. Furthermore, assuring good mechanical firmness of the contact leads to overdimensioning the device and consequently, to the use of a relatively large quantity of expensive material.

The overdimensioning of the contact elements also increases the dimensions of the alveoli, or terminal block slots, where they are placed and consequently the dimensions of the entire connector. This naturally constitutes an important disadvantage when the objective is basically to miniaturize the components, including the means of joining and connecting them. Reduction of contact dimensions to save space also introduces the problem of aging of copper alloys, or more specifically of creep aging under stress within a period of time and particularly at high temperatures of utilization. The creep aging problem leads to relaxation of the contact material, tending to diminish, over a period of time, the pressure of the arms which define the joining slot upon the wire.

Brief summary of the invention The present invention proposes to avoid the above mentioned disadvantages by providing a particularly low cost contact element which does not need an overdimensioning of the parts of an active contact that are made of a good and relatively expensive electric conductor, but which is mechanically strong, is reliable, and reusable due to the incorporation of materials insensible to the phenomenon of creepage.

The contact element defined herein is a two-piece element employing an active contact element made from a good electrical conductor material and used for the actual connection, together with a supporting element of material chosen only for its mechanical properties. The active contact element is assembled into the supporting element, and the combination is placed into a slot in the terminal block. The active contact element comprises a central anvil and two parallel lateral arms defining a slot on each side of the anvil. In the assembled condition, the supporting element provides elastic force tending to close the slots so as to maintain pressure on wires inserted therein. The supporting element is made of a mechanically very resistant elastic material, insensible to creepage under stress over a period of time at high temperature, such as spring steel.The supporting element comprises a main body, supporting means for elasticaily pushing the lateral arms of the active contact element toward the anvil, retaining means for mounting the active contact element on the main body and locking means for locking the assembly of the supporting element and the integral active contact element into position in the alveolus, or slot, of a terminal strip or junction block.

According to one form of preferred embodiment of the contact element according to the invention, the anvil comprises on each side a boss that delimits longitudinally the corresponding contact slot. These bosses are placed and dimensioned for constituting supporting stops for the lateral arms of the active contact element when the elements are pushed in the direction of the anvil by the supporting means of the supporting element.

The stops are preferably dimensioned so as to define a lower limit for the width of the contact slots. The effect of this limitation is to assure that the conductor of a wire which is to be connected is not deeply notched by the cutting edges of the slot.

According to another characteristic of the present invention, the active contact element is made of one piece during a stamping operation, permitting it to be cut from a sheet of a good electric conductor material, a copper alloy for example. Due to the fact that the lateral arms of the active contact element need not assume the mechanical function of the prior art contact elements, i.e. they are not required to be elastic in order to exercise a sufficient pressure on the conductor introduced into the contact slot, the active contact element can be relatively thin, and need not have the combination of good mechanical and electrical properties which is required in the prior art. Savings are therefore achieved in both the quantity and quality of the required material.The use of thinner material also reduces fabrication cost, because the anvil and the lateral arms of the active contact element can be cut so that at the start, i.e.

prior to the mounting of the active contact element on the supporting element, the spacing separting the anvil from the lateral arms, at least in the corresponding zone of the contact slot, is greater than the thickness of the raw metal sheet. This feature facilitates the cutting and also expedites electrolytic coating of the active contact.

The supporting element of the contact element according to the invention comprises a flat base making up the main body and at least two elastic arms, folded back in a right angle relative to the flat base and adapted for forming the supporting means acting upon the lateral arms of the active contact element.

Due to the fact that they are made of an elastic material insensitive to creepage after a period of time, these elastic arms compensate for the lack of elasticity of the lateral arms of the active contact elements by assuming the mechanical function of the contact element according to the invention. Moreover, the supporting element of spring steel, relatively nonexpensive, permits saving the necessary noble material for producing the active contact element by avoiding the need for overdimensioning such as is practiced in the prior art to obtain adequate strength.

According to one preferred form of embodiment, the lateral arms of the active contact element comprise each a first shoulder oriented toward the outside and arranged essentially at the upper end of the arm, and a second shoulder equally outwardly oriented and arranged essentially at the lower end of the arm, these shoulders serving as a support and cooperating with the respectively upper and lower ends of the elastic arms of the supporting element, so as to keep the active contact element in position on the supporting element and for pushing the lateral arms of the active contact element against the stops constituted by the lateral bosses of the anvil.

In addition, the flat base of the main body of the supporting element comprises at least one extension arranged between elastic arms and provided with a rectangularly folded back tip for being hooked upon the upper edge of the alveolus of a terminal strip into which the contact element is placed.

In another detailed embodiment of the contact element according to the invention, the element is symmetrical with two perpendicular axes and comprises four connecting slots placed symmetrically two-by-two relative to the axes of symmetry. In this embodiment, the active element of contact comprises a central plane part extended of opposite ends to form an' anvil and lateral arms arranged on both sides of the anvils. In this same embodiment, the supporting element comprises a flat base, four elastic arms placed symmetrically two-by-two, relative to the two axes of perpendicular symmetry between them and two extensions which extend from the central flat base and which extend respectively between each pair of elastic arms.Each one of these extensions comprises at its free end a tip, or lug, folded back in a right angle, arranged for leaning against the edge of the slot receiving the contact element on one of the faces of the connector block. These tips bent in a right angle serve, on the one hand, the purpose of maintaining firmly the contact element at the inside of the connector slot, but they may equally serve to hold the parts of the terminal strip together as will be explained later. This characteristic permits the realization of a connection unit of two or more joined parts, permitting an important simplification of the molded cavities necessary for the fabrication of insulating elements of such joined units.

The flat base of the supporting element, the inner surface of the elastic arms, the inner surface of the extensions of the flat base, and clamp arms which are integral with and bent in right angle relative to the elastic arms constitute a cage in the inside of which the active contact element is placed after having been mounted on the supporting element. At the moment of mounting, the shoulders of the lateral arms of the active contact element cooperate with the upper and lower ends of the elastic arms of the supporting element for realizing a mounting by latching and locked-in positioning of the active contact element on the supporting element. The tips folded back in right angle relative to the surface of the extensions of the supporting element are hooked on the faces of the terminal strip at the openings of the receiving slots for the contact element. The extensions and consequently the tips being blocked in position at the moment of the introduction of the active contact element prevents an accidental withdrawal of the contact element from its receiving slot.

The placement of the contact element ac cording to the invention is made by the initial introduction of the supporting element into the corresponding slot followed by the introduction of the active contact element into the supporting element. Because of the shoulders arranged on the lateral arms of the active contact element, the latter is firmly held in position relative to the supporting element.

And, after the introduction of the active contact element on the supporting element, the latter is kept firmly in the slot by means of the tips bent back in a right angle. It is evident that the contact element according to the invention is equally easily dismountable by realizing the operations in the reverse sense.

In order to remove the contact element from the corresponding alveolus of a joining unit, it is necessary to first free the shoulders of the lateral arms of the active contact element by actuating in the outward direction the elastic arms of the supporting element, and to then disengage the active contact element from the cage consitituted by the ensemble of the parts of the supporting element. Removal of the active element permits the retreat by elasticity of the extensions carrying the folded-back tips which permits finally withdrawing of the supporting element from its receiving slot.

Brief description of the drawings The invention will be now described in detail with reference to the accompanying drawings representing preferred embodiments of the contact element according to the pre set invention.

Figure 1 represents a view in elevation of one embodiment of the active contact element of the contact element according to the invention; Figure 2 represents a perspective view of a form of the supporting element corresponding to the active contact element in Fig. 1; Figure 3 is a front view illustrating partially the active contact element and the supporting element mounted and placed in the corresponding slot of a terminal block; Figure 4 is a perspective view illustrating another embodiment of a contact element according to the invention placed in the corresponding receiving slot with a terminal block represented partially and in a schematic form; Figures 5A and 5B are perspective views and illustrate another embodiment of the contact element according to the invention; Figure 6 is a perspective view illustrating a variant of the contact element in Figs. 5A and 5B; and Figure 7 is a perspective view illustrating a terminal block connection unit the insulating part of which is made of two pieces maintained together by contact elements corresponding to the embodiment illustrated by Figs. 1 to 3.

Detailed description of the invention In reference to Figs. 1 to 3, the represented active contact element 10 comprises a longitudinal axis of symmetry 11 and a transverse axis of symmetry 12, perpendicular to the axis 11. The element 10 proper is constituted by a flat central region 1 3 of approximately square or rectangular form that is prolonged in the direction of the longitudinal axis of symmetry 11 by two central anvils 14 and 15. On both sides of the anvil 14, and arranged symetrically relative to the longitudinal axis of symmetry 11, are two lateral arms 1 6 and 1 7 connected at their base to the central region 1 3 of the active contact element 10.Similarly, two lateral arms 1 8 and 1 9 are arranged on both sides of the anvil 15, symmetrically relative to the longitudinal axis of symmetry 11, their bases being attached to the central region 1 3 of the active contact element 1 0.

The lateral arms 16, 17, 18, and 19 are symmetric relative both to the longitudinal axis of symmetry 11 and to the transversal axis of symmetry 1 2. Prior to mounting active contact element 10 on the supporting element, the lateral arms are relatively spaced from their respective anvils, this spacing permitting both easy fabrication and an efficient application of an electrolytic coating. The anvil 14 comprises two bosses 10 and 21, the purpose of which is to serve as supporting stops for the lateral arms 1 6 and 17, when the latter are pushed in the direction of the anvil 1 4 by the supporting element, as will be described later.Similarly, the anvil 1 5 comprises two bosses 22 and 23 the task of which is identical to that of the bosses 20 and 21 in cooperation with the lateral arms 1 8 and 19. The lateral arms 16, 17, 18, and 19 comprise each a connection zone 1 6a, 1 7a, 1 8a, and 1 9a, fixed respectively to the free ends of the narrow supporting portions 1 6b, 1 7b, 1 8b, and 1 9b, the other ends of which are integral with the flat central region 1 3.

The connection regions have a larger width than those of the corresponding supporting portions. The inner edges 16c, 1 7c, 1 8c, and 1 9c of the respective connection zones 1 6a, 1 7a, 1 8a, and 1 9a cooperate with the edges relative to the anvils 14 and 15, in order to constitute connection slots which will be described in more detail in reference to Fig. 3.

The outer edges of the connection zones 1 6a, 1 7a, 1 8a and 1 9a comprise respectively shoulders mating with the upper ends of the elastic arms of the supporting element in a manner described hereafter in greater detail.

At the place of junction of the supporting portions 1 6b, 1 7b, 1 8b and 1 9b with the central region 13, a series of shoulders consisting of flat edges 1 6e, 1 7e, 1 8e, and 1 9e is placed in parallel with the axis and arranged for serving as support to the lower ends of the elastic arms of the supporting element in some of the applications described in the following.

The supporting element 30, corresponding to the active contact element 10, is represented in detail by Fig. 2. It is basically composed of a flat base 31 of approximately rectangular form, prolonged in the longitudinal sense by two extensions 32 and 33, placed symmetrically relative to the transverse axis of symmetry 34. The upper end of each of the longitudinal extensions 32 and 33 comprises a tip 35, 36 folded back rectangularly relative to the plane of the corresponding extension. On both sides of the extension 32 two elastic support arms 37 and 38 are attached at their lower part to the sides of the flat base 31. Similarly, two elastic arms 39 and 40 are placed on both sides of the longitudinal extension and are attached at their lower part to the sides of the flat base 31.These arms are preferably cut simultaneously with the other parts of the supporting element 30 from sheet stock of a metal which is insensitive to creepage under stress over a period of time and at maximum temperature of utilization, for example a spring steel, and are rectangularly folded back relative to the flat base 31. The elastic support arms 37, 38, 39, and 40 comprise each a lower end 37a, 38a, 39, and 40 comprise each a lower end 37a, 38a, 39a, and 40a adapted to bear against the corresponding flat edge 16e, 17e, 18e, and 1 9e of the active contact element 10, when the latter is mounted on the supporting element 30.The upper ends of the elastic arms, 37b, 38b, 39b, and 40b are arranged for engaging the corresponding shoulders 16d, 17d, 18d, and 1 9d of the active contact element 10 when it is mounted on the supporting element 30. The elastic arms 37, 38, 39, and 40 include integral projections forming clamps 37c, 38c, 39c, and 40c, folded back rectangularly to be parallel to the flat base 31 of the supporting element 30.

As it clearly appears in Fig. 3, the supporting element 30 is conceived so as to form a cage in which the active contact element 10 will be placed, maintained solidly in position in its axial sense by the cooperation of the flat couples of shoulder-edges 16d, 16e; 17d, 17e; 18d, 18e; and 19d, 19e, respectively, with the couples of the ends of the elastic arm 37a, 37b; 38a, 38b; 39a, 39b; and 40a, 40b. The arms of the supporting element 30, being elastic, open slightly for permitting the lateral arms 16, 17, 18, and 19 of the contact element 10 to pass at the moment of its mounting on the supporting element 30, until the moment when the upper ends of the support arms are latched under the upper shoulders of the lateral arms.Moreover, the contact element 10 is maintained in the direction of its thickness on the supporting element by cooperation of the extensions 32 and 33 parallel to one of the faces of the anvils 14 and 1 5 of the contact element 10 and of the corresponding clamps 37c, 38c, 39c, and 40c, parallel to the other faces of the anvils 14 and 15, for constituting an elastic cage that contains the active contact element 10.

Referring particularly to Fig. 3, representing partially the active contact element 10 mounted on the supporting element 30, it is seen that the elastic arms 37 and 38 of the supporting element bear against the lateral arms 1 6 and 1 7 of the active contact element with sufficient pressure to cause the latter to abut against the bosses 20 and 21 of the anvil 1 4. In this position, the inner edge 1 6c of the connection zone 1 6a of the lateral arm 1 6 cooperates with the edge relative to 1 4a of anvil 1 4 in order to define a connection slot 41.Similarly, the inner edge 1 7c of the connection zone 1 7a of the lateral arm 1 7 cooperates with the edge relative to 1 4b of the anvil 14 in order to define a second connection slot 41. As it can be seen, the slots 41 comprise each at their entrances a notch 42, 43 the opening of which is at least equal to the diameter of the greatest wire to be connected. The lower part of the notch communicates with the intermediate zone 44, 45 the edges of which merge inwardly from corresponding notches 42 and 43 and end with a construction 46, 47 limiting the upper ends of the connecting zones 48 and 49.

These zones of connection are limited below by the upper edges of the bosses 20 and 21.

The edges of the slots 41, particularly in the intermediate zones 44 and 45, present cutting edges arranged for cutting through the insulation of an electric wire, thereby permitting an efficient connection of the conductor with the active contact element. The constrictions 46 and 47, as. well as the projecting points at the junctions between the junction slots 48, 49 and the intermediate zones 44, 45, constitute a means for preventing the loosening of the wires introduced into the slots when the connection is submitted to vibration.

The elastic force of arms 37 and 38 of the supporting element 30 is transmitted to the lateral arms 1 6 and 1 7 of the active contact element 10 for pushing the latter against the bosses 20 and 21 constituting abutment supports. It will be readily understood that the dimensioning of these bosses defines in fact the width of the connection slots and limits the minimal width of the slots. The ensemble of the active contact element 10 and supporting element 30 is placed in the slot 50 of an insulating unit 51 constituting a body of a terminal block, for example.

Fig. 4 is a perspective view representing another embodiment of the contact according to the invention, placed in a slot 60 of the insulating body of a terminal strip 61. According to this embodiment, the active contact element 62 comprises again an anvil 63, placed between two lateral arms 64 and 65, these three elements being connected at their lower ends by a flat central region (not represented). The supporting element 66 comprises a base 67 prolonged upwardly by an extension 68 the end of which is folded back rectangularly in the form of a tip 69 and by two lateral arms 70 and 71 the upper ends of which lean under two shoulders arranged as described above at the upper part of the lateral arms 64 and 65.The contact element of Fig. 4, comprising two connection slots 72 and 73, corresponds approximately to the upper half of the above described contact element in reference to Fig. 1 to 3. In the example of Fig. 4, it can be easily understood that the part of the tip 69 must bear against the upper edge of the insulating piece of the terminal strip 61 in order to position axially and transversely the contact element in the alveolus.

Figs. 5A and 5B represent another embodiment of the contact element according to the invention in which the active contact element 80 comprises two joining slots 81 and 82 such as above-described and placed at an end of the active contact element, with a contact in the shape of a lyre 83 arranged at the other end of the active contact element 80.

The active contact element 80 is mounted again into a supporting element 84, comprising two lateral arms 85 and central extension 86 of the flat base 87. The flat base 87 comprises an elastic plate 88 which cooperates with the tip 89 of the free end of the extension 86 for positioning the supporting element in the alveolus of a connector block or terminal strip and for locking it into position in the alveolus or slot. As above, the clamps 90 and 91 cooperate with the flat base 87 and the extension 86 for constituting a cage in the inside of which is placed the active contact element 80.

Fig. 6 represents a variant of the contact element illustrated by Fig. 5. The supporting element 100 is identical to the supporting element 84 of the above-described contact element. The active contact element comprises again at one of its ends two joining slots 101 and 102, while its opposite end is constituted by an outlet 103 for a wire wrap or other connection.

Fig. 7 represents partially a connector block 110 the insulating part of which is made of two pieces 111 and 11 2. Such a realization facilitates molding techniques by simplifying the mold design. The junction unit 110 comprises a series of alveoli 11 3 disposed in lines and arranged so as to receive contact elements 11 4 such as those described in reference to Figs. 1 to 3. For mounting the contact elements 11 4 in the inside of the alveoli 11 3 of the joining unit 110, the parts 111 and 11 2 of the insulating body are first assembled, then the support elements are introduced inside the alveoli, and finally the active contact elements are mounted on the supporting elements.In this arrangement, the tips 115, folded back rectangularly, and their symmetrical (not represented) correspondents provide a double function: firstly, as above described, they maintain the support element in position at the inside of the alveolus; and, secondly, they constitute a means for assembling the parts 111 and 112, constituting the insulating body of the joining unit 110, and means for maintaining these pieces in their places the one upon the other.

Beside the functional characteristics of the tip 35 (Fig. 2), 69 (Fig. 4) and 115 (Fig. 7), this tip serves as a supporting abutment against which the end of the connected wire is cut, preferably by means of the same tool which assures the introduction of the wire into the slot and, at the end of the wiring introduction, cuts the end of the wire. The utilization of the tip as supporting abutment prevents the cutting tool from notching the insulating unit, eliminating the risk of damage from the great number of successive joining operations to which the described contact element may be exposed. The preceding description illustrates how the contact element according to the invention, comprising an active contact element and by a supporting element is assembled and mounted into the receiving alveolus of a terminal block.It can be easily deduced from this description that the contact according to the invention is dismountable. The dismounting operations correspond logically to the mounting operations but are realized in reverse. For dismounting the contact element according to the invention, it is initially necessary to free the lateral arms of the active contact element by spreading apart the elastic arms of the supporting element, to then withdraw the active contact element from its cage constituted by the flat base, the longitudinal extension or extensions, and the clamps integral with the lateral arms. After withdrawal of the active contact element, the extensions will pivot backward due to their elasticity which causes the disengagement from the terminal block slots of the folded-back tips, freeing the supporting element to be withdrawn from its receiving alveolus.

The concept and realization of the contact element according to the invention consists of two different parts having clearly distinct functions, one assuming the electrical function, the other assuming the mechanical function.

The thus realized contact element can be produced economically, is dismountable, is insensitive to creepage under stress, and can serve also as means for assembling the constituent parts of the insulating body of a connector block.

From the foregoing, it can be readily realized that this invention can assume various embodiments, thus, it is to be understood that the invention is not limited by the specific embodiments described herein, but is to be limited only by the appended claims.

Claims (11)

1. A contact member for insertion in a slotted terminal block and for electrically contacting the conductor of an electrical wire comprising: an active contact element of an electrically conductive material, at least one end of said element having three parallel branches arranged substantially parallel and coplanar, the central branch of said three branches being an anvil and the two lateral said branches arranged symmetrically on opposite sides of said anvil, the respective inner edges of said lateral branches and the outer edges of said anvil defining two longitudinal conductor contact slots, each said slot having an open end for insertion of wires to be contacted; and a supporting element of a high-strength elastic material selected for creep resistance, said supporting element comprising: support means for resiliently forcing said lateral arms of said active contact element toward said anvil; retaining means for holding said active contact element and said supporting element together as a unit; and locking means for locking said active contact element and said supporting element within a slot in the terminal block.

2. A contact member as claimed in Claim 1, wherein said anvil further comprises two bosses, one boss projecting from each side of said anvil within said longitudinal slots, said bosses abutting said lateral arms of said active contact element when said lateral arms are resiliently forced toward said anvil by said supporting means of said support element.

3. A contact member as claimed in Claim 1, wherein: the ends of said parallel branches of said active contact form notches at said open ends of said longitudinal slots, the opening of each said notch being at least equal to the diameter of the largest wire to be contacted and a portion of each edge of said longitudinal slots adjacent to said notches is divergently tapered toward said notches to define respective cutting edges.

4. A contact member is claimed in Claim 1 wherein; said active contact element is stamped in one piece from a sheet of metal; and the width of said longitudinal slots is greater than the thickness of said sheet of metal.

5. A contact member as claimed in Claim 1, said supporting element comprising: a base sheet having a substantially planar surface with opposite lateral edges and with end edges; at least one pair of opposed support arms attached to and disposed along said lateral edges of said base in opposed relation, said support arms being proximate to said planar surface of said base and providing resilient force from each arm of said pair toward the other, said support arms constituting said support means in said supporting element; an integral projection from each of said arms, each said projection directed toward the other of said pair of support arms, said projections being parallel to said planar surface of said base and spaced away from said base, said projections constituting said retaining means in said supporting element; and a resilient extension projecting from at least one end edge of said base and positioned between at least one said pair of arms, said extension being a prolongation of said base sheet between said arms, said extension extending out of the plane of said planar surface and between said support arms and having a tip folded back toward said plane of said planar surface, said tip extending beyond the plane of said base sheet on the side opposite said planar surface when said extension is forced toward the plane of said planar surface, said extension forming said locking means, and wherein said active contact element is inserted between said planar surface and said projections from said arms, said at least one end of said active contact element which has three parallel branches being disposed between said at least one pair of support arms of said supporting element; the insertion of said active contact element forcing said tip of said extension toward the plane of said planar surface, whereby said folded tip can engage the terminal block.

6. A contact member as claimed in Claim 5, wherein said lateral branches of said active contact element extend beyond the ends of said arms of said supporting element and wherein each said lateral branch further comprises: a first shoulder on the edge of each said branch which is away from said anvil, whereby the tip of said lateral branch is widened transversely, said shoulder forming an abutment for the end of an arm of said supporting element.

7. A contact member as claimed in Claim 6, wherein said active contact element has second shoulders projecting outwardly on opposite sides in the plane of said branches, each of said shoulders abutting the attachment point of one of said support arms of said supporting element when said active contact element is inserted into said supporting element, said first and second shoulders cooperating with the ends of said support arms to secure said active contact element into position within said supporting element.

8. A contact member as claimed in Claim 5, having a longitudinal axis of symmetry and a transverse axis of symmetry, said active contact element having said three parallel branches at each end pointing oppositely along said longitudinal axis of symmetry, thereby providing four contact slots arranged symmetrically relative to each said axis of symmetry.

9. A contact member as claimed in Claim 8, for use in a slotted terminal block having two halves divided transversely to said slots, said supporting element further comprising a pair of said support arms and one said extension from each end extending oppositely along said longitudinal axis of symmetry, said folded tips of said extensions each engaging one of the halves of said terminal block, whereby said contact element is retained within said terminal block and said halves are held together by said tips.

10. A contact member as claimed in Claim 1, having a longitudinal axis defining two ends, one said end of said active contact element having said three parallel branches and the opposite said end of said active contact having a connector element.

11. A contact member as claimed in Claim 10, wherein said connector element is in the form of a lyre.

1 2. A contact member as claimed in Claim 10, wherein said connector element is a pin for a wire-wrap connection.