GB2112586A

GB2112586A - A holder for bus-bars

Info

Publication number: GB2112586A
Application number: GB08230638A
Authority: GB
Inventors: Hans Wagener
Original assignee: Rittal Werk Rudolf Loh GmbH and Co KG
Current assignee: Rittal Werk Rudolf Loh GmbH and Co KG
Priority date: 1981-11-03
Filing date: 1982-10-27
Publication date: 1983-07-20
Also published as: SE462883B; SE8702557L; SE8702557D0; SE455746B; NL8203957A; NL185046C; NL185046B; FR2515856B1; GB2112586B; SE8206215L; FR2515856A1; SE8206215D0

Abstract

A holder for bus-bars, includes a parallelpiped-shaped carrier portion (10) which is provided with a plurality of groove-like notches (11) for receiving bus-bars (40) and means (26) for securing the bus- bars (40) which are introduced into the notches (11). To enable bus- bars (40) of different widths and thicknesses to be secured in a holder of this type, insert elements (30), adapted to the dimensions bus-bars (40), are non-detachably insertable and are retainable therein by means of a common cover member (20). The holder is capable of being widened at either end for additional bus-bars by means of an additional carrier portion (50 Figs. 14 & 15 not shown) and an additional cover portion (70). <IMAGE>

Description

SPECIFICATION A holder for bus-bars The present invention relates to a holder for bus-bars, including a parallelpiped-shaped carrier portion which is provided, in its top portion, with a plurality of groove-like notches for receiving bus-bars and means for securing the bus-bars which are introduced into the notches.

A holder of this type is disclosed in German Gebrauchsmuster (Utility Model) No. 75 21 773. In such disclosure, the notches formed in the plastics material carrier portion have different depths and are adapted to the width of the bus-bars. Grooves are formed in the lateral walls of the notches, and a slide member may be inserted into said grooves in order to secure the bus-bar which has been introduced into the notch. These slide members act as the means for securing the bus-bars and are integrally moulded on the carrier portion by means of resilient webs. Several pairs of grooves lying opposite one another are provided in the lateral walls of the notches formed in the carrier portion and, in consequence, bus-bars of different thickness, but with identical widths may be secured in a notch.

As disclosed in German Gebrauchsmuster No. 77 09 147, it is also already known to insert bus-bars into a notch formed in a carrier portion either individually or in groups. So that the top ends of the bus-bars lie in a common plane, spacer elements of various thicknesses are used in order to fill the depth of the notches. All the notches do, of course, have such a depth that they can receive the maximum number of grouped bus-bars.

These known holders for bus-bars are suitable for receiving bus-bars which have identical widths but different thicknesses, and their field of application is therefore restricted to one specific group of bus-bars. There are also, in fact, bus-bars which, in addition to having different thicknesses, e.g. 3 mm, 4 mm, 5 mm, 8 mm, and 10 mm, also have different widths, e.g. 16 mm, 20 mm, 25 mm and 30 mm.

The invention seeks to provide a holder for bus-bars of the above-described type, whereby bus-bars having different thicknesses and different widths may be positively secured in identical manner.

According to the invention, there is provided a holder for bus-bars, including a parallelpiped-shaped carrier portion which is provided, in its top end, with a plurality of groove-like notches for receiving bus-bars and means for securing the bus-bars introduced into the notches, wherein the width of the notches formed in the carrier portion is greater than the associated, maximum crosssectional dimensions of bus-bars to be retained therein, and the depth of these notches being identical to or greater than the associated, maximum cross-sectional dimensions of the bus-bars to be retained therein, and insert elements are non-detachably insertable into the notches formed in the carrier portion, which insert elements are adapted to the dimensions of the notches and each have, in their top ends, a respective notch which are dimensioned to correspond to one of a range of sizes of bus-bars to be retained, threaded bushes are provided into the top of the carrier portion between the notches, the carrier portion being covered by, and connected to, a parallelepiped-shaped cover member which is provided with stepped bores aligned with the threaded bushes of the carrier portion for receiving connecting screws provided with a head, and which cover member is provided with countersunk threaded bushes above the notches formed in the carrier portion and, in consequence, above the notches of the insert elements, which bushes may receive tightening screws.

This arrangement of the notches in the carrier portion and the use of simple insert elements, which are adapted to the notches and have a receiver member for one quite specific dimension of the bus-bar, allow the new two-part holder to be used universally. In such case, the countersunk threaded bushes facilitate not only the connection between the carrier portion and the cover member, but also the securing of the bus-bars in the receiver members of the insert elements.

According to one embodiment, the nondetachable insert between the carrier portion and the insert elements is achieved by providing the insert elements and the notches formed in the carrier portion with co-ordinated elements of dovetail joints on the walls which extend perpendicularly to the base and mounting surface of the carrier portion. In such case, it may be preferable to design the elements of the dovetail joints on the walls of the notches formed in the carrier portion as dovetail grooves, and to design the elements of the dovetail joints on the walls of the insert elements as dovetail webs.

According to a possible alternative embodiment, the insert elements may be retained in the notches formed in the carrier portion even more satisfactorily, when the bases of the notches formed in the carrier portion are provided with blind bores, and the facing underside of the insert elements is provided with corresponding insert pins.

According to one arrangement, the holder may be secured in a switchgear or distributor cabinet wherein each end of the carrier portion is designed as a mounting block having a stepped fixing bore formed therein.

In such a case, the threaded bushes of the carrier portion are introduced from the top into blind bores formed therein and terminate flush with the top end of the carrier portion.

However, the threaded bushes of the cover member are inserted into through-bores formed in the cover member, which threaded bushes extend over only a portion of the through-bore from the underside facing the carrier portion and terminate flush with the underside of the cover member.

So that the cover member may be ciamped on the carrier portion by means of the connecting screws, one embodiment provides stepped bores formed in the cover member for the connecting screws which may have portions of greater diameter, for receiving the head of the connecting screw, facing the top of the cover member.

A uniform distribution of the notches formed in the carrier portion then leads to an identical distribution of the bus-bars over the holder when provision is made for the insert elements to be distributed symmetrically with a central axis extending perpendicularly to the longitudinal dimension of the carrier portion.

If the distribution of the notches in the carrier portion should differ from the distribution of the bus-bars, a further embodiment may provide for the receiver member to be offset relative to the central axis of the insert element.

If the entire depth of the notched formed in the carrier portion is to be utilised for the busbar, one advantageous embodiment is characterised in that the insert elements are formed from two separate, preferably identical, partial insert elements. Then the partial insert elements only assume further adjustment in terms of the width of the bus-bars.

So that the holdder may be widened to provide further receiver members for bus-bars without involving a great deal of assemblywork and where the assembly work is restricted to the wider bus-bars, one embodiment provides that there is an additional carrier rail, which is provided with further notches for receiving bus-bars with mounting blocks. There is also an associated additional cover rail, that the mounting block is set-back at one end of the additional carrier rail by the height of the mounting blocks of the basic carrier rail relative to the underside of the additional carrier rail forming the mounting surface. The mounting blocks, disposed above one another, for the additional carrier rail and the basic carrier rail may be interconnectable, or are connectable to a support or the like, by means of a fixing screw.

An additional holder formed from an additional carrier rail and an additional cover rail may be attached, at each end, to the basic holder formed from a basic carrier rail and a basic cover rail without adversely affecting the secure mounting of the bus-bars in the basic holder. The subsequent assembly is therefore restricted to the attachment of the additional holder and the securing of the additional busbars in this additional holder. Depending on its length, the fixing screw at the junction between the basic holder and the additional holder may be used solely to join the mounting blocks of the basic carrier rail and the additional carrier rail or may be used, however, for the simultaneous securing of the basic holder and the additional holder to the support or the like.

According to a further alternative embodiment, the fixing of the additional carrier rail to the basic carrier rail may be facilitated in that the upper ends of the fixing bores formed in the basic carrier rail each have a portion of wider diameter, and the mounting block of the additional carrier rail, which block is setback relative to the mounting surface, has a sleeve-like attachment member in the region of its fixing bore. The sleeve-like attachment member is insertable into the widened portion of the fixing bore formed in the mounting block of the basic carrier rail. The additional carrier rail automatically adopts, therefore, the correct position relative to the basic carrier rail for the introduction of the fixing screw.

If the basic carrier rail and the additional carrier rail are only supposed to be interconnected in the region of their junction, then one advantageous embodiment is characterised in that each of the lower ends of the fixing bores formed in the mounting blocks of the basic carrier rail is also provided with a portion of wider diameter. The widened portions of the fixing bores accommodate a nut in flush manner, so that there is no projection at the fixing surface of the basic carrier rail and the additional carrier rail.

According to another alternative embodiment, the fixing screw which connects the additional carrier rail to the basic carrier rail may also be used to connect the additional cover rail to the additional carrier rail, in that the additional cover rail is provided with a fixing bore which is in alignment with the fixing bores formed in the mounting blocks of the additional carrier rail and the basic carrier rail. The additional cover rail is connectable to the additional carrier rail and the basic carrier rail by means of a fixing screw which extends therethrough.

One particularly advantageous embodiment provides that the basic carrier rail is provided with three notches for receiving bus-bars in a horizontal plane, and the additional carrier rail is provided with two notches for receiving bus-bars, whereby the notch facing the setback mounting block is disposed in the plane of the notches formed in the basic carrier rail, while the notch facing the mounting block, which is not set-back, is disposed a shorter distance away from the mounting face of the additional carrier rail.

The advantage of using bus-bars of different thicknesses and different widths both in the basic holder and in the additional holder is retained because insert elements are non-detachably insertable into the notches formed in the basic carrier rail and the additional carrier rail, which insert elements are adapted to have the same dimensions as the notches, and their top ends are provided with receiver members which are distributed over the crosssection of the bus-bars.

According to another further alternative embodiment, the additional holder formed from an additional carrier rail and an additional cover rail may also be mounted separately from the basic holder if provision is made for the additional carrier rail to be connectable, by means of its set-back mounting block, to a separate mounting member which comprises an inserted threaded bush for the fixing screw and, in addition to the threaded bush, is provided with a fixing bore located externally of the additional carrier rail.In this case also, the connection between the additional carrier rail and the separate mounting member is facilitated because the mounting member has a bore portion of wider diameter in the region of the threaded bush which extends from the underside of the mounting member over only a portion of the height, the bore portion serving as the means for receiving the sleevelike attachment member disposed on the underside of the setback mounting block of the additional carrier rail.

The invention will now be described more fully, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a side view of a carrier portion of a holder according to the invention; Figure 2 is a plan view of the carrier portion shown in Fig. 1; Figure 3 is an end elevational view of the carrier portion of Fig. 1; Figure 4 is a side view of the cover member; Figure 5 is a plan view of the cover member shown in Fig. 4; Figure 6 is an end elevational view of the cover member of Fig. 4; Figure 7 is a side view of a first insert element:: Figure 8 is a plan view of the insert element shown in Fig. 7; Figure 9 is a side view of a second insert element; Figure 10 is a plan view of the insert element shown in Fig. 9; Figure ii is a side view of an insert element formed from two partial insert elements; Figure 12 is a plan view of the partial insert elements of Fig. 11; Figure 13 is a sectional view of a holder composed of carrier portion, cover member and insert element; Figure 14 is a schematic view showing the alignment of an additional holder, formed from an additional carrier rail and an additional cover rail, at one end of the holder shown in Fig. 13; and Figure 15 is a sectional view of the additional holder which is formed from an additional carrier rail and an additional cover rail and is extended, by means of a separate mounting member, to form an independently mountable holder.

A holder for bus-bars according to the invention comprises a carrier portion 10, as illustrated in Figs. 1 to 3, a cover member, as illustrated in Figs. 4 to 6, and various insert elements such as are illustrated, for example, in Figs. 7 to 12.

The carrier portion 10 is preferably made of plastics material and is parallelepiped-shaped.

The two ends of the carrier portion 10 are designed as mounting blocks 1 7 having stepped fixing bores 18 formed therein. Since these fixing bores 1 8 have a portion of wider diameter both at the bottom end and at the top end thereof, the carrier portion 1 8 may be mounted downwardly and upwardly.

The top end of the carrier portion 10 is provided with three notches 11 when three bus-bars are required for a three-part system.

The number of notches 11, and hence the length of the carrier portion 10, is dependent on the number of bus-bars to be secured. In terms of width, the notches 11 are greater than the maximum width of the bus-bars, and the depth of the notches 11 may be equal to or greater than the maximum thickness of the bus-bars. Adjacent to the notches 11 are raised portions 1 9 of the carrier portion 10, and threaded bushes 1 6 are introduced centrally into the raised portions 1 9 of the carrier portion 10 from the top end, as illustrated in Fig. 2.These threaded bushes 1 6 are so inserted into blind-end bores that they terminate flush with the top surface of the carrier portion 1 0. However, the threaded bushes 1 6 may also be injected as plastics injection moulded parts during manufacture of the carrier portion 1 0. The lateral walls of the notches 11 are provided with the elements 1 2 and 1 3 of dovetail joints, which elements are in the form of dovetail grooves in the embodiment shown. In addition, the two blind-end bores 1 4 and 1 5 are provided in the base of each notch 11.As can clearly be seen from the view in Fig. 2, the notches 11 are symmetrical with a central axis which extends at right angles to the longitudinal axis of the carrier portion 1 0.

The cover member 20 illustrated in Figs. 4 to 6 is also parallelepiped-shaped and is provided with stepped bores 21, in alignment with the threaded bushes 1 6 in the carrier portion 10, for receiving connecting screws.

The region of wider diameter of each bore 21 for the head 28 of the connecting screw 27 faces towards the top end of the cover member 20, as illustrated in the sectional view in Fig. 1 3. Thus, the cover member 20 may be firmly connected to the carrier portion 10, the connecting screws 27 being screwed into the threaded bushes 1 6 in the carrier portion 10 and each being disposed on either side of the notches 11. The cover member 20 has bores 25, in alignment with the central axis of the notches 11 in the carrier portion 10, into which threaded bushes 22 are also inserted from the underside, facing the carrier portion 10. These threaded bushes 22 extend over only a portion of the bores 25 and terminate flush with the underside of the cover member 20.As illustrated in Fig. 13, these threaded bushes 22 accommodate tightening screws 26 by means of which the bus-bar 40 may be secured, which bus-bar 40 has been inserted into a receiver portion 37 of an insert element 30. Blind-end bores 23 and 24 are countersunk into the top end of the cover member 20 for receiving the insert pins of name-plates or of a cover plate.

Such a cover plate may cover the bus-bars, axially non-displaceably secured between at least two holders, in such a manner that they are not readily accessible.

Insert elements 30 are provided which may be inserted into the uniformly distributed notches 11 formed in the carrier portion 10, and the lateral walls of such insert elements 30 are provided with the elements 34 and 36 of the dovetail joints. In the embodiment shown, these elements 34 and 36 are in the form of dovetail webs, which correspond to the elements 1 2 and 1 3 of each notch 11, such elements 12 and 1 3 being in the form of dovetail grooves.

In addition, the underside of each insert element 30 is provided with two insert pins 31 and 32, as illustrated in Figs. 7 to 10, which insert pins 31 and 32 are correspondingly dimensioned and arranged to mate with the blind-end bores 1 4 and 1 5 formed in the base of the notches 11. A notch 37 or 37' is provided in the top end of the insert element 30 for receiving one particular dimension of bus-bar. The notch 37 of the insert element 30 is therefore provided, for example, with a width of 30 mm and. a depth of 5 mm, as illustrated in Figs. 7 and 8, so as to be able to accommodate a bus-bar of corresponding measurements. In the case of the insert element 30 illustrated in Figs. 9 and 10, however, the notch 37' is narrower and deeper and is provided for a bus-bar of different size, for example 16 mm X 8 mm.In such case, it can also be seen that the central axis of the notch 37' may be offset relative to the central axis of the insert element 30. The distribution of the spacings between the bus-bars may differ, therefore, from the distribution of the notches 11 in the carrier portion 1 0.

It is readily apparent that merely differently shaped insert elements 30 are needed to adapt the holder 10 to receive bus-bars of different measurements. Care should just be taken here to ensure that the notches 11 formed in the carrier portion 10 have a width which is greater than the maximum width of the bus-bars. In addition, there are also the portions 33 and 35 of the insert element 30 which define the notch 37 or 37', respectively.

The depth of the notches 11 formed in the carrier portion 10 may be equal to or greater than the maximum thickness of the bus-bars.

If the thickness of the bus-bar is equal to the depth of the notches 11 in the carrier portion 10, then two identical partial insert elements 30.1 and 30.2 are used, as illustrated in Figs.

11 and 12, and the two identical partial insert elements 30.1 and 30.2 are inserted into the notch 11 solely with the elements 34 and 36 of the dovetail joints. These partial insert elements 30.1 and 30.2 only compensate then for the width of the bus-bar, so that the notch 11 in the carrier portion 10 is entirely filled.

The basic holder assembly for bus-bars illustrated in Fig. 1 3 comprises the basic carrier 10 as shown and described in respect of Figs.

1 to 3, and the basic cover 30, as shown and described in connection with Figs. 4 to 6, as well as various insert elements 30 as shown and described in connection with Figs. 7 to 12, which are inserted into the notches 11 formed in the basic carrier rail 1 0.

Insert elements 30 are inserted into the uniformly distributed notches 11 with the two insert pins 31 and 32 on the lower sides of the insert elements 30 inserted into the blindend bores 14 and 15 of the notch 11. The insert elements 30 are selected in dependence on the dimensions of the bus-bars 40, and serve as the means to adapt the bus-bars to the dimensions of the carrier 10 which are always constant.

The cover 30 is mounted on the carrier base 10 and retained by connecting screws 27 which are screwed into the threaded bushes 1 6 of the carrier 10, so that the cover 20 is firmly connected to the carrier 1 0. The tightening screws 26 provided in bores 25 are screwed into these threaded bushes 22 and non-displaceably secure the bus-bar 40, which is inserted into the notch 37 of an insert element 30.

As illustrated in Fig. 14, an additional holder may be attached to either or both ends of the basic holder 10, 20, 30, illustrated in Fig.

1 3. This additional holder comprises an additional carrier portion 50 and the additional cover portion 70. The ends of the additional carrier rail 50 are formed as mounting blocks 59 and 61. The mounting block 59 terminates flush with the underside of the additional carrier portion 50, and is provided with a fixing bore 60 similar to fixing bores 1 8 formed in the mounting blocks 1 7 of the carrier portion 1 0. However, the mounting block 61 with the fixing bore 51 extending therethrough is set-back relative to the under side of the additional carrier rail 50 by the height of the mounting block 1 7 of the basic carrier rail 10, and in addition, a sleeve-like attachment member 52 is moulded on the underside of the set-back mounting block 61, which is insertable into the widened portion 34 of the fixing bore 1 8 formed in the mounting block 1 7 to such an extent that the underside of the additional carrier portion 50 is flush with the mounting faces of the mounting blocks 1 7 of the carrier portion 1 0.

As can also be seen in Fig. 15, the additional carrier portion 50 has two notches 53 with dovetail elements 56 and 57, as well as blind-end bores 54 and 55 which correspond to the notches 11 formed in the carrier 1 0.

The notches 53 may therefore accommodate similar insert elements 30 to those for the notches 11.

The additional cover rail 70 has stepped bores 71 for the connecting screws 27, such screws 27 having heads 28 and being screwed into threaded bushes 58 of the additional carrier portion 50. The tightening screws 26 are adjustable in threaded bushes 77 and are inserted in bores 72 formed in the additional cover portion 70. A connecting screw 33, which is introduced into the aligned bores 71 and 51 of the additional cover portion 70 and the additional carrier portion 50, extends also into the bore 1 8 formed in the mounting block 1 7 of the basic carrier portion 10. In such case, the lower, widened portion 36 of the fixing bore 1 8 may accommodate a nut for the connecting screw 33.

However, the connecting screw 33 may also project from the fixing bore 1 8 of the mounting block 1 7 and be screw-connected to a support member or the like. At the junction point between the basic holder and the additional holder, therefore, the fixing screw 33 may selectively join together the additional cover portion 70, the additional carrier portion 50 and the basic carrier portion 10, or it may join such components to a support member or the like. The length of the connecting screw 33 is merely to be selected accordingly for this purpose.

As illustrated in Fig. 15, the set-back mounting block 61 of the additional carrier portion 50 may also be connected to a separate mounting member 73. For this purpose, a threaded bush 75 is inserted into this mounting member 73, and the connecting screw 33 is screwed into said threaded bush 75. The threaded bush 75 extends over only part of the height of the mounting member 73. Above the threaded bush 75, the bore has a portion 76 of widened diameter which accommodates the sleeve-like attachment 52 of the set-back mounting block 61 of the additional carrier portion 50. The mounting member 73 protrudes beyond the end of the additional carrier portion 50 and, in this region, is provided with a fixing bore 74 which corresponds to the fixing bores 1 8 in the mounting blocks 1 7 of the basic carrier portion 10 and also has widened portions at each end. In this manner, the additional holder formed from the additional carrier portion 50 and the additional cover portion 70 may also be mounted by means of the mounting block 59 of the additional carrier rail 50 and the mounting member 73, separately from the basic holder formed from a basic carrier portion 10 and a basic cover portion 20.

Claims

1. A holder for bus-bars, including a parallelepiped-shaped carrier portion which is provided, in its top end, with a pluraltiy of groove-like notches for receiving bus-bars and means for securing the bus-bars introduced into the notches, wherein the width of the notches formed in the carrier portion is greater than the associated, maximum crosssectional dimensions of bus-bars to be retained therein, and the depth of these notches being identical to or greater than the associated, maximum cross-sectional dimensions of the bus-bars to be retained therein and insert elements are non-detachably insertable into the notches formed in the carrier portion, which insert elements are adapted to the dimensions of the notches and each have, in their top ends, a respective notch which are dimensioned to correspond to one of a range of sizes of bus-bars to be retained, threaded bushes are provided into the top of the carrier portion between the notches, the carrier portion being covered by, and connected to, a parallelepiped-shaped cover member which is provided with stepped bores aligned with the threaded bushes of the carrier portion for receiving connecting screws provided with a head, and which cover member is provided with countersunk threaded bushes above the notches formed in the carrier portion and, in consequence, above the notches of the insert elements, which bushes may receive tightening screws.

2. A holder according to claim 1, in which the insert elements and the notches formed in the carrier portion are provided with co-ordinated elements of dovetail joints on the walls which extend perpendicularly to the base and mounting surface of the carrier portion

3. A holder according to claim 1 or 2, in which the bottom end of the notches formed in the carrier portion is provided with blindend bores and the underside of the insert elements are provided with corresponding insert pins.

4. A holder according to one of claims 1 to 3, in which each end of the carrier portion is formed as a mounting block having a stepped bore formed therein.

5. A holder according to one of claims 1 to 4, in which the threaded bushes of the carrier portion are so inserted in blind-end bores, which are provided in the carrier portion from the top end, that they are flush with the top end of the carrier portion.

6. A holder according to one of claims 1 to 5, in which the threaded bushes of the cover member are inserted into through-bores formed in the cover member, which threaded bushes extend over only a portion of the through-bore from the side facing the carrier portion and terminate flush with the underside of the cover member.

7. A holder according to one of claims 1 to 6, in which the stepped bores formed in the cover member for the connecting screws have a portion of wider diameter for receiving the head of the connecting screw facing the top end of the cover member.

8. A holder according to one of claims 1 to 7, in which the insert elements are symmetrically arranged with a central axis extending perpendicularly to the longitudinal dimension of the carrier portion.

9. A holder according to claims 1 to 7 in which the notch is offset relative to the central axis of the insert element.

1 0. A holder according to one of claims 1 to 9, in which the insert elements are formed from two separate, preferably identical, partial insert elements.

11. A holder according to claim 2, in which the elements of the dovetail joints on the walls of the notches formed in the carrier portion are in the form of dovetail grooves, and the elements of the dovetail joints on the walls of the insert elements are in the form of dovetail webs.

1 2. A holder according to one of claims 1 to 11, in which additional blind-end bores are formed in the top of the cover member.

13. A holder according to one of claims 1 to 12, in which the notches of the insert elements are located on upright or flat busbars.

1 4. A holder according to one of claims 1 to 13, in which an insert element has a plurality of notches located one beside the other.

1 5. A holder according to one of claims 1 to 14, in which an additional carrier portion is provided having additional notches for receiving bus-bars and with mounting blocks, together with an associated additional cover portion, one of the mounting blocks being setback at one end of the additional carrier portion by an amount corresponding to the height of the mounting blocks of the basic carrier portion relative to the underside of the additional carrier portion, so that the mounting blocks of the additional carrier portion and the basic carrier portion may be disposed one above the other and are interconnectable, or are connectable to a support of the like, by means of a securing member.

1 6. A holder according to claim 15, in which the upper ends of the fixing bores formed in the basic carrier portion each have a portion of wider diameter and the mounting block of the additional carrier portion, which is set-back relative to the mounting block of the carrier portion, has a sleevelike attachment member in the region of its fixing bore, which is insertable into the widened portion of the fixing bore formed in the mounting block of the basic carrier portion.

1 7. A holder according to claim 1 5 or 16, in which each of the lower ends of the fixing bores formed in the mounting blocks of the basic carrier portion is also provided with a diametrically widened portion.

1 8. A holder according to one of claims 1 5 to 17, in which the additional cover portion has a fixing bore formed therein, which bore lies in alignment with the fixing bores formed in the mounting blocks of the additional carrier portion and the basic carrier portion, and the additional cover portion is connectable to the additional carrier portion and the basic carrier rail by means of the securing member.

1 9. A holder according to one of claims 1 5 to 18, in which the basic carrier member has three notches for receiving bus-bars in a horizontal plane, and the additional carrier portion has two notches for receiving busbars, the notch nearest the set-back mounting block being disposed in the plane of the notches formed in the basic carrier portion, while the notch nearest the mounting block, which is not setback, is disposed a shorter distance from the mounting surface of the additional carrier portion.

20. A holder according to one of claims 1 5 to 19, in which insert elements are nondetachably insertable into the notches formed in the basic carrier portion and the additional carrier portion, and the insert elements are adapted to have corresponding dimensions to the notches and are provided, in their top ends, with respect notches which are dimensioned to correspond to one of a range of sizes of bus-bars to be retained.

21. A holder according to one of claims 1 5 to 20, in which the additional carrier portion is connectable to a separate mounting member by means of its set-back mounting block, which fixing member has an inserted threaded bush for the securing member and, in addition to the threaded bush, is provided with a fixing bore located externally of the additional carrier portion.

22. A holder according to claim 21, in which the fixing member has a diametrically widened bore portion in the region of the threaded bush, which bush extends from the underside of said fixing member only over a portion of the height thereof, and the diametrically widened bore portion acts as the means for receiving the sleeve-like attachment member which is disposed on the underside of the set-back mounting block of the addi tional carrier portion.

23. A holder for bus-bars substantially as herein described with reference to and as illustrated in the accompanying drawings.