The invention relates to a casing system for laying electric supply conductors and, if desired, signal conductors along the outer surface of walls of buildings, comprising unitary elongated casing sections of insulating material and of a variety of fixed lengths, each such section having a front wall and a rear wall and at least two longitudinal cavities extending from end to end of the section in positions mutually displaced in a transverse direction parallel to said front wall, an electric supply conductor being mounted in each of at least two such longitudinal cavities at a loose fit and being held therein against longitudinal displacement, each casing section being constructed with a number of access modules distributed over the length of the section and each provid¬ ing access for the touch and creep proof connection of outer con¬ ductors or installation components from the front side of the casing section to the supply conductors in the longitudinal cavities, sliding cover sections profiled for positive sliding engagement with said casing sections and having a shape and a length such as to be capable of covering a gap of substantial length between two aligned casing sections, corner sections having two legs disposed at an angle to each other, and end sections having one leg, each leg being shaped for positive sliding engagement with a sliding cover section in such a manner as to define a confined space between the sliding cover- and the leg and to be capable of covering a gap of substantial length between the leg considered and the end of an aligned casing section, said sliding cover sections being constructed for fixation relative to a wall of a building along which one or more casing sections are mounted, and in which each supply conductor is provided with a contact piece in the area of each access module, and access slots are provided in the front wall of the casing section in front of each such contact piece, the system further comprising connectors each having forked contact legs adapted to be pushed through said access slots into contact making engagement with said contact pieces, thereby defining

a position of use of the connector, means for securing said connect¬ or in its position of use, and cover means adapted to be secured in a position to cover said access slots belonging to an access module at any time not in sue for accomodating a connector, holding means penetraging from the exterior into said cavities in the area of each access module in such a manner as to hold the contact pieces in position behind the access slots.

A casing system of this kind is known from PCT/DK88/00030 published as WO 88/06361 on 25th August 1988.

As explained in the description of PCT/DK88/00030, this known system has many advantages in respect of ease of mounting, neatness of appearance, flexibility in the choice of take-off positions, and safety against accidental access to the supply conductors. Thus, it will always be possible, when the length of wall to be covered is known, to determine the optimum combination of available casing section lengths, and it is then a very simple job to secure these to the wall, while at the same time placing the required number of sliding cover sections in engagement with the profile of the casing sections. In this manner it becomes possible, without cutting or in any other way adapting the parts as manufactured and delivered, to establish casings running from corner to corner or from corner to door frame along one or more walls of a room, and after the casings have been secured to the walls, completion of the wiring by estab¬ lishing electrical connection with external conductors, and between the built-in conductors of adjacent casing sections may be performed easily and quickly, and thereafter the system is ready for the plugging in of installation components, such as wall sockets or other electrical connectors at the location of any one of the access modules, which may e.g. be distributed along the casing sections at a spacing of 1 m or less, so that the system is very flexible for adaptation to changing installation needs.

In the embodiments disclosed in PCT/DK88/00030, the casing sections are fastened to a wall by means of screws passing through one of the longitudinal cavities, and the supply conductors are in turn carried by the casing sections with the aid of holding means in the areas of the access modules.

This arrangement has the drawback that if the temperature rises in an access module area owing to heat developed by the surface contact resistance between the contact pieces and the contact legs of a connector, the extruded plastic material, of which the casing section consists, loses its hardness, so that the casing section no longer forms an adequate supporting structure for the conductors.

It is an object of the present invention to eliminate this drawback, and with this object in view, according to the invention, the holding means for the supply conductors comprise matching interloc¬ ked front and rear holders penetrating into the interior of the casing section from the front side and rear side, respectively, the rear holders being constructed for attachment to a wall of a build¬ ing.

Since the rear and front holders are not extruded parts, they can be molded from a plastics material having a greater hardness at elevat¬ ed temperatures than the plastics materials available for extrusion in the making of the casing sections, and the holders therefore form a heat resistant structure supporting both the supply conductors and the casing sections.

A further advantage of the holder arrangement is that since the attachment of the casing section to a wall takes place without the use of screws passing through the casing section, the arrangement permits utilization of the whole cross-sectional area of the section for longitudinal cavities accommodating conductors.

This is, however, only possible if the required auxiliary structural elements can likewise be attached to the front wall of the casing without the use of screws.

To achieve this, according to a further feature of the invention, the front wall of a casing section is formed with an outwardly open undercut groove, in the following referred to as fixation groove, for the fixation of auxiliary structural elements to the front wall of the casing, each such auxiliary element having fixation noses, which in one angular position are freely slidable along the fixation groove and by forcible turning of the noses in the fixation groove

are clampable in the inner, undercut portion of the fixation groove at a firm grip.

The invention will now be described in further detail with reference to the accompanying drawing, in which

Fig. 1 illustrates on a reduced scale an embodiment of the invention in the form of an end section, a sliding cover section and a casing section, all forming part of a casing length running along the intersection of a vertical wall and a horizontal ceiling, as seen in front view in an upwardly inclined direction as indicated by the arrow I in Fig. 2,

Fig. 2 is a section on an enlarged scale along the line 11-11 in Fig. 1,

Fig. 3 is a section along the line III-III in Fig. 1,

Fig. 4 is a section along the line IV-IV in Fig. 1,

Fig. 5 is a section along the line V-V in Fig. 1,

Fig. 6 is an exploded sectional view corresponding to Fig. 5,

Fig. 7 is a section along the line VII-VII in Fig. 1,

Fig. 8 is a section along the line VIII-VIII in Fig. 1,

Fig. 9 is a section along the line IX-IX in Fig. 1,

Fig. 10 is a rear view of a front holder also illustrated in Fig. 6,

Fig. 11 is a front view of a rear holder also illustrated in Fig. 6,

Fig. 12 is a side view, as seen in the direction of the arrow XII in Fig. 5, illustrating the suspension of a casing section from a wall and a ceiling by means of an angular fixture and a front and rear holder assembly, a portion of the casing section being broken away,

Fig. 13 illustrates the mounting of a contact piece of a conductor to be built into the casing section of Fig. 12,

Fig. 14 is a front view of a connector base member mounted on a casing section and also illustrated in Figs. 8 and 9, a cover being omitted in Fig. 14,

Fig. 15 is a front view illustrating the establishment of cable connections between two aligned casing sections, each being provided at its end with a terminal box, and

Fig. 16 is a diagrammatic, developed view of a corner section having two hingedly connected legs.

Fig. 1 illustrates a casing length adapted to be mounted in an inclined position along the intersection of a vertical wall and a horizontal ceiling so as to form a decorative element which may be referred to as "electrical stucco". The casing length illustrated comprises an end section 101, a sliding cover section 102 and a casing section 103, all made from an extruded plastics material.

As will be seen in Fig. 3, the end section 101 has a profile fitting in the angle between the wall 104 and the ceiling 105, to which it can be attached by means of screws 106,106. The profile of the end section 101 is formed with channel portions 107, 107, accomodating the heads of the screws 106,106, and with forwardly extending side portions 108,108 which at their front edges are constructed with outwardly open guiding grooves 109,109.

The casing section 103, see Fig. 4, has a front wall 110 and a rear wall 111 between which a number of longitudinal cavities 112, 113, 114, 115, 116 run side by side from one end of the casing section to the other. All of these cavities may be used for accomodating conductors belonging to a system of conductors for which the casing system is used. These will include at least two power supply con¬ ductors 117, 117, see Fig. 6, to be accomodated in the cavities 113, 115.

The central cavity 114 is rearwardly offset relative to the other

cavities to provide space for an outwardly open undercut groove 118 serving for the fixation of auxiliary structural elements, as will be explained later.

The sliding cover section 102, see Figs. 3 and 4, has a front wall 119 and two side walls 120, 120 carrying inwardly extending guiding ribs 121.

In the finished installation, as illustrated in Fig. 1, the sliding cover section 102 closes the space within the end section 101 and at the same time covers the gap between the ends of the end section 101 and the casing section 103, and is in positive sliding engagement with both, viz. by engagement of the guiding ribs 121 of the sliding cover section 102 in the guiding grooves 109 of the end section 101 and behind the rear wall 111 of the casing section 103. From this position the sliding cover section 102 may be slid to the right in Fig. 1 so as to expose the interior of the end section 101 and the left hand end of the casing section 103. Now, connection may be established from the conductors in the longitudinal cavities of the casing section 103, e.g. by means of cables passing through holes 122 of an end plug 123 fitted in the end section 101 and through the contiguous wall of the building to conductors in a similar casing system in an adjoining room. If no such cable connections are to be established, the interior of the end section 101 will remain empty. In either case the sliding cover section will be slid back to the position illustrated in Fig. 1, in which it covers the left hand end of the casing section 103 and forms a neat termination of the casing length running in the whole length of a wall. In this position the sliding cover section is fixed to the end plug 123 by means of a screw 183.

Similarly, a sliding cover section may be used for covering a gap between successive aligned casing sections or between a casing section and one leg of a corner section, as will be later described.

Each casing section is constructed with a number of access modules distributed over its length. These may be selectively used for establishing electrical connection from installation components to the power supply conductors in the casing section. Fig. 1

illustrates at X an access module ready for use, at Y an access module not in use, and at Z an access module in use for receiving a connector, to be described later.

In the area of each access module, the power supply conductor 117 in each of the cavities 113, 115 is provided with a cylindrical contact piece 124 with flared ends 125, as best seen in Fig. 12. The contact piece 124 is clamped around the respective conductor 117, as illu¬ strated in Fig. 13, and, if deemed necessary, consolidated by soldering.

Moreover, in the area of each access module, the casing section 103 is constructed with a holder assembly comprising a front holder 126 and a rear holder 127, each having four legs A, B, C, D and a, b, c, d, respectively, cf. Figs. 10 and 11, penetrating into the cavities 113, 115 through rectangular holes H, Fig. 6, in the front and rear walls, respectively, of the casing section 103, in which they fit tightly. The legs a and b form a pair penetrating into the cavities 113, 115, respectively, and the same applies to the legs c and d, the two pairs being spaced in the longitudinal direction of the casing section. All four legs project from a base member 128 fitting against the rear wall 111 of the casing section.

Similarly, the legs A, B, C, D of the front holder form pairs A, B and C, D located opposite the pairs a,b and c,d. The legs A,B project from a transverse bridge member 129 fitting in a recess of the front wall 110 of the casing section and having a depression 130 fitting in the front groove 118 in the front wall 110 of the casing section. The legs C,D are similarly connected by means of a bridge member 131 having a depression like 130. The two bridge members 129 and 131 are interconnected at their depressed portions 130 by means of a thin longitudinal bridge member 133 fitting in the bottom of the front groove 118.

The mutually facing ends of the legs A, B, C, D of the front holder 26 and the respective legs a, b, c, d of the rear holder are formed with mutually matching end faces 134 and 135 which in the middle have concave face portions 136, 137 which grip around the contact pieces 124 on the conductors 117,117 to hold these in well defined

positions in their respective cavities 113,115. Owing to the flared ends 125 of the contact pieces 124, the conductors 117,117 are at the same time locked against axial displacement, however, with a certain clearance to allow for manufacturing inaccuracies, tempera- ture variations, etc..

In front of each contact piece 124, the front wall 110 of the casing section has two inclined access slots 132 through which forked contact legs of a connector can be pushed into contact making engagement with the contact pieces 124, as will later be described with reference to Fig. 9.

In manufacturing the casing section the contact pieces 124 are clamped around the conductors 117 in positions at a spacing corre- sponding to that of the access modules, and the conductors 117,117 are then introduced into the cavities 113, 115 from one end of the casing section. When the contact pieces are in correct positions in the access modules, the front and rear holders 126, 127 are pushed into the cavities 113, 115 in each contact module to grip the contact pieces 124 and to engage the bridge member 129 and the base member 128 with the front and rear surfaces of the casing section 103. In this position the front and rear holders are permanently interlocked, e.g. by means of self-locking straps 139 of well known kind which are tightened around body portions of both holders. All access modules are now ready for use. An access module ready for use is illustrated at X in Fig. 1.

When an access module is not to be used for accomodating a connec¬ tor, the access slots 132 should be covered by means of a front cover 140, as illustrated at Y in Fig. 1, and in Fig. 7. The front cover illustrated is a flat cover of square configuration with rounded corners. On its rear side it is provided with fixation noses 141,142, which in one angular position of the cover are freely slidable along the fixation groove 118, but by a 90° turning of the cover 140 are clampable in the inner, undercut portion of the fixation groove 118 at a firm grip to lock the cover against acci¬ dental removal. For the turning of the cover from its loose position to its locked position, the cover is provided on its front face with tool engageable means illustrated in the form of two projections 143

forming a groove 144 for a screw driver.

When an access module is to be used, the cover 140 is turned loose and removed, and a connector is placed on the access module. An example of a connector is illustrated at Z in Fig. 1, and in Figs. 8, 9 and 14. This connector has a base member 145 comprising a flat bottom 146 and side and end walls 147, 148 forming a shallow open cavity 149. On the bottom 146 are mounted two terminal blocks 150 of solid copper. The blocks have a square cross-section which is tilted at the same angle as the access slots 132. A thin flat contact leg 151 is clamped to a side face of each of the terminal blocks 150 by means of a screw 182 and extends through the bottom 146 of the connector. The extending ends of the contact legs 151 are adapted to be pushed through the access slots 132 and are forked for contact making engagement with the contact pieces 124.

The terminal blocks 150 also have bores 152 for receiving the bared ends of the two conductors of an insulated wire, and terminal screws 153 for clamping said bared ends in the bores 152. The insulated wire can be passed through a slot 154 in either one of the end walls 147,148 and can be clamped for pull release by means of screws 155 acting on a clamping member 156, the ends of which are slidable in a transverse slot 157 provided in the end walls 147,148. Such a wire may e.g. be used for the installation of a lamp suspended from the ceiling. Wire guides (not shown) attached to the casing section by means of fixation noses, such as 141, 142, may be used for the neat arrangement of such wires.

A plug 158 is rotatably mounted in the bottom 146 and is provided at its rearwardly extending end with fixation noses 159 corresponding to the noses 141,142 of the cover 140. At its free inner end, the plug 158 has a screw driver notch 160. Thus, when the connector has been placed in its contact making position, it can be fixed in that position by turning the plug 158.

At either side of the plug 158, the bottom 146 is constructed with two longitudinal projections 161 of a shape to form a fixation groove 162 corresponding to that of the casing section. By means of this fixation groove a cover 140 may be firmly attached to the

connector to close its cavity.

Reverting now to the holder arrangement illustrated in Figs. 5, 6, 10, 11, 12, it will be seen that the base member 128 of the rear holder is constructed at its back with longitudinally extending channel sections 163 for snap engagement with an angular fixture 164 attached to the wall and ceiling by means of screws 165. Thus, it will be seen that in the area of each access module the conductors 117 with their contact pieces 124 are supported directly from the wall and ceiling by means of the holder assembly 126,127. This is a very important arrangement because the holders can be molded from a plastics material having a greater hardness at elevated temperatures than the plastics materials available for extrusion in the making of the casing sections. In fact, the access modules constitute the delicate spots in which heat may be developed in the case of defec¬ tive contact making, and it is therefore important that the struct¬ ure carrying the conductors in these areas should be capable of standing a hardness test at the temperature reached in a load test.

When a casing section is suspended from the ceiling and the wall in the access module areas, as described, no other means are required for attaching the casing section to the building structure.

Fig. 15 shows two aligned casing sections 103, each of which is constructed at its end with a terminal box 166,166. As delivered to the user, terminal boxes at each end form integral parts of the casing sections. The casing sections 103 are identical to that previously described. Each terminal box 166 has the same outer profile as the casing section 103, but the front wall is omitted, and the interior of the terminal is divided into three separate compartments by means of insulating partitions 167,168. In the middle compartment a terminal block 169 is mounted on the rear wall of the box. At its free end the terminal box has an end wall with passages for receiving multi-core insulated cables 171, which can be clamped in the passages by means of clamping screws 172.

The terminal boxes facilitate the establishment of connections between conductors in the cavities 112,113,114,115,116 in one casing section and corresponding conductors in a next following casing

section by means of suitable multi-core cables. Thus, in the example shown, a number of insulated signal conductors in the cavities 112 and 116, two non-insulated supply conductors in the cavities 113, 115 and two insulated supply conductors in the cavity 114 are connected to the corresponding conductors in the corresponding cavities of the next following casing section. When the connections have been established, a sliding cover section 102, which has been pushed aside on the right hand casing section during the performance of the connecting operation, is slid back into position to cover the gap between the casing sections, including the terminal boxes which are thereby closed so that the compartments formed by the partitions 167,168 are completely isolated from one another. The sliding cover section can now be fixed relative to the wall by means of a fixation screw, not shown, which is screwed into a threaded hole in a bracket 173 which is permanently attached to the wall and/or ceiling and has a configuration such that it is also covered by the sliding cover section.

In order to provide space for carrying out the connecting operation (the "wiring" of the system), the sliding cover section must have a length sufficient to cover a gap of substantial length between successive casing sections.

Where an end of a casing section is located next to a leg of an end section or a corner section, the terminal box of the casing section will serve to establish connection between the conductors in the cavities of the casing section to external cables or, as far as a corner section is concerned, to the conductors in the cavities in the casing section next to the other leg of the corner section.

Fig. 16 illustrates diagrammatically an example of a corner section having legs 201, 202, which are hingedly connected with each other by means of hinge parts 203,204,205,206. Such a corner section is suitable for use in corners having different angles between the walls, and both for inner and outer corners. Fig. 16 also illustra¬ tes attachments 207 for supporting external insulated cables emanat¬ ing from the terminal box of an adjacent casing section.

It will be understood that by using flattened fixtures instead of

the described angular fixture 164 and shallow end and corner sec¬ tions the casing system described with reference to Figs. 1-16 can be constructed for attachment to a vertical wall of a building with the casing sections in an upright instead of an inclined position.

The term "wall", as used in this application, is to be understood as also including ceilings and other surfaces of building structures in the widest sense of this concept.