1.  Field of the Invention
The present invention relates generally to fixing a device of any kind, such as a socket outlet or a telecommunication jack, into conduit of any kind, such as a baseboard, coving, column or other form of conduit, used for electrical power and/or telecommunication installations in domestic or business premises. 
2.  Description of the Prior Art
In some installations, in the case of both new construction and renovation, conduit fixed to the wall is often used for electrical or optical wiring.  The conduit therefore runs horizontally along the walls, at the bottom in the manner of a baseboard, at the top in the manner of coving, or vertically against a wall, in a corner or on a column.  The conduit provides a functional and protected internal wiring path enabling easy and reliable connection to diverse electrical or telecommunication devices. 
The electrical devices are generally housed individually or in groups in a support frame or housing which is usually fixed directly to the wall, being recessed into the wall to a greater or lesser degree, and adjoins the conduit, or even overlaps it locally, in the transverse direction relative to its longitudinal direction. 
This has the advantage of fast installation and facilitates subsequent work.  However, it has the disadvantage of a relatively large footprint on the wall (or the column), which is somewhat unesthetic and difficult to reconcile with localized problems of congestion.  Moreover, xe2x80x9cmade to measurexe2x80x9d recessing of the housing and the device(s) that it contains into the receiving wall is not always desirable or convenient. 
In other installations, the conduit, which in this case is usually referred to as trunking, is deep enough to receive not only the electrical conductors but also the entire depth of the device(s) to be fixed.  In this type of installation, the devices are either attached directly to the trunking or accommodated in a housing or on a support frame which is in turn attached to the trunking.  An apertured plate (shield) is generally locally substituted for the cover section of the trunking to provide access via an opening of appropriate dimensions to the active front face of the device(s), which is then flush with the shield attached in this way.  The housing containing the device(s) is thus entirely accommodated within the trunking, without projecting from it at the front or at the rear, the trunking being deep enough to contain the entire depth of the housing and the device(s) that it contains. 
This type of installation, which has the advantage of reducing the width of the footprint on the wall, has the major disadvantage of requiring the trunking to be relatively deep throughout its length, which is highly unesthetic and usually represents a heavy penalty on the general ergonomics of the interior space delimited by the wall in question.  Clearly, because of its depth, the trunking projects a relatively large distance from the wall, impeding the installation of furniture, and even the circulation of persons, trolleys or other vehicles. 
In further installations, as shown in the document FR 2,729,255, for example, each electrical device is individually received in a housing that is accommodated in the conduit and has an overall depth greater than that of the conduit; it passes through the bottom of the conduit by means of an opening formed locally for this purpose therein.  The surplus part of its depth, which projects from the bottom of the conduit, is received in a corresponding recess formed in the wall specifically for this purpose.  The above document therefore proposes a system for building an electrical device into a wiring conduit whose depth is less than that of the device, including a support provided with means for fixing it in the conduit and means for receiving the electrical device so that the front face of the device is flush with the front face of the conduit through a corresponding opening formed therein, and a patttess, i.e., an open-ended box, typically for accommodating an electrical device, adapted to pass through a corresponding opening formed in the bottom of the conduit and to form therein a recess to receive the rear part of the device.  The pattress, which projects externally from the rear face of the base section of the conduit, is received in the associated recess in the wall, in which it delimits a specific volume, and protects the device. 
However, in this system, the device support and the pattress are made in one piece forming the previously mentioned housing for individually receiving each device.  This leads to the following two major disadvantages.  On the one hand, the resulting housing is relatively bulky and therefore difficult to store and transport.  On the other hand, and more importantly, each housing is associated with a single device and it is therefore necessary to fix to the conduit as many housings as there are devices, which complicates installation, to the detriment of cost.  On the other hand, the support part of the housing must be matched to the type of device to be installed, and it is therefore necessary to provide several types of housing matching the various types of device, which increases manufacturing and distribution costs and complicates installation. 
The object of the invention is to overcome the above drawbacks as much as possible. 
To this end, the invention provides a system for building at least one electrical device into a wiring conduit whose depth is less than the depth of the device, the system including:
at least one support provided with means for fixing it in the conduit and means for receiving the electrical device(s) so that a front face of each device is flush with a front face of the conduit via an opening formed in corresponding relationship therein, and
at least one pattress adapted to pass through an opening formed in corresponding relationship to it in the bottom of the conduit and to form therein a recess for accommodating a rear part of the device, in which system the pattress is separate from the support and has its own means for fixing it to the conduit. 
It is therefore possible to provide a standard pattress that can be associated with different types of support corresponding to the different types of device that can be installed in the conduit.  This reduces fabrication and distribution costs, because only the support, to be more precise its means for receiving the device(s), requires diversification.  Clearly fabrication, transport and storage of the support alone are simpler and consequently less costly than in the case of a more complex assembly including the device support and the pattress, as was the case in the prior art previously mentioned. 
Also, during installation, it is particularly convenient to be able to use a standard pattress so that it is possible to use only one type of drilling and recessing tool, also of standard design, to form the opening in the bottom of the conduit and the recess in the wall. 
Similarly, in the chronological sequence of installation operations, it is easier for the operator, after forming the opening in the bottom of the conduit and the recess in the wall, to install the pattress or pattresses which then delimit a specifically delimited and protected volume in the wall and in the recess in the back of the conduit.  The device(s) with their support(s) can be fitted and fixed to the conduit subsequently by means of the recess delimited in this way and protected by the pattress.  Clearly it is more convenient for the operator, when installing the devices, to have a clear view of the recessed volume in which the devices are to be received, delimited by the pattress.  Also, and most importantly, the ability to dissociate fitting the pattress into the recess in the wall through the opening in the bottom of the base section of the conduit from fixing the support with its device to the base section, in correspondence with the pre-installed pattress, proves to be not only more convenient but also propitious to obtaining an installation of good quality. 
It is therefore clear that dissociating these operations provides a clear delimitation of the various steps of the assembly process, which is propitious to rationalizing the tasks to be carried out.  In fact, because of the dissociation of the pattress and the device support, it is possible to start by installing a plurality of pattresses belonging to a plurality of built-in fixing systems distributed between different device installation areas of one or more conduits of the same room or the same site and then to install the supports pre-equipped with their devices subsequently. 
In accordance with one advantageous feature of the invention, the system includes a single support whose longitudinal dimensions and receiving means are adapted to receive a plurality of devices and a plurality of pattresses each associated with one of the devices.  However, the support can be designed to receive only one device, of course. 
Using a single support for several electrical devices in this way has the advantage, which in practice is invaluable, of enabling the support to be pre-equipped with different devices to be installed and the pre-equipped support, with all of the devices, then to be fitted onto the base section of the conduit in a single operation.  It is in particular possible to prefit the support with the various devices in the manufacturing plant, and even to prewire them.  Compared to the prior art, which has entailed using an individual housing for each device, the operator saves a considerable amount of time since, instead of fixing and wiring the housings one by one on the base section of the conduit, he can fix the common support and thereby install all of the devices simultaneously in a single operation and make the electrical connections to the resulting assembly. 
In accordance with another advantageous feature of the invention, the system includes at least two pattresses each having a line of weakness adapted to enable the detachment of a lateral portion of the pattress along a lateral cut edge delimiting a lateral opening by which two adjacent pattresses can be combined so that they are contiguous at their respective lateral cut edges.  In this way, from two standard pattresses, a double pattress is obtained able to accommodate two juxtaposed devices or a single large device. 
Advantageously, in this case, each pattress has a lateral envelope of globally cylindrical shape and the line of weakness is in a plane that is parallel to the axis of the cylindrical envelope but does not contain the axis optionally, to associate three or more pattresses, each pattress has two lines of weakness symmetrical to each other with respect to the axis of the cylindrical envelope. 
In one advantageous embodiment, the means for fixing the support to the conduit include at least two lateral skids adapted to be engaged with two associated slides formed longitudinally on the bottom of the conduit.  This method of attaching the device support to the conduit is not only simple but also convenient for the installer or a subsequent worker.  In fact it is sufficient to engage the skids of the support with the associated slides of the base section of the trunking, for example with a simple clipping action, and then to adjust the longitudinal position of the device support on the conduit by causing the skids to slide in the slide. 
To facilitate further use of the system and to reinforce the immobilization of the support on the bottom of the conduit, at least one of the lateral fixing skids of the support can be mobile laterally between a configuration in which it is immobilized by friction on the corresponding slide of the conduit, a configuration in which it can slide freely on the slide, and a configuration in which it is completely released from the slide. 
Advantageously, in this case, the mobile skid is acted on by a locking member mobile between a locking position holding the mobile skid in its configuration immobilized on the slide and an unlocking position leaving the mobile skid tree to revert to its configuration of freely sliding on the slide or of complete release from the slide. 
For example, the locking member of the mobile skid includes a cam member pivotally mounted on the support and adapted to receive an actuator of any kind for pivoting it between two angular positions constituting the locking and unlocking positions.  In particular, the two angular positions of the cam member can be separated by one quarter-turn.  This is the case, for example, if the cam member comprises a journal received to pivot freely in a well or bearing formed on the support, a head disposed at one of the two ends of the journal and on which is formed an imprint adapted to cooperate with a screwdriver or like tool, and a shoe disposed at the other end of the journal and having the overall shape of a parallelepiped elongate transversely to the pivot axis of the journal. 
To make locking more reliable, the shoe of the cam member can have a boss adapted to be received in an imprint formed in a corresponding part of the support to immobilize the cam member temporarily in a locking position. 
To simplify manufacture and reduce costs, the cam member, its journal, its head and its shoe can be molded in one piece from a plastics material. 
Similarly, the support and its lateral fixing skids are molded in one piece from a plastics material.  In this case, the mobility of the mobile shoe is the result of the resilience of the shoe, with a relaxed configuration corresponding to the configuration in which it is interengaged with and slides freely on the corresponding slide of the conduit. 
Again in an advantageous embodiment of the invention, the means for fixing the pattress to the conduit include rigid bearing lugs projecting radially outward at the open front edge of the pattress and adapted to bear on the bottom of the conduit.  The means for fixing the pattress to the conduit can further include at least two locking fingers formed at the open top edge of the pattress and adapted to interengage with the corresponding slide of the bottom of the conduit after radial outward deformation of the pattress. 
Other features and advantages of the invention will become apparent in the light of the following description of one particular embodiment, which description as given by way of non-limiting example and with reference to the accompanying drawings.