Patent Description:
Installation boxes are mounted in holes in a wall of a building. Such a hole may be provided according to the circumstances at hand. If the wall is a solid wall, for example made of concrete or brickwork, a blind hole with a predetermined depth, depending on the thickness of the wall, may be provided. The installation box may be provided with projections for a mechanical engagement with an inner wall of the hole, to avoid a displacement of the installation box after mounting thereof in the hole in the wall.

<CIT> discloses an installation box comprising a housing provided with a bottom wall and a cylindrical circumferential wall that is upright from the bottom wall and has a centre line, wherein the circumferential wall comprises a circular circumferential edge that faces away from the bottom wall and bounds an opening of the housing. Around the circumferential wall, the housing is provided with integrally formed groups of positioning protrusions, placement protrusions and alignment protrusions in the form of ribs, strips or flaps. The groups of protrusions are divided into groups and extend radially outward from the outer surface of the circumferential wall. The protrusions are slightly flexible and are adapted for getting into contact with or engaging onto the hole in the wall in order to position, secure and/or align the installation box in there.

Further, for example, <CIT> discloses an installation box provided with resilient strips arranged on a side wall of the installation box, for placement of the box in a hole in a wall.

As another example, <CIT> discloses an installation box provided with sideward deformable bending flaps arranged on a side wall of the installation box, to retain the box in a hole in a wall.

A need exists to improve a mechanical engagement of the installation box with an inner wall of the hole in the wall.

It would be desirable to provide an improved or at least alternative installation box having an improved mechanical engagement with an inner wall of a hole in a wall.

To better address this concern, according to the invention an installation box for mounting in a hole of a wall according to claim <NUM> is provided.

The longitudinal axis of the installation box is a central axis running through a centre of the mouth of the installation box, and through a centre of the bottom wall of the installation box.

Herein, the adjectives 'upper' and 'lower' are associated with an installation box position in which the mouth of the installation box is upwards, and the bottom wall of the installation box is downwards.

The retaining projections can be part of different types of installation boxes, including but not limited to installation boxes with a variable height or installation boxes with a fixed height, wherein the retaining projections are located on a side wall of the installation box, and wherein the installation box is configured to be mounted in a hole in a wall, the hole having an inner side wall, and having transverse dimensions slightly larger than the transverse dimensions of the installation box.

The retaining projections aid in stabilizing a position of the installation box in a hole in the wall.

When inserting the installation box according to the invention into a hole in a wall, which hole may be congruent with the transverse dimensions of the installation box, the retaining arms have a centering function when the side wall(s) of the hole urge the retaining arms to be bent, i.e. the retaining arms urge the installation box to be centered with respect to the hole, when viewed in a plane at right angles to the longitudinal axis of the installation box. During the same insertion of the installation box into the hole in the wall, the side wall(s) of the hole urge the retaining flaps to be bent upwardly, i.e. in the direction of the box mouth, wherein free ends of the retaining flaps are elastically forced against the side wall(s) of the hole, and act as barbs against removal of the installation box from the hole. The retaining arms, having the centering function, prevent one or more of the retaining flaps to become bent to a degree that they become less effective, which they would be when the plane of the free ends of the retaining flaps extend at a small angle, such as less than <NUM> degrees, to the longitudinal axis of the installation box. Accordingly, with the combination of retaining arms and retaining flaps, the installation box is held securely in the hole in the wall. Installation boxes may be inserted into holes having different transverse dimensions. With retaining flaps of different radial lengths, as measured from the longitudinal axis of the installation box, it may be assured that at least one retaining flap of a group performs its retaining function with respect to the hole in the wall in an optimum manner, whereas each one of the remaining retaining flaps may be inoperative, i.e. not contact the side wall of the hole, or be less operative in its retaining function, e.g. by being little bent, or being overly bent, or even broken as a result of overly bending.

It is noted that the installation box, as well as the hole, may have a substantially cylindrical cross-section with a predetermined diameter, such that the box mouth and the bottom wall are circular, or may have another cross-section, in particular a polygonal cross-section, such as a rectangular or square cross-section.

In an embodiment of the installation box, each retaining arm comprises structured ribs extending parallel to the longitudinal axis and radially to enhance a grip of the retaining arm on an inner wall of the hole.

The ribs primarily increase a force needed to move the installation box in a circumferential direction. The ribs further resist the installation box to move into, or out of the hole.

In an embodiment of the installation box, the retaining arms are equidistantly spaced along the circumference of the side wall.

A good centering function of the retaining arms is reached when the retaining arms are equidistantly spaced along the circumference of the side wall of the installation box.

In an embodiment of the installation box, the retaining arms are placed to be diagonally anti-symmetrical.

Placing the retaining arms diagonally anti-symmetrical with respect to the longitudinal axis of the installation box, i.e. one retaining arm at one circumferential position on the side wall opposite to an opposite retaining arm at an opposite circumferential position on the side wall, provides a good centering function as seen in a plane including the longitudinal axis and said circumferential positions.

In an embodiment of the installation box, each retaining flap comprises a free end being structured to enhance a grip of the retaining flap on an inner wall of the hole.

The structured free ends of the retaining flaps primarily increase a force needed to move the installation box parallel to its longitudinal axis into, or out of the hole. The ribs further resist the installation box to move in a circumferential direction.

In an embodiment of the installation box, each group of retaining flaps comprises three retaining flaps.

Three retaining flaps each having a different radial length can ensure a retaining function in a variety of holes which are found in practice.

In an embodiment of the installation box, the radial lengths vary between a shortest length closest to the bottom wall of the installation box and a largest length closest to the box mouth of the installation box.

The radial length of the uppermost retaining flap, i.e. the retaining flap closest to the box mouth of the installation box, is larger than the radial length of the lowermost retaining flap, i.e. the retaining flap closest to the bottom wall of the installation box. A retaining flap located in between the uppermost retaining flap and the lowermost retaining flap, has a radial length which is larger than the radial length of the lowermost retaining flap, and which is smaller than the radial length of the uppermost retaining flap. In this way, a bending of a retaining flap during and after insertion of the installation box in a hole does not compromise the retaining function of a retaining flap located lower, i.e. closer to the bottom wall of the installation box.

In an embodiment of the installation box, the groups of retaining flaps are spaced equidistantly along the circumference of the side wall.

A good retaining function of the retaining flaps is reached when the retaining flaps are equidistantly spaced along the circumference of the side wall of the installation box, thereby enhancing the centering function of the retaining arms.

In an embodiment of the installation box, the retaining arms are located closer to the box mouth of the installation box than the retaining flaps.

For the retaining flaps to perform their retaining function best, and at the same time the retaining arms to perform their centering function best, the retaining arms are located further away from the bottom wall of the installation box than the retaining flaps. Thus, in particular during the last stage of inserting the installation box into a hole in the wall, the retaining arms prevent that similar retaining flaps at different locations along the circumference of the side wall of the installation box are loaded differently, and thus bent differently, which would occur if the installation box would be mounted obliquely in the hole.

In an embodiment of the installation box, a retaining arm is located at the same circumferential position of the side wall of the installation box as a retaining flap.

Locating a retaining arm above or below a retaining arm provides ample space at the side wall for making provisions for coupling different installation boxes, or coupling a pipe portion to the installation box.

These and other aspects of the invention will be more readily appreciated as the same becomes better understood by reference to the following detailed description and considered in connection with the accompanying drawings in which like reference symbols designate like parts.

<FIG> depict (parts of) an embodiment of an installation box <NUM> configured for mounting in a hole of a wall. The installation box <NUM> has an (imaginary) longitudinal axis <NUM> (as shown in <FIG>). The installation box <NUM> comprises a rigid cylindrical upper side wall portion <NUM> having a first upper edge region <NUM> defining an open box mouth which is configured to be closed off by a cover (not shown), and a first lower edge region <NUM>. Furthermore, the installation box <NUM> comprises a deformable cylindrical lower side wall portion <NUM> having a second upper edge region <NUM> adjoining the first lower edge region <NUM>, and a second lower edge region <NUM>. A circular bottom wall <NUM> adjoins the second lower edge region <NUM>.

The lower side wall portion <NUM> comprises a plurality of support strips <NUM> spaced along the circumference of the lower side wall portion <NUM>. In the depicted embodiment, eight support strips <NUM> are present. However, in other embodiments, less or more than eight support strips may be included, depending on the configuration and/or sizes of the support strips and the use conditions. Each support strip <NUM> extends between the second upper edge region <NUM> and the second lower edge region <NUM> in the direction of the longitudinal axis <NUM>. The lower side wall portion <NUM> further comprises a plurality of lower side wall parts <NUM> made from a flexible material. Each lower side wall part <NUM> extends between two adjacent support strips <NUM> and between the second upper edge region <NUM> and the second lower edge region <NUM>.

As will be explained in more detail below, each support strip <NUM> is configured to remain in an extended state under a force exerted in a direction along the longitudinal axis <NUM> of the installation box <NUM> when said force is less than or equal to a predetermined force, and to fold outwardly along a folding line <NUM> (<FIG>) extending transverse to the longitudinal axis <NUM> of the installation box <NUM> from the extended state to a folded state when said force exceeds said predetermined force.

The upper side wall portion <NUM> mainly is made from a rigid material, such as a plastic material, in particular polypropylene, with the exception of window parts <NUM> which are made from a flexible material, and may be pierced to allow the passage or wires, cables or other installation material. This flexible material may be the same as the flexible material of the lower side wall parts <NUM>, or may differ therefrom. Overall, the structure of the upper side wall portion <NUM> is essentially rigid, at least when considered in the direction of the longitudinal axis <NUM> of the installation box <NUM>.

The lower side wall portion <NUM> comprises a cylindrical layer of flexible material <NUM>, and the support strips <NUM>. The layer <NUM> extends over, and is in contact with the side of the support strips <NUM> facing away from an interior of the installation box <NUM>. The lower side wall parts <NUM> are integral with the layer <NUM>. In other embodiments, the lower side wall parts <NUM> may alternate with the support strips <NUM>, so that there is no layer <NUM>, in particular there is no flexible material, on the side of the support strips <NUM> facing away from an interior of the installation box <NUM>, and there is only the flexible material of the lower side wall parts <NUM> between adjacent support strips <NUM>.

The width of each support strip <NUM> in a circumferential direction of the lower side wall portion <NUM> is smaller than the length of the support strip <NUM> in a direction along the longitudinal axis <NUM> of the installation box <NUM>. In the embodiment shown in the Figures, a ratio of the width to the length of the support strip is about <NUM>. In other embodiments, the ratio may be between <NUM> and <NUM>. The supports strips <NUM> are equidistantly spaced along the circumference of the lower side wall portion <NUM>. The width of each support strip <NUM> in the circumferential directions of the lower side wall portion <NUM> is the same. Also, the width of each support strip <NUM> is the same along its length. A ratio of the width of a support strip to a width of a lower side wall part <NUM> is about <NUM>. In other embodiments, the ratio may be between <NUM> and <NUM>.

The bottom wall <NUM> comprises a frame <NUM> made from a rigid material, and comprising windows <NUM>, <NUM> made from a flexible material. The window <NUM> comprises a window part <NUM> having the same function as the window parts <NUM> to provide, upon piercing, a passage for wires, cables and other installation material.

The parts of the installation box <NUM> made from a rigid material, and the parts of the installation box <NUM> made from a flexible material may be obtained through a two-component injection moulding process by injecting, for example, polypropylene as the rigid material, and thermoplastic elastomer, TPE, as the flexible material. Other materials providing the required rigidity and flexibility, respectively, and showing suitable elasticity, may be applied as well.

Referring to <FIG>, each support strip <NUM> is provided with a recess or groove <NUM> at the side of the support strip <NUM> facing the interior of the installation box <NUM>. The groove may have a semi-circular, a triangular, a rectangular, or another suitable cross-section.

The groove <NUM> determines a folding line <NUM> (<FIG>). A distance between the groove <NUM> and the second upper edge region <NUM> is substantially equal to the distance between the groove <NUM> and the second lower edge region <NUM>. The groove <NUM> and its location on the support strip <NUM> ensures that the support strip <NUM> will fold radially outwardly at the groove <NUM> once a compressive force exerted on the support strip <NUM> in the direction of the longitudinal axis <NUM> exceeds a predetermined force, since the side of the support strip <NUM> facing away from the interior of the installation box <NUM> is able to absorb more force than the opposite side. The installation box <NUM> is designed such that the predetermined force may be applied by a person using manual power.

As illustrated in <FIG>, each support strip <NUM> may be curved along the circumference of the lower side wall portion <NUM>, with a concave side of the support strip <NUM> facing an interior of the installation box <NUM>. This curvature promotes the outward folding of the support strip <NUM> once said predetermined force is exceeded, and prevents an inward folding.

At the second upper edge region <NUM>, each support strip <NUM> may be hingeably connected to the first lower edge region <NUM>. In practice, an upper end of each support strip <NUM> may be rigidly connected to the first lower edge region <NUM> when the support strip <NUM> is in an extended state, and may be bent or broken at this connection, indicated with arrow <NUM> (<FIG>), when the support strip <NUM> is in a folded state, whereby the adjacent layer <NUM> made from flexible material provides a hinge function.

Similarly, at the second lower edge region <NUM>, each support strip <NUM> may be hingeably connected to the bottom wall <NUM>, in particular to the frame <NUM> thereof. In practice, a lower end of each support strip <NUM> may be rigidly connected to the bottom wall <NUM> when the support strip <NUM> is in an extended state, and may be bent or broken at this connection, indicated with arrow <NUM> (<FIG>), when the support strip <NUM> is in a folded state, whereby the adjacent layer <NUM> made from flexible material provides a hinge function.

The installation box <NUM> is provided with coupling portions <NUM> each defining a groove member and a hook member. The embodiment of the installation box <NUM> shown comprises ten coupling portions <NUM> on the outer side of the installation box <NUM>: four circumferentially equidistant pairs of coupling portions <NUM>, each pair adjacent to, and on opposing sides of respective window parts <NUM>, and one pair of coupling portions <NUM> adjacent to, and on opposing sides of window part <NUM> on the bottom wall <NUM>. Each pair of coupling portions <NUM> allows the installation box <NUM> to be coupled to another installation box, or allows a pipe portion comprising similar coupling portions to be coupled to the installation box <NUM>. The coupling takes place by inserting the hook members of two coupling portions <NUM> of a first pair into groove members of two coupling portions <NUM> of a second pair, and at the same time inserting the hook members of the two coupling portions <NUM> of the second pair into groove members of the two coupling portions <NUM> of the first pair.

As shown e.g. in <FIG>, no support strip <NUM> is provided in a circumferential position of the installation box where a centre of a coupling with another installation box (i.e. a centre of a pair of coupling portions <NUM> or, in other words, a centre of a window part <NUM>) is envisaged, thereby preventing a folded support strip of one of coupled installation boxes to mechanically interfere with a folded support strip the other one of the coupled installation boxes in case the support strips of the coupled installation boxes would need to enter into a folded state thereof during and after mounting of the coupled installation boxes. Instead, a folded support strip of one of the coupled installation boxes may extend into a flexible lower side wall part <NUM> of the other one of the coupled installation boxes, and be folded properly.

The upper side wall portion <NUM> is provided with radially outwardly extending retaining projections, comprising (as seen in cross-section) J-shaped retaining arms <NUM> and retaining flaps <NUM>, to anchor the installation box <NUM> in a hole in a wall. In the embodiment shown, the installation box comprises four retaining arms <NUM> and twelve retaining flaps <NUM>, however, in other embodiments these numbers may be selected differently. The projections are flexible and elastic to ensure a firm grip on, and a mechanical engagement with an inner wall of the hole, to avoid a displacement of the installation box <NUM> after mounting thereof in the hole in the wall.

The retaining projections can be part of the installation box in the embodiment as shown, but can also be part of other types of installation boxes, including but not limited to installation boxes with a variable height or installation boxes with a fixed height, wherein the retaining projections are located on a side wall of the installation box, and wherein the installation box is configured to be mounted in a hole in a wall, the hole having an inner side wall, and having transverse dimensions slightly larger than the transverse dimensions of the installation box.

Each retaining arm <NUM> is connected to the outer surface of the upper side wall portion <NUM> at one end thereof, the connection extending substantially parallel to the longitudinal axis <NUM>. The retaining arm <NUM> may be elastically bent relative to said connection to deform when urged to do so during the mounting of the installation box <NUM> in a hole. The retaining arms comprise a centring function for the installation box <NUM> in the hole, in particular a hole in a massive wall. Structured ribs <NUM> extending parallel to the longitudinal axis <NUM> and radially from the retaining arm <NUM> enhance a grip of the retaining arm <NUM> on an inner wall of a hole in a wall. The retaining arms <NUM> are equidistantly spaced along the circumference of the upper side wall portion <NUM>, and are configured to be diagonally anti-symmetrical. The retaining arms <NUM> mainly serve to centre the installation box <NUM> and hold the installation box <NUM> in a hole in a wall in a circumferential direction, but also resist a displacement of the installation box <NUM> in a direction of the longitudinal axis <NUM>.

Each retaining flap <NUM> is connected to the outer surface of the upper side wall portion <NUM> at one end, the connection extending substantially in a circumferential direction. In the embodiment shown, four groups of three retaining flaps <NUM> each are provided, wherein a group of retaining flaps <NUM> is spaced in the direction of the longitudinal axis <NUM> and comprises retaining flaps <NUM> having different radial lengths, varying between a shortest length closest to the first lower edge region <NUM> and a largest length closest to the first upper edge region <NUM>. The retaining flaps <NUM> each extend in a plane transverse to the longitudinal axis <NUM>. Each retaining flap <NUM> may be elastically bent relative to said connection to deform upwardly when urged to do so during the mounting of the installation box <NUM> in a hole. Free ends <NUM> of the retaining flaps <NUM> are structured to enhance a grip of the retaining flap <NUM> on an inner wall of a hole in a wall. The groups of retaining flaps <NUM> are spaced equidistantly along the circumference of the upper side wall portion <NUM>, and mainly serve to hold the installation box <NUM> in a hole in a wall in a downwards direction along the longitudinal axis, resisting a displacement of the installation box <NUM> in an upwards direction along the longitudinal axis <NUM>, but also resisting a displacement of the installation box <NUM> in a circumferential direction. The different radial lengths of the retaining flaps <NUM> enable the installation box to be retained in holes having different diameters, wherein the retaining flaps <NUM> having the shortest length are particularly effective in holes having a relatively small diameter (wherein the retaining flaps <NUM> having the largest length are less effective), whereas the retaining flaps <NUM> having the largest length are particularly effective in holes having a relatively large diameter (wherein the retaining flaps <NUM> having the shortest length are less effective). The retaining flaps having an intermediate length are most effective in holes having a medium diameter (wherein the retaining flaps <NUM> having the shortest length and those having the largest length are less effective).

The mounting of the installation box <NUM> in a hole in a wall is illustrated with the aid of <FIG>. For clarity, the layer <NUM> is omitted in these Figures.

During mounting the installation box <NUM> in a hole of a wall (an outer plane of the wall being indicated by dashed line <NUM>), the bottom wall <NUM> of the installation box <NUM> may move relatively soft material, such as hardened plaster, aside from the inner wall of the hole, by breaking it away or breaking it to pieces, or pulverizing it, for example. For this purpose, a force which may be referred to as a mounting force exerted on the installation box <NUM>, for example at the box mouth (or the first upper edge region <NUM>), or at a part of the box mouth, is transmitted through the rigid upper side wall portion <NUM> to at least some of the support strips <NUM> to the bottom wall <NUM> in a direction along the longitudinal axis <NUM> of the installation box <NUM>. At this stage, the mounting force, as distributed across one or more support strips <NUM>, may lead to a force on each support strip <NUM> being less than or equal to the predetermined force under which the support strip maintains its extended state, and stays in its extended state, yet high enough to move the installation box <NUM> into the hole in the wall and remove obstacles of relatively soft material in the mounting path of the installation box <NUM>. At this stage, the installation box <NUM> retains its maximum, first height. The lower side wall parts <NUM>, being made from a flexible material, cannot transfer any substantial force in the direction of the longitudinal axis <NUM> of the installation box <NUM>.

The hole in the wall may be as deep as, or deeper than (see distance D1 in <FIG>), the maximum, first height of the installation box <NUM>. If the force on each support strip <NUM> is not higher than said predetermined force, in this case the mouth of the installation box <NUM> may be mounted flush with the outer plane <NUM> of the wall in which the hole is provided, retaining its maximum, first height, with all support strips <NUM> in their extended state, providing a maximum volume at the interior of the installation box <NUM> for wiring and mounting installation material.

On the other hand, assuming that the depth of the hole is less (see distance D2 in <FIG> and distance D3 in <FIG>) than the maximum, first height of the installation box, then during the mounting of the installation box <NUM> there will be a point where the bottom wall <NUM> of the installation box <NUM> contacts the hole bottom <NUM>, so that the bottom wall <NUM> of the installation box <NUM> cannot move any further into the hole. Next, by increasing the mounting force to exceed said predetermined force at each support strip <NUM> under which the support strips <NUM> transfer from their extended state into their folded state, the support strips <NUM> will collapse and fold along their folding line <NUM>, whereby the height of the lower side wall portion <NUM> may decrease, and the upper side wall portion <NUM> may move further into the hole until the box mouth is substantially flush with the outer plane <NUM> of the wall in which the hole is provided. When collapsing, each support strip <NUM> comprises an upper strip section <NUM> on one side of the folding line <NUM>, and a lower strip section <NUM> on the other side of the folding line <NUM>. In the collapsed state of the support strip <NUM>, the respective upper strip section <NUM> and lower strip section <NUM> in itself may remain straight, or may bend and be curved as seen in a plane extending through the longitudinal axis <NUM> of the installation box. In the illustrated embodiment, the upper and lower strip sections <NUM>, <NUM> remain straight. The flexible lower side wall parts <NUM> will be locally stretched in the folded state of the adjacent support strips <NUM>, however, they will keep each mesh formed between edges of adjacent support strips <NUM>, the second upper edge region <NUM> and the second lower edge region <NUM> closed or sealed.

When the installation box <NUM> is flush mounted, still assuming that the depth D2 or D3 of the hole is less than the maximum, first height of the installation box <NUM>, for each support strip <NUM> at least part of the strip section <NUM>, <NUM> of the support strip <NUM> on one side of the folding line <NUM> may be oriented at an angle of less than <NUM>° to at least part of another strip section <NUM>, <NUM> of the support strip <NUM> on the other side of the folding line <NUM>. At most, said angle is <NUM>° when the two (parts of the) respective strip sections <NUM>, <NUM> rest against each other, whereby the lower side wall portion <NUM> has a minimum height, and accordingly also the installation box <NUM> has its minimum height, as illustrated in <FIG>. However, depending on the depth D1, D2 or D3 of the hole in the wall, any angle between (and including) <NUM>° and <NUM>° is possible.

Accordingly, the installation box <NUM> will fit into holes in a wall having different depths, while providing optimum space in the interior of the installation box <NUM>, both with the support strips <NUM> in an extended state and with the support strips <NUM> in a folded state.

In the embodiment of the installation box <NUM> discussed above, in the extended state of the support strip <NUM>, the support strip <NUM> is straight, as illustrated in the longitudinal cross-sectional view according to <FIG>. In other embodiments, the support strip in its extended state may be bent or curved, like the support strip 116B as illustrated in the longitudinal cross-sectional view according to <FIG>, wherein the concave side of the support strip 116B will be facing the interior of the installation box. In still other embodiments, the support strip in its extended state may be angled, where a straight upper support strip section extends at an angle to a straight lower support strip section, like the support strip 116C as illustrated in the longitudinal cross-sectional view according to <FIG>, wherein the concave side of the support strip 116C will be facing the interior of the installation box.

As explained above, an installation box for mounting in a hole of a wall has a longitudinal axis, and comprises a side wall having an upper edge region defining a box mouth, and a lower edge region adjoining a bottom wall, wherein the side wall on its outer surface is provided with radially extending retaining projections for clamping the installation box inside the hole of the wall. The retaining projections are flexible and elastic, and comprise retaining arms and retaining flaps. The retaining arms each have a J-shaped cross-section, each retaining arm being connected to the outer surface of the side wall at one end of the retaining arm, the connection extending substantially parallel to the longitudinal axis. Each retaining arm is configured to be elastically bent relative to said connection to deform when urged to do so during the mounting of the installation box in the hole. The retaining flaps are connected to the outer surface of the side wall at one end of each retaining flap, the connection extending substantially in a circumferential direction. Each retaining flap extends in a plane transverse to the longitudinal axis, and is configured to be elastically bent relative to said connection to deform upwardly when urged to do so during the mounting of the installation box in the hole.

As required, detailed embodiments of the present invention are disclosed herein. However, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which can be embodied in various forms. Further, the terms and phrases used herein are not intended to be limiting, but rather, to provide an understandable description of the invention.

Claim 1:
An installation box (<NUM>) for mounting in a hole of a wall, the installation box having a longitudinal axis (<NUM>), and comprising:
a side wall having an upper edge region defining a box mouth, and a lower edge region adjoining a bottom wall (<NUM>), wherein the side wall on its outer surface is provided with radially extending retaining projections (<NUM>, <NUM>) for clamping the installation box inside the hole of the wall, wherein the retaining projections (<NUM>, <NUM>) are flexible and elastic, and comprise retaining flaps (<NUM>) connected to the outer surface of the side wall at one end of each retaining flap (<NUM>), the connection extending substantially in a circumferential direction, each retaining flap (<NUM>) extending in a plane transverse to the longitudinal axis (<NUM>), and being configured to be elastically bent relative to said connection to deform upwardly in a direction of the box mouth when urged to do so during the mounting of the installation box (<NUM>) in the hole, wherein groups of retaining flaps (<NUM>) are provided, wherein the retaining flaps (<NUM>) of a group are spaced in the direction of the longitudinal axis (<NUM>),
characterized in that the retaining projections further comprise retaining arms (<NUM>) each having a J-shaped cross-section, each retaining arm (<NUM>) being connected to the outer surface of the side wall at one end of the retaining arm (<NUM>), the connection extending substantially parallel to the longitudinal axis (<NUM>), each retaining arm being configured to be elastically bent relative to said connection to deform when urged to do so during the mounting of the installation box (<NUM>) in the hole; and
each group of retaining flaps (<NUM>) comprises retaining flaps (<NUM>) having different radial lengths.