EP0748004B1

EP0748004B1 - An electrical device for sectional structures to be mounted on walls, with a body which is transparent at the rear

Info

Publication number: EP0748004B1
Application number: EP96201440A
Authority: EP
Inventors: Fabrizio Fabrizi; Roberto Peano
Original assignee: BTicino SpA
Current assignee: BTicino SpA
Priority date: 1995-05-29
Filing date: 1996-05-23
Publication date: 1999-10-27
Anticipated expiration: 2016-05-23
Also published as: ES2139306T3; ITMI951110A0; IT1279246B1; DE69604864T2; EP0748004A1; DE69604864D1; ITMI951110A1

Description

The subject of the present invention is an electrical device for sectional structures to be mounted on walls, of the type disclosed in GB-A-2 232 016 and GB-A-2 242 078 and as defined in the preamble of claim 1.
For greater clarity, it is appropriate to indicate that the term electrical device used in this description and in the following claims should be understood, in a generally accepted meaning, as defining those components of electrical installations for public buildings and the like which are usually fitted on the walls of rooms; various devices such as light switches, electrical sockets, bells, controls and knobs for operating various devices such as thermostatic regulators or timers, light and/or sound indicators, fuses, connections for radio or television aerials and anything else which may be used in the installations considered above thus fall within this definition.
As is known, nowadays, most of the devices just mentioned are fitted in corresponding sectional structures of the type mentioned above; this sectional arrangement is in fact intended to give the structures a modular character, that is, to permit interchangeable use of various parts which make up the structure in order to satisfy the various requirements of use; for example, it is possible to have structures which can house a single device or a plurality of devices of different kinds without the need, however, to produce cover plates, support frames and other suitable structural parts for the various devices. In general, these sectional structures give rise to a series of coordinated products with considerable economy and rationalization as regards the production and commercial aspects.
More specifically, the electrical devices in question are fitted in seats in the support frames of the sectional structures and they are fitted by means of a snap-engagement by virtue of which the devices can then be removed, possibly with a pointed tool such as a screwdriver or the like, in order to be replaced.
The electrical devices are constituted essentially by hollow bodies of electrically insulating material, for example, plastics or the like, inside which the various electrical components of the device such as the contacts and terminals are housed, as will be described further below; the body is usually formed by two portions joined together in a box-like configuration.
A first portion is disposed at the front facing an operator when the device is mounted, together with its structure, on a wall and the active element of the device, that is, the lever of a switch, the push-button of a bell or the knob of a thermostatic regulator, etc., according to the type of device fitted, is disposed therein; this active element is accessible from outside the body of the device and is also on the front of the structure mounted on the wall.
The rear portion of the body of the device, however, is represented by a base in which the terminals for electrical connection to the current-conducting wires provided in the wall in a position behind the device are disposed; the rear portion of the body therefore has holes through which the aforementioned wires can extend towards its interior.
A fairly important practical aspect which is known to operators and concerns the good operation of the devices consists of their correct electrical connection to the current-conducting wires.
For this purpose, there are currently precise standards for the safety of electrical devices which impose considerable constraints on their structure and which are also intended to ensure their correct electrical connection; for example, the connection terminals must be accessible from outside by means of suitable holes provided in the body of the device, some of which are intended for the passage of the ends of conductor wires which are left uncovered by their protective sheath, whereas others serve for the insertion of screws for clamping these ends in the terminals. The distances between the terminals and between the holes and the dimensions of these elements in general are subject to precise limitations to prevent the formation of harmful electric arcs when the device is in operation as well as to prevent connections with incorrect polarity, particularly when there are more than two terminals.
In general, it can be confirmed that, although, on the one hand, the limitations provided for by the above-mentioned standards afford the electrical devices the necessary safety, on the other hand, they do not facilitate the work of the operators who have to handle these devices for any reason, for example, for repair or maintenance operations on the electrical installations.
In this connection, it should be pointed out that, currently, as disclosed in the prior publications cited at the beginning of this description, it is possible to check the electrical connections of devices from outside the body without the need either to disassemble the connection temporarily or to use a suitable instrument (for example a tester).
The object of the present invention is to provide an electrical device such as that considered at the beginning which has improved structural and operational characteristics.
This object is achieved by a device defined in general in claim 1.
For a better understanding of further characteristics and the advantages achieved by the invention, a description of an embodiment thereof is given below by way of nonlimiting example, with the aid of the appended drawings.
In the latter, Figure 1 is an axonometric view of a device according to the invention, with parts disconnected, and Figures 2 and 3 are a side view and a rear view of the device of Figure 1, respectively, in an assembled condition.
In the aforementioned drawings, the device according to the invention is generally indicated 1 and is constituted by a normal light switch intended for a sectional structure, shown in broken outline in Figure 1.
The device has a hollow body 2 formed by a front portion 2a and a rear portion 2b coupled with one another in a box-like configuration; the front portion 2a is in front of the rear portion 2b when the device is fitted in the structure on a wall and has an opening 3 in which the active element 4 of the device, in this case constituted by the lever of the switch, is disposed.
The rear portion 2b of the body is made of transparent material which affords visual access to the interior of the body 2; more particularly, in the transparent rear portion 2b, there are terminals 6 for the electrical connection of the device and, in a position beside these, the rear portion 2b has a series of holes 8, 9 and 10. These represent respective holes for the passage of the ends (not shown in the drawings) of conductor wires ( holes 8a, 9a, 10a) and of screws ( holes 8b, 9b, 10b) for clamping these ends in the terminals; these holes are formed in projections 11 and 12 disposed on the rear of the body and having profiles matching those of the terminals. This provides a better view of the terminals from outside the body.
It is clear that, by virtue of its transparency, the rear portion 2b of the box-like body of the device enables an operator to make a direct visual check of the electrical elements housed in the body; this enables the state of the electrical connection of the device to be checked at any time.
Moreover, this check is made more effective simply by the fact that the terminals and the other components of the device inside the body can be illuminated from outside.
Finally, it should be underlined that the results referred to above are achieved without reducing the safety features of the device.
In fact, by virtue of the use of the transparent material to form the rear portion of the housing body, it has not been necessary to introduce structural alterations to the body of the device such as, for example, slots, grooves or the like, nor was it necessary to change the shape or size of the holes 8, 9, 10 which detail could have adverse effects as far as the prevailing standards are concerned.
Moreover, it hardly needs to be pointed out that plastics materials with electrically insulating properties such that the devices conform perfectly to the safety standards required for electrical applications, can be used to form the rear portion of the transparent body.
Finally, it should not be overlooked that the visual access to the interior of the devices also enables checks to be carried out at the production stage in order to check for any defects in the items produced.

Claims

An electrical device for sectional structures to be mounted on walls, comprising an active element (4) associated with a body (2) housing terminals (6) for the electrical connection of the device, the body comprising a front portion (2a) in which the active element (4) is situated so as to be accessible from outside when the structure is mounted on the wall, and a rear portion (2b) in which the terminals (6) are disposed and which has holes (8a, 9a, 10a) for the passage of conductors, the rear portion of the body being coupled to the front portion and being made of a transparent, electrically insulating, plastics material,
characterized in that the rear portion is shaped with projections (11, 12) having profiles matching the profiles of the terminals.
A device according to Claim 1, characterized in that the holes (8a, 9a, 10a) are formed in the corresponding projections (11, 12) of the rear portion (2b) of the body of the device.
A device according to claim 1 or 2, characterized in that further holes (8b, 9b, 10b) are formed in the projections (11, 12) for the passage of screws for clamping the conductors in the terminals (6).