Electrical devices such as modular automatic breakers and the like generally have terminals operated by actuation screws which can be accessed through holes in which it is possible to insert the tip of a screwdriver or other tool.

Sometimes the device must not be tampered with by unauthorized personnel after installation; accordingly, it is necessary to apply seals capable of clearly indicating any tampering. So-called hole plugs are usually used for this purpose.

The aim of the present invention is to provide a plate to be applied to terminals of electrical devices in order to prevent access to the terminals and clearly indicate tampering therewith.

An object of the invention is to provide a plate which is cheap and simple from the point of view of production.

This aim, this object and others which will become apparent hereinafter are achieved by a tamper-proof plate for electrical terminals as claimed in the appended claim.

Further characteristics and advantages will become apparent from the description of the tamper-proof plate for electrical terminals, which is illustrated by way of non- limitative example in the accompanying drawings, wherein:

Fig. 1 is a perspective view of the tamper-proof plate according to the invention; Figs. 2, 3, and 4 are lateral elevation views, showing respectively the plate inserted in a terminal strip of an electrical device, during extraction, and fully extracted from the terminal strip of the electrical device.

With reference to the above figures, the tamper-proof plate according to the invention, generally designated by the reference numeral 1, includes a central portion 3 which is elastically hinged to a structural portion 5 and is advantageously formed monolithically and made of plastic, for example by molding.

The structural portion 5 includes two rings 7, each of which forms a hole whose dimensions are suitable for the insertion of a lead wire 11 or other similar device which can be used for security seals.

The pair of rings surrounds an interference member 9 which is rigidly coupled to the central portion 3, so that the presence of the wire 11 in the rings 7 prevents the interference member from entering the space 13 between the rings.

The operation of the tamper-proof plate is very simple and is evident from the figures. The tamper-proof plate 1 can be inserted in a seat 15 of an electrical device 17, for example at the access holes 19 of terminals 21. The tamper-

proof plate 1 is inserted in the seat 15 by elastically moving the portion 3 as shown in Fig. 3. When the plate 1 is fully inserted, the central portion 3 elastically returns to its natural inclined position and the edges 23 of the central portion abut against the abutment 25 of the seat 15, making it impossible to extract the plate without elastically deforming the central portion. When the plate is inserted in the seat, as shown in Fig. 2, it is possible to insert the lead wire 11 in the rings 7.

In practice it has been found that the invention achieves the intended aim and objects.

The materials used, as well as the dimensions, may of course be any according to the requirements and the state of the art.

Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly, such reference signs do not have any limiting effect on the scope of each element identified by way of example by such reference signs.