This invention lies in the field f electrical appliances and electrical goods, in particular plugs, sometimes called wall plugs, as they are plugged into a plug socket in a wall. Such plugs are also plugged into plug sockets of extension cables or plug adapters.

BACKGROUND

For many years the experience of users has been that plugs fail, due to the often repeated pulling out and pushing back in of the plugs. The construction of the plugs that fail is that they have a base and a cover and the cover is gripped when a plug is pulled out. After many repetitions, or not many if the plug socket is tight, which sometimes happens, the cover comes away from the base, leaving the base in the plug socket. The plug socket may be live, due to a wall plug socket switch having been left on, or due to the plug being plugged into an extension cord of the type, which are common, which have no switch. This exposes the terminal posts of the plug pins and wiring, which are live and hence a serious danger of electrocution. Even for a person who is aware of this danger and careful the plug is then very difficult to pull out of the plug socket, without the plug base it is well nigh impossible to grasp the plug base safely, or at all, in order to pull it out. Many people resort to use of a screw driver or knife inserted between the plug base and plug socket, to lever the plug base out of the plug socket. If the plug socket is still live this is very dangerous, as the screw driver or knife may contact a live pin of the plug, again causing electrocution.

Plugs provided as original equipment with new appliances may be of the type in which the plug is an integral injection moulded body with the wiring entering the body and the plug pins projecting from the plug body. The invention is not applicable to this type of plug. Although there are different shapes and sizes of plugs and plug pin configurations, the purpose of the plug cover, in plugs that have them, is to allow connection of wiring to the plug pins, usually by connection to binding posts. The plug cover is removed to allow connection of the wiring to the binding posts and then replaced to protect against the danger of electrocution. The design principle of these plugs is thus that the plug base serves the function of mounting the plug pins and binding posts and the plug cover protects against electrocution and is removable to allow connection of wiring. The fault of these plugs arises because the plug cover is grasped to pull the plug out of a plug socket, due to the fact that the base is close up against the plug socket.

THE INVENTION

An electrical plug in accordance with this invention has a plug base, a plug cover, electrical pins for connection with a plug socket, binding means for connection of electrical wiring and is characterized in that the electrical pins are mounted in the plug cover.

The plug pins pass through holes in the plug base when the plug lid is connected to the plug base. It will be appreciate although, that the connection of the plug cover to the plug base is not subjected to the stress that the type of prior plugs described above are when the plug is pulled out of a plug socket.

The plug may be further characterized by its base being given features of shape that cause it to clamp wiring onto the binding means when the lid and base are connected. These features of shape may include an aperture through which the wiring enters the plug, passages which lead the wiring to the holes for the pins and springy parts of the holes which clamp the wire to the pins upon connecting the base and cover of the plug. The plug may be given clamps that hold wiring firmly in the plug at the aperture where the wiring enters the plug, once the base and cover are assembled together.

The binding posts may be conventional in that they have holes into which wiring is inserted and screws that clamp the wiring in the holes. The binding posts may often be an integral extension of the plug pins.

The plug pins may be given formations at a base area of the pins, which enhances a bond between the plug pin and the plug cover in which it is mounted. Thus the ends of the plug pins may be embedded in the plug cover, when the cover is injection moulded, and that end of the pin may be given an undercut, a slot, a spread panel, a projection or another shape that helps the bond.

The cover may be fastened to the base by means of a screw or screws, e.g. of the type that are currently used to join the base and cover and which give the trouble described above. This trouble does not arise with the present invention, for the reason given.

THE DRAWINGS

The invention is more fully described by way of the following description of preferred embodiments, in which : -

Figure 1 is a view of a plug from the rear, with base and lid partly separated for illustration purposes,

Figure 2 is a view of a plug from the side, with base and lid partly separated for illustration purposes,

Figure 3 is a view of the inside of the plug base of the plug shown in figure 1 , Figure 4 is a view of the inside of the cover of the plug shown in figure 1 ,

Figure 5 is a view of another plug, seen diagonally from the rear, with base and lid partly separated for illustration purposes,

Figure 6 is a view of the lid of the plug shown in figure 5,

And

Figure 7 is a view of the base of the plug shown in figure 5.

THE PREFERRED EMBODIMENTS

As shown in figures 1 to 4, an electrical plug 1 has a plug base 2, a plug cover 3, electrical pins 4, 5 and 6 for connection with a plug socket (not shown), binding means in the form of holes 7, 8 and 9 respectively and screws 10, 11 and 12 for connection of electrical wiring (not shown) and is characterized in that the electrical pins 4, 5 and 6 are mounted in the plug cover 3.

The plug pins 4, 5 and 6 pass through holes 13, 14 and 15 in the plug base when the plug lid is connected to the plug base.

The plug is given clamps 16 and 17 that hold wiring firmly in the plug at the aperture 18A -18B where the wiring enters the plug, once the base and cover are assembled together.

The ends of the plug pins are embedded in the plug cover when the cover is injection moulded and the embedded ends of the pins are given an undercut (not shown) that helps the bond between pin and cover.

Tests conducted on prototypes have shown that the pull-out force that is required to pull the pins out of the cover is larger than any that could be encountered in use. The cover is fastened to the base by means of screws 19 and 20, shown in the views of figures 2 to 4 screwed into posts 21 and 22 that are moulded integrally with the cover; to screw the cover to the base the screws are first passed through the holes 23 and 24 in the base and then screwed into the posts in the cover.

As shown in figures 5 to 7, the plug has the same features as have been described with reference to figures 1 to 4 and in addition the plug's base has features of shape that cause it to clamp wiring onto the pins when the lid and base are connected. After the wiring enters the plug through aperture 18B, passages 25 lead the wiring to grooves 26, 27 and 28 over which each wire passes and holes 29, 30 and 31 into which the bared (insulation stripped off) wire enters. The holes have a springy part 32, 33 and 34, which allows the diameter to open under force. When the pins enter the holes they engage with the wires and connect electrically with them, the springy parts of the holes yielding to the extent necessary and keeping a good pressure and hence good electrical contact. The pins enter the holes when the cover and base are brought together, this example shows a clip connector 35 for keeping the cover and base connected.