GB2131632A - Electric plugs - Google Patents

Abstract

An electric plug is provided having contact pins 3, 4, 5 for cooperation with a main supply socket, and a plurality of sets of terminals 10-12 for wiring respective supply leads 15 to the plug. The live terminals 13 are connected to the live pin 5 through respective fuses 14 and/or a common fuse 9. <IMAGE>

Description

SPECIFICATION Electric plugs This invention relates to electric plugs, and in particular electric plugs of the kind which are attached to the electric leads of electrical appliances and are used for connecting the appliances to a mains supply system.

It is usual for the power supply circuit of a building to include a given number of outlet sockets installed at fixed locations. It is a common experience to find that the number of sockets ata particular location is insufficientforthe number of appliancesto be powered, especially when there area number of appliances which are normally used together, for examplethe separate units in a hi-fi system ora computer system. As a solution to this- problem there are known adaptors which plug into a socket and provide a plurality of outlets to receive respective plugs associated with different appliances.The adaptors are supported in asocket by the contact pins of the adaptor and it is often found that the adaptor becomes loosened underthe combined weight of the adaptor and the plugs it carries, with the result that the currentsupplycan be interrupted. In addition adaptors with several plugs can be unsightly. It is also known to provide an extension lead consisting of an electric cable having a plug attached at one endfor connection to a mains socket, and a socket assembly attached to the other end and providing a series, typically four socket outlets for receiving respective plugs associated with different appliances. This device can also be unsightly and can be a nuisance since the socket assembly is free to move around at the end of the cable.

The present invention seeks to provide a solution to the problem mentioned above and at the same time avoid the drawbacks of the known adaptors and extension leads. According to the invention this aim is achieved in an elegantly simple way by a plug comprising a body, a set of contact pins carried by the body for co-operation with a main supply socket, a plurality ofterminal sets supported in the body forthe connection of respective electric leads, each said set including a plurality ofterminals connected electrical ly to the respective contact pins and each adapted for securing a respective lead conductor thereto.

In a preferred embodiment one contact pin is connected with a terminal of each terminal set through a common fuse and a respective fuse.

Another embodimentwould include a common fuse only and would omit the individual outletfuses.

A plug according to the invention may be substan tialtylighter in weightthan an adaptor in combination with a number of individual plugs and will remain firmly supported by a socket. It can also be much neater in appearance.

Some plugs embodying the invention are described in more detail below with reference to the accompanying drawings, in which: Figure 1 is an end view of a first plug; Figure 2 is a schematic view ofthe plug with the cover removed; Figure 3 is a perspective view of the plug of Figures 1 and 2; and Figure 4 is a perspective view of a second plug.

The plug illustrated in Figures 1-3 of the drawings has a body of rectangular configuration formed buy a base 1 and a removable cover 2. Projecting through the base adjacent one end is a set of contact pins consisting of earth, neutral and live pins 3-5 shaped and arranged in conventional manner in accordance with the form of socket with which the plug is to be used.The inner ends of the pinsareconnectedto respective bus-bars 6-8 which extend along the base 1 in parallel with each other,the bus-bar 8 including a gap which is bridged bya mainfuse9. Spaced apart along the plug are foursets 10 ofterminals, each set including an earth terminal 11 connected to the busbar 6, a neutral terminal 12 connected to the bus-bar7, and a live terminal 13 connected to the bus-bar 8 through a respective secondaryfuse 1 4. Each terminal 11 -1 3 is equipped with means, such as a screw for clamping a cable conductor.The plug body defines a series of four cable entry openings 18 along one side andeach may be provided with a cable grip (notsltown) for clamping the cableto the body in well known manner.

In use the plug maybe usedfor one, two, three or four appliances each having its own power lead. Each cable 15 is inserted through a respective one of the entry openings 18 and has its conductors 16 connected in the proper sense to the corresponding set 10 ofterminals. In use each appliance is protected by its own fuse 14, and the main fuse 9 can ensure that the total current drawn by all the appliances does not exceed the rating ofthesupplycircuittowhichthey are connected. It will be appreciated thatthe fuse 14 will normally have a lower rating than the main fuse 9.

Many modifications are possible to the plug without departing from the scope of the invention. For example, number of cable outlets and the exact arrangement of the terminal sets, the connecting bus-bars and the cable entry openings are unimportans and may be varied as required. Although the plug is shown to be of the standard "square" pin type the invention is of course applicableto plugswith other pin shapes and arrangements. The contact pins may be located at either end or even at an intermediate position along the plug, as desired. In the plug illustrated in Figure 4 the contact pins 3-5 are disposed at a medial location along the base and are arranged so thatthe body will be oriented substantially vertically when the plug is fitted to a conventional socket.In addition the contact pins are carried by a part of the base which is recessed to define shoulders 20. These shoulders are adapted to engage the opposite edges ofthe fascia plate of the socket to assist in supporting the plug and, in particular, to resistanyturning moment applied to the plug.

If required the plug of the invention could include switches for controlling the supply of electric powerto the respective sets of terminals whereby individual appliances could be isolatedfrom the main supply although others remain connected to the supply.

Other modifications are also possible and will occur to skilled readers.

1. An electric plug for connecting electrical ap pliances to a mainssupply system, comprising a body,

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (9)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Electric plugs This invention relates to electric plugs, and in particular electric plugs of the kind which are attached to the electric leads of electrical appliances and are used for connecting the appliances to a mains supply system. It is usual for the power supply circuit of a building to include a given number of outlet sockets installed at fixed locations. It is a common experience to find that the number of sockets ata particular location is insufficientforthe number of appliancesto be powered, especially when there area number of appliances which are normally used together, for examplethe separate units in a hi-fi system ora computer system. As a solution to this- problem there are known adaptors which plug into a socket and provide a plurality of outlets to receive respective plugs associated with different appliances.The adaptors are supported in asocket by the contact pins of the adaptor and it is often found that the adaptor becomes loosened underthe combined weight of the adaptor and the plugs it carries, with the result that the currentsupplycan be interrupted. In addition adaptors with several plugs can be unsightly. It is also known to provide an extension lead consisting of an electric cable having a plug attached at one endfor connection to a mains socket, and a socket assembly attached to the other end and providing a series, typically four socket outlets for receiving respective plugs associated with different appliances. This device can also be unsightly and can be a nuisance since the socket assembly is free to move around at the end of the cable. The present invention seeks to provide a solution to the problem mentioned above and at the same time avoid the drawbacks of the known adaptors and extension leads. According to the invention this aim is achieved in an elegantly simple way by a plug comprising a body, a set of contact pins carried by the body for co-operation with a main supply socket, a plurality ofterminal sets supported in the body forthe connection of respective electric leads, each said set including a plurality ofterminals connected electrical ly to the respective contact pins and each adapted for securing a respective lead conductor thereto. In a preferred embodiment one contact pin is connected with a terminal of each terminal set through a common fuse and a respective fuse. Another embodimentwould include a common fuse only and would omit the individual outletfuses. A plug according to the invention may be substan tialtylighter in weightthan an adaptor in combination with a number of individual plugs and will remain firmly supported by a socket. It can also be much neater in appearance. Some plugs embodying the invention are described in more detail below with reference to the accompanying drawings, in which: Figure 1 is an end view of a first plug; Figure 2 is a schematic view ofthe plug with the cover removed; Figure 3 is a perspective view of the plug of Figures 1 and 2; and Figure 4 is a perspective view of a second plug. The plug illustrated in Figures 1-3 of the drawings has a body of rectangular configuration formed buy a base 1 and a removable cover 2. Projecting through the base adjacent one end is a set of contact pins consisting of earth, neutral and live pins 3-5 shaped and arranged in conventional manner in accordance with the form of socket with which the plug is to be used.The inner ends of the pinsareconnectedto respective bus-bars 6-8 which extend along the base 1 in parallel with each other,the bus-bar 8 including a gap which is bridged bya mainfuse9. Spaced apart along the plug are foursets 10 ofterminals, each set including an earth terminal 11 connected to the busbar 6, a neutral terminal 12 connected to the bus-bar7, and a live terminal 13 connected to the bus-bar 8 through a respective secondaryfuse 1 4. Each terminal 11 -1 3 is equipped with means, such as a screw for clamping a cable conductor.The plug body defines a series of four cable entry openings 18 along one side andeach may be provided with a cable grip (notsltown) for clamping the cableto the body in well known manner. In use the plug maybe usedfor one, two, three or four appliances each having its own power lead. Each cable 15 is inserted through a respective one of the entry openings 18 and has its conductors 16 connected in the proper sense to the corresponding set 10 ofterminals. In use each appliance is protected by its own fuse 14, and the main fuse 9 can ensure that the total current drawn by all the appliances does not exceed the rating ofthesupplycircuittowhichthey are connected. It will be appreciated thatthe fuse 14 will normally have a lower rating than the main fuse 9. Many modifications are possible to the plug without departing from the scope of the invention. For example, number of cable outlets and the exact arrangement of the terminal sets, the connecting bus-bars and the cable entry openings are unimportans and may be varied as required. Although the plug is shown to be of the standard "square" pin type the invention is of course applicableto plugswith other pin shapes and arrangements. The contact pins may be located at either end or even at an intermediate position along the plug, as desired. In the plug illustrated in Figure 4 the contact pins 3-5 are disposed at a medial location along the base and are arranged so thatthe body will be oriented substantially vertically when the plug is fitted to a conventional socket. In addition the contact pins are carried by a part of the base which is recessed to define shoulders 20. These shoulders are adapted to engage the opposite edges ofthe fascia plate of the socket to assist in supporting the plug and, in particular, to resistanyturning moment applied to the plug. If required the plug of the invention could include switches for controlling the supply of electric powerto the respective sets of terminals whereby individual appliances could be isolatedfrom the main supply although others remain connected to the supply. Other modifications are also possible and will occur to skilled readers. CLAIMS

1. An electric plug for connecting electrical ap pliances to a mainssupply system, comprising a body, a set of contact pins carried by the body for cooperation with a mains supply socket, a plurality of terminal sets supported in the bodyforthe connection of respective electric leads, each said set including a plurality of terminals connected electrically to the respective contact pins and each adapted for securing a respective lead conductor thereto.

2. An electric plug according to claim 1, wherein the body defines a plurality of cable entry openings each associated with a respective one ofsaidterminal sets.

3. An electricplug accordingtoclaim 1 or2, wherein one contact pin is connected with a terminal of each set through a common fuse.

4. An electric plug according to claim 1,2 or 3, wherein one contact pin is connected to a terminal of each set through a respectivefuse.

5. An electric plug according to any one of claims 1 to 4, wherein the body includes means arranged to engage the fascia plate of a supplysocketto assist in supporting the plug when fitted to the socket.

6. An electric plug according to claim 5, wherein said means comprises shoulders provided on the body to engage opposed peripheral edges of the socket fascia.

7. An electric plug according to any of claims 1 to 6 wherein the body is substantially rectangular and the contact pins are located at a medial position along the body.

8. An electric plug according to any one of the preceding claims, wherein one contact pin is con nected to a terminal of each set through a respective switch for selectively interrupting said connection.

9. An electric plug substantially as herein described with reference to the accompanying drawings.