GB2161331A - Electric plugs - Google Patents

Abstract

To facilitate correct wiring of an electric plug the current carrying pins (L, N) are provided with differently coloured insulating sleeves (4, 5). The sleeves are preferably the same colour as the insulation of the respective cable conductors to be connected to the pins. <IMAGE>

Description

SPECIFICATION Electric plugs This invention concerns rewirable electric plugs for connecting electrical appliances to a mains electricity supply system. Such plugs normally comprise a body of insulating material, contact pins projecting from the body for cooperation with the contacts of an electric socket, and terminals housed in the body for connecting to the respective contact pins the conductors of a flexible cable leading to the appliance.

It is known to provide the current carrying pins of an electric plug with insulating sleeves which cover the portions of the pins protruding from the body. The sleeves reduce the risk of accidental electric shocks occuring due to a person handling the plug touching inadvertently the pins as the plug is pushed into or withdrawn from a socket.

To help ensure that an electric plug is correctly wired, it is common for appropriate symbols, such as "L" for live, "N" for neutral and "E" for earth to be provided adjacent the corresponding terminals within the body. These symbols are usually produced on the body during moulding and as a rule are not easy to see. Frequently, close inspection of the plug interior is needed to find and identify the symbols.

The present invention provides a particularly simple solution to this problem and resides in an electric plug having contact pins with insulating sleeves, wherein said sleeves are coloured differently to indicate the polarities or current phases of the respective pins.

An electric plug embodying the invention is described in detail below with reference being made to the accompanying drawing which shows the plug in perspective view.

The illustrated plug is for the most part of well known construction. It includes a hollow body of insulating material formed by a base 1 and a removable cover 2. As shown, the cover includes a cable entry 3. The base 1 carries the contact pins, namely a live pin L, a neutral pin N and an earth pin E. A cable grip (not shown) is provided on the base and accommodated within the body are terminals for connecting the cable conductors to the corresponding contact pins. The live pin L is preferably connected to its terminal through a fuse housed in the plug body.

The live and neutral pins are provided with insulating sleeves 4, 5 which cover the portions of these pins protruding from the body. In accordance with the present invention the sleeves 4, 5 have different colours. The colours preferably correspond to those normally used for the insulation of cable conductors, which at present in this country are brown for the live conductor and blue for the neutral conductor. Thus, the live pin L is fitted with a brown sleeve 4 and the neutral pin N is fitted with a blue sleeve 5. With the pins coded by the colours of their respective sleeves they are easily identifiable at a glance so that the risks of the plug being wired incorrectly are significantly reduced.In fact, the marking of the pins in this way is so prominent that is cannot go unnoticed, and a person is not required to take the deliberate step of inspecting the interior of the body for the symbols provided hitherto in order to determine the correct connections to make. In addition, with the pin sleeve colour being the same as that of the insulation of the conductor to be connected to that pin, it is not necessary to know the brown wire should be connected to the live pin and that the blue one should be connected to the neutral pin. It is only necessary to match the colours.

The sleeves 4, 5 may be applied to the pins L, N by any convenient method, e.g. by moulding them over the pins or heat-shrinking lengths of tube onto the pins.

While the invention has been specifically described in relation to a three pin plug with rectangular pins, it is to be understood that the inventive concept is equally applicable to other forms of electric plug, such as two pin plugs with pins of circular cross-section.

1. A rewirable electric plug comprising an insulating body, contact pins projecting from the body, terminals accommodated in the body for connecting respective cable conductors to the pins, and insulating sleeves of different colouring respectively covering the portions of at least two contact pins protruding from the plug body.

2. A rewirable electric plug according to claim 1,wherein each insulating sleeve is of the same colour as the insulation of the cable conductor to be connected electrically to the pin on which said sleeve is located.

3. A rewirable electric plug according to claim 2, wherein the contact pins include a live pin with a brown insulating sleeve, and a neutral pin with a blue insulating sleeve.

4. A rewirable electric plug substantially as herein described with reference to the accompanying drawings.

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

Claims (4)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Electric plugs This invention concerns rewirable electric plugs for connecting electrical appliances to a mains electricity supply system. Such plugs normally comprise a body of insulating material, contact pins projecting from the body for cooperation with the contacts of an electric socket, and terminals housed in the body for connecting to the respective contact pins the conductors of a flexible cable leading to the appliance. It is known to provide the current carrying pins of an electric plug with insulating sleeves which cover the portions of the pins protruding from the body. The sleeves reduce the risk of accidental electric shocks occuring due to a person handling the plug touching inadvertently the pins as the plug is pushed into or withdrawn from a socket. To help ensure that an electric plug is correctly wired, it is common for appropriate symbols, such as "L" for live, "N" for neutral and "E" for earth to be provided adjacent the corresponding terminals within the body. These symbols are usually produced on the body during moulding and as a rule are not easy to see. Frequently, close inspection of the plug interior is needed to find and identify the symbols. The present invention provides a particularly simple solution to this problem and resides in an electric plug having contact pins with insulating sleeves, wherein said sleeves are coloured differently to indicate the polarities or current phases of the respective pins. An electric plug embodying the invention is described in detail below with reference being made to the accompanying drawing which shows the plug in perspective view. The illustrated plug is for the most part of well known construction. It includes a hollow body of insulating material formed by a base 1 and a removable cover 2. As shown, the cover includes a cable entry 3. The base 1 carries the contact pins, namely a live pin L, a neutral pin N and an earth pin E. A cable grip (not shown) is provided on the base and accommodated within the body are terminals for connecting the cable conductors to the corresponding contact pins. The live pin L is preferably connected to its terminal through a fuse housed in the plug body. The live and neutral pins are provided with insulating sleeves 4, 5 which cover the portions of these pins protruding from the body. In accordance with the present invention the sleeves 4, 5 have different colours. The colours preferably correspond to those normally used for the insulation of cable conductors, which at present in this country are brown for the live conductor and blue for the neutral conductor. Thus, the live pin L is fitted with a brown sleeve 4 and the neutral pin N is fitted with a blue sleeve 5. With the pins coded by the colours of their respective sleeves they are easily identifiable at a glance so that the risks of the plug being wired incorrectly are significantly reduced.In fact, the marking of the pins in this way is so prominent that is cannot go unnoticed, and a person is not required to take the deliberate step of inspecting the interior of the body for the symbols provided hitherto in order to determine the correct connections to make. In addition, with the pin sleeve colour being the same as that of the insulation of the conductor to be connected to that pin, it is not necessary to know the brown wire should be connected to the live pin and that the blue one should be connected to the neutral pin. It is only necessary to match the colours. The sleeves 4, 5 may be applied to the pins L, N by any convenient method, e.g. by moulding them over the pins or heat-shrinking lengths of tube onto the pins. While the invention has been specifically described in relation to a three pin plug with rectangular pins, it is to be understood that the inventive concept is equally applicable to other forms of electric plug, such as two pin plugs with pins of circular cross-section. CLAIMS

1. A rewirable electric plug comprising an insulating body, contact pins projecting from the body, terminals accommodated in the body for connecting respective cable conductors to the pins, and insulating sleeves of different colouring respectively covering the portions of at least two contact pins protruding from the plug body.

2. A rewirable electric plug according to claim 1,wherein each insulating sleeve is of the same colour as the insulation of the cable conductor to be connected electrically to the pin on which said sleeve is located.

3. A rewirable electric plug according to claim 2, wherein the contact pins include a live pin with a brown insulating sleeve, and a neutral pin with a blue insulating sleeve.

4. A rewirable electric plug substantially as herein described with reference to the accompanying drawings.