GB2201306A

GB2201306A - Electrical plug terminals and cable clamp

Info

Publication number: GB2201306A
Application number: GB08803041A
Authority: GB
Inventors: Jeremy David Osborn Ranger
Original assignee: IDC PLUGS Ltd
Current assignee: IDC PLUGS Ltd
Priority date: 1987-02-21
Filing date: 1988-02-10
Publication date: 1988-08-24
Anticipated expiration: 2008-02-10
Also published as: GB8704084D0; GB2201306B; GB8803041D0; ZA881051B

Abstract

A electrical plug (1) includes: a base (3) carrying internal recesses (13) each incorporating an electrically conductive terminal connected to a respective terminal pin of the plug, the recesses (13) receiving the bare ends (17) of electric leads; and a cap (2) including internal protrusions (20) which mate, when the cap (2) is secured upon base (3), with respective recesses (13) whereby to hold the ends (17) of the electrical leads against the terminals. Arms (12) moulded with the base (3) provide a cable clamp. The entrance to each recess is provided with a notch to grip a respective lead. The plug body may be translucent so as to allow a neon lamp (36) to shine through it. <IMAGE>

Description

Improvements in or Relating to Electrical Plugs This inventions relates to electrical plugs. More particularly, although not exclusively, this invention relates to plugs of the kind commonly known as "13 amp plugs" (and hereinafter so referred to) intended for use with outlet sockets of "ring" electrical mains in domestic, commercial and light workshop environments.

Such plugs, usually having rectangular section pins for live, neutral and earth connection, are provided internally with a fuse connected in the live terminal of a current rating up to 13 amps.

Over the years very many designs of this form of 13 amp plug have evolved and been used.

It is an object of the present invention to provide an electrical plug of effective design and operation capable of convenient and straightforward assembly to wiring from a unit requiring a plug.

In accordance with one aspect of the present invention, there is provided an electrical plug having a lower body portion and a upper body portion, the lower body portion carrying internal recesses incorporating electrically conductive members or portions connecting to appropriate terminal pins of the plug, said recesses being adapted to receive the bare ends of electric leads, and the upper body portion including means for securing it upon the lower body portion and having internal protrusions adapted to mate, when the upper body portion is secured upon the lower body portion, with the internal recesses within the lower body portion whereby to hold the ends of the electrical leads against the electrically conducting members or portions for electrical connection to the terminals of the plug.

In one embodiment of the invention, the upper body portion may be connected to the lower body portion by means of a hinge-member, the protrusions from the upper portion engaging with the recesses in the lower portion on turning the upper portion about the hinge upon the lower portion so as to close the plug together. The hinge may be provided by a flexible plastics member. Screw-means may be provided for securing upper and lower portions firmly together.

In one embodiment of the present invention the plug is a 13 amp plug, the lower body portion including three internal recesses each carrying an electrical connecting member respectively linking with a live terminal, via a fuse, a neutral terminal and an earth terminal each protruding from the base of the lower body portion, and the upper body portion including three internal protrusions adapted, when the upper body portion is secured upon the lower body portion to mate with the internal recesses thereof whereby in use bared ends of live, neutral and earth leads disposed in the recesses are pressed into contact with the appropriate connecting members by the protrusions from the upper body portion.

The recesses in the lower body portion may be disposed side-by-side across the width of the lower body portion so that electrical cable can be provided with equal length bare wire ended leads for co-operation with the recesses.

The recesses may be comprised by or be provided with insulating insert channels colour-coded to match the standard colour-coding of leads from the incoming electrical cable for ease of recognition and avoidance of mistake in connecting the appropriate lead to the appropriate connecting member.

Means may be provided for gripping the bared ends of the leads and holding them in the recesses. Where insert channels are provided such means may comprise a portion thereof such as restricted width entrances thereto.

A fuse may be provided in the lower body portion of the plug and may be arranged for extraction from below the lower body portion, thereby avoiding the need to separate the upper body portio'n and the lower body portion.

Removal may be by means of a snap-out cover member, which may also serve as a holder for the fuse.

In another embodiment of the invention, the lower body portion is provided adjacent an entrance for an electrical cable, internal flaps moulded integrally therewith, inclined inwardly one on each side of the entrance and adapted to grip the incoming cable such that any attempt to pull the cable away from the lower body portion causes inner edges of the integral flaps to be urged together whereby to grip more tightly the cable and prevent its removal.

In accordance with yet another embodiment of the invention the electrical plug incorporates within it a recess holding a lamp, such as a neon lamp, connected between the live and neutral terminals thereof, the plug being made of a plastics material sufficiently translucent as to permit light from the lamp to glow through the body when the plug is connected to a live socket.

In a still further embodiment of the invention the plug is provided with at least some terminals mounted on plastic pegs moulded integrally with the base of the plug and extending therebelow.

In order that the invention may be more readily understood one embodiment thereof will now be described by way of example with reference to the accompanying drawings which illustrate one form of 13 amp plug in accordance with the invention and in which: Figure 1 is an over plan view of the lower body portion with the upper body portion removed of a 13 amp plug in accordance with the invention; Figure 2 is an underplan view of the upper body portion with the lower body portion removed of the plug of Figure 1; Figures 3 and 4 are side elevations of Figures 1 and 2 respectively; Figure 5 is a section on line V - V of Figure 1 with electrical leads included; Figure 6 is a perspective view from above of the plug of Figures 1 and 2 with the upper body portion hinged open from the lower body portion; and Figure 7 is a perspective view from below of the plug of Figures 1 and 2 with the fuse and fuse holder partly removed.

Referring now to the drawings it will be seen that the 13 amp plug 1 is basically comprised of an upper body portion 2 and a lower body portion 3 connected together by means of a hinge 4 of polypropylene material fitting within recesses 40, 41 within portions 2 and 3 respectively, the body portions of the plug being injection moulded from an appropriate thermoplastic material, such as a flame retardant material.

Depending from the lower body portion are the usual three rectangular section brass pins comprising a live terminal 5, a neutral terminal 6 and an earth terminal 7 respectively. As can be seen the earth terminal 7 is mounted within the lower body portion, whilst the live and neutral terminals 5 and 6 are mounted within and depend from downwardly extending insulating pegs 8 moulded integrally with the lower body portion 3.

The lower body portion 3 is provided with a side wall 9 which is broken to provide an entrance 11 at its front for insertion of an electrical cable 10. Within the entrance 11 are a pair of inwardly inclined flaps 12 one one each side thereof moulded integrally with the lower body portion 2 and adapted to hold firmly in place the electrical cable once passed therethrough. Thus the cable 10 on being passed into the lower body portion 3 will open out the flaps 12, but their internal inclination is such that any attempt to pull the cable out from the lower body portion again will urge the flaps to close so as to engage more tightly with the cable thereby preventing removal.

Located substantially in line across the lower body portion are three thermoplastic 'U' shaped members 13 adapted to receive the three standard colour-coded leads 14 from the cable 10. Located in the base of each colourcoded 'U' shaped member is a brass or phosphor bronze contact connected respectively with the neutral terminal 6 (via a connector strip 42), the earth terminal 7 and, via a fuse 16, the live terminal 5. In use, an electrical cable 10 laid into the lower body portion with its three leads 14 disposed within the appropriately colour-coded recess members 13 has its bare wire ends 17 disposed over the contacts 15 within the recesses, the recess members having narrow entrance slots 18 for the wire ends to assist holding them in place in the recesses.

It is to be noted that the fuse 16 of the 13 amp plug is located within the height of the lower body portion and is accessible from below the body portion, it being carried by a snap-in holder 19. By this means, the height of the plug can be kept to a minimum, since there is no extra height required for the fuse and its mountings.

In a similar manner it is to be noted that there is no screw-type connection of any form associated with the electrical lead connections into the plug lower body portion. This again assists in maintaining a low height to the lower body portion, and hence the totality of the 13 amp plug. Electrical contact between the bare ends of the leads and the connecting members within the lower body portion is ensured by pegs 20 carried by the upper body portion and depending inwardly thereof The pegs 20 are of such a length as to ensure that when the upper body portion 2 is turned upon the hinge 4 to lie with its side wall 21 mating with the corresponding side wall 9 of the lower body portion (by means of shoulder 39) the pegs 20 press into the recess members 13 of the lower body portion and press the ends of the leads disposed therein against the contacts 15 and hence into electrical connection with the three terminals of the plug.

Three locating pegs 22 also depend inwardly of the upper body portion 2 and fit within equivalent recesses 23 in the lower body portion 3 when the plug is closed.

The upper body portion 2 is provided with a cable entrance 24 in its side wall 21, downwardly extending protrusions 25 on each side of the entrance 24 being adapted to co-operate with the entrance 11 of the lower body portion to restrict the width of the cable entrance to the plug.

The upper body portion is also provided with two downwardly extending protrusions 26 and 27 adapted to cooperate with recesses 28 and 29 between corresponding upwardly extending protrusions 30 and 31 within the lower body portion to ensure separation, for safety reasons, of the three leads 14.

The outer side walls of both the lower and upper body portions are provided with recesses 32 to assist in manual handling of the plug.

Securement of the lower and upper body portions is by means of a screw 33 passing through a bore in the lower body portion from the base and engaging in a suitably threaded phosphor bronze bush 34 recessed into a downwardly extending protrusion 35 from the upper body portion.

A neon lamp 36 together with its associated appropriate resistor 37 is disposed within a recess 38 of the lower body portion and is connected electrically across the live and neutral terminals. The material of the plug is such that it is sufficiently translucent to transmit the glow when the neon lamp is on which is, therefore, a visual indicator of when the plug is connected across a live socket.

By means of the embodiment of the invention as herein illustrated, we have provided a compact, low profile 13 amp plug in which connection of the incoming cable leads is most simply done without need for any screwdriver or similar implement; the fuse may be replaced without separating the upper and lower body portions; colour coded channels are provided to ensure that the risk of misconnection of incoming leads is reduced to a minimum; an integrally moulded (and therefore never lost) incoming cable grip is provided at the entrance to the plug; a simple form of neon light glowing through the body of the plug is provided; and there is an inexpensive form of providing insulation on the live pins by means of mounting the pins within pegs moulded with the plugs.

Claims

CLAIMS:

1. An electrical plug having a lower body portion and a upper body portion, the lower body portion carrying internal recesses incorporating electrically conductive members or portions connecting to appropriate terminal pins of the plug, sad recesses being adapted to receive the bare ends of electric leads, and the upper body portion including means for securing it upon the lower body portion and having internal protrusions adapted to mate, when the upper body portion is secured upon the lower body portion, with the internal recesses within the lower body portion whereby to hold the ends of the electrical leads against the electrically conducting members or portions-for electrical connection to the terminals of the plug.

2. An electrical plug as claimed in Claim 1 wherein the upper body portion is connected to the lower body portion by means of a hinge-member, the protrusions from the upper portion being arranged for engagement with the recesses in the lower portion on turning the upper portion about the hinge so as to close the plug together.

3. An electrical plug as claimed in Claim 2 wherein the hinge is provided by a flexible plastics member.

4. An electrical plug as claimed in Claim 2 or 3 wherein screw-means are provided for securing upper and lower portions firmly together

5. An electrical plug as claimed in any one of the preceding claims wherein the plug is a 13 amp plug, the lower body portions including three internal recesses each carrying an electrical connecting member respectively linking with a live terminal a neutral terminal and an earth terminal, each terminal protruding from the base of the lower body portion; and the upper body portion including three internal protrusions for mating with the respective internal recesses whereby in uses bared ends of live, neutral and earth leads disposed in the recesses are pressed into contact with the appropriate connecting members.

6. An electrical plug as claimed in any one of the preceding claims wherein the recesses in the lower body portion are disposed side by side across the width of. the lower body portion.

7. An electrical plug as claimed in any one of the preceding claims wherein the recesses in the lower body portion are comprised by or provided with insert channels colour-coded to match standard colour-coding of leads from the incoming electrical cable.

8. An electrical plug as claimed in any one of the preceding claims including means for gripping, in use, bared ends of electrical leads and holding them in the recesses.

9. An electrical plug as claimed in Claim 8 wherein the gripping means comprises restricted width entrances to the recesses.

10. An electrical plug as claimed in any one of the preceding claims wherein a fuse is provided in the lower body portion of the plug arranged for extraction from below the lower body portion.

11. An electrical plug as claimed in Claim 10 wherein the fuse is carried by a holder which additionally acts as a snap-out cover member on the base of the lower body portion.

12. An electrical plug as claimed in any one of the preceding claims wherein the lower body portion is provided, adjacent an entrance for an electrical cable, with internal flaps moulded integrally therewith inclined inwardly one on each side of the entrance and adapted to grip the incoming cable.

13. An electrical plug as claimed in any one of the preceding claims wherein the lower body portion incorporates a recess holding a lamp connected between the live and neutral terminals thereof, the plug being made of a plastics material sufficiently translucent as to'permit light from the lamp to glow through the body when the plug is connected to a live socket.

14. An electrical plug as claimed in any one of the preceding claims wherein at least some terminal pins are mounted on plastic pegs moulded integrally with the base of the lower body portion and extending therebelow.

15. An electrical plug substantially as shown in and as hereinbefore described with reference to the accompanying drawings.