GB2256323A - Electrical trailing socket with switches - Google Patents

Abstract

A multi-outlet electrical trailing socket 1 has an individual switch 19 for each of its socket outlets. The switches are mounted in compartments separate from those in which the socket contacts are mounted (fig 2). Each switch comprises a rocker (59) actuating a switch in the live circuit (fig 5). <IMAGE>

Description

Electrical Trailing Socket This invention relates to electrical trailing sockets, that is to say self-contained units which are intended to be connected to one end of a flexible electrical lead, the other end of which will be connected to a supply of electricity, normally at mains voltage such as 110 or 240 Volts, for example by means of a plug to be connected to a standard wall mounted socket. The invention will be described in relation to square pin three pin plugs and sockets but it will be apparent that it can be applied to plugs and sockets of other configurations. Such trailing sockets, which normally have at least three individual outlets have various functions. One is to increase the number of outlets provided by a single fixed socket. The trailing socket thus provides a means of connecting a number of electrical appliances safely to a single wall socket outlet.A further purpose is to reposition thë point at which an electrical supply is available without the need for permanently rewiring and reinstalling a wall mounted socket. This is particularly useful where the wall mounted socket is not easily accessible.

According to the present invention, in a trailing multi-outlet electrical socket at least one of the socket outlets has an individual switch. Preferably there are at least three socket outlets and preferably each of the socket outlets is provided with an individual switch.

The normal trailing socket has no switch means so that switching can only be achieved either at the wall mounted socket if such socket has a switch, and as pointed out above the socket may be inaccessible, or by the switches on the individual pieces of apparatus which are connected to the trailing socket; however such pieces of apparatus do not always have switch means or such switch means may be inconvenient. By means of the present invention each individual piece of electrical apparatus may be switched on and off conveniently at the trailing socket.

Preferably the trailing socket will be substantially totally enclosed except for a port through which a flexible electrical lead can pass and the socket openings to receive the pins on the plugs.

In general no means will be provided for fastening (or permanently and immovably fastening) the trailing socket to a supporting surface as is the case with wall mounted sockets.

Preferably the trailing socket is divided into two compartments, the first of which contains terminals for connection to a flexible lead and the second of whizz contains the sockets themselves and the individual switches.

The invention may be carried into practice in various ways and one trailing socket embodying the invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a perspective view showing the trailing socket with the cover to the terminal compartment removed; Figure 2 is a front view with the cover to the terminal compartment and the cover to the socket/switch compartment removed; Figure 3 is a partial front view with the main body shown in outline and showing the construction of the socket shrouds; Figure 4 is a scrap section on line II-II of Figure 3; Figure 5 is a section or line V-V of Figure 2; and Figure 6 is an exploded view of the main parts of the switch shown in Figure 5.

The trailing socket 1 shown in the drawings comprises a base moulding 2, a terminal compartment 3 with a cover 3a and a socket and switch compartment 4 with a cover 4a. The socket and switch compartment cover 4a is secured to the base moulding 2 by means of three screws which pass through holes 5 in the base moulding into threaded wells in posts depending from the underside of the cover 4a while the terminal compartment cover 3a is secured by similar screws extending through holes 6 in the base moulding into posts in the cover 3a and by hooks 7 which engage under ledges, not shown, on the underside of the cover 4a.

It will be seen from Figure 1 that the end of the cover 4a adjacent the terminal compartment has a wall 8 and this provides a rebate 9, the inner surface of the cover 3a being formed with a complimentary rebate so that the break line between the two covers does not provide a straight line of access to the interior of the socket.

Referring now to Figure 2, it will be seen that mounted on the base moulding 2 are the connectors and switches relating to three sockets A, B and C. Since the three sockets are substantially identical only socket A will be described. Socket A has connectors to receive the three pins of a plug, namely an earth connector 10A, a live connector llA and a neutral connector 12A. Each connector is formed of copper sheet folded into a generally U-shape with the outer ends of the limbs turned outwards to provide a resilient mouth. The earth connector 10A has a lateral tab 13A which is folded over an earth bus 14 which connects the earth connectors of the three sockets to a terminal 15 in the terminal compartment. This is provided with the usual aperture and grub screw for retaining one end of a conductor of the flexible lead, not shown.The neutral connector 12A is connected to a neutral bus 16 by the bus passing between the limbs of the U-shaped connector. The bus 16 extends to a terminal 17 in the terminal compartment for connection to a conductor of the flexible lead. The live connector IlA can be connected to a live bus 18 through a switch 19A to be described below, the connector IlA being connected to the switch 19A by a bridge 21 having a downwardly turned tab 22 which extends between the two limbs of the connector llA. The live bus 18 extends to a terminal 23 for connection to a conductor of the flexible electric lead.

The earth and neutral buses 14 and 16 are made of brass strip which are seen edge-on in Figure 2, the bus 14 being notched at 24 to provide adequate separation from the bridge 21 which is also made of brass strip and is seen flat on in Figure 2. The live bus 18 is of copper strip and is seen flat-on in Figure 2.

Each of the sockets A, B and C is provided with a shroud 31 details of the construction of which are shown in Figures 3 and 4. Each shroud 31 comprises a T-shaped moulded element 32 which is mounted to slide within walls moulded to the underside of the socket compartment cover 4a, the element being biased towards the shrouding position shown on the left of Figure 3 by a spring 34 which is located in a trough in the element and extends between one end of this trough and a post 35 which is moulded on and depends from the underside of the socket compartment cover 4a. The free end of the stem of the T is formed as a ramp and is, when no plug is in place, in line with the aperture to receive the earth pin of a plug while the two side limbs of the T cover the live and neutral apertures.When the earth pin of a plug is initially entered into the earth pin aperture the pin will engage the ramp and will move the shroud element 32 in the direction of the arrow 37 in Figure 3 against the bias of the spring 34 to uncover the neutral and live apertures and allow the plug to be pushed home. On removal of the plug, the spring 34 will cause the shroud element 32 to move in the direction of the arrow 38 to again cover the pin apertures.

The construction of the switch 19A can be seen in Figures 5 and 6. The switch has a lower body portion 51 which is in the form of a well and is moulded integrally with the base moulding 2 and an upper body portion 52 which is in the form of an inverted cup and is secured to the lower body portion by screws extending through lugs 53 into tapped holes in the lower body portion. The lower body portion includes a trough 54 into which extends a lug 55 projecting from one side of the live bus 18. The lug is T-shaped in plan and L-shaped in section, the limbs of the T sitting in notches in the sides of the trough. Resting see-saw fashion on the edge of the upturned end of the lug is a rocker connector 56 having lateral lugs 57 which are received in the notches 55.The underside of the rocker in way of the lugs is silvered to provide a good electrical connection between the underside of the rocker and the edge of the upturned end of the lug 53 on which the rocker pivots. One free end of the rocker carries a silvered button 58 which is vertically aligned with a silvered button 59 on the end of the connector 21. Trapped within the upper body portion 52 of the switch housing and projecting through a clot 60 in its upper wall is a dolly 59 on each side of which there is a drop-shaped projection 61 the upper end of which forms a knife edge which engages the top of an inverted V-shaped depression 62 in the inside of the side wall of the upper body portion 52 of the switch.

A central boss 63 projecting downwards from the major body portion of the rocker 59 is moulded with a blind bore to slidably receive a plunger 64 which is biased outwardly of the bore by a coil spring 65; the spring extends between the bottom of the blind core and a collar 66 on the plunger.

Figure 5 shows the switch in the open condition-.

If the dolly 59 is rotated by depressing the left hand end of the dolly as seen in Figure 5, the lower end of the plunger 64 which is pressed against the rocker 56 moves to the right as seen in Figure 5 and when it moves beyond the upturned end of the lug 55 the rocker changes position from that shown to a position in which the right hand end of the rocker is down and the left hand is up thus bringing the button 58 into contact with the button 59 and making the contact to provide a path between the live bus 18 and the connector llA.

Although it is not intended that the trailing socket should be permanently attached to a surface, means are provided for its temporary location, these means consisting of keyhole apertures 71,72 extending through the bottom wall of the base moulding 2, these apertures being surrounded by an upwardly extending peripheral wall 73 to prevent access to live parts within the socket compartment through the keyhole apertures. The keyhole apertures can loosely receive the heads of screws screwed into a surface with the heads proud. Penetration of the screw heads through the apertures beyond a predetermined distance is prevented by stops 74 moulded on the upper body portions 52 of the switches.

A neon indicator bulb 81 is connected between the live and neutral buses. This lamp will glow when the socket is connected across the mains and is visible through a red window 82 in the socket compartment cover.

Claims (10)

1. A trailing multi-outlet electrical socket in which at least one of the socket outlets has an individual switch.

2. A socket as claimed in Claim 1 which includes at least three socket outlets.

3. A socket as claimed in Claim 1 or Claim 2 in which each of the socket outlets has an individual switch.

4. A socket as claimed in any one of the preceding claims which is substantially totally enclosed except for a port through which a flexible electrical lead can pass and the socket openings to receive the pins on the plugs.

5. A socket as claimed in any one of the preceding claims which includes no means for permanently and immovably fastening the trailing socket to a supporting surface.

6. A socket as claimed in any of the preceding claims which is divided into two compartments, the first of which contains terminals for connection to a flexible lead and the second of which contains the sockets themselves and the individual switches.

7. A socket as claimed in any one of the preceding claims for use with three pin plugs which includes a neutral bus, an earth bus and a live bus and individual switches for connecting the live bus to the live connector of each plug receiving socket.

8. A socket as claimed in Claim 7 in which the earth bus extends between the neutral bus and the live bus, the individual switches are located on the side of the earth bus remote from the neutral bus and there are bridging connectors extending from the switches to the live connectors of each of the pin receiving sockets.

9. A socket as claimed in any of the preceding claims in which the or each of the switches comprises a see-saw connector of conductive material, a rocking switch dolly and a spring-loaded plunger member located between the rocking dolly and the see-saw member.

10. A trailing multi-outlet electrical socket substantially as described herein with reference to the accompanying drawings.