WO2008125813A1

WO2008125813A1 - Electrical connectors for power supply

Info

Publication number: WO2008125813A1
Application number: PCT/GB2008/001244
Authority: WO
Inventors: Emil Aminollah Baruch
Original assignee: Baruch Enterprises Ltd.
Priority date: 2007-04-11
Filing date: 2008-04-10
Publication date: 2008-10-23
Also published as: GB0706985D0; GB2457217A

Abstract

An electrical connector (10) for power supply, adapted to be connected in cascade (34) with one or more like connectors (10), comprises a housing (22) provided with a plug power port (12), a socket power port (14) and a cable power port (16), and circuit-protecting means (24) operated by switching means (28) and arranged to protect a cable-connected appliance (20) in a first mode (switching means (28) in position (30)) if the connector (20) is connected as the first one of a plurality of like connectors (10) connected in cascade (34) and in a second mode (switching means (28) in position (32)) if the connector (10) is connected as the second or a later one in such a cascade (34). The switching means (28) are operated by a spring-loaded probe (42) which is pressed into the housing by a normal wall socket surface plate (11) in position (30) and allowed to spring out by a recess (54) in the previous connector (10) in position (32) (or any other suitable proximity means or sensing device (42) may be used). One connector (10) is held physically to the next by a catch (72) of the former engaging a latch (74) of the latter, releasable by a button (80). As shown in Figure 16) each pin (12) and its socket (14) of a connector (10) can be mutually offset to enable the housing (22) to be thinner than the length of a pin (12).

Description

Title: ELECTRICAL CONNECTORS FOR POWER SUPPLY

FIELD OF THE INVENTION

This invention relates to electrical connectors for power supply.

BACKGROUND

Many electrical and household appliances are powered directly by the mains electricity, e.g. TVs, radios, computers, printers, and there are many others. Normally, in the UK, this power is obtained by a connection made via a 13A plug which is inserted into a wall-mounted socket. With the increasing number of such appliances, particularly in and around the home, office or kitchen, the need for extra mains sockets has increased tremendously. The costs associated with such wall sockets are very high and most people prefer instead to use one or more multi-outlet (multi- socket) extension cable connectors and to plug their appliances into sockets thereof, so that each appliance is connected through such a socket via the common cable of the extension cable connector to a common mains plug which is then plugged into the wall socket Such a connector can be awkward, be hazardous and/or use up too much space.

THE INVENTION

According to one aspect of the invention, there is provided an electrical connector for power supply, comprising a plug power port, a socket power port and a cable power port. The cable power port is not internal of the connector but is external, e.g. for connection thereto of a power-consuming appliance. The connector might have more than one cable power port. The cable port may comprise an actual cable connected to, or for connection to, e.g. a power- consuming appliance, or may comprise means for (non-plug-in) electrical connection thereto of a cable, e.g. terminals, e.g. of a sσew kind, or of a clamping kind e.g. that effect electrical connection when a cover portion of a housing (e.g. a clam-like housing) of the connector is closed.

According to another aspect of the invention, there is provided an electrical connector for power supply, comprising a housing provided with a plug power port, a socket power port and a cable power port.

In embodiments of the invention, the connector is adapted to be connected in cascade with one or more like connectors, as explained below.

Preferably, the connector comprises circuit-protecting means, which themselves preferably comprise circuit-breaking means, more preferably fuse means. The circuit-protecting means are preferably arranged to protect in a first mode if the connector is connected as the first one of a plurality of like connectors connected in cascade and in a second mode if the connector is connected as the second or a later one in such a cascade, and it may be that whether or not they are operable to select a said mode when this connector is plugged in they are not so operable when a succeeding connector is plugged into this connector. In a preferred involvement, the circuit-protecting means are normally in said second mode when this connector is not plugged in, and are operable to select said first mode when this connector is plugged in as a said first connector. For this purpose, the connector is preferably able to detect when it is the first one in a said cascade by detecting whether or not that into which it is plugged is a like connector, e.g. it detects that it is not plugged into a like connector if it is plugged into a flat wall-socket plate.

The connector preferably comprises ensuring means arranged to ensure that, if the connector is connected as the first one of a plurality of like said connectors connected in cascade and conditions at said cable port are such as to cause circuit-breaking by said circuit-protecting means, then this shall interrupt power supply to the remainder of the cascade. Such a first connect to thus acts as a master.

Further, the connector preferably comprises ensuring means arranged to ensure that, if the connector is connected as the second or a later one of a plurality of like said connectors connected in cascade and conditions at said cable port are such as to cause circuit-breaking by said circuit-protecting means, then this shall not interrupt power supply to the next connector down the cascade. Such a second or later connector thus acts as a slave.

Preferably, the circuit-protecting means are arranged to be switchable between a first position protecting both the socket port and the cable port and a second position protecting the cable port but not the socket port.

In particular embodiments, the circuit-protecting means may comprise circuit-breaking means interposed in the line connection between the plug and cable power ports, and switching means to connect either side of the circuit- breaking means to the line connection of the socket port The switching means may be arranged to connect the socket port line connection to the cable port side of the circuit-breaking means in said first mode and to the plug port side of the circuit-breaking means in said second mode.

The connector preferably has proximity means to enable sensing of whether the connector is plugged into a preceding like connector. The proximity means may comprise a sensing device to sense whether this connector is plugged into a preceding like connector and the connector also comprises an indicating device to indicate to a succeeding like connector that it is plugged into this connector. The said circuit-protecting means may be connected to be responsive to the proximity means, and possibly so as to be in said first position in said first mode and in said second position in said second mode.

It may be that the proximity means are mechanical and the circuit-protecting means are mechanically operable thereby to be responsive as aforesaid. Alternatively, the sensing means may utilise electrical proximity means, which may be light-operable, or take other forms as mentioned below.

Said sensing device preferably comprises a probe; more preferably, the plug port comprises electrical connecting pins and the probe is in the region of (e.g. arranged on a common face of the connector as) the pins. Preferably, the indicating device comprises a recess to accommodate without interference the probe of said succeeding like connector to indicate to that connector that it is plugged into this connector. The connector may comprise indicator means to indicate when the connector is plugged into a like connector and/or when the connector is not plugged into a like connector and/or when the connector is plugged into a connector not being a like connector. The connector may comprise indicator means to indicate which ports are protected by circuit- protecting means, e.g. the indicator means comprising means to light up adjacent each port (currently) protected.

Preferably, the said plug and socket ports are on opposite sides of the aforesaid housing. It may then be that the plug port comprises electrical connecting pins and the socket port comprises sockets for like pins, and corresponding said pins and sockets are in line.

Alternatively, the plug port comprises electrical connecting pins and the socket port comprises sockets for like pins, and corresponding said pins and sockets are offset. It may then be that the connector is thin enough to be penetrated completely through by at least one said pin of a like connector next down a cascade of like connectors and has recess means to accommodate such pin or pins projecting through such next connector from the next but one like connector down the cascade. Preferably, in that case, at least the power supply (e.g. line and neutral) pins have external root and end portions that are externally insulated.

Preferably, the connector, adapted to be connected in cascade with one or more like connectors, comprises releasable latch means whereby one such connector can be fastened to an adjacent said connector in said cascade. For example, said releasable latch means comprise a catch and a latch, and the connector comprises said latch on one side of the connector to catch the catch of the next preceding connector in said cascade and comprises said latch on its opposite side to be caught in the catch of the next succeeding connector in said cascade.

A connector embodying the invention will usually be provided in which the plug port comprises an earth pin and two electrical power (e.g. line and neutral) pins shorter than the earth pin, the socket port comprises an earth socket and two power (e.g. line and neutral) sockets, and there is a protective cover for the power sockets adapted to be moved away by initial insertion of the (longer) earth pin of a like connector into the earth socket. Preferably, the plug and socket ports are in accordance with an official standard specification, more preferably in accordance with British Standard 1363 relating to the 13-amp system.

The connector may have a said cable power port adapted for (non-plug-in) removable connection thereto of a cable, and/or may have, connected to a said cable power port, a cable and/or power-consuming appliance.

According to another aspect of the invention, there is provided a cascade of connectors, each embodying the invention. Preferably, the first of the connectors in the cascade is plugged into a power source, e.g. a wall socket. More preferably, the first connector has circuit-protecting means arranged to protect itself and the remainder of the cascade, and/or each of said connectors after the first one in the cascade has circuit-protecting means arranged to protect itself but none of the other said connectors in the cascade. In preferred embodiments, there is provided a said cascade in which the said circuit-protecting means are identical in all of the said connectors (though switched to different modes). According to another aspect of the invention, there is provided a wander plug and socket hybrid unit for mains supply.

Preferred embodiments of the invention aim to solve the problem of the disadvantages mentioned above by providing an alternative means to power multiple appliances via a mains wall socket, in a safe and secured way, other than using a common multi-outlet extension lead. The plug which is connected to the electrical appliance in this case will also act as a socket for another appliance to be plugged into it. As such, and by taking appropriate precautions, a chain or cascade of such plug and socket connectors can be connected to each other to give multiple use of a single wall socket in the same manner as an extension cable. By using these embodiments instead of an extension lead, the user gains an extra socket from the connector as it doubles up to power yet another appliance. A chain/cascade of such connectors can be formed to provide a multiple source of power for a range of appliances via one mains socket.

By using these embodiments, the cost of purchasing and installing a mains wall socket for each appliance is eliminated, as each such connector embodiment acts as a socket as well as a plug.

Another advantage over using a common extension lead is that in the case of the connector embodiment, the appliance can be re-wired from its regular 13A plug to a connector embodying the invention; therefore, it becomes a 2-in-1 unit: i.e. a socket and plug.

As indicated above, the first connector in a cascade thus acts as a master and each subsequent connector as a slave. The unplugged connector defaults to being a slave.

PARTICULAR DESCRIPTION RELATING TO THE DRAWINGS

Reference will now be made by way of example to the accompanying drawings, which:

Figure 1 is a perspective view of a prior art common multi-way extension lead and a wall socket therefore;

Figure 2 is a perspective view of a typical sequence of connectors embodying the invention showing how they will connect together to form a cascade that plugs into a wall socket, and comprises a master connector and slave connectors embodying the invention;

Figure 3 is a circuit diagram showing master and slave connection circuitry;

Figure 4 is schematic side view of a conventional wall socket, and a connector embodying the invention about to be plugged into the wall socket and act as a master;

Figure 5 is a view like Figure 4, showing an intermediate stage of the master being plugged into the wall socket, and a probe just about to be operated by the wall socket; Figure 6 is a view like Figure 5, showing the master plugged into the wall socket, and showing the probe pushed back into a recess in the connector being then fully operated by the wall socket;

Figure 7 is a view like Figure 6 showing the master fully plugged into the wall socket and a slave partly plugged into the master, and showing a probe of the slave just entering a recess in the master, thereby distinguishing (to the probe) the master from a conventional wall socket;

Figure 8 is a view like Figure 7 showing the master fully plugged into the wall socket and the slave fully plugged into the master;

Figure 9 is a partial vertical section through the wall socket and master at the intermediate stage shown in Figure 5, showing how the probe is about to actuate switching means of the master;

Figures 10-15 are various views (detailed below) showing the construction and operation of a latch mechanism for releasable fastening adjacent said connectors together; and

Figure 16 is a schematic side view of another embodiment of the invention, showing how housings of the connectors can be thinner than the lengths of their pins.

Referring to the drawings, Figure 1 shows a prior art multi-way mains extension lead 110 having several sockets 114 and a plug 112 that plugs into a wall socket 111.

The other Figures show embodiments of the invention. In the Figure 2 embodiment, an electrical connector 10 for making power supply connections comprises a plug power port 12 comprising pins 12, a socket power port 14 comprising socket holes 14, and a cable power port 16. Port 16 comprises an actual cable 18 connected to a power- consuming appliance 20. A housing 22 is provided with the plug power port 12, the socket power port 14 and the cable power port 16. The connector 10 is adapted, e.g., by its plug port 12 and its socket port 14 being on opposite sides of its housing 22, to be connected in cascade with one or more like connectors 10 as seen in Figures 2 and 16, as explained below.

Referring to Figure 3, the connector 10 comprises circuit-protecting means 24, comprising circuit-breaking means 26, more particularly fuse means 26, and switching means 28. The circuit-protecting means 24 are arranged to protect in a first mode (switching means 28 in position 30) if the connector 10 is connected as the first one of a plurality of like connectors 10 connected in cascade and in a second mode (switching means 28 in position 32) if the connector 10 is connected as the second or a later one in such a cascade 34.

The circuit-protecting means 24 of connector 10, whether or not operable to select a said mode when this connector 10 is plugged in, are not so operable when a succeeding connector 10 is plugged into this connector 10, as will be explained in relation to Figures 4 to 9 below. The circuit-protecting means 24 are normally in said second mode when this connector 10 is not plugged in, and are operable to select said first mode when this connector 10 is plugged in as a said first connector (master) 36. For this purpose, the connector 10 is able to detect when it is the first one in a said cascade 34 by detecting whether or not that into which it is plugged is a like connector 10, e.g. "not" if it is plugged into a flat wall-socket plate 11.

The connector 10 comprises ensuring means (comprising circuit-protecting means 24 and proximity means 42, 44 described below) arranged to ensure (hat, if the connector 10 is connected as the second (slave), e.g. 38, or a later one of a plurality of like said connectors 10 connected in cascade and conditions at said cable port 16 are such as to cause circuit-breaking by said circuit-protecting means 24, then this shall not interrupt power supply to the next connector, e.g. 40, down the cascade 34. The ensuring means 24, 42, 44 are also arranged to ensure that, if the connector 10 is connected as the first one 36 of a plurality of like said connectors 10 connected in cascade and conditions at said cable port 16 are such as to cause circuit-breaking by said circuit-protecting means 24, 42, 44, then this shall interrupt power supply to the remainder of the cascade 34.

The circuit-protecting means 24 are arranged to be switchable between a first position 30 protecting both the socket port 14 and the cable port 16 and a second position 32 protecting the cable port 16 but not the socket port 14. The circuit-protecting means 24 comprise circuit-breaking means 26 interposed in the line L (not neutral N or earth E) connection 46 between the plug (12) and cable (16) power ports, and switching means 28 to connect either side of the circuit-breaking means 26 to the line connection 48 of the socket port 14. The switching means 28 comprise a single pole double throw switch 28 arranged to connect the socket port line connection 48 to the cable port side 50 of the circuit-breaking means 26 in said first mode (30) and to the plug port side 52 of the circuit-breaking means 26 in said second mode (32).

The connector, e.g. 38, has proximity means 42, 44 to enable sensing of whether the connector 38 is plugged into a preceding like connector 36. The proximity means 42, 44 comprise a sensing device 42 to sense whether this connector 38 is plugged into a preceding like connector 36 and the connector 38 also comprises an indicating device 54 to indicate to a succeeding like connector 40 that it is plugged into this connector 38. Means 42, 44 of connector 38 co-operate with neighboring device 54 of the preceding connector 36. When the connector 10 is the first in the cascade 34, e.g. master 36, its sensing device 42 is actuated by e.g. the wall-plate 11, in the manner illustrated in the series of Figures 4 to 6, pushing sensing device into its housing 22 against spring means 44, and in turn operates switching means 28 as seen in Figure 9. (When connector 36 is withdrawn from wall-plate 11, spring means 44 pushes sensing device 42 back out to its original position seen in Figure 4.) When the connector 10 is a second or later one in the cascade 34, i.e. a slave, e.g. slave 38, sensing device 42 is unactuated by indicating device 54 when connector 38 is plugged into connector 36, as illustrated in Figures 7 and 8, thus leaving switching means 28 in position 32.

Thus, the circuit-protecting means 24 are connected to be responsive to the proximity means 42, 44, and are connected to be responsive to the proximity means 42, 44 so as to be in said first position 30 in said first mode and in said second position 32 in said second mode, and the proximity means 42, 44 are mechanical and the circuit- protecting means 24 are mechanically operable thereby, as seen in Figure 9, to be responsive as aforesaid. Said sensing device 42 comprises a probe 42 in the region of the pins 12, in fact arranged at the centre of the common face of (the housing 22 of) connector 10 as the pins 12, and said indicating device 54 of e.g. connector 36 comprises a recess 54 to accommodate without interference the probe 42 of said succeeding like connector 38 to indicate to that connector 38 that it is plugged into this connector 36. Probes 42 and indicating devices 54 are present in each connector 10 in the Figure 2 embodiment, but are not shown for the sake of clarity.

Connector 10 also comprises indicator means 56, e.g. comprising neon bulbs, lamps or LEDs 56, connected as shown in Figure 3 to indicate when fuse 26 has broken circuit, or connected by any suitable means (not shown but apparent to one skilled in the art) to indicate at least the position of switching means 28 and hence indicate when the connector is plugged into a like connector (position 32 and the line connection 50 live) and/or when the connector is not plugged into a like connector (e.g. being off when not plugged in and off when plugged in and the switching means 28 are in position 30) and/or when the connector is plugged into a connector not being a like connector (position 30). Similar indicator means 56 can indicate which ports 14, 16 are protected by circuit-protecting means 26, e.g. comprising means 56 arranged to light up adjacent each port 14, 16 (cuπrently) protected.

Since the said plug and socket ports 12, 14 are on opposite sides of the housing 22 and the plug port 12 comprises electrical connecting pins 12 and the socket port 14 comprises sockets 14 for like pins (12 of the next connector 10 down the cascade 34), corresponding said pins 12 and sockets 14 are in line, as seen clearly in Figures 2 and 4.

In an alternative embodiment, illustrated in Figure 16, the plug port electrical connecting pins 12 and their corresponding (line for line, neutral for neutral, earth for earth) socket port sockets 14 are offset. This allows the connectors 10 to be thin enough for one connector, e.g. 40, to be penetrated completely through by the said pins 12 of the like connector 41 next down the cascade 34 of like connectors 36, 38, 40, 42 and each connector, e.g. 38, has recess means 58 to accommodate such pins 12 projecting through such next connector 40 from the next but one like connector 42 down the cascade 34. To satisfy safety considerations due to the fact that pins 12 of the first slave connector 38 cannot completely penetrate master connector 36 (when this is plugged into wall-plate 11) and are partially exposed at root portion 60 and the pins 12 of the second slave connector 40 will then have their end portions 62 exposed beyond connector 38, the power supply (line and neutral) pins 12 have such external root and end portions 60, 62 externally insulated. In either position of a pin 12, i.e. as seen within connector 36 or within connector 38, electrical contact of the remaining, uninsulated portion 64 of the pin 12 within its accepting socket 14 is made possible because each pin 12 has a doubly cranked, springy, electrical contact blade 66 extending into that socket 14 in the two relevant positions.

In either embodiment, but shown only in the Figure 2 embodiment for clarity, the connector 10, adapted to be connected in cascade with one or more like connectors 10, comprises releasable latch means 70 whereby one such connector 10 can be fastened to an adjacent said connector 10 in said cascade 34. Said releasable latch means 70 comprise a catch 72 and a latch 74; and the connector, e.g. 38, comprises said latch 74 on one side (the upstream side) of the connector 38 to catch the catch 72 of the next preceding connector 36 in said cascade 34 and comprises said catch 72 on its opposite (downstream) side to be caught in the latch 74 of the next succeeding connector 40 in said cascade 34. The construction and action of catch 72 and latch 74 are shown in more detail in Figures 10-15, as follows.

Figure 10 is a schematic top view (schematically corresponding to a horizontal section through the line 10-10) and a corresponding side view and sectional end view of a catch 72 shown schematically in Figure 2;

Figure 11 is a schematic front view (schematically corresponding to a vertical section through the line 11 -11 ) and a corresponding bottom view of a latch 74 to engage the catch 72;

Figure 12 is a view like Figure 10 showing the catch 72 (seen in horizontal cross-section) engaged by the latch 74;

Figure 13 is a view like Figure 11 showing the latch 74 at the Figure 7 stage, before the catch 72 has approached it;

Figure 14 is a view like Figure 13 showing the catch 72 just before the Figure 8 stage, a chamfer 76 thereof having borne like a cam 76 against the internal shoulders 78 of the latch 74 to depress it against a spring 86;

Figure 15 is a view like Figure 14 showing the catch 72 at the Figure 8 stage, fully engaged by the latch 74, as shown in schematic top view in Figure 12.

Button 80 is depressed to depress latch 74 to release catch 72.

in each connector 10, the plug port 12 comprises an earth pin 12 and two electrical power (i.e. line and neutral) pins 12 shorter than the earth pin 12, and in each connector 10 and in the wall-plate 11, the socket port 14 comprises an earth socket 14 and two power (i.e. line and neutral) sockets 14, and there is a protective cover 68 for the power sockets 14 adapted to be moved away by initial insertion of the (longer) earth pin 12 of a connector 10 into each earth socket 12. In each connector 10, the plug and socket ports 12, 14 are in accordance with an official standard specification, in particular British Standard 1363 relating to the 13-amp system.

In the cascade 34 of connectors 10 each as described above, the first of the connectors 10 in the cascade 34 is plugged into a power source 11 , e.g. a wall socket 11 , the first connector 36 has circuit-protecting means 24 arranged to protect itself and the remainder of the cascade 34, each of said connectors 38 etc after the first one in the cascade 34 has circuit-protecting means 24 arranged to protect itself but none of the other said connectors 38 etc in the cascade 34, and the said circuit-protecting means 24 are identical in all of the said connectors 10, though switched to different modes in connector 36 and in connectors 38 etc.

The connector 10 may also have an electronic box 82 for monitoring, signaling onto the line L or out of the connector 10 (e.g. by radio or ultrasonic) or (connected as shown) to act as a current surge protector 82, e.g. a filter 82 for current or voltage spikes.

The maximum current is determined as follows: Ic = Chain (cascade) current

(lc)max = Maximum allowed chain current (which is 13A in the UK) from a wall socket

If Ic > (Ic) max then the master fuse 26 in the master connector 36 blows.

For the chain to operate:

Im + ∑lsx < (lc)max for x = 1 to n

Where:

Im - Master current

Isx = Slave current in the xth slave 38 etc n = Total number of slaves 38 etc

For safe operation, the maximum current in such a chain must be limited to 13A in the UK which equates to about 3000 watts of power in the chain arrangement 34. In other countries it could be other values.

In the case of the current limit being exceeded through the chain 34, the fuse 26 is blown to protect the chain 34. In this manner, the current in the chain is limited to the value of the fuse in the master connector 36. This feature safeguards all the fuses 26 in all the slave connectors 38 etc, as the fuse 26 in a slave 38 etc. in the chain 34 only protects the over current in the appliance 20 it is connected to.

Each connector 10 comes with a latch means 70, that hooks onto the next connector 10 connected to it; this will secure the chain 34 against inadvertent or accidental breaking or coming apart. There is a release button 80 to unlatch the relevant connectors 10 from one other. There is also a neon lamp power indicator 56. In a master connector 36, the neon lamp 56 indicates power in both the appliance 20 connected to the master 36 and the chain 34. In the slave connector 38 etc, the neon lamp 56 will indicate power only in the chain 34. The neon light 56 is on when there is power in the appliance 20 and the fuse 26 is intact. Switches 84 are for disconnecting the relevant individual appliances 20. The neon lamps 56 and these switches 84 are optional.

As described above, when a slave connector 10 is inserted into a wall mains socket 11 or any other connector not having the proximity feature, the probe is pushed mechanically as shown in Figure 6, activating the double-throw switch 28. Activation of this switch 28 can alternatively be done electronically by means of an LED and an optoelectronic sensor receiver which then activates a relay to initiate the changeover. However, the mechanical means comprising probe 42 is more favourable as it can be cheaper and safer. The activation can, in a farther alternative, be done magnetically using proximity switches, however, in this case the connector 10 would need to be defaulted to be a master 36, and use of a relay would also be necessary. These embodiments rely on a switching mechanism 28 to activate the master circuit mode 36 and there can be numerous means by which this activation is done, e.g.:

^■ In the case of the preferred embodiment by a mechanical means and a switch.

^■ Optically by means of a transmitter and a receiver.

^■ Magnetically using proximity switches.

• Electrically by means of a contact, where the presence or absence of a contact can activate the relay.

Note that it is the absence of a recess in the wall mount socket 11 that indicates to the connector 36 that it is being plugged into a "non-family member". The probe 42 is pushed in as it cannot find a said recess 54 in the wall socket 11. This action will consequently activate switch 28. When a second connector 38 is then plugged into the master connector 36, the master 36 has a recess 54 into which the probe 42 of slave 38 enters during the plugging-in action of the connector 38 into connector 36. Therefore, connector 38 being identical to the first connector 36, the probe 42 slides into the recess 54, inhibiting any inhibiting any action on the part of probe 42 to cause switching of switch 28 to take place, thus leaving the switch 28 in its default position 30 and its connector 38 remaining in its default slave mode.

For safety reasons, switch 28 is arranged to be in its neutral (default) position 30 or already in its final position 32 before the mains current can flow through the chain 34. In this way, sparking can be avoided and the switching of the mains supply through the chain 34 is not interrupted as the connector 10 is positioned as master connector 36 into the wall socket 11 , or as the next connector 38 etc is plugged into this one. The length of probe 42 in this case is critical to the extent that it is long enough to operate the switch 28 to change over from default slave, as 38, to master 36 before the live pin 12 of the plug port 12 touches the live socket 141 of the wall socket 11.

The changeover from slave to master could be manual, but is far better if automatic, as provided in the above- described embodiments, e.g. using probe 42.

Claims

1 An electrical connector for power supply, adapted to be connected in cascade with one or more like connectors, compπsmg a housing provided with a plug power port, a socket power port and a cable power port, and circuit-protecting means arranged to protect in a first mode if the connector is connected as the first one of a plurality of like connectors connected in cascade and in a second mode if the connector is connected as the second or a later one in such a cascade

2 A connector as claimed in claim 1 , in which the circuit-protecting means comprises circuit-breaking means

3 A connector as claimed in claim 2, in which the circuit-breaking means compnse fuse means

4 A connector as claimed in any one of claims 1 to 3, in which the circuit-protecting means whether or not operable to select a said mode when this connector is plugged in are not so operable when a succeeding connector is plugged into this connector

5 A connector as claimed in claim 4, in which the circuit-protecting means are normally in said second mode when this connector is not plugged in, and are operable to select said first mode when this connector is plugged in as a said first connector

6 A connector as claimed in any one of claims 1 to 5, comprising ensuπng means arranged to ensure that, if the connector is connected as the second or a later one of a plurality of like said connectors connected in cascade and conditions at said cable port are such as to cause circuit-breaking by said circuit-protecting means, then this shall not interrupt power supply to the next connector down the cascade

7 A connector as claimed in any one of claims 1 to 6, compπsing ensuπng means arranged to ensure that, if the connector is connected as the first one of a plurality of like said connectors connected in cascade and conditions at said cable port are such as to cause circuit-breaking by said circuit-protecting means, then this shall interrupt power supply to the remainder of the cascade

8 A connector as claimed in any one of claims 1 to 7, in which the circuit-protecting means are arranged to be switchable between a first position protecting both the socket port and the cable port and a second position protecting the cable port but not the socket port

9 A connector as claimed in any one of claims 1 to 8, in which the circuit-protecting means compnse circuit- breaking means interposed in the line connection between the plug and cable power ports, and switching means to connect either side of the circuit-breaking means to the line connection of the socket port

10 A connector as claimed in claim 9, in which the switching means are arranged to connect the socket port line connection to the cable port side of the αrcurt-breaking means in said first mode and to the plug port side of the circuit-breaking means in said second mode

11 A connector as claimed in any one of claims 1 to 10, having proximity means to enable sensing of whether the connector is plugged into a preceding like connector

12 A connector as claimed in claim 11, in which the proximity means compnse a sensing device to sense whether this connector is plugged into a preceding like connector and the connector also compnsing an indicating device to indicate to a succeeding like connector that it is plugged into this connector

13 A connector as claimed in claim 11 or 12, in which the circuit-protecting means are connected to be responsive to the proximity means

14. A connector as claimed in claim 11 or 12, when appending directly or indirectly to claim 8, in which the circuit-protecting means are connected to be responsive to the proximity means so as to be in said first position in said first mode and in said second position in said second mode.

15. A connector as claimed in any one of claims 11 to 14, in which the proximity means are mechanical and the circuit-protecting means are mechanically operable thereby to be responsive as aforesaid.

16. A connector as claimed in claim 15, when appending directly or indirectly to claim 12, in which said sensing device comprises a probe.

17. A connector as claimed in claim 16, in which the plug port comprises electrical connecting pins and the probe is in the region of (e.g. arranged on a common face of the connector as) the pins.

18. A connector as claimed in claim 16 or 17, in which the indicating device comprises a recess to accommodate without interference the probe of said succeeding like connector to indicate to that connector that it is plugged into this connector.

19. A connector as claimed in any one of claims 1 to 18, comprising indicator means to indicate when the connector is plugged into a like connector and/or when the connector is not plugged into a like connector and/or when the connector is plugged into a connector not being a like connector.

20. A connector as claimed in any one of claims 1 to 19, comprising indicator means to indicate which ports are protected by circuit-protecting means.

21. A connector as claimed in claim 19, in which the indicator means comprise means to light up adjacent each port (currently) protected.

22. A connector as claimed in any one of claims 0 to 21, in which the said plug and socket ports are on opposite sides of the housing.

23. A connector as claimed in claim 22, in which the plug port comprises electrical connecting pins and the socket port comprises sockets tor like pins, and corresponding said pins and sockets are in line.

24. A connector as claimed in claim 22, in which the plug port comprises electrical connecting pins and the socket port comprises sockets for like pins, and corresponding said pins and sockets are offset.

25. A connector as claimed in claim 24, which is thin enough to be penetrated completely through by at least one said pin of a like connector next down a cascade of like connectors and has recess means to accommodate such pin or pins projecting through such next connector from the next but one like connector down the cascade.

26. A connector as claimed in claim 25, in which at least the power supply (e.g. line and neutral) pins have external root and end portions that are externally insulated.

27. A connector as claimed in any one of claims 1 to 26, comprising releasable latch means whereby one such connector can be releasable fastened to an adjacent said connector in said cascade.

28. A connector as claimed in claim 27, in which said releasable latch means comprise a catch and a latch, and the connector comprises said latch on one side of the connector to catch the catch of the next preceding connector in said cascade and comprises said latch on its opposite side to be caught in the catch of the next succeeding connector in said cascade.

29. A connector as claimed in any one of claims 1 to 28, in which the plug port comprises an earth pin and two electrical power (e.g. line and neutral) pins shorter than the earth pin, the socket port comprises an earth socket and two power (e.g. line and neutral) sockets, and there is a protective cover for the power sockets adapted to be moved away by initial insertion of the (longer) earth pin of a like connector into the earth socket.

30. A connector as claimed in claim 29, in which the plug and socket ports are in accordance with an official Standard specification.

31. A connector as claimed in claim 30, in which the plug and socket ports are in accordance with British Standard 1363 relating to the 13-amp system.

32. An electrical connector for power supply, substantially according to any example hereinbefore described other than the Figure 1 arrangement.

33. An electrical connector for power supply, substantially according to any example hereinbefore described with reference to the accompanying drawings other than Figure 1.

34. A connector as claimed in any one of claims 1 to 33, having a cable power port and connected thereto a power-consuming appliance.

35. A cascade of connectors, each as claimed in any one of claims 1 to 34.

36. A cascade as claimed in claim 35, in which the first of the connectors in the cascade is plugged into a power source.

37. A cascade as claimed in claim 36, in which the first connector has circuit-protecting means arranged to protect itself and the remainder of the cascade.

38. A cascade as claimed in claim 36 or 37, in which each of said connectors after the first one in the cascade has circuit-protecting means arranged to protect itself but none of the other said connectors in the cascade.

39. A cascade as claimed in claim 38, in which the said circuit-protecting means are identical in all of the said connectors.

40. A cascade of electrical connectors for power supply, substantially according to any example hereinbefore described other than the Figure 1 arrangement.

41. A cascade of electrical connectors for power supply, substantially according to any example hereinbefore described with reference to the accompanying drawings other than Figure 1.