Abstract:
A control system for controlling the supply of electrical power to an apparatus, the system comprising a supply control device and a remote control, the supply control device comprising a power input, a power output, a control data input and a controller, the power input being arranged to receive electrical power from a supply, the power output being arranged to output electrical power to the apparatus, the control data input being arranged to receive control data from the remote control, wherein the controller is arranged to control the flow of electricity from the input to the output, the controller is further arranged to detect disconnection of the device from the apparatus or the power supply, and to send a signal to the remote control, and the remote control is arranged to respond to receipt of the signal by producing a warning arranged to notify a user of the disconnection.

Description:
FIELD OF INVENTION  
       [0001]     This invention relates to an electricity supply control device and a method of electricity supply control. More particularly, but not exclusively, it relates to a programmable device, and method, for controlling an electricity supply, that utilizes PIN code control to regulate electricity supplied to apparatus, for example a personal computer (PC) or a games console.  
       BACKGROUND  
       [0002]     The control and regulation of a voltage supply of apparatus, for example a PC, games console or television, is important where a child is using the apparatus away from parental supervision, particularly in regard of controlling unsupervised access to the Internet.  
         [0003]     Plugs and timers that plug directly into wall sockets are known. Timers typically include either an analogue or digital timer device that is mounted in a wall socket, and which receives a standard plug from the apparatus. A user of the timer sets a start and finish time. The timer acts as a switch, allowing electricity to be supplied to the apparatus from the start time to the finish time and then preventing the supply of electricity.  
         [0004]     Such a timer has a number of disadvantages associated with it. For example, the timer is easily circumvented by merely removing the timer from the socket and inserting the plug directly into the socket. Also, a user can readily alter, or override, the start and finish time associated with the timer. These disadvantages makes these known prior art timers unsuitable for controlling electricity supply where third party, for example parental or management, control of the apparatus is desired.  
       SUMMARY OF THE INVENTION  
       [0005]     According to a first aspect of the present invention there is provided an electricity supply control device comprising an input, an output, control data input means and processing means, the input being arranged to receive electricity from a supply, the output being arranged to selectively output electricity to an apparatus, the control data input means being arranged to receive control data, the processing means being arranged to control the flow of electricity from the input to the output dependent upon verification of user identification data, which comprises at least part of the control data, by the processing means.  
         [0006]     This control device has the advantage over prior art devices that the use of user identification data allows a user, for example a parent, to restrict access to the apparatus by securely controlling the flow of electricity to the device.  
         [0007]     The control data input means may comprise a keypad, which may comprise part of the device. The control data input means may comprise an infra-red or radio receiver, or transceiver, arranged to receive a control signal from a remote control, typically comprising a keypad. The device may be arranged to receive an encrypted control data signal from the remote control, and the processing means may be arranged to decrypt the encrypted control data signal. The remote control may be used for controlling a number of the devices independently, for example by transmitting a user identification data that is specific to a given device.  
         [0008]     The control data input means may be arranged to transmit status data to the remote control. The status data may relate to any one, or combination, of the following: whether the device is operating in timed or constant mode, time remaining for the supply of electricity to the apparatus when the device is operating in timed mode, status of the supply.  
         [0009]     The use of a remote control allows the setting of the device by a user who is not necessarily in the same room as the device. The use of a remote control also increases the utility of the device, as sockets are often located close to ground level, in awkward places such as under desks or beds. Thus, the remote control allows a user to set the device without having to crawl under, for example, a desk to set the device.  
         [0010]     The device may comprise a display. The display may comprise a liquid crystal display (LCD). The display may be arranged to display the status of the flow of electricity through the device. The display mat be arranged to display the time remaining before the supply of electricity to the apparatus is prevented.  
         [0011]     The user identification data when received by the device may comprise a numeric code, or an alphanumeric code. Typically, the code will comprise a four digit numeric code. The processing means may be arranged to prevent access to the device until recognized user identification data is entered at the control data input means.  
         [0012]     The control data when received at the device may comprise a start time and a finish time that define a time period during which electricity is to be supplied to the apparatus.  
         [0013]     The device may comprise a switching element arranged to control the flow of electricity through the device in response to a signal from the processing means. The processing means and/or the control data input means may be at least partially electrically screened from the switching means.  
         [0014]     The screening of the switching means results in electromagnetic spikes generated on the execution of a switching operation not interfering with the operation of the processing means and/or the control data input means.  
         [0015]     The device may comprise audio output means. The audio output means may comprise a speaker. The audio output means may be arranged to output an audible signal upon the data input means receiving the control data. The audio output means may be arranged to output an audible signal a predetermined time interval prior to the device preventing the flow of electricity to the apparatus. The time interval may be any one, or combination, of the following: 10 minutes, 5 minutes, 1 minute, 30 seconds, 10 seconds. The device may be arranged to execute an automatic shutdown of an apparatus of which the device comprises a part.  
         [0016]     An audible warning prior to the device stopping the flow of electricity to the apparatus allows a user of the apparatus to make suitable preparations for a controlled shut down of the apparatus in order to prevent the loss of data. For example, applications upon a PC can be shut down and data saved. Similarly in the case of a games console a game can be saved at whatever stage a player has attained.  
         [0017]     The device may have visual indicator means arranged to indicate that either, the device is receiving electricity from the supply, or that the device is operating in a programmed timer mode or both.  
         [0018]     The device may comprise an internal power supply, for example a battery, which may be rechargeable, and which may recharge directly from the supply. Alternatively, or additionally, the device may be arranged to receive power from the supply, typically via a transformer.  
         [0019]     According to a second aspect of the present invention there is provided a method of controlling the supply of electricity to an apparatus comprising the steps of: entering user identification data at a data entry means; validating said user identification data at processing means; and allowing electricity to be supplied to an apparatus should said user identification data be successfully validated at step ii).  
         [0020]     The method may comprise entering a time period over which electricity is to be supplied at the data input means and supplying electricity to the apparats during said time period should said user identification be successfully validated at step (ii). The method may comprise preventing the supply of electricity to the apparatus one the time period has expired.  
         [0021]     The method may comprise providing the data input means as a remote control which is remote from means for validating the user identification.  
         [0022]     The method may comprise displaying the status of the flow of electricity upon either, or both, of the remote control or/and the means for validating the user identification.  
         [0023]     The method may comprise outputting an audible warning a pre-determined amount of time prior to the end of the time period.  
         [0024]     According to third aspect of the present invention there is provided a remote control suitable for use with a device according to the first aspect of the present invention.  
         [0025]     The remote control may comprise a transceiver arranged to communicate with the device.  
         [0026]     The remote control may comprise an audio output means arranged to output an audible signal in response to status data received from the device. The remote control may comprise a display means arranged to display a symbol indicative of status data received from the device.  
         [0027]     According to a fourth aspect of the present invention there is provided a plug comprising a device according to the first aspect of the present invention.  
         [0028]     According to a fifth aspect of the present invention there is provided electrical apparatus comprising a device according to the first aspect of the present invention.  
         [0029]     The electrical apparatus may comprise any one, or combination, of the following: television, PC, games console, compact disc (CD) player, digital versatile disc (DVD) player, video cassette recorder (VCR), electric fire, photocopier, fax machine or any other suitable electrical apparatus.  
         [0030]     According to a sixth aspect of the present invention there is provided an electrical adapter comprising a device according to the first aspect of the present invention.  
         [0031]     The adapter may comprise a current monitoring means in communication with the processing means. The processing means may be arranged to generate a notification signal which can be transmitted to a remote control if the current monitoring means detects an interruption in electricity supply through the adapter.  
         [0032]     The adapter may comprise a voltage monitoring means in communication with the processing means. The processing means may be arranged to generate a notification signal which can be transmitted to a remote control if the voltage monitoring means detects an interruption in electricity supply through the adapter.  
         [0033]     The adapter may comprise a switching circuit in communication with the processing means. The processing means may be arranged to generate a notification signal which can be transmitted to a remote control if the switching circuit is open detects an interruption in electricity supply through the adapter. The switching circuit may comprise at least one biased contact associated with a cover of a socket opening. 
     
    
     DESCRIPTION OF THE DRAWINGS  
       [0034]     The invention will now be described, by way of example only, with reference to the accompanying drawings in which:  
         [0035]      FIG. 1  is a schematic representation of a device and a remote control according to an embodiment of the present invention;  
         [0036]      FIG. 2  is a schematic circuit diagram of an embodiment of a device according to at least an aspect of the present invention;  
         [0037]      FIG. 3  is a schematic circuit diagram of a remote control according to at least an aspect of the present invention;  
         [0038]      FIG. 4  is a schematic representation of a second embodiment of a device according to at least an aspect of the present invention;  
         [0039]      FIG. 5  is a representation of a games console comprising a device according to at least an aspect of the present invention;  
         [0040]      FIG. 6  is a flow chart detailing a method of controlling the supply of electricity to an apparatus according to an embodiment of the present invention;  
         [0041]      FIG. 7  is a schematic representation of an electrical adapter comprising an embodiment of the present invention;  
         [0042]      FIG. 8  is a schematic representation of an electrical adapter comprising a further embodiment of the present invention;  
         [0043]      FIG. 9  is a schematic representation of an electrical adapter comprising a further embodiment of the present invention; and  
         [0044]      FIG. 10  is a schematic representation of a connector according to a further embodiment of the invention. 
     
    
     DETAILED DESCRIPTION  
       [0045]     Referring now to FIGS.  1  to  3 , a timer device  100  comprises a mains electricity input  102 , a mains electricity output  104 , and control circuitry  106 . The electricity input  102  typically takes the form of a plug bayonet and the electricity output  104  typically takes the form of a plug socket.  
         [0046]     The control circuitry  106  comprises a power supply unit  108  arranged to draw power from the electricity input  102 , a transceiver  110 , a microcontroller  112 , a triac  114 , two light emitting diode (LED) indicators  115 ,  116 , an audio enable/disable switch  117  and an audio loudspeaker  118 , typically a piezoelectric.  
         [0047]     The power supply unit  108  draws power from the electricity input  102  and feeds the remainder of the control circuitry  106 . The transceiver  110  is arranged to communicate with a remote control  120 , to be described in detail hereinafter. The transceiver  110  typically operates at a frequency of 433 MHz, or thereabouts. It is envisaged that in some embodiments the transceiver may operate at infra-red wavelengths.  
         [0048]     The LED indicator  115  is lit as long as the power supply unit  108  supplies power to the microcontroller  112 . The switch  117  is used to enable and disable the loudspeaker  118 .  
         [0049]     Control data received by the transceiver  110  from the remote control  120  is passed to the microcontroller  112 . The microcontroller  112  processes the control data received by the transceiver in order to verify that 8-bit encrypted user identification (UID) data transmitted by the remote control  120  corresponds to UID data stored in the microcontroller  112 . If the received UID does not match the stores UID the microcontroller  112  ignores the remainder of the control data transmitted by the remote control  120 . However, if the received UID and the stored UID do match the microcontroller  112  processes the remainder of the control data. The control data typically includes a start time and a finish time that define a time interval during which electricity is to be supplied to an apparatus, typically a PC, games console or the like. The microcontroller  112  compares these times to an internal clock thereof and outputs power to the LED  116  that is illuminated to indicate that the device  100  is operating in a timed program mode.  
         [0050]     The default status of the triac  114  is to prevent the passage of electricity thereacross. At the start time detailed in the control data the microcontroller  112  outputs a control signal to a gate  122  of the triac  114  in order to allow it to conduct in both forward and reverse directions, a necessity where unrectified a.c. voltages are required. This allows electricity to flow between the input  102  and the output  104 .  
         [0051]     Should the switch  117  be in an “Audio On” position, at a predetermined time prior to the finish time detailed in the control data, typically five minutes prior to the finish time, the microcontroller  112  outputs an audio signal to the loudspeaker  118  that emits a warning sound so that a user of the apparatus has the opportunity to close down the apparatus and any applications running thereupon in a controlled manner. A similar, or different, warning sound can be emitted from the loudspeaker  118  at, for example, thirty seconds prior to the finish time detailed in the control data.  
         [0052]     Upon the finish time contained in the control data being reached the microcontroller  112  ceases to output the control signal to the gate of the triac  114 , and the triac  114  reverts to its default non-conducting state, thereby preventing the flow of electricity between the input  102  and the output  104  of the device  100 .  
         [0053]     It is also envisaged that the control data can include a change to the UID to be stored in the microcontroller  112 , or instructions to synchronise the clock of the microcontroller  112  with an internal clock of the remote control  120 .  
         [0054]     The remote control  120  comprises a keypad  122 , an LCD display  124 , a battery  126  with an associated charging circuit  128  and control circuitry  130 .  
         [0055]     The battery  126  provides power for the remote control  120 , and is typically an AA size NiCd battery. The recharging circuitry  128  allows the battery  126  to be recharged from a mains electricity supply whilst still in the remote control  120 , for example in a charging cradle, or a standard a.c. adapter.  
         [0056]     The control circuitry  130  comprises a transceiver  132 , a microcontroller  134 , up and down keys  136 ,  138 , a menu key  140  and a set key  142 .  
         [0057]     The transceiver  132  operates at the same frequency as the transceiver  110  of the device  100 .  
         [0058]     A user of the remote control  120  presses the menu key  142  and is requested to enter a four digit UID on the key pad  122 . The keystrokes pass to the microcontroller  134  where the UID entered by the user is compared to a UID stored therein. Should the UID entered by the user match the UID stored in the microcontroller  134  the user has access to a number of options that are displayed on the LCD display  124 . The options typically include such options as set time, lock, set UID, input time interval. The options can be scrolled through using the up and down keys  136 ,  138  and selected using the set key  142 .  
         [0059]     Whilst the remote control  120  is in standby mode the LCD display  124  displays the time, in twenty-four hour. The time displayed on the LCD display  124  can be set by navigating through the menu options on the display  124  using the menu key  140  and pressing the set key  142 . The desired time is selected using the up and down keys  136 ,  138  and the pressing the set key  142  once more. The setting of the time resets an internal clock within the microcontroller  134 . This function is unavailable when the remote control  120  is locked as this prevents unauthorized alteration of the time in the microcontroller  112  of the device  100 .  
         [0060]     Should the user elect the lock option, the microcontroller  134  disables all functions except UID code entry, and the time and the word “LOCKED” are displayed upon the LCD display  124 . In order to unlock the remote control a UID matching that stored in the microcontroller  134  must be entered at the keypad  122  and verified by the microcontroller  134 .  
         [0061]     In order to change the UID, the current UID must be entered at the keypad  122  and verified by the microcontroller  134 . A new UID is then entered at the keypad  122  by the user and stored in the microcontroller  134 . The new UID must be re-entered by the user in order that it can be confirmed by the microcontroller  134 .  
         [0062]     The remote control  120  can be used to set the device  100  to operate in a non-timed constant mode to allow the constant supply of electricity to a device if desired  
         [0063]     The time interval input is the period of time during which electricity is to be allowed to flow between the input  102  and the output  104  of the device  100 . This is entered in terms of a start time and a finish time in the same manner as setting the time on the remote control  120  as described hereinbefore. Alarm periods are preferably set by the manufacturer, these are the periods prior to the end of the time interval that audible warnings are to be emitted by the loudspeaker  118  of the device  100 , for example five bleeps five minutes prior to the electricity supply being stopped and a continuous sound one minute prior to the electricity supply being stopped. It is envisaged that is some embodiments the user may be able to define their own alarm period.  
         [0064]     Once the time interval, and any alarm periods, have been entered it is sent along with a remote control UID from the microcontroller  134  to the transceiver  132  as a stream of control data. Typically, the transceiver  132  transmits the control data to the device  100 , as an eight bit encrypted signal, where it is processed as described hereinbefore. The remote control  120  is in communication with the device  100  and the status of the device  100  is passed to the remote control  120 . For example, the device  100  is arranged to monitor whether electricity is flowing through it from the power input to the power output. This can be used as an indication of whether the device  100  has been disconnected or bypassed. This information is sent to the remote control  120  which is arranged to display an appropriate message on its screen  124 . This enables a person operating the remote control  120  to monitor the status of the device  100  and hence to detect if the device, and hence the timing control that it provides, has been bypassed. The device  100  can be arranged to monitor its status in a number of ways, examples of which are described in relation to other embodiments described below. However, it will be appreciated that designing other circuits to detect the disconnection of the device  100 , either from a wall socket or from the apparatus to which it is supplying power, is within the abilities of the man skilled in the art. Other information about the status of the device  100  can also be transmitted to and displayed on the remote control  120 , such as the amount of time before a timed period of usage will end.  
         [0065]     Referring now to  FIG. 4 , a second embodiment of the a timer device  400  comprises an keypad  402 , an LCD screen  404 , a mains output socket  406 , up and down keys  408 , a menu key  410 , a set key  412  and two LED indicators  414 ,  416 .  
         [0066]     The timer device  400  operates in a similar manner to the timer device  100  except that code entries are made directly to a microcontroller (not shown) at the keypad  402 , rather than via a remote control. This removes the need for the transceiver  110  of the device  100 . The screen  404 , up and down keys  408 , the menu key  410  and the set key  412  carry out the same functions as they do on the remote control  120 . The LED indicators  414 ,  416  correspond to the LED indicators  115 ,  116  of the device  100 .  
         [0067]     Referring now to  FIG. 5 , it is envisaged that a timer device according to the present invention need not be mounted into a socket but can be incorporated directly into the apparatus that it is intended to regulate the supply of electricity to, for example a games console  500 . The console  500  comprises a processor unit  502  that receives electricity via a timer device  504  according to an embodiment of the present invention. This allows access to the console to be controlled by the use of a UID code typically transmitted from a remote control  506 .  
         [0068]     Thus, a parent can control the amount of time a child spends playing on a games console, accessing the Internet or watching television without necessarily being present in the same room as the child. Similarly, a manager can maintain out of office hours control over access to apparatus such as a photocopier, a fax machine or a PC.  
         [0069]     It will be understood that it is envisaged that a device according to the present invention can be incorporated into any suitable electrical apparatus.  
         [0070]     It is also envisaged that a device according to the present invention can be hard wired onto a cable as a plug, the plug will have a standard fuse mounting arrangement to allow matching to the plug to it&#39;s expected loading. The device can be moulded onto a mains lead, for example a D-plug that fits most PC&#39;s and supplied with a PC. Alternatively, the device can be mounted in a wall socket.  
         [0071]     Referring now to  FIG. 6 , a method of controlling the supply of electricity to an apparatus comprises the steps of entering user identification data at a keypad (Step  600 ). The user identification data is validated at a processor (Step  602 ) and a time period over which electricity is to be supplied is entered at the keypad (Step  604 ). Electricity is supplied to an apparatus over the defined time period if the user identification data is successfully validated (Step  606 ). The supply of electricity to the apparatus is prevented once the defined time period has expired (Step  608 ).  
         [0072]     Referring now to  FIG. 7 , an adapter  700  comprises a body  702  having a socket arrangement  704  in a first face  706  thereof and a plug arrangement  708  projecting from a second face  710  thereof. The socket arrangement  704  and plug arrangement  708  are in electrical communication with each other. The body  702  houses control circuitry  712  arranged to regulate the flow of electricity through the adapter  700  in response to the entry of a UID as described hereinbefore in relation to the transceiver-microcontroller arrangements FIGS.  1  to  6 .  
         [0073]     Adapters have the known problem that they can be removed from a wall socket or an appliance&#39;s plug can be removed from the adapter and the appliance plugged directly into the wall socket thereby circumventing the control circuitry  712 .  
         [0074]     In order to overcome this the adapter  700  comprises a current sensing circuit  714  arranged to detect the flow of electrical current through the adapter  700  to an appliance. The current sensing circuit  714  is in communication with the control circuitry  712  and the control circuitry  712  is arranged to determine whether a load, i.e. an appliance, is attached to the socket  704  and also if the adapter  700  is programmed to allow current to flow to the appliance.  
         [0075]     If the current sensing circuit  714  determines that a current is not flowing to the appliance, i.e. the appliance has been disconnected from the adapter  700  or the adapter  700  has been disconnected from the wall socket, and that the adapter  700  is programmed to allow current to flow to the appliance, the control circuitry  712  is arranged to send a signal to a remote control, not shown but substantially as described hereinbefore with reference to  FIGS. 1, 3  and  5 . The warning signal causes the remote control to either emit an audible warning, display a message upon a screen thereof or both. This warning alerts a user of the device to the fact that the wall socket-adapter-appliance plug arrangement has been tampered with and an attempt made to circumvent the control circuitry  712 .  
         [0076]     Referring now to  FIG. 8 , an adapter  800  comprises a body  802  having a socket arrangement  804  in a first face  806  thereof and a plug arrangement  808  projecting from a second face  810  thereof. The socket arrangement  704  and plug arrangement  708  are in electrical communication with each other. The body  802  houses control circuitry  812  arranged to regulate the flow of electricity through the adapter  800  in response to the entry of a UID as described hereinbefore in relation to the transceiver-microcontroller arrangements FIGS.  1  to  6 .  
         [0077]     The openings  814  of the socket  804  have cover plates  816  that are biased into a closed position, typically by springs  818 . The cover plates  816  are forced into an open configuration by the pins of an appliance&#39;s plug as they are located in the adapter  800 . A base plate  820  is attached to a spring  818  adjacent the cover plate  816  and has a rod  822  projecting away from the cover plate  816  internally of the spring  818 . The rod  822  extends to close to the opposite end of the spring  818  from the cover plate  816  but does not pass beyond said opposite end of the spring  818 . A switch  824  is mounted in the adapter  800  adjacent the free end of the rod  822  such that as the cover plates  816  is opened by the pins of the appliance&#39;s plug the switch  824  is closed. The closing of the switch  824  completes a circuit  826  which indicated to the control circuitry  812  that the appliance&#39;s plug is located in the adapter  800 .  
         [0078]     If the switch  824  is opened the circuit  826  is broken and the control circuitry  812  determines that the appliance&#39;s plug has been disconnected from the adapter  800 . The control circuitry  812  then determines if the adapter  800  is programmed to allow current to flow to the appliance or not. If the circuit  826  is broken, and the adapter  800  is programmed to allow current to flow to the appliance, the control circuitry  812  is arranged to send a signal to a remote control, not shown but substantially as described hereinbefore with reference to  FIGS. 1, 3  and  5 . The warning signal causes the remote control to either emit an audible warning, display a message upon a screen thereof or both. This warning alerts a user of the device to the fact that the wall socket-adapter-appliance plug arrangement has been tampered with and an attempt made to circumvent the control circuitry  812 .  
         [0079]     Referring now to  FIG. 9 , an adapter  900 , as described hereinbefore with reference to either of  FIG. 7  or  8 , comprises a body  902 , typically a plastics molding, having a socket arrangement  904  and a plug arrangement  906  upon opposite faces thereof. The socket arrangement  904  and the plug arrangement  906  are in electrical communication. The adapter  900  comprises an electricity supply control device as described hereinbefore in relation to FIGS.  1  to  6  to regulate the flow of electricity through the adapter  900 . A current sensing circuit as described hereinbefore in relation to  FIG. 7  and/or a spring-switch arrangement as described hereinbefore in relation to  FIG. 8  can also be included in the adapter  900  to provide notification of tampering with the adapter to a user.  
         [0080]     The body  902  has a recess  908  therein about the socket arrangement  904 . Two latches  910   a,b  are mounted in openings in walls of the recess  908 , typically opposite each other. Each latch  910   a,b  has a disc shaped end portion  912  that resides within the body  902  and a trapezoidal free head portion  914 . Respective elongate neck portions  916  join the end portion  912  to the head portion  914  of each latch  910   a,b.  Each neck portion  916  passes through a mounting post  918  in the body  902  such that respective springs  920   a,b  are compressed between the mounting posts  918  and the head portion  914  of each latch  910   a,b  and bias the head portion  914  into the recess  908 . The end portion  912  lies on the opposite side of the post  918  and retains each latch  910   a,b  in position.  
         [0081]     As a plug  922  is inserted into the recess  908  sloping surfaces  924   a,b  of the head portions  914  are engaged and the latches  910   a,b,  are forced outward of the recess  908  into the body  902  and allow the plug  922  to pass into the recess  908  and engage the socket arrangement  904 . The latches  910   a,b  are biased inward of the recess once the plug has almost fully, or fully, engaged the socket arrangement  904 . Flat undersurfaces  926   a,b  of the head portion  914  act to prevent removal of the plug  922  from the adapter  900  without active outward biasing of the latches  910   a,b  thereby preventing accidental removal of the plug  922  from the adapter  900 .  
         [0082]     It is envisaged that with the embodiments of the invention described in relation to  FIGS. 7 and 8  an appliance&#39;s standard plug will typically be retained in the adapter by use of mechanical means, strap, slides or cover or other means, thereby minimizing the risk of accidental removal of the plug from the adapter and their associated warnings.  
         [0083]     Referring to  FIG. 10 , in a further embodiment of the invention, the timer and control device is incorporated in the plug  1010  of a connector lead  1012 . The plug  1010  has connector pins  1014  to enable it to be inserted into a standard wall socket power supply. The other end of the lead  1012  includes a further plug  1016  for connection to the apparatus to be powered via the lead. The plug  1010  can include the features of any of the embodiments of FIGS.  1  to  8 .