GB2342232A

GB2342232A - Electrical plug immobiliser

Info

Publication number: GB2342232A
Application number: GB9817809A
Authority: GB
Inventors: Michael Stokes
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-08-14
Filing date: 1998-08-14
Publication date: 2000-04-05
Also published as: GB9817809D0

Abstract

A device 1 acts as a barrier to a plug 4 to prevent it from being connected to a socket. The device 1 is attached to the plug 4 by a locking screw clamping means 8 which tightens on a pin 6 of the plug 4 where is passes through an aperture 5 in the device 1. The clamping means 8 is preferably set in a bore 7 which means that the clamp 8 can only be actuated by a tool 12 such as a screwdriver. The tool 12 may be a captive component of the device 1, in which case it could be of a spring-loaded 17 childproof type which requires continuous axial pressure to be applied to its head 14 to allow it to unscrew the clamp 8. An aperture 19 may be provided to receive the hasp of a padlock to prevent access to the head of the screw 8.

Description

-1 2342232 1 ELECTRICAL PLUG IMMOBILISER This invention relates to a

device for immobilising an electric plug of the kind having one or more pins that engage holes in a socket to make an electrical connection, such a plug being commonly used as a power supply plug.

There is a need for a simple device that can be attached to a plug to prevent it from being zn t inserted into a socket. For example, some electrical appliances such as heaters, kettles, hairdryers, drills, mowers and chain-saws, are potentially dangerous for children to use, and it may also be desirable to prevent some appliances, such as computers and hi-fi equipment, from being used by unauthorised persons.

According to the invention, this need is satisfied by providing a device comprising a t> t> barrier member having an aperture to receive a pin of the plug, and a locking screw 0 threaded within the barrier member so that it can be advanced laterally of the pin into clamping engagement with it to retain the barrier member on the plug, thereby preventing ZD it from being engaged with a socket.

Preferably, the locking screw is located within the body of the barrier member so that it can only be operated by a tool, such as a screwdriver, which is inserted through an aperture to encra-e the head of a screw. In one such embodiment designed to be childproof, the tool 4:1 zn 2 may be provided as a captive component of the device rotatably mounted on the barrier member and axially moveable into working engagement with the head of the screw. A spring may be provided to urge the tool axially away from the screw so that it will disengage from the screw unless a constant axial pressure is maintained as it is rotated, this task being sufficiently difficult for most young children to accomplish.

C) In the case of a device for use with a three-pin power plug, such as used in the United Kingdom, the barrier member has an aperture to receive the earth pin of the plug, and extends laterally therefrom between the live and return pins, the locking screw being located between the earth pin and the other two pins.

If a higher level of security is required, a removable locking device may be fitted to block access to the locking screw. For example, the hasp of a padlock may be inserted through an aperture in the barrier member so as to block access to the head of the locking screw.

The invention will now be described with reference to the accompanying drawings in which:

Figure I illustrates a general plan view of a device according to the invention as fitted to a three-pin power plug; 4:) Figure 2 shows a side elevation of the device and plug assembly shown in Figure 1; and 3 Fig3Are 3 shows an alternative embodiment of the invention in which a captive screwdriver is attached to the head of the device of Figures 1 and 2.

The illustrated immobilising device comprises an elongate body 1, which may be rectangular, circular or elliptical in section, and which has a width such as to be a close fit between the live and return pins 2,3 of a three-pin plug 4. The body 1 may be moulded or machined in plastics or may be composed of other suitable material. An aperture 5 extends through the full thickness of the body 1 on its centreline towards one end so as to receive the earth pin 6 of the plug as a friction fit, with the body extending therefrom between the other two pins 2,1 This aperture 5 is rectangular in section to receive the standard rectangular section earth pin used in three pin power plugs in the United Kingdom. A cylindrical aperture 7 is formed longitudinally within the body 1, between the aperture 5 and that end of the body furthest from the aperture 5, and has a clamping screw 8 located fully within it at its inner end in threaded engagement with a nut 9 in a recess 10 in the body 1. The recess 10 opens laterally from the body to allow the nut 9 to be inserted through it into alignment with the aperture 7 for engagement by the screw 8 as it is inserted through the open end of the aperture 7.

A screwdriver is inserted into the aperture 7 after the screw 8, and engages the head of the screw to thread it into the nut 9 and advance it into clamping engagement with the earth pin 6. This clamping engagement prevents the body 1 from being easily removed 4 without the use of a screwdriver to release the clamping screw S. The section of the body 1, and its close fit between the pins 2,3 prevents it from being twisted in an attempt to release it from the earth pin 6.

Once attached to the plug 4 in the above manner, the body I prevents the plug from being inserted into a power socket. Also, the body will overlie the normal fastening screw 11 that holds the two body sections of the plug together, so they cannot be released to allow the plug to be unwired and replaced.

In an alternative embodiment of the invention illustrated in Figure 3, a screwdriver 12 is rotatably fitted in the open end of the aperture 7 so as to be held captive on the body I and to be axially moveable against a spring force into engagement with the head of the screw 8. The screwdriver has a cup-shaped head 14 that fits rotatably over the end of the body I and is held captive axially thereon by two dowel pins 15 inserted through the side wall of the head into a groove 16 in the outer wall of the body 1. A coiled compression spring 17 located within the head 14 acts against the end of the body I and extends the screwdriver away from the screw 8. In order to operate the screw, the head of the screwdriver has to be depressed so that the blade 18 of the screwdriver engages the head of the screw 8, and the screwdriver has to be rotated whilst held in this position. This degree of manipulative skill is beyond that normally expected of young children, so once the body I is clamped to a plug by an adult, it will be safe against use by young children.

4D In yet another embodiment of the invention, a lateral hole 19 (shown in broken lines in Figure 1) is provided across the width of the body I adjacent the head of the screw 8 so that a security device such as the hasp of a padlock can be inserted and fastened in the hole to prevent access to the head of the screw 8. A similar lateral hole 19 is formed in the body I of the embodiment of Figure 3 so as to provide the same security features.

In other embodiments of the invention, the barrier member may be adapted for use with two pin plugs. For example, the body I may have two apertures, one for each pin, with a clamping screw provided within the body to engage just one of the pins.

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Claims

1. A device for immobilising an electric plug comprising a barrier member having an aperture to receive a pin of the plug, and a locking screw threaded within the barrier member so that the screw can be advanced laterally of the pin into clamping engagement with the pin to retain the barrier member on the plug, thereby preventing the plug from being engaged with a socket.

2. A device as claimed in claim 1 in which the locking screw is located within a body of the barrier member so that the screw can only be operated by a tool which is inserted through an aperture in the body to engage the screw.

3. A device as claimed in claim 2 in which the locking screw has a head which is engageable by a screw driver inserted through said aperture.

4. A device as claimed in claims 2 or 3 in which said tool is provided as a captive component of the device rotatably mounted on the barrier member and axially moveable into working engagement with the screw.

5. A device as claimed in claim 4 in which a spring may be provided to urge the tool axially away from the screw so that the tool will disengage from the screw unless a constant axial pressure is maintained as it is rotated.

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6. A device as claimed in any one of the preceding claims and adapted for use with a three-pin power plug, the barrier member having an aperture to receive one pin of the plug, and extending laterally therefrom between the two other pins, the locking screw being located between said one pin and said other two pins.

7. A device as claimed in any one of the preceding claims which is adapted so that a removable locking device may be fitted to block access to the locking screw.

8. A device as claimed in claim 7 in which an aperture is formed in the barrier member so as to receive the hasp of a padlock to block access to the screw.

9. A device for immobilising an electrical plug substantially as herein described with reference to the accompanying drawings.