AU2005100761A4 - A Power Lead - Google Patents

Description

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Tassone Property Group Pty Limited

AUSTRALIA

Patents Act 1990 INNOVATION PATENT: "A Power Lead" The invention is described in the following statement:- NA POWER LEAD TECHNICAL FIELD The present invention relates to power leads, and in particular to power leads for use with electrical devices.

BACKGROUND

It is known in the art to use extension cords, power boards, and adaptors to compliment installed electrical wiring to power electrical devices. However, when a S 10 worker uses more than one electrical device, the prior art devices are inconvenient and often pose significant problems to productivity and safety. This is particularly relevant to industrial sites and with portable electrical devices. In trade worksites, two portable electrical devices are commonly required for a given job. Having to unplug then plug-in electrical devices slows productivity, especially when working in a difficult position such as on a ladder, for example. In some instances, the worker may need to leave the immediate area in order to swap power to the electrical device that is needed. Leaving the immediate worksite is particularly troublesome if the worksite must be put in a safe condition before the worker can leave. Having to reestablish working conditions, such as re-aligning components or making measurements, before being able to resume work is equally time consuming. It is unsatisfactory having to stop work every time the other electrical device is required and must be plugged into the power afresh.

While extension cords may be used to distribute electrical power at a distance from an installed electrical socket, they allow powering of only one electrical device at a time. However, using multiple extension cords is problematic as installed electrical sockets are limited in number and become quickly exhausted. This is also problematic as it doubles the number of extension cords that must be kept in inventory and accordingly doubles the number of times electrical safety inspections and tests must be undertaken. Using additional extension cords is generally inconvenient and specifically causes unnecessary safety hazards, such as tripping over cords, and the potential for fire and electric shocks, around a worksite.

One attempt to overcome the problems above has been attaching a power board to the end of an extension cord or making a power board with a long power cord.

However, power boards are designed for stationary needs like supplying the components of home electronic systems. The additional weight of the larger power board and the restriction of its movement caused by the other plugged in components makes the board unsuitable to be moved, even temporarily. The friction between a plug's pins and the recesses of the socket is often insufficient to maintain the plug's connection under the weight of the power board and the restriction caused by the other plugged in cords.

The multiple sockets of a power board also readily allow the plugging in of too many devices, which could cause over-current and over-heating hazards capable of destroying components and causing fires. To address these hazards, residual current devices such as fuses or circuit breakers are usually required to meet electrical safety standards. However, residual current devices can fail and are intended to be merely a backup means for safety as opposed to being relied upon in the first instance.

The power boards are also frequently arranged to sit with their sockets facing upwards, creating collection points for debris and liquids. In jobs where no more than two electric devices are commonly plugged in, the remaining unused and unnecessary sockets still contain live electrical connections. While the live connections are not readily accessible, they are prone to collecting electricityconducting debris, objects and liquids, which can cause phase-to-phase or phase-toearth faults, as well as present an electric shock hazard to workers.

For these reasons, power boards are often not used in industrial areas. Furthermore, some government regulations can prohibit power boards from being used in certain areas, such as construction sites, due to the safety concerns outlined above.

Other prior art devices include electric adaptors, such as a double adaptor, that are used in conjunction with an extension cord. One of the biggest problems with adaptors is the inherent risk of being able to plug in too many devices to a single socket and thereby introducing overload risks. For this reason, adaptors are often prohibited from industrial areas such as construction sites.

Adaptors are further inconvenient because they are easily lost or stolen and thus maintaining their proper inventory becomes a problem. Adaptors must also be carried to the jobsite and can be easily dropped, which poses a significant danger to other workers when working aloft. Even when adaptors are available, their use is further undesirable because they add another plug-to-socket mating point in the circuit, which can present a problem for two reasons. Firstly, plugs can inadvertently become detached from their sockets, which stops work and can cause electric arcing.

Secondly, the electrical mating point between a plug and socket usually has a higher resistance than their conductors, which leads to unnecessary power losses and higher heat than when not using an adaptor. For the above reasons, adaptors are not generally suitable for powering electrical devices, particularly portable electrical devices in industrial areas.

The present invention seeks to provide a power lead that will ameliorate or overcome at least one of the deficiencies of the prior art, or will provide a useful alternative.

SUMMARY OF THE INVENTION In a first aspect the present invention consists in a power lead for use with electrical devices, the power lead comprising a flexible electrical cable having a plug at one end adapted to engage an electrical power supply and a socket portion at the other end having first and second sockets with respective first and second socket axes, the first and second sockets adapted to mate with respective power plugs from the electrical devices, the flexible cable adapted to engage with or enter the socket portion via an aperture having a central axis, wherein at least one of the socket axes is disposed at an acute angle to the central axis and wherein when the power lead is in use the socket portion is not detachable from the flexible cable.

Another aspect of the invention concerns a socket portion for use with a power lead, the power lead for use with electric devices, the socket portion having at least first and second sockets with first and second socket axes respectively, the first and second sockets adapted to mate with respective power plugs from electrical devices, the socket portion adapted to affix to a flexible electrical cable via an aperture having a central axis, wherein at least one of the socket axes is disposed at an acute angle to the central axis and wherein when the power lead is in use the socket portion is not detachable from the flexible cable.

Preferably, both the first and second socket axes are disposed at acute angles to the central axis. Preferably, the first and second sockets are symmetrically disposed about the central axis.

Optionally, the power lead may include at least one safety device. Preferably, the safety device may be a residual current device, or an overload protection device.

Optionally, the power lead may include at least one switch adapted to allow a worker to electrically isolate at least one of the socket portions from the plug.

BRIEF DESCRIPTION OF THE DRAWINGS A preferred embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 is an isometric view of a power lead according to the present invention; Figure 2 is a cutaway side view of a portion of the power lead shown in Figure 1; and Figure 3 is an isometric view of and alternative version of the socket portion of a power lead in accordance with the invention.

BEST MODE OF CARRYING OUT INVENTION Figure 1 shows a power lead according to a preferred embodiment of the present invention. Power lead comprises a socket portion connected to plug by flexible cable Flexible cable allows a worker to power two electrical devices at a long-range distance from installed electrical wiring. Socket portion has first socket and second socket for powering up to two electrical devices (not shown).

The flexible electric cable is a normal electric cable that is able to carry an electric current. It may be a three strand cable, with positive, negative and earth wires within the cable, or a two strand cable, with just the positive and negative wires, or another version suitable for other types of electric devices. The cable is wired to the sockets (6 and 7) in a normal manner, but is attached firmly to the socket portion (2) by any method used in the manufacture of extension cables, so that in normal use the cable and socket portion cannot be dismantled.

As most worksite trade jobs commonly require an average of two electrical devices, power lead minimises the number of times a worker has to swap plug arrangements as is the case when using an extension cord of the prior art. Using only first and second sockets 7) avoids problems of the prior art power boards of extra bulk, unnecessary electrical hazards, and potential for plugging in too many devices.

When the power lead is in use, the socket portion cannot be detached from the flexible cable Because the socket portion is not detachable, it is not susceptible to the problems of inventory management, separate safety inspections, potential for inadvertent separations, or unnecessary resistance of electrical mating points. Such problems are inherent to double adaptor and piggy back type adaptors that have been used with extension cords in the past. In the example shown in the drawings, the first socket and second socket are surrounded by safety skirt (8) to minimise the ingress of debris and liquids when a plug (not shown) is inserted.

Figure 2 shows a cross section of socket portion Like reference numerals denote like components to those in Figure 1. Flexible electrical cable 4 extends from aperture which extends along central axis Aperture (14) is disposed in the opposite side of socket portion from first and second sockets First socket and second socket are centred about first socket axis (11) and second socket axis respectively. First socket axis (11) and second socket axis (12) are perpendicular to the first socket face (15) and the second socket face (16), respectively. First socket face (15) is in a plane that intersects second socket face (16) at an angle. Both first socket axis (11) and second socket axis (12) are disposed at acute angles to central axis First socket and second socket are also substantially symmetric about central axis (13).

The configuration shown in Figure 2 and described above ensures that first and

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second socket axes (11, 12) are not parallel to central axis which is _advantageous for several reasons. In general, a plug is susceptible to becoming disconnected, or unplugged, when the electrical device is pulled away from flexible cable creating tension forces at the plug's pin in socket portion Two common examples of this are when a worker walks too far away from power lead (1) or when socket portion is suspended, such as when receiving power from a higher storey or working on a ladder. As first socket axis (11) and second socket axis (12) are offset at an angle from central axis the tension force on the pin will have a component that is normal to the socket axis and thus increases the frictional forces and opposes unplugging. The symmetric, angled configuration also allows socket portion to have a narrower profile with lighter weight. The lighter weight also helps to keep the plugs connected to socket portion when it is temporarily lifted or moved. The final advantage of this configuration is that flexible cable prevents socket portion from resting with first and second sockets 7) facing directly upwards. Sockets in power boards, on the other hand, do face directly upwards and readily trap falling conducting debris and liquids. For this reason, power boards and other upward facing devices of the prior art are not desirable in industrial areas.

Figure 2 further shows residual current device (10) having test pushbutton and reset pushbutton housed within socket portion The residual current device acts to electrically isolate both first and second sockets 7) when an imbalance, or difference, occurs between current being supplied from and current returning to flexible cable The imbalance being detected is that due to current leakage occurring as insulation resistances first become degraded. Residual current device is preferred to residual current devices, such as fuses and circuit breakers, that require a high current condition before isolating circuits. Including a residual current device (10) in power lead enhances safety because many installed power outlets do not have adequate earth leakage protection. Furthermnore, workers are often required to work in remote jobsites. At a remote jobsite, whilst residual current devices might be permanently installed in power outlets, the worker cannot ensure that they have been kept in a safe working condition. By bringing power lead to a contracted jobsite, they are protected by a residual current device that they have maintained and tested to their satisfaction.

In another (not shown) preferred embodiment, a third socket may be disposed adjacent to first and second sockets The third socket has a third socket axis that is disposed at an acute angle to central axis (13) and the three sockets are disposed symmetrically about central axis (13).

In yet another (not shown) embodiment, residual current device (10) is integral with flexible cable In this embodiment, socket portion may be lighter or enable incorporating simple on/off switches to selectively isolate power from portable devices. This embodiment also allows putting the residual current device near plug in order to protect the worker from faults in insulation along the length of flexible cable In an alternative preferred embodiment, power lead incorporates overload protection devices such as fuses or circuit breakers, to prevent high current conditions from continuing.

As one option, the socket portion is moulded integrally with the flexible cable such that the socket portion cannot be rewired. This version is advantageous in meeting some strict safety regulations for certain industrial areas. As another option, and especially for less strict applications, the socket portion may be sold separately and wired to the flexible electric cable by a qualified technician. After socket portion is wired to the flexible cable it is ready for use and is not detachable without disassembling the combined power lead The method of wiring shown in Figure 2 is optional, and other methods of electrical connection to the sockets and may be utilised.

In another alternative, the present invention comprises a power lead for use with electrical devices, the power lead comprising a flexible cable having a plug at one end adapted to engage an electrical power supply and a socket portion at the other end having at least first and second sockets adapted to mate with respective power plugs from the electrical devices, the flexible cable adapted to enter the socket portion via an aperture having a central axis, wherein the face of the first socket is disposed at an angle to the face of the second socket and wherein when the power lead is in use the socket portion is not detachable from the flexible cable.

Figure 3 shows a slightly different version of the socket portion of a power lead according to the invention. The socket portion is connected to the flexible cable in order to allow a worker to power two electrical devices. Socket portion has first socket and second socket for powering two electrical devices.

The foregoing describes only a preferred embodiment of the present invention and modifications, obvious to those skilled in the art, can be made thereto without departing from the scope of the present invention.

Claims (4)

1. A power lead for use with electrical devices, said power lead comprising a flexible electrical cable having a plug at one end adapted to engage an electrical power supply and a socket portion at the other end having at least first and second sockets with first and second socket axes respectively, said first and second sockets adapted to mate with respective power plugs from said electrical devices, said flexible cable adapted to engage with said socket portion via an aperture having a central axis, wherein at least one of said socket axes is disposed at an acute angle to said central axis and wherein when said power lead is in use said socket portion is not detachable from said flexible cable.

2. A socket portion for use with a power lead, said power lead for use with electric devices, said socket portion having at least first and second sockets with first and second socket axes respectively, said first and second sockets adapted to mate with respective power plugs from electrical devices, said socket portion adapted to affix to a flexible electrical cable via an aperture having a central axis, wherein at least one of said socket axes is disposed at an acute angle to said central axis and wherein when said power lead is in use said socket portion is not detachable from said flexible cable.

3. A power lead as defined in claim 1, or a socket portion as defined in claim 2, which has only said first and second sockets, and wherein both said first and second socket axes are disposed symmetrically about said central axis and at acute angles to said central axis.

4. A power lead as defined in claim 1, wherein said power lead includes: at least one safety device selected from a residual current device or an overload protection device, or at least one switch adapted to allow a worker to electrically isolate at least one of said socket portions from said plug. A power lead, or a socket portion, substantially as herein described with reference to the drawings. 11 Dated this 15 th day of September 2005 TASSONE PROPERTY GROUP PTY LTD HODGKINSON McINNES PAPPAS; (Patent Attorneys for the Applicant)