GB2248527A

GB2248527A - Electrical apparatus

Info

Publication number: GB2248527A
Application number: GB9024845A
Authority: GB
Inventors: Duncan John Salton
Original assignee: D J S ELECTRICAL MANUFACTURERS
Current assignee: D J S ELECTRICAL MANUFACTURERS
Priority date: 1990-08-17
Filing date: 1990-11-15
Publication date: 1992-04-08
Anticipated expiration: 2010-11-15
Also published as: GB9024845D0; GB9018102D0; GB2248527B

Abstract

A first adaptor 11 and a second adaptor 12 arrangement is provided wherein the provision of a coding lug (100B, Fig. 8B), together with sprung 21, 16, 17 and unsprung 14, 22 (23, Fig 5) electrical contacts, prevents accidental insertion of standard electrical equipment, such as normal dual contact lamps, into a live electricity supply. A cable has a plurality of first adaptors mounted along its lengths. Such cable may be mounted within a building or on a building site and lighting equipment may be installed as and when required. Because of the reciprocating nature of sprung and unsprung electrical contacts only specific equipment may be used in conjunction with the cable. <IMAGE>

Description

ELECTRICAL APPARATUS This invention relates to an electrical apparatus and more specifically but not exclusively, it relates to an adaptor for use, in one embodiment, with electrical lighting equipment.

It is well known that fluorescent tubes are preferable to conventional filament bulbs. One reason why fluorescent tubes are preferred is because they do not cast shadows. However, fluorescent lighting requires an earth connection.

A problem in the past, for example on building sites or inside closed rooms and passageways within buildings, where work has been carried out, has been that areas have required lighting because the ambient light levels were too low. As soon as work had been carried out, it was sometimes necessary to remove the temporary lighting and re-install it in a different part of the site or building. If this was not done the result was that large parts of the construction site or building were illuminated unnecessarily. Alternatively one or more electricians were employed to ensure that adequate lighting was available in the correct vicinity as and when work was to be carried out.In the former case excessive use of lighting was uneconomic, and in the latter case, because power points were not always available in the most convenient places, excessive extension leads were used and often makeshift connections were made to the nearest available main cable so as to provide a temporary power source for other branch cables. Clearly such practices were not only inefficient but in the latter cases were sometimes dangerous. This was especially the case where so called festoon lighting was used, that is several lights in parallel sharing a common source.

A problem with festoon lighting arrays was that they were difficult to connect together because the fluorescent tubes required significant electrical equipment such as starters, ballast and fuses so as to ensure that they received the correct level of power supply. Also, because of the necessity to connect the fluorescent tubes in parallel to one another, complicated electrical paths were required from one electrical junction box to the next. The connections between adjacent junction boxes were complicated so as to permit an electrician to use one, some or all of the possible junction boxes available to him. Another problem was that the festoon connections and junction boxes were bulky and considerable effort was required to erect them. Scmetimes this entailed two or three electricians working together.The paradoxical situation arose that temporary lighting was sometimes required to erect the temporary lighting.

According to a first aspect of the present invention there is provided an adaptor having means for coupling, and two electrical contacts, one of the contacts being supported on a resilient support and one of the contacts being supported on a deformable support.

Preferably the means for coupling is a bayonet connector. The adaptor may be used in conjunction with an electrical connector, such as a cable. The cable may be a three core cable, in which case three electrical contacts are provided within the adaptor.

Preferably a standard bayonet holder encloses three separate electrical contacts. One contact of which is preferably supported on a solid support and the other two are supported on sprung supports. The advantage of such an arrangement is that, despite having the appearance of a standard bayonet connector, it is impossible to insert a standard bayonet fitting light bulb into the adaptor. As a result of this only specific equipment may be used and there is no danger of people inserting anything apart from that specific equipment into a redundant adaptor.

Preferably the three electrical contacts are arranged at 120 degrees to one another.

Preferably the adaptor is shaped to receive an insert, which may be a holder or a similar adaptor connected to a fluorescent tube. The insert may be a weatherproof cap, which seals those adaptors which are not in use. Alternatively the insert may be another adaptor of a different connector.

Contacts of the other adaptor or insert are arranged such that those electrical contacts in contact with the solid contacts are sprung contacts; and those electrical contacts in contact with sprung contacts are solid. Such an arrangement of contact pairs, each having a sprung and a solid contact, ensure that only adaptors of the correct type may be used in conjunction with one another. In practice this means that only the specific type adaptors may be used to connect fluorescent tubes to the electrical cable. This ensures that stringent safety standards are maintainable whilst enabling a network of fluorescent lamps to be easily erected, as and where required, not necessarily by a skilled electrician.

When it is required to move the fluorescent lamps to a different vicinity of a building site, the fluorescent tubes and their back-up equipment are simply unplugged from the adaptors and carried to where they are needed. Such an arrangement is efficient both from the point of view of the amount of cable used and from the point of view of utilisation of electricians' time.

According to a second aspect of the present invention there is provided an electrical connector comprising an elongate electrical conductor having a first adaptor disposed at an end thereof and a plurality of second adaptors disposed in parallel along its length.

Preferably the adaptors disposed along the length of the electrical conductor are each capable of receiving a light source. The light source may be a fluorescent tube.

As a result of this temporary lighting, in the form of self contained boxes with a fluorescent tube and requisite electrical back-up and supply equipment, can be easily connected to the electrical connector.

One advantage of the present invention is that light from a fluorescent tube previously connected can serve to illuminate or partially illuminate an area "ahead" of itself so as a subsequent fluorescent tube may be connected, whilst the current is switched on.

The adaptor disposed at the end of one electrical conductor is preferably a standard plug but it may be of the type connectable to an adaptor disposed along the length of a second electrical conductor. This may be achieved by arranging that electrical adaptors disposed at one or both ends of the electrical conductors are of a male type fitting and electrical adaptors disposed along the length of electrical conductors are of a female type fitting. Of course adaptors disposed at the ends of electrical conductors may be female and those along the length of a conductor may be male.

In an alternative embodiment the adaptor has three, instead of two, lugs disposed around its periphery.

These lugs are disposed in such a manner so as to ensure the connection of an adaptor and holder may only be made in one orientation. This is achieved by disposing bayonets and receptors around the periphery of adaptors and holders in a non symmetrical arrangement.

It may be possible that by accident, or perhaps in the dark, an electrician attempts to insert a male adaptor ino a conventional bayonet holder. Because of the combination of sprung and unsprung electrical contacts full insertion would not be possible. However, in one orientation the two contacts of the adaptor could momentarily touch the live and earth contacts in the holder with the possibility of miscontact. This could result in a "short".

By using three lugs, it is impossible to even partially insert a standard dual bayonet lamp into a three phase and/or higher power adaptor. Thus the third "coding" bayonet guarantees against the partial accidental insertion of a dual contact lamp into a live supply. Although a standard two pin bayonet lamp cannot be inserted into the holder, it could momentarily contact a live and earth contact and cause a short. The adaptor is otherwise identical to that described above.

Embodiments of the present invention will now be described by way of example onlyr and with reference to the figures in which: Figure 1 is a diagrammatical representation of an electrical connector showing first and second type adaptors with a fluorescent tube connected to the connector; Figure 2a is a section showing the mating together of first and second adaptors; Figure 2b is an underplan view of Figure 2a; Figure 3 is a side elevational view of the first adaptor; Figure 4 is an end view of the adaptor of Figure 3; Figure 5 is an end view of a second adaptor; Figure 6 is a side elevational view of the adaptor of Figure 5; Figure 7A is a side elevational view of an adaptor insert; Figure 7B is an end view of the adaptor insert of Figure 7A; Figure 8A is a side elevational view of an adaptor with an additional coding lug;; Figure 8B is an end view of the adaptor of Figure 8A; Figure 9A is an end view of the adaptor holder; and Figure 9B is an end view showing bayonet lugs.

Referring to Figure 1, an electrical cable 10 comprises a three core insulated wire. Along the length of the cable 10 there is disposed six adaptors 11 (shown in detail in Figures 3 and 4). Each adaptor 11 has a solid earth contact 14 and two sprung electrical contacts 16 and 17. Connected to a second type of adaptor 12 is a fluorescent tube 24 and support box 25 which contains the necessary electrical equipment such as starters, fuses and ballast (not shown).

At either end of the electrical cable 10 there may be disposed this second type of adaptor 12. However, a conventional plug may be used.

The second type of adaptor 12 (as shown in Figures.

5 and 6) has two solid electrical contacts 22 and 23 and a sprung earth contact 21. Respective solid and sprung contacts are arranged in so-called mirrored pairs, so that each pair of touching electrical contacts comprises one sprung and one unsprung contact. This arrangement enables only electrical equipment of the same type, having the same dimensions and same spatial arrangement of contacts to be used in conjunction with each other.

Thus for example several connectors having these types of adaptors may be linked together in a so-called network.

Figures 2a and 2b show the mating together of the first adaptor 11 and second adaptor 12. Figure 2a shows in detail how the "mirrored" pairs of reciprocating contacts mutually engage with one another so that only electrical equipment having the same spatial arrangement of electrical contacts may be used in conjunction with the connector 10 or with like equipment. A sheathing 14A which surrounds the electrical earth 14 permits the two adaptors to counter-rotate with respect to one another relatively easily. This is because the end of the sheathing 14A lies flush with the electrical contact 14 and engages the sprung contact 21 on insertion of the bayonet into the connector. The sprung contact is thus depressed on insertion and remains so during the twisting action of connecting. Adaptor 11 has a housing 13. The housing 13 is formed from a plastics material.

Adaptor 12 is also formed from a plastics material and may be connected to a fluorescent tube, to a weather-proof cap or it may be part of another electrical connector 20. In the latter case the connection together of one electrical connector to another, enables a tailor made network of connectors to be produced. Such a network greatly facilitates lighting in dark corridors of buildings under construction or refurbishment. The connectors 10 are re-usable once the network has been dismantled. Also they enable more efficient use of cable as one electrical connector 10 may be joined to another instead of leading all connectors having to lead back to a common power source and connecting them to this in a hap-hazard manner as was previously the case.

Figures 3 and 4 show adaptor 11 with housing 13 removed. A solid electrical earth contact 14 is mounted on a plastics base 15. The plastics base 15 may be injection moulded. Sprung electrical contacts 16 and 17 are also mounted on the base 15. The earth contact 14 is solid and longer than the two other contacts 16 and 17. As a result of this it is impossible to introduce a conventional bayonet filament lamp (not shown) into either adaptor 11 or 12. A separator 18, which may also be of a plastics material, is disposed between the three contacts which are themselves disposed at 1200 from one another. The separator 18 not only gives strength to the adaptor but also isolates the contacts from one another thereby minimising the risk of a short circuit.

Contacts 16 and 17 carry live two phase current.

Figures 5 and 6 show the second adaptor 12 in detail. In Figure 5 the adaptor 11, has a plastics base 19 and two bayonet connectors 20A and 20B are shown. A single sprung electrical earth contact 21 and two solid contacts 22 and 23 are again disposed at 1200 to one another. The spatial arrangement of the contacts 21, 22 and 23 and the bayonet connectors 20A and 20B are such that the adaptors may only be used in one orientation.

This ensures that the correct phase contacts and earth contacts of one adaptor 11 contact those of the other adaptor 12. This is very important when considering that it may be necessary to assemble networks of connectors together in poor visibility or even in pitch darkness.

Because the sprung contacts are flush with their plastic housing, the electrical contact which they touch keeps the spring depressed whilst the two adaptors engage. This is possible because of the manufacturing process of the adaptors. The steps of manufacture involve firstly pressing the brass electrical contacts into the injection moulded plastics housing, then connecting the respective electrical cables and finally encapsulating the adaptor. Similarly the manufacturing of the second type of adaptor involves pressing brass pins into the injection moulded insert and connecting the wires. This pressing of earth pins ensures that they remain flush with the plastics insulating surround.

The adaptors described when used in conjunction with electrical equipment therefor permit quick and simple erection of lighting and/or power facilities for example on working sites or at the scene of a disaster or emergency; they provide a network for safe power transmission which is custom made for the chosen site and ensure efficient utilisation of electricians' time.

Although it is impossible to fully insert a standard two bayonet lamp into the twin bayonet adaptor of the aforementioned embodiment, because of the unsprung earth contact and plastics surround it may be conceivable that by accident, or perhaps in the dark, an electrician could attempt to insert an adaptor into a conventional twin bayonet holder. Because of the combination of sprung and unsprung electrically contacts, full insertion would not be possible. However, in one orientation the two contacts of the lamp could momentarily touch the live and earth contacts in the second type of adaptor, the so-called holder. This would result in a "short", as described above.Figures 8 and 9 show how the adaptor 12 and holder 11 have been modified so as to permit the insertion of only the correct equipment even by accident, by the addition of coding lugs 100A, 100B and 100C and thereby prevent the aforementioned from occurring. This is achieved by adding an extra lug onto the adaptor. The lugs 100 are shown orientated in a trefoil fashion, with two lying at 1800 to one another and the third interposed at 900 to both of them. The disposition of the lugs ensures that the adaptor and holder may only engage (even partially) in one orientation.

Bayonet receptors 102 are similarly oriented so as to receive, the lugs 100. The addition of the extra coding lug 100B is only really necessary with equipment which will be live and into which components may be inserted.

Figure 7 shows an adaptor insert 103. The insert 103 is arranged and shaped to receive sheathed wires.

The wires, are urged into theinsert at the assembly stage. The insert serves to hold the three wires at the correct orientation to one another i.e. at 1200, during the fabrication process. One or more slots 104 or location tags on the insert, mate with a raised groove or sympathetic depression in the adaptor 12 or holder 11. These slots 104 serve to locate the insert 103 with respect to the adaptor 12 or holder 11. The wires (not shown) are therefore held in place during manufacture and do not kink, twist or move away from their respective electrical contacts during the bonding stage when the adaptor or holder is made.

The same reference numerals have been used for figures 7, 8 and 9 as have for the other figures 1-6.

It will be appreciated that the above description has been by way of an example only and that variation may be made to the invention. For example the equipment may be utilised as a permanent way of power transmission and the connectors with adaptors may be fixed permanently to a ceiling or wall. Lighting equipment may therefore be used in conjunction with a network of connectors as and when required.

Claims

1. An adaptor comprising: means for coupling and two electrical contacts, one of the contacts being supported on a resilient support and one of the contacts being supported on a deformable support.

2. An adaptor according to claim 1 having three electrical contacts and wherein two of the contacts are supported on resilient supports.

3. An adaptor according to claim 1 or 2 wherein the deformable support is resiliently deformable.

4. An adaptor according to claim 3 wherein the resiliently deformable support comprises a spring.

5. An adaptor according to claim 3 or 4 wherein the third contact on the resiliently deformable support is an earth contact.

6. An adaptor according to any of claims 2 to 5 wherein the three contacts are spaced at 1200 to each other.

7. An adaptor according to any preceeding claim wherein the means for coupling comprises at least two bayonet lugs.

8. An adaptor according to claim 7 wherein three bayonet lugs are provided.

9. An adaptor according to claim 8 wherein two of the bayonets are disposed at 1800 to one another and the third being disposed at 900 to the other two.

10. An adaptor according to any preceding claim for insertion into a holder.

11. A holder for receiving the adaptor of any of claims 2 to 10.

12. A holder according to claim 11, when dependant on claim 2, having three electrical contacts,two contacts being supported on resiliently deformable members and a third contact being supported on a resilient member.

13. A holder according to claim 12 wherein the resiliently deformable members comprise a spring.

14. A holder according to any of claims 11 to 13 having slots for receiving a bayonet lug.

15. A holder according to claim 14 when dependant on claim 7 having two slots spaced 1800 to one another.

16. A holder according to claim 14 when dependant on claim 9 having three slots; two of the slots being disposed at 1800 to one another and the third being disposed at 900 to the other two.

17. A holder according to any of claims 12 to 16 where the earth contact is supported on the resilient member.

18. A holder according to claim 17 wherein the earth contact is sheathed with an insulating material.

19. An adaptor according to claims 1 to 10 or a holder according to claims 11 to 18 having an insert which is arranged to splay wires so that they are held in a correct configuration.

20. A method of manufacturing an adaptor or a holder comprising the steps of: splaying a three core cable; passing the cable through an orifice of a body portion of the adaptor or holder, clamping the splayed cable with an insert; arranging for the splayed ends of wire to touch respective electrical contacts and bonding the adaptor body portion to the contacts such that the insert is sandwiched between the body portion and the electrical contacts with the splayed ends of wire contacting the electrical contacts.

AMENDMENTS TO THE CLAIMS HAVE BEEN FILED AS FOLLOWS 1. An adaptor comprising: means for coupling and two electrical contacts, one of the contacts being supported on a non-deformable support and one of the contacts being supported on an axially deformable support.

2. An adaptor according to claim 1 having three electrical contacts and wherein two of the contacts are supported on non-deformable supports.

5. An adaptor according to claim 3 or 4 wherein the electrical contact, on the resiliently deformable support, is an earth contact.

8. An adaptor according to claim 7 wherein three bayonet lugs are provided.

9. An adaptor according to claim 8 wherein two of the bayonets are disposed at 1800 to one another and the third is disposed at 900 to the other two.

10. An adaptor according to any preceding claim for insertion into a holder.

11. A holder for receiving the adaptor of claim 2, the holder comprising three electrical contacts, two of the contacts being supported on deformable members and the third being supported on a non deformable member.

12. A holder according to claim 11 wherein the deformable members are resiliently deformable.

13. A holder according to claim 12 wherein the deformable members comprise a spring.

14. A holder according to any of claims 11 to 13 having slots for receiving bayonet lugs.

15. A holder according to claim 14, having two slots spaced 1800 to one another.

16. A holder according to claim 14 having three slots; two of the slots being disposed at 1800 to one another and the third being disposed at 900 to the other two.

17. A holder according to any of claims 11 to 16 wherein an earth contact is supported on the non-deformable member.

18. A holder according to claim 16 wherein the earth contact is sheathed with an insulating material.

19. An adaptor for insertion into a holder so as to connect together at least three electrical contacts, the adaptor and the holder comprising at least one deformable and at least one non-deformable contact and means to orientate the electrical contacts during an on insertion of the adaptor into the holder.