GB2224168A

GB2224168A - Fused electrical accessory

Info

Publication number: GB2224168A
Application number: GB8920048A
Authority: GB
Inventors: Brian Dunlop
Original assignee: MasterPiece Cabinets Ltd
Current assignee: MasterPiece Cabinets Ltd
Priority date: 1988-09-14
Filing date: 1989-09-05
Publication date: 1990-04-25
Anticipated expiration: 2009-09-05
Also published as: GB8920048D0; GB8821524D0; GB2224168B

Abstract

In an electrical accessory (1) provided with fusing, an improved fuse carrier (9) to prevent accidental electrocution, the fuse carrier having a lower platform 13, 15 affording isolation of the fuse from contact with terminals (39) therefor until the fuse carrier is disposed in the housing by an amount then shielding external access to the fuse. An upper platform 19 and cover part 23 assist in this regard. Stepped side parts (25) of the fuse holder provide for snap-in retention of same in the electrical accessory (1) and secure location. The fuse holder is frictionally held more firmly so it is partially withdrawn for fuse charging. <IMAGE>

Description

Title: Fused Electrical Accessory DESCRIPTION The present invention relates to a fused electrical accessory, especially for mains use.

Regulations dictate the provision of fusing in electrical accessories for which the live conduction path of such as a mains plug is broken by spaced terminals providing for snap-fitting therebetween of a cartridge type fuse, typically cylinderical, to make connection therebetween for normal/intended current carrying capacity and to break connection if desired current/ampage is exceeded.

Increasing attention is being paid to provisions of such fusing with safety in mind also avoiding actual disassembly of any electrical component, be it plug, socket or other fused accessory, for which an externally accessible fuse carrier has been proposed facilitating insertion and removal of a fuse.

A known fuse carrier comprises a loop-like holder for a cartridge fuse facilitating insertion of a fuse for making electrical contact with connections therefor, and also facilitating insertion/removal as a push/pull action. The holder has a plate providing closure of aperturing in the accessory. In providing such a fuse carrier safety considerations dictate provision of shielding to inhibit contact with electrically conducting parts by the person even accidentally as far is practicable. This is especially important for electrical accessories which could be connected when the fuse is being accessed. On removal of the known carrier uninterrupted access is given to the fuse terminals which presents a potential safety hazard.Furthermore, with the simple loop type fuse holder following intrinsically unsafe installation procedures i.e. with mains connected, could present a potential hazard as rocking of the fuse could result in its energisation while still within hand contact. It is the aim of the present invention to overcome the above mentioned problems.

According to the present invention then an electrical accessory provided with fusing comprises a housing having therein terminals for receiving therebetween a fuse (such as a cartridge type fuse in common use in mains electrical accessories), a fuse carrier slidably received in the housing by way of aperturing and cooperably engagable with the fuse, and wherein the fuse carrier has a lower platform affording isolation of the fuse from contact with the terminals until the fuse carrier is disposed in the housing by an amount then shielding external access to the fuse.

Particularly convenient is to have the fuse received in an elongated tube-like housing of the fuse carrier providing for freedom of movement of the fuse in the installation direction, also to have the lower platform extend in length by an amount substantially corresponding to the length of the fuse, certainly to an extent to cover the fuse receiving terminals although possibly wasted therebetween. Each of the fuse terminals is preferably formed as a claw-like connection and it is preferred to have the lower platform dimensioned for passage between the gripping limbs of each terminal.More preferably the width of the platform is slightly greater than the free width of the terminals so that on installation the lower platform forces apart the terminals also usefully serving as a stop for fuse installation purposes and also advantageous in assisting in introducing the fuse into its installed position.

It is also preferred to have an upper platform or shield effectively as an extension of the upper boundary of the elongate tube-like housing. That platform also extends in length by an amount corresponding substantially to the length of the fuse and preferably with a width to obstruct access to the fuse through the aperturing.

The fuse carrier has a grip part also providing a closure for the aperturing when fully pushed home and with the closure spaced above the upper platform.

A further advantageous feature is to have the fuse carrier received captively in the housing and slidable between a fuse installed position and a position disconnecting the fuse and allowing replacement. This can be conveniently referred to as a fuse inserted position and a fuse installation position and is conveniently achieved by providing at least one mutually engagable lug or shoulder between the fuse carrier and the housing. More preferably lugging is disposed to opposite sides of the fuse holder i.e.

flanking the fuse. A particularly convenient construction results from a pair of oppositely disposed shoulders on the fuse carrier arranged to abut with shoulders of the housing generally bounding the aperturing. It is particularly advantageous if the shouldering has a tapered lead to permit snap-fitting of the carrier through aperturing then preventing removal.

In order to stabilise the fuse carrier in particular to resist rocking thereof, the fuse carrier and housing have mutually engagable guide channels conveniently provided by slotting to wall and to housing flanking the fuse and extending into the housing from the aperturing. Slotting is conveniently engaged by end faces by the aforesaid shoulders. We also find it advantageous to have that slotting tapered, actually converging towards the aperturing in the housing so as to provide increasing grip between the fuse carrier and housing when moving the fuse carrier from the installed position. We also find it convenient to have the cross-section of fuse carrier tapered to its external surface, preferably stepped, so as to provide increasing sideways location on withdrawal of the fuse holder by cooperation with a housing part bounding the aperture.Tapering in the two planes inhibits rocking of the fuse carrier in its withdrawn position both longitudinally and transverse relative to fuse direction.

The present invention will now be described further, by way of example only, with reference to the accompanying drawings; in which: Figure 1 is a perspective view of a fuse holder, Figure 2 is a fragmentary perspective view of an electrical accessory housing, and Figure 3 is a cross-sectional view of a fuse holder assembled in a housing showing the fuse holder raised permitting insertion and removal of the fuse disconnected from the fuse terminal.

Referring to the drawings a part of an electrical accessory 1 having fusing is shown in Figure 2 broken away to show aperturing 3 generally rectangular having four sides as walls 3a, b, c or as rib 3d extending away therefrom two of which 3a, 3b are provided with slightly tapered slots 5 leading to an upper ledge 7.

The boundaries to the slots 5 define ribs 8 which converge to their upper ends when viewed in the transverse direction i.e. through the cross-section of the fuse. The aperturing can be incorporated into any electrical accessory be it plug or socket which is required to be provided with fusing. A fuse carrier 9 is shown in perspective in Figure 1 and comprises an elongate tube-like part 11 with arcuate ends dimensioned to receive a cylindrical fuse shown dotted, with clearance for movement in the direction shown by the arrow A. The fuse carrier has a lower platform provided in part by the lower end of the elongate tubular part and/or ribbing thereof and by extensions thereof 13, 15. The lower platform has a length corrresponding substantially to that of the fuse to be installed and a chordal width slightly smaller than the diameter of the fuse.As shown the platform is reinforced by elongate rib 17 running along the length thereof. The upper bondary of the elongate tubular part forms part of an upper platform or shield 19 formed by outward extensions of the upper boundary of arcuate configuration, and having length and width corresponding substantially to that of the lower platform.

The fuse carrier has a grip part 21 formed by a closure 23 corresponding in size and shape to the aperturing to be received therein and spaced above the upper platform by webb parts both longitudinal 20 and transverse 22. Also shown is a shoulder 25 with tapered lead 27, seen more clearly from Figure 3.

The fuse carrier is dimensioned to be received slidably within the side parts 3a, b, c, d depending from around the aperturing 3 between a first position in which the closure plate 23 is substantially planar with the top surface 31 of the housing received within the aperturing 3 and a raised position as shown in Figure 3 in which the fuse may be introduced and/or removed from the elongate carrier, actually inserted endwise and slid into position. In the raised position the the shoulders 25 to opposite sides of the fuse carrier abut against the shoulders 7 of the housing so limiting the upward movement of the fuse carrier and ensuring that it is retained captive to the accessory.

On first introduction of the fuse carrier into the housing the tapered shoulders 27 serve to force apart the side walling of the housing allowing the shoulders to pass past the abutments 7 whereupon the resilience of the housing causes it to close round the fuse holder which is then retained captively in place. It will be seen from Figure 3 that the external shape of the fuse holder in cross-section is generally tapered actually as steps and that the external side surfaces of the fuse holder are dimensioned to contact the inner sides 8 of the web like reinforcing edges to slots 5 by an increasing amount as the fuse carrier is pulled up.

This provides lateral stability for the fuse carrier.

It should also be noted that opposite end faces 35 of the central loop of the carrier and shoulders 25 are arranged to cooperate with tapered sides 37 of the slottings 5 in the housing. This cooperation increases as the fuse carrier is pulled out to provide longitudinal stability for the carrier.

From Figure 3 it will be seen that the fuse terminals comprise generally claw like parts 39 which are longer than that required simply to accommodate the fuse and this provides to accommodate the lower platform. The chordal width of the lower platform is slightly greater than the end spacing of the terminals 39 and serves to force these apart as the fuse carrier is pressed downwardly. This also serves to provide a resistance to downward movement thereby ensuring that the lower platform is spaced above the terminals on introduction of the fusing and can also serve to assist in introduction of the fusing by initially splaying apart of the terminals.

Claims

1. An electrical accessory provided with fusing comprises a housing having therein terminals for receiving therebetween a fuse (such as a cartridge type fuse in common use in mains electrical accessories), a fuse carrier slidably received in the housing by way of aperturing and cooperably engageable with the fuse, and wherein the fuse carrier has a lower platform affording isolation of the fuse from contact with the terminals until the fuse carrier is disposed in the housing by an amount then shielding external access to the fuse.

2. An electrical accessory as claimed in claim 1 in which the fuse is received in an elongated tube-like housing of the fuse carrier providing for freedom of movement of the fuse in the installation direction.

3. An electrical accessory as claimed in claim 1 or 2 in which the lower platform extends in length by an amount substantially corresponding to the length of the fuse.

4. An electrical accessory as claimed in any one of claims 1, 2 or 3 in which each of the fuse terminals is formed as a claw-like connection and the lower platform dimensioned for passage between the gripping limbs of each terminal.

5. An electrical accessory as claimed in any one of claims 1 to 4 in which the width of the platform is slightly greater than the free width of the terminals so that on installation the lower platform forces apart the terminals also serving as a stop for fuse installation purposes.

6. An electrical accessory as claimed in any one of claims 1 to 5 in which the fuse carrier further comprises an upper platform or shield effectively as an extension of the upper boundary of the elongate tube-like housing which platform extends in length by an amount corresponding substantially to the length of the fuse.

7. An electrical accessory as claimed in claim 6 in which said upper platform or shield is of a width to obstruct access to the fuse through the aperturing.

8. An electrical accessory as claimed in claims 6 or 7 in which the fuse carrier has a grip part also providing a closure for the aperturing when fully pushed home and with the closure spaced above the upper platform.

9. An electrical accessory as claimed in any one of the preceding claims in which the fuse carrier received captively in the housing and slidable between a fuse installed position and a position disconnecting the fuse and allowing replacement.

10. An electrical accessory as claimed in claim 9 in which captive retention of the fuse carrier is provided by means of at least one mutually engageable lug or shoulder between the fuse carrier and the housing.

11. An electrical accessory as claimed in claim 10 in which lugging is disposed to opposite sides of the fuse holder i.e. flanking the fuse.

12. An electrical accessory as claimed in claim 11 in which the lugging comprises a pair of oppositely disposed shoulders on the fuse carrier arranged to abut with shoulders of the housing generally bounding the aperturing.

13. An electrical accessory as claimed in claim 12 in which the shouldering has a tapered lead to permit snap-fitting of the carrier through the aperturing then preventing removal.

14. An electrical accessory as claimed in any one of the preceding claims in which, in order to stabilise the fuse carrier in particular to resist rocking thereof, the fuse carrier and housing have mutually engageable guide channels conveniently provided by slotting to wall and to housing flanking the fuse and extending into the housing from'the aperturing.

15. An electrical accessory as claimed in claim 14 in which said slotting is conveniently engaged by end faces by the aforesaid shoulders.

16. An electrical accessory as claimed in claim 14 or 15 in which said slotting is tapered, actually converging towards the aperturing in the housing so as to provide increasing grip between the fuse carrier and housing when moving the fuse carrier from the installed position.

17. An electrical accessory as claimed in any preceding claim in which the cross-section of fuse carrier is tapered to its external surface so as to provide increasing sideways location on withdrawal of the fuse holder by cooperation with a housing part bounding the aperture.

18. An electrical accessory as claimed in claim 17 in which said tapered external surface of the fuse carrier is tapered stepwise.

19. An electrical accessory when provided with a fuse carrier constructed and arranged substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

20. A fuse carrier for an electrical accessory constructed and arranged substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.