GB2041667A

GB2041667A - Electrical connection box

Info

Publication number: GB2041667A
Application number: GB8001547A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1979-01-18
Filing date: 1980-01-17
Publication date: 1980-09-10
Also published as: GB2041667B

Abstract

An electrical connection box has at least two apertures 12, optionally blanked-off by a removable web of material 11, in the sidewalls 9 thereof for receiving a conduit or armoured cable, and an assembly of nuts 15 removably located relative to the box and interconnected by means of connecting members 16 secured thereto, there being provided one nut 15 for co-operation with each aperture 12. The box may have a channel 13 for maintaining each nut 15 in an operative position relative to its associated aperture 12. The nuts 15 may be engaged with electrical conduits, or with cable glands when armoured cables are to be connected. <IMAGE>

Description

SPECIFICATION Electrical connection box and associated parts thereof This invention relates to electrical connection boxes of the type utilised for connecting electrical cables together and which are, in most instances, desirably waterproof.

Still more particularly, but not exclusively, the invention relates to electrical connection boxes which are made of an electrically insulating material such as a plastics material. In such cases, the problem exists as to the effective electrical interconnection of either electrically conductive conduits which may be connected to the box and which serve, at least to some extent, as an earth conductor, or more importantly cases where armoured cables are connected to such a connection box and the armour wires of the cables must be electrically interconnected to function as an effective earth.

In the latter case, cable glands are utilised to secure the armoured cables to the electrical connection box through apertures provided therefor in the side walls of the box. The cable glands serve to anchor the free ends ofthe armourwires and are, in fact, electrically connected to such armour wires. It is generally considered unsatisfactory to provide conductors which are loose and which interconnect the cable glands on the inside of the electrical connection box to provide continuity between the armour wires of the cables connected to the box.

As a result of this unsatisfactory situation, there has been proposed an electrical connection box having internally screw-threaded sleeves moulded integral therewith and wherein the sleeves of a plurality of apertures to the box are interconnected by electrical conductors also moulded into the plastics material of which the box is manufactured. Such a construction is relatively complex and, whilst serving the required function, has been found to be inadequate when used in conjunction with some cable glands.

The reason for this is that the sole moisture protection provided between the armour wires and the exterior of the assembly is an elastomeric shroud which, when buried underground, often proves to be ineffective over prolonged periods of time. This tends to lead to corrosion of the armour wires and the ultimate problem which can be experienced is that the armour wires become electrically disconnected from the sleeves moulded into the box and thereby open the earth circuit. Should such armour wires become electrically energised due to a fault, a dangerous situation can arise.

Even where the earth continuity is not required, a plurality of separate units can be a nuisance where such is provided.

It is the object of this invention to provide a simplified and more effective electrical box and associated parts for use in conjunction therewith whereby interconnection of earthing sheaths may be achieved if required and the nuisance of a plurality of separate nuts can be avoided.

In accordance with this invention there is provided an electrical connection box having at least two apertures, optionally blanked-off by a removable web of material, in the sidewalls thereof for connection to a conduit or armoured cable, and an assembly of nuts removably located relative to the box and interconnected by means of connecting members secured thereto, there being provided one nut in said assembly thereof for co-operation with each of said apertures in the box and means for maintaining each nut in an operative position relative to its associated aperture.

Further features of the invention provide for the electrical connection box to be moulded from an optionally reinforced electrically insulating plastics material; for the connecting members to be of electrically conductive material; for the nuts of said assembly thereof to be interconnected by means of substantially rigid rods, bars, straps or the like adapted to hole the nuts in fixed spaced relationship relative to each other and in their desired special positions for co-operation with screw-threaded conduits or portions of cable gland assemblies extending through the apertures of the box in use; and for the box to embody locating means adapted to prevent rotation of said nuts relative to their respective apertures.

The assembly of nuts may be interconnected by flexible electrically conductive members if required, and in such a case, lipped channels are preferably provided for locating the nuts relative to the apertures.

The invention also provides an electrical connection box having at least one aperture in the sidewall thereof, optionally closed by means of a removable web of material, and having locating means formed integral with the box to co-operate with a nut adjacent the aperture in a manner preventing rotation thereof in use.

It is further an important feature of the invention that the box have a lid which is screw threaded at or towards its periphery to co-operate with complementary screw-threads on the box itself. The lid may be sealed to the box in the closed condition by an O-ring engaging between the lid and the uppermost edge of the screw-threaded wall of the box.

Preferably the electrical connection box is provided with shallow channel formations which may be inwardly lipped for locating the nuts relative to the apertures, the formations being directed towards an open mouth of the electrical connection box to enable a rigid assembly of nuts to be slid into said channel formations so as to be located opposite their respective apertures. Conveniently, the electrical connection box can assume the conventional circular shape so as to provide a squat cylindrical box whereof one end defines an access aperture and has a lid for co-operation therewith to seal the box in a closed condition when required.

In such a case, the channel formations are directed towards said open end to allow the assembly of nuts, which are rigidly interconnected by means of conductive rods or the like, to be installed in an axial direction.

It is preferred that the electrical connection box be moulded from a suitable plastics material with four equally angularly spaced prospective apertures in the sidewall thereof each of which is sealed in a closed condition by means of a suitable thickness of web of plastics material which can be drilled or broken out if required. In this manner a single electrical connection box can be utilised to connect two, three or four electrically conductive conduits or armoured cables to each other. In each case an appropriate assembly of nuts, interconnected by means of electrically conductive members, can be utilised but it will be appreciated that an assembly of nuts comprised of four such nuts could be utilised in any case to connect two, three or four conduits or cables to each other.

It is envisaged that the broadest application of the invention will be to the interconnection of armoured cables and in such a case the nuts are fabricated to co-operate with portions of cable glands embodying both inner and outer seals for engagement on the outer surface of the inner sheath containing the electrical conductors and the other sheath which houses, within it, the armour wires.

A particular feature of this invention is an assembly of nuts of the above described type and interconnected by means of rigid connecting members whether they be conductive or not and such an assembly of nuts is intended to fall within the scope of this invention as well as such an assembly interconnected by means of flexible, conductive connecting members.

In order that the invention may be more fully understood, one embodiment thereof will now be described with reference to the accompanying drawings in which: Figure 1 is an exploded isometric view of an electrical connection box (with the lid partly sectioned) and an assembly of nuts interconnected by rigid electrically conductive members, and, Figure 2 is a sectional plan view through one aperture of an electrical connection box to which has been attached a cable gland having both an inner and an outer seal.

In the embodiment of the invention illustrated an electrical connection box 1 is moulded from a suitable electrically insulating plastics material, preferably reinforced with glass fibres, and assumes the conventional circular shape so as to define a squat cylindrical box. One end of the box is open and is adapted to be sealed in a closed condition by means of a lid 2 secured thereto by means of screw-threads 3 co-operating with complementary screw-threads 4 provided on the outer surface of the cylindrical wall of the box. An O-ring seal 5 is located in a groove 6 in the lid to co-operate, in the closed condition with the edge 7 of the box.

The closed end wall 8 of the box is substantially planar and is moulded integral with the sidewalls 9 of the box. There is, however, ridges 10on the inside of the end wall for defining the positions of the conductors interconnecting the nuts as described below.

There are moulded into the sidewalls 9 of the box four equally angularly spaced formations adapted to define apertures through the sidewall of the box in use when required. Each of these formations initially is closed by means of a web or wall 11 of plastics material moulded integral with the sidewall and each of which is capable of being broken or drilled out easily to form an aperture 12.

In the illustrated embodiment of the invention three of such webs of material have been removed so that three armoured cables or conductive conduits can be connected to this particular box.

Located on each side of the aperture or prospective aperture in each case is a formation 13 extending parallel to the axis of the cylindrical housing.

Each pair of formations 13 defines a shallow channel shape dimensioned to receive therebetween the flats 14 of an electrically conductive nut 15 of conventional shape and dimensions. The composite, channelshaped, formation is dimensioned to receive such a nut neatly in position with the formations 13 locating the flats 14 of each nut.

As mentioned above, the particular embodiment being described is adapted to be connected to three conduits or armoured cables, and in this instance, three such nuts 15 are provided. These nuts are rigidly interconnected by means of suitably electrically conductive bars or rods 16 which have their ends welded or otherwise electrically conductively secured to the nuts to hold them in fixed spaced relationship relative to each other. The nuts are held in position so that they will all simultaneously be capable of being slid axially into their respective channel-shaped formations so as to locate each nut opposite its co-operating aperture 12.

It will be understood that where only two such nuts can be provided and likewise where four nuts are required an assembly of four electrically interconnected nuts can be provided. The nut assemblies can easily be manufactured by locating the nuts in a suitable jig and welding the electrically conductive interconnecting members 16 thereto, and to each other where required.

In use with the nuts suitably located opposite their respective apertures electrical conduits can easily be connected thereto simply by rotating the conduit to engage the nut and then tightening a nut on the exterior of the box so as to clamp a sealing washer between it and the external surface of the box.

However, it is envisaged that the broadest application of the invention will be to the securing of armoured cables to the electrical connection box and in such a case, cable glands of the type illustrated in Figure 2 of the accompanying drawings are preferred. As shown, such cable glands 17 each have an externally screw-threaded sleeve or spigot 18 passing through the aperture 12 in the box to co-operate with the respective nut 15.

A sealing washer 19 is provided between a portion 20 of the cable gland and the outer surface of the electrical connection box to provide an effective seal relative thereto.

Each cable gland further embodies an inner seal 21 and an outer seal 22 for engagement with the inner sheath containing the electrical conductors and the outer sheath which houses the armour wires of the cable. Between the two seals an armour clamp 23 is provided.

Whilst it is not considered to be essential, there may ne provided, for use with such a cable gland, a conventional elastomeric shroud which, at one end thereof sealingly engages the outer surface of the outer sheath of a cable, and at the other end thereof engages a groove (not shown) surrounding the aperture in the box.

It will be understood that the above type of electrical box assembly will be highly effective in use, simple to manufacture, and provide the additional advantage that during assembly of the cable glands on to the box, the nuts need not be held to prevent rotation thereof. It will therefore also be understood that even where the members 16 interconnecting the nuts are made of a non-electricaliy conductive material, the assembly of nuts provides a distinct advantage over the prior art electrical box assemblies in that the nuts need not be held in order to prevent rotation thereto. The nut assemblies therefore form an important feature of the invention and are, in themselves, considered to form a part of this invention.

It will be understood that numerous variations may be made to the above described embodiment of the invention without departing from the scope hereof. For example, the formations 13 may be omitted completely if required in which case the members 16 interconnecting the nuts can be relied upon to locate the nuts relative to each other.

Alternatively the formations may have inwardly lipped edges to locate the reverse side of each nut, if required, and and particularly where flexible conductive connecting member are used. Also the electrical connection box may be, if desired, made of an electrically conductive material, without totally detracting from advantages provided by this invention.

Finally, the electrical connection box may have an aperture in the closed end 8 thereof for connection to a cable or conduit. In such a case a nut for co-operation with an aperture in the sidewall could have a conductor secured thereto and a washer or nut located relative to the first mentioned nut so as to be located opposite the aperture in said closed end.

Claims

1. An electrical connection box having at least two apertures optionally blanked-off by a removable web of material, in the sidewalls thereof for connection to a conduit or armoured cable, and an assembly of nuts removably located relative to the box and interconnected by means of connecting members secured thereto, there being provided one nut in said assembly thereof for co-operation with each of said apertures in the box and means for maintaining each nut in an operative position relative to its associated aperture.

2. An electrical connection box as claimed in claim 1 in which the box is moulded from electrically insulating plastics material.

3. An electrical connection box as claimed in claim 2 in which the plastics material is reinforced with glass fibres.

4. An electrical connection box as claimed in any one of the preceding claims in which the nuts of said assembly are interconnected by means of substantially rigid rods, bars, straps or the like adapted to hold the nuts in fixed spaced relationship relative to each other with the individual nuts adjacent their respective apertures.

5. An electrical connection box as claimed in any one of the preceding claims in which means are provided for preventing rotation of the nuts relative to their respective apertures.

6. An electrical connection box as claimed in any one of the preceding claims in which the box is of a squat shape having formations extending away from the open mouth thereof and adapted to co-operate with a nut assembly to locate the nuts thereof relative to their respective apertures.

7. An electrical connection box as claimed in any one of the preceding claims in which a lid is provided and the lid and box have complementary screwthreads whereby the lid can be screwed on to the box.

8. An electrical connection box as claimed in claim 7 in which the lid has an O-ring seal therein adapted to co-operate with the edge of the cooperating screw-threaded part of the box.

9. An electrical connection box substantially as herein described or exemplified with reference to the accompanying drawings.

10. An electrical connection box having at least one aperture in the sidewall thereof, optionally closed by means of a removable web of material, and having locating means formed integral with the box to co-operate with a nut adjacent the aperture in a manner preventing rotation thereof in use.

11. An electrical connection box particularly adapted to receive an assembly of nuts to define a connection box as claimed in any one of claims 1 to 9.

12. An assembly of nuts, interconnected by means of connecting members and particularly adapted to form part of an electrical connection box as claimed in any one of claims 1 to 9.