GB2275565A - An electric cable - Google Patents

Abstract

An electric cable structure 1 comprises two cables 2, 3, a jacket of flexible insulating material extruded about the cables 2, 3 to surround each of the cables and maintain them in untwisted generally parallel relation. The jacket is substantially circular in cross-section, being comprised of halves 5, 6 each of a substantially semi-circular cross-section joined together at the central axis of the cable structure by a thin web 7 to permit, if desired, each half 5, 6 of the jacket to be separated from the other. The separated halves each have a flat surface so that they can be mounted easily on a ceiling, wall or floor. <IMAGE>

Description

AN ELECTRICAL CABLE The present invention relates to an electrical cable structure and, in particular, to an electrical cable which comprises two conductors, each enclosed by an insulating layer, generally called a bi-jacket electrical cable.

There are a number of different constructions of bi-jacket electrical cables known in the relevant field.

GB 1,371,211 discloses a cable comprising two or more parallel and coplanar conductors wherein at least one of such conductors has insulation and a rubber or plastics covering, the covering having a uniform wall thickness over a major part of its periphery. The covering encloses the conductors in a single bore and has a cross section made up by arcuate end parts joined by re-entrant intermediate parts. The conductors are individually insulated and are separated by an earth conductor. The cover is not bonded to the conductors or conductor insulation so that stripping of the cable is facilitated.

U.S. Patent No. 3,715,458 discloses an electrical cable in which two separate cables are enclosed within a single extruded jacket, which jacket includes a recess extending along its outer surface equidistant from and parallel with the first and second cables. The recess serves to form a retainer for a further cable inserted therein, if desired.

When in use, it is common to tear apart the two halves of a cable and to have each half lie against a generally flat surface. A major shortcoming of the known prior art is that when the two halves of a cable are separated, each is not in a generally hemispherical cross section and thus it is not readily adapted to be placed onto flat surfaces. Even if the separated halves are made to lie against a flat surface, they are likely to become twisted eventually.

Another disadvantage of known bi-jacket cables lies in the fact that the entire assembly may be perceived as being a cheap and less aesthetically pleasing alternative to a conventional two or three core domestic electrical cable enclosed within a single cylindrical jacket.

The present invention seeks as an object to provide a cable assembly having the advantages of conventional bi-jacket cables but in which, when split, part of each half may be adapted to be placed on a flat surface leaving only a smooth hemispherical outer surface exposed; and when not split the cable looks like a conventional two or three core domestic cable having a one-piece cylindrical jacket.

According to the present invention, there is provided an electrical cable structure comprising first and second cables, a jacket of flexible insulating material extruded about said first and second cables to surround each of the cables and maintain them in untwisted generally parallel relation, characterized in that the jacket is substantially circular in cross section, being comprised of two halves each of a substantially semi-circular cross section, each such half surrounding a respective first or second cable, the two halves being joined together at the central axis of the cable structure by a thin web to permit, if desired, each half of the jacket to be separated from the other, the arrangement being such that when the cables are not separated the cable structure resembles a single electrical cable of a circular cross section.

When each such half of the jacket structure is separated from the other, each may lie substantially flat against a flat surface, e.g. the floor or wall, leaving only a smooth surface exposed.

The invention will now be more particularly described by way of example only with reference to the accompanying drawings, in which: Fig. 1 is a perspective view of an electrical cable structure in accordance with the present invention; and Fig. 2 is a cross section of the electrical cable structure shown in Fig. 1 taken along the line II-II.

Fig. 1 and 2 show an electrical cable structure generally designated as 1 in accordance with the present invention.

The electrical cable structure 1, which is of a substantially circular cross section, comprises a first cable 2 and a second cable 3. The first cable 2 and the second cable 3 are surrounded by a jacket 4 of flexible insulating material which is substantially circular in cross section as a whole. The jacket 4 comprises of two halves 5 and 6, each of a substantially semi-circular cross section.

The two halves 5 and 6 of the jacket 4 are joined together at the central axis of the electrical cable structure 1 by a web 7 to permit easy separation, possibly by hand, of the two halves 5 and 6. At either ends of the web 7, the two halves 5 and 6 are separated by gaps 8 and 9.

When the two halves 5 and 6 are separated from each other, each assumes a substantially semi-circular cross section.

Such a configuration is suitable for the purpose of placing or fixing the separated half 5 or 6 onto flat surfaces, such as the ceiling, walls or the floor, as it avoids further twisting of the separated half 5 or 6. When a separated half 5 or 6 is so secured to a flat surface, only the smooth arcuate surface will be exposed, thus enhancing the aesthetic appearance.

While the drawings show that the shape of the cross section of each of the two halves 5 and 6 is very close to a semi-circle, the exact shape of the jacket 4 and the two halves 5 and 6 will very much depend on the workmanship of the die from which the electrical cable structure 1 is to be extruded. It should also be noted that the electrical cable structure 1 may contract upon cooling after leaving the die, and the two halves 5 and 6 may thus become further apart and the gaps 8 and 9 therebetween widened. Thus, each half 5 or 6 may assume a shape which is less semi-circular than that as shown in the accompanying drawings. It is however the idea of the invention to make the cross section of the jacket 4 as close to a circle as possible and thus the cross section of each of the two halves 5 and 6 as close to a semi-circle as possible, subject to the limitations imposed by molding technology.

If the cable structure 1 twists at all, the gaps 8 and 9 between the two halves 5 and 6 will close thus making the entire cable structure 1 even more like a conventional cylindrical cable.

It should be noted that the above only describes one possible embodiment of the invention and various modifications may be made to the described embodiment without departing from the spirit or scope of the invention.

For example, to avoid unnecessary wastage of insulating materials, each of the cables 2 and 3 may have a generally elliptical flattened cross section to better utilize available insulation.

Claims (3)

1. An electrical cable structure comprising first and second cables, a jacket of flexible insulating material extruded about said first and second cables to surround each of the cables and maintain them in untwisted generally parallel relation, characterized in that the jacket is substantially circular in cross section, being comprised of two halves each of a substantially semi-circular cross section, each such half surrounding a respective first or second cable, the two halves being joined together at the central axis of the cable structure by a thin web to permit, if desired, each half of the jacket to be separated from the other, the arrangement being such that when the cables are not separated the cable structure resembles a single electrical cable of circular cross section.

2. An electrical cable structure according to Claim 1 further characterized in that when each half of the jacket is separated from the other, each is adapted to lie substantially flat against a flat surface, leaving only a smooth arcuate surface exposed.

3. An electrical cable structure substantially as hereinbefore described with reference to and as shown in the accompanying drawings.