Fire-resistant safety cable provided with a single insulating covering

1. A fire-resistant safety cable, comprising:

at least two electrical conductors separated from each other by at least one space; and

an outer jacket;

wherein the cable also comprises a common insulating layer surrounding the at least two electrical conductors and being surrounded by the outer jacket, the common insulating layer filling the at least one space and being formed from at least one polymeric material that is adapted to be converted, at least on a surface of the at least one polymeric material, to a ceramic state at high temperatures in a fire.

2. The cable of claim 1 , wherein the common insulating layer forms a mechanically integral envelope including the at least two electrical conductors.

3. The cable of claim 1 , wherein the common insulating layer has, in cross-section, an external outline that substantially matches a shape of an envelope of the at least two electrical conductors.

4. The cable of claim 1 , wherein the common insulating layer has a thickness that is approximately constant over an external surface of the at least two electrical conductors.

5. The cable of claim 1 , wherein the at least one polymeric material is a polysiloxane.

6. The cable of claim 1 , wherein the at least one polymeric material comprises:

a filler that forms a ceramic under the effect of the high temperatures in a fire.

7. The cable of claim 1 , wherein the at least one polymeric material is expanded.

8. The cable of claim 1 , wherein a material of the outer jacket comprises:

one or more of an ethylene/vinyl acetate copolymer, a polysiloxane, a polyolefin, and a polyvinyl chloride.

9. The cable of claim 1 , wherein a material of the outer jacket comprises:

mineral fillers adapted to be converted to residual ash under the effect of the high temperatures in a fire.

10. The cable of claim 1 , wherein a material of the outer jacket is expanded.

11. The cable of claim 1 , wherein the outer jacket comprises:

several layers of polymeric material or materials.

12. The cable of claim 1 , wherein an external profile of the cable in cross-section is round.

13. The cable of claim 1 , wherein the cable has, in cross-section, at least two substantially plane faces that are substantially parallel to a plane in which axes of the at least two electrical conductors lie.

14. The cable of claim 13 , wherein the cable has an approximately rectangular external profile.

15. The cable of claim 13 , wherein the cable has, in cross-section, two substantially rounded lateral portions that are joined to the at least two substantially plane faces.

16. The cable of claim 1 , wherein the outer jacket has an external outline that substantially matches the common insulating layer.

17. A process for manufacturing the cable of claim 1 , the process comprising:

feeding the at least two electrical conductors into a same extrusion head; and

extruding the at least one polymeric material over the at least two electrical conductors.

18. A fire-resistant safety cable, comprising:

at least two electrical conductors separated from each other by at least one space;

wherein the cable also comprises a common insulating layer surrounding the at least two electrical conductors, the common insulating layer filling the at least one space and being formed from at least one polymeric material that is adapted to be converted, at least on a surface of the at least one polymeric material, to a ceramic state at high temperatures in a fire, and

wherein the cable has, in cross-section, at least two substantially plane faces that are substantially parallel to a plane in which axes of the at least two electrical conductors lie.

19. The cable of claim 18 , wherein the at least one polymeric material is a polysiloxane.

20. The cable of claim 18 , wherein the at least one polymeric material comprises:

a filler that forms a ceramic under the effect of the high temperatures in a fire.