ELECTRICAL WIRING CONTAINMENT AND PROTECTION SYSTEM AND METHOD

Abstract: Electrical wiring that is run through a conduit in a fuel tank of an aircraft is protected by covering the electrical wiring with a material having sufficient size so as to substantially center the electrical wiring within the conduit and/or eliminate relative movement between the electrical wiring and the conduit. The material may be thermoplastic. The covering may be provided in layers for different sizes of conduits. An interior surface of the conduit may be a low friction material.

Description: ELECTRICAL WIRING CONTAINMENT AND PROTECTION SYSTEM AND METHOD Technical Field of the Invention The present invention relates to an electrical wiring containment and protection system and method. Background of the Invention Various wiring configurations are used to route electrical wiring for a diversity of applications. For exam¬ ple, in an aircraft application, a typical wiring configura¬ tion includes a metal conduit which is connected to end fit- ting assemblies that secure and seal the metal conduit to structural points in and about an aircraft's fuel tanks. These metal conduits are provided in various sizes and have various bends depending upon the application in which the metal conduits are installed. Currently, electrical wiring, usually provided in bundles, is routed through the metal conduit. The electrical wiring may include, for example, a bundle of single conduc¬ tors, where each conductor is covered with its own extruded dielectric barrier. An additional insulating layer, such as PTFE shrink tubing, may be added over the bundle of individual conductors. Under certain conditions, the metal conduit may chafe the wiring bundle. Over time, this chafing can wear away the insulation or dielectric barrier of the electrical wiring thereby exposing the metal conductors. As a result, electrical shorts, sparks, or arcing may occur when an exposed conductor comes into contact with another exposed conductor or with the inside surface of the metal conduit in which the electrical wiring is run. Any electrical short or spark in this area can cause system failure. One of the conditions that causes this chafing is vibration. Vibration causes the electrical wiring to displace relative to the inside surfaces of the conduit in which the electrical wiring is run to the point where the electrical wiring impacts the interior walls of the conduit . Frequent impact over time damages the wiring and chafes the insulation and dielectric barrier that encases the conductors of the electrical wiring. Also, chafing may result when the electrical wiring is inserted through a metal conduit that has bends and that has an inside surface with imperfections. The present invention is arranged to solve one or more of the above noted problems . Summary of the Invention According to one aspect of the present invention, a method of protecting electrical wiring running through a conduit comprises the following steps: a) inserting the electrical wiring through a material having sufficient size to substantially center the electrical wiring within the conduit; and b) inserting the material through the conduit . According to another aspect of the present inven¬ tion, a wiring assembly comprises a metal conduit, insulated electrical wiring within the metal conduit, and a thermoplas¬ tic covering. The thermoplastic covering surrounds the insu¬ lated electrical wiring, and the thermoplastic covering pro¬ vides dielectric resistance between the insulated electrical wiring and the metal conduit . According to still another aspect of the present invention, a method of protecting electrical wiring that is run through a conduit comprises the following steps : a) inserting the electrical wiring through a material arranged to substantially eliminate relative movement between the electri- cal wiring and the conduit; and b) inserting the material through the conduit . According to yet another aspect of the present invention, a method of protecting electrical wiring that is run through a conduit comprises the following steps: a) coating an interior surface of the conduit with a low friction coating material; and b) inserting the electrical wiring through the coated conduit . According to a further aspect of the present inven¬ tion, a wiring assembly comprises electrical wiring and a covering. The covering is around the electrical wiring, and the covering has sufficient size to substantially center the electrical wiring within a conduit. According to a still further aspect of the present invention, a wiring assembly comprises electrical wiring and a covering. The covering is around the electrical wiring, and the covering is arranged so that relative movement between the electrical wiring and a conduit is substantially eliminated. According to yet a further aspect of the present invention, a wiring assembly comprises a conduit and electri¬ cal wiring within the conduit . An interior surface of the conduit is a low friction material. Brief Description of the Drawing These and other features and advantages will become more apparent from a detailed consideration of the invention when taken in conjunction with the drawings in which: Figure 1 shows protective tubing which is used in accordance with the present invention in order to protect electrical wiring within conduits; and, Figure 2 shows a wiring assembly in which electrical wiring, that is routed through a conduit, is protected by the protective tubing of Figure 1. Detailed Description of the Invention As shown in Figures 1 and 2, a wiring assembly 10 includes electrical wiring 12, a first protective tubing 14, a second protective tubing 16, and a conduit 18. The electrical wiring 12, for example, may comprise single copper conductors each of which has its own its own dielectric insulator. The electric wiring 12 may be surrounded by an additional insulat¬ ing sleeve such as PTFE shrink tubing 21. The first and second protective tubing 14 and 16 are preferably, but not necessarily, constructed of similar material and are prefera¬ bly flexible to permit the first and second protective tubing 14 and 16 to bend as they are run through the conduit 18. The first and second protective tubing 14 and 16, for example, may each comprise a high profile thermoplastic tubing, where the outside diameter of the second protective tubing 16 may be greater than about twice its inside diameter. Also, the second protective tubing 16 may be convolutional having a pitch of about two turns per inch. The outside diameter of the first protective tubing 14 may be substan¬ tially equal to the inside diameter of the second protective tubing 16. The outside to inside diameter ratio of the first protective tubing 14 is dependent upon the size of the wiring bundle that it is to contain. The first protective tubing 14 may also be convolutional and, generally, the pitch of the first protective tubing 14 may be greater than the pitch of the second protective tubing 16. The material that is used for the first and second protective tubing 14 and 16 is pref¬ erably arranged to provide dielectric resistance between the electrical wiring 12 and the interior of the conduit 18. The conduit 18, for example, may be stainless steel and/or alumi- num tubing. The electrical wiring 12 is run through the first protective tubing 14, and the combination of the electrical wiring and the first protective tubing 14 is run through the second protective tubing to form a wiring subassembly 20. The wiring subassembly 20 is then run through the conduit 18. Without the protection of the first and second protective tubing 14 and 16, vibration of the wiring assembly 10 tends to cause the conduit 18 to chafe away the insulation of the electrical wiring 12 exposing the conductors thereof . As noted above, exposing the conductors of the electrical wiring 12 can lead to shorting, arcing, and/or sparking which could cause system failure. However, the first and second protective tubing 14 and 16 avoid this chafing because the first and second protec¬ tive tubing 14 and 16 substantially eliminate relative move¬ ment between the electrical wiring 12 and the conduit 18. Accordingly, the sizes of the first and second protective tubing 14 and 16 are chosen so that the wiring subassembly 20 takes up substantially all of the interior space of the con¬ duit 18 thereby preventing relative movement between the electrical wiring 12 and the conduit 18. As shown in Figure 2, the conduit 18 has an interior dimension which is larger than the outer dimension of the first protective tubing 14. Accordingly, the second protec¬ tive tubing 16 is added to the wiring subassembly 20. How¬ ever, the use of concentric layers of protective tubing de¬ pends upon the interior dimension of the metal conduit and the available protective tubing. If the interior dimension of the conduit 18 is small enough, or if the available protective tubing is large enough, a single protective tubing having an outer dimension arranged to substantially fill the conduit 18 may be used. Although the first and second protective tubing 14 and 16 may be arranged to position the electrical wiring 12 at any distance from the interior of the conduit 18, it is pref¬ erable that the first and second protective tubing 14 and 16 be arranged to center the electrical wiring 12 within the conduit 18. Accordingly, the spacing and dielectric resis¬ tance between the electrical wiring 12 and the conduit 18 is substantially uniform throughout the length of the wiring assembly 10. As a result of the above arrangement, relative movement between the electrical wiring 12 and the conduit 18 is substantially eliminated, the electrical wiring 12 is consistently centered along the length of the conduit 18, and dielectric resistance is provided between the electrical wiring 12 and the interior of the conduit 18. Therefore, chafing of the electrical wiring 12 is substantially elimi¬ nated so that electrical shorts and sparks from bare conduc- tors do not occur. Certain modifications of the present invention have been discussed above. Other modifications will occur to those practicing in the art of the present invention. For example, in order to reduce friction and possible chafing between the second protective tubing 16 and the conduit 18, the interior of the conduit 18 may be provided with a Teflon or other low friction coating 22. Alternatively, the conduit 18 may be a low friction conduit or may be provided with a low friction insert . Also, the insertion of the electrical wiring 12 through the first and second protective tubing 14 and 16 and the insertion of the first and second protective tubing 14 and 16 through the conduit 18 may occur in any desired order. For example, as described above, the electrical wiring 12 is inserted through the first protective tubing 14, the first protective tubing 14 is then inserted through the second protective tubing 16, and the second protective tubing 16 is then inserted through the conduit 18. However, this order may be reversed so that the second protective tubing 16 is first inserted through the conduit 18, the first protective tubing 14 is then inserted through the second protective tubing 16, and the electrical wiring 12 is then inserted through the first protective tubing 14. Other orders are possible. Moreover, although the first and second protective tubing 14 and 16 are shown as cylindrical tubing, tubing having other shapes may be used for the first and second protective tubing 14 and 16. Furthermore, material other than tubing may be used. Accordingly, the description of the present inven- tion is to be construed as illustrative only and is for the purpose of teaching those skilled in the art the best mode of carrying out the invention. The details may be varied sub¬ stantially without departing from the spirit of the invention, and the exclusive use of all modifications which are within the scope of the appended claims is reserved.

Claims: WHAT IS CLAIMED IS: 1. A method of protecting electrical wiring running through a conduit comprising the following steps: a) inserting the electrical wiring through a mate- rial having sufficient size to substantially center the elec- trical wiring within the conduit; and, b) inserting the material through the conduit. 2. The method of claim 1 wherein step a) comprises the step of inserting the electrical wiring through a thermo- plastic material having sufficient size to substantially center the electrical wiring within the conduit. 3. The method of claim 1 wherein step a) comprises the step of inserting the electrical wiring through layers of material which collectively have sufficient size so as to substantially center the electrical wiring within the conduit. 4. The method of claim 1 wherein step a) comprises the step of inserting the electrical wiring through layers of thermoplastic material which collectively have sufficient size so as to substantially center the electrical wiring within the conduit . 5. The method of claim 1 wherein step a) comprises the step of inserting the electrical wiring through the mate- rial so as to substantially eliminate relative movement be- tween the electrical wiring and the conduit. 6. The method of claim 1 wherein an interior sur- face of the conduit is a low friction material. 7. The method of claim 1 wherein the material has a high profile. 8. The method of claim 1 wherein the material is convolutional. 9. A wiring assembly comprising: a metal conduit; insulated electrical wiring within the metal con- duit; and, a thermoplastic covering surrounding the insulated electrical wiring, wherein the thermoplastic covering provides dielectric resistance between the insulated electrical wiring and the metal conduit . 10. The wiring assembly of claim 9 wherein the thermoplastic covering has sufficient size so as to substan- tially center the insulated electrical wiring within the metal conduit . 11. The wiring assembly of claim 9 wherein the thermoplastic covering comprises layers of the thermoplastic covering. 12. The wiring assembly of claim 9 wherein the thermoplastic covering is arranged to substantially eliminate relative movement between the insulated electrical wiring and the metal conduit . 13. The wiring assembly of claim 9 wherein an interior surface of the metal conduit is a low friction mate- rial . 14. The wiring assembly of claim 9 wherein the thermoplastic covering has a high profile. 15. The wiring assembly of claim 9 wherein the thermoplastic covering is convolutional. 16. A method of protecting electrical wiring that is run through a conduit comprising the following steps: a) inserting the electrical wiring through a mate- rial arranged to substantially eliminate relative movement between the electrical wiring and the conduit; and, b) inserting the material through the conduit. 17. The method of claim 16 wherein step a) com- prises the step of inserting the electrical wiring through a thermoplastic material so as to substantially eliminate rela- tive movement between the electrical wiring and the conduit . 18. The method of claim 16 wherein step a) com- prises the step of inserting the electrical wiring through layers of material so as to substantially eliminate relative movement between the electrical wiring and the conduit. 19. The method of claim 16 wherein step a) co - prises the step of inserting the electrical wiring through layers of thermoplastic material so as to substantially elimi- nate relative movement between the electrical wiring and the conduit . 20. The method of claim 16 wherein an interior surface of the conduit is a low friction material. 21. The method of claim 16 wherein the material has a high profile. 22. The method of claim 16 wherein the material is convolutional. 23. A method of protecting electrical wiring that is run through a conduit comprising the following steps: a) coating an interior surface of the conduit with a low friction coating material; and, b) inserting the electrical wiring through the coated conduit . 24. The method of claim 23 further comprising the step of inserting the electrical wiring through a material so as to substantially eliminate relative movement between the electrical wiring and the conduit. 25. The method of claim 23 further comprising the step of inserting the electrical wiring through a material so as to substantially center the electrical wiring within the conduit . 26. The method of claim 25 wherein the material has a high profile. 27. The method of claim 25 wherein the material is convolutional. 28. The method of claim 23 further comprising the step of inserting the electrical wiring through layers of material so as to substantially eliminate relative movement between the electrical wiring and the conduit . 29. The method of claim 23 further comprising the step of inserting the electrical wiring through layers of material so as to substantially center the electrical wiring within the conduit. 30. The method of claim 23 further comprising the step of inserting the electrical wiring through a thermoplas- tic material so as to substantially eliminate relative move- ment between the electrical wiring and the conduit . 31. The method of claim 23 further comprising the step of inserting the electrical wiring through a thermoplas- tic material so as to substantially center the electrical wiring within the conduit . 32. A wiring assembly comprising: electrical wiring; and, a covering around the electrical wiring, wherein the covering has sufficient size to substantially center the electrical wiring within a conduit . 33. The wiring assembly of claim 32 wherein the covering is a thermoplastic material having sufficient size to substantially center the electrical wiring within the conduit running . 34. The wiring assembly of claim 32 wherein the covering comprises layers of material which collectively have sufficient size so as to substantially center the electrical wiring within the conduit . 35. The wiring assembly of claim 32 wherein the covering comprises layers of thermoplastic material which collectively have sufficient size so as to substantially center the electrical wiring within the conduit . 36. The wiring assembly of claim 32 wherein the covering is arranged so as to substantially eliminate relative movement between the electrical wiring and the conduit . 37. The wiring assembly of claim 32 further com- prising a low friction material forming an interior surface of the conduit . 38. The wiring assembly of claim 32 wherein the covering has a high profile. 39. The wiring assembly of claim 32 wherein the covering is convolutional. 40. A wiring assembly comprising: electrical wiring; and, a covering around the electrical wiring, wherein the covering is arranged so that relative movement between the electrical wiring and a conduit is substantially eliminated. 41. The wiring assembly of claim 40 wherein the covering is a thermoplastic material. 42. The wiring assembly of claim 40 wherein the covering comprises layers of material which collectively are arranged so that relative movement between the electrical wiring and the conduit is substantially eliminated. 43. The wiring assembly of claim 40 wherein the covering comprises layers of thermoplastic material which collectively are arranged so that relative movement between the electrical wiring and the conduit is substantially elimi- nated. 44. The wiring assembly of claim 40 wherein the covering is arranged so as to substantially center the elec- trical wiring within the conduit . 45. The wiring assembly of claim 40 further com- prising a low friction material forming an interior surface of the conduit . 46. The wiring assembly of claim 40 wherein the covering has a high profile. 47. The wiring assembly of claim 40 wherein the covering is convolutional. 48. A wiring assembly comprising: a conduit, wherein an interior surface of the con- duit is a low friction material; and, electrical wiring within the conduit. 49. The wiring assembly of claim 48 further com- prising a covering surrounding the electrical wiring, wherein the covering is arranged so as to substantially eliminate relative movement between the electrical wiring and the conduit 50. The wiring assembly of claim 49 wherein the covering has a high profile. 51. The wiring assembly of claim 49 wherein the covering is convolutional. 52. The wiring assembly of claim 48 further com- prising a covering surrounding the electrical wiring, wherein the covering is arranged so as to substantially center the electrical wiring within the conduit . 53. The wiring assembly of claim 48 further com- prising layers of material surrounding the electrical wiring, wherein the layers are arranged so as to substantially elimi- nate relative movement between the electrical wiring and the conduit . 54. The wiring assembly of claim 48 further com- prising layers of material surrounding the electrical wiring, wherein the layers are arranged so as to substantially center the electrical wiring within the conduit. 55. The wiring assembly of claim 48 further com- prising a thermoplastic material surrounding the electrical wiring, wherein the thermoplastic material is arranged so as to substantially eliminate relative movement between the electrical wiring and the conduit. 56. The wiring assembly of claim 48 further com- prising a thermoplastic material surrounding the electrical wiring, wherein the thermoplastic material is arranged so as to substantially center the electrical wiring within the conduit .

Inventors: PERCIGO MANUEL CELESTINO, STEIKUNAS DOBILAS JONAS, PERCIGO, MANUEL, CELESTINO, STEIKUNAS, DOBILAS, JONAS
Applicants: JOSLYN SUNBANK COMPANY LLC, JOSLYN SUNBANK COMPANY, LLC.
Application year: 1999
Main classification: H02G3
IPC codes: H02G3