Patent Application
20120073853
This invention relates to electric handwells, handholes and the like.
An electric handwell comprises a chamber in the ground in which electrical wiring may be connected together or through which electrical conduits may extend. The handwell has a removable cover so that a worker may access electrical conduits that extend therethrough and/or access electrical conductors therein. Handwells, which are akin to small manholes, are also sometimes referred to as handholes and pull boxes. As used herein, the term “handwell” is used to refer to any such construct.
Referring to
Vertically extending wall 12 has an upper end 16 and a lower end 18 and may be of any desired length. Handwell 10 may be positioned in a sidewalk or road, which has an upper surface 22. An access cover 24 is removably mounted above chamber 14. Preferably, the upper surface 32 of access cover 24 is level or essentially level with upper surface 22. Typically, a liner ring 34 made of metal is provided. Access cover 24 may be seated on liner ring 34 and, accordingly, may be flush with upper surface 22. As exemplified, vertically extending wall 12 extends so as to be flush with surface 22 and upper surface 32. Liner ring 34 may be seated in a recess formed in vertically extending wall 12 and may be secured thereto by any means known in the art, such as one or more screws 36. For example, liner ring 34 may be seated in the wet concrete used to from wall 12. When the concrete has cured, one or more screws 36 may be installed. Alternately, for example if the upper end of wall 12 is below grade, a concrete slab (e.g., for a sidewalk) may be poured over wall 12. Re-bar may be used to secure wall 12 and the sidewalk slab together. In such a case, liner ring 34 may be seated in the wet concrete that is used to form the sidewalk slab during initial construction.
One or more openings 28 may be provided in vertically extending wall 12. A plurality of openings 28 may be provided, each of which may have an electrical conduit 26 extending thereto. Electrical conductors (e.g. wires) may extend through conduits 26 and the terminal ends of the wires may be connected together inside chamber 14.
Typically, access covers are constructed from cast metal. More recently, a lightweight plastic access cover has been proposed (see U.S. Pat. No. 7,361,834 Trangsrud et al). As set out in Trangsrud et al, an access cover is provided having a plurality of vertical channels that extend between the top and bottom walls whereby a type of internal corrugated structure is formed. As exemplified therein, the central portion of the lower surface of the access cover is generally flat and the outer annular region of the lower surface is angled upwardly towards the perimeter of the access member.
Over time, the electrical insulating coating on wires in a handwell may degrade. If the wires contact a conductive member of the handwell, e.g. a metal access cover as is traditionally used, a metal liner of the handwell or the concrete wall when the concrete wall is wet, stray electrical current may be conveyed to the surface. Any person or animal in the vicinity of the handwell may accordingly experience an electrical shock. This problem can be acerbated if the ground surrounding the handwell is wet due to a rainfall, an in-ground sprinkler system or the like or if the interior of the handwell is flooded.
While the use of a plastic access cover as disclosed in Trangsrud et al can prevent electrical currents being conducted to upper surface 32 of the access cover, the wires in the hand well may still transmit stray electrical currents such as via liner ring 34 (which is typically constructed from metal) or from contacting the vertical wall 12 of the handwell.
In accordance with an aspect of this invention, an access cover for a handwell is provided wherein the access cover is configured to reduce the likelihood of a person or animal standing on or adjacent the access cover receiving an electric shock from the wiring in a handwell. For example, the lower surface of the access cover may be configured to inhibit radial outward migration of wires positioned in the handwell. An example of such a construction is to provide the lower surface of the access cover with a raised central area such as by configuring the lower surface to be dome shaped. Accordingly, the arched walls forming the dome will inhibit wires positioned in the central portion of the handwell at a height proximate the lower surface of the access cover migrating outwardly. The arched walls provide an upwardly and inwardly extending surface that will tend to prevent wires migrating outwardly towards vertical wall 12.
In accordance with another aspect, the access wall may be provided with a depending wall, which may extend away from the lower surface of the access cover, so as to prevent or reduce the likelihood of wires in the handwell migrating to contact the sidewalls of the handwell. The deepening wall, which is constructed from an electrical insulating material, provides a liner between chamber 14 and at least an upper portion of vertical wall 12. Accordingly, even if the wires were to migrate towards vertical wall 12, the wires may tend to contact the depending wall thereby inhibiting the transmission of electrical current through vertical wall 12 and/or liner ring 34 to the exterior of the handwell.
Accordingly, in one aspect of this invention there is provided an access cover for a hand well or hand hole comprising:
In one embodiment, the surface has a raised central portion. Preferably the lower surface is dome shaped.
In another embodiment, the lower surface comprises a plurality of depending ribs, the ribs having a radial inner end and a radial outer end. Preferably, the radial inner end of the ribs have a height and the radial outer end of the ribs have an increased height. Alternately, or in addition, the top member, the depending wall and the ribs are integrally molded.
In another embodiment, the access cover is integrally molded.
In another embodiment, the access cover further comprises an opening provided at a location in the top member for passage therethrough of a securing member. Preferably, the opening is provided in the flange and the depending wall is recessed inwardly at the location.
In another embodiment, the access cover is constructed from a thermoplastic or thermoset material.
In another embodiment, the access cover is constructed from polyurethane or polyamide.
In another embodiment, the upper surface is generally flat and is provided with traction members.
In accordance with another aspect, there is provided a method of reducing the incidence of electrical shock emanating from a hand well comprising:
In one embodiment, the lower surface has a raised central region and the method further comprises positioning the terminal ends in the raised central region.
In another embodiment, the method further comprises securing the access cover to the hand well at a location exterior to the depending wall. Preferably, the method further comprises providing an inward recess of the depending wall at the location.
In another embodiment, the method further comprises constructing the access cover from a thermoplastic or thermoset material.
In another embodiment, the method further comprises constructing the access cover from polyurethane or polyamide.
In another embodiment, the method further comprises removing an existing cover and installing a liner ring constructed from an electrical insulating material prior to step (c).
In another embodiment, the method further comprises providing the liner ring and the access cover with inter fitting members.
In accordance with another aspect, there is provided an access cover for a hand well or hand hole comprising a top member having an upper surface, a lower surface and a perimeter, the lower surface being configured to inhibit radial outward migration of wires positioned in the hand well, wherein the top member is constructed from an electrical insulating material.
In one embodiment, the lower surface has a raised central portion. Preferably, the lower surface is dome shaped.
In another embodiment, the lower surface comprises a plurality of depending ribs, the ribs having a radial inner end and a radial outer end. Preferably, the radial inner end of the ribs have a height and the radial outer end of the ribs have an increased height. Alternately, or in addition, the top member and the ribs are integrally molded.
In another embodiment, the access cover is integrally molded.
In another embodiment, an opening provided at a location in the top member for passage therethrough of a securing member. Preferably, the opening is provided in a flange.
In another embodiment, the access cover is constructed from a thermoplastic or thermoset material.
In another embodiment, the access cover is constructed from polyurethane or polyamide.
In another embodiment, the upper surface is generally flat and is provided with traction members.
In accordance with another aspect, there is provided a method of reducing the incidence of electrical shock emanating from a hand well comprising:
In one embodiment, the lower surface has a raised central region and the method further comprises positioning the terminal ends in the raised central region.
In another embodiment, the method further comprises constructing the access cover from a thermoplastic or thermoset material.
In another embodiment, the method further comprises constructing the access cover from polyurethane or polyamide.
In another embodiment, the method further comprises removing an existing cover and installing a liner ring constructed from an electrical insulating material prior to step (c).
In another embodiment, the method further comprises providing the liner ring and the access cover with inter fitting members.
Reference is made in the detailed description through the accompanying drawings in which:
Referring to
Access cover 100 may be sized to fit in an existing handwell. As exemplified in
Optionally, access cover 100 may be removably secured to the handwall by any means known in the art such as by one or more screws, integrally molded plastic bolts, integrally molded snap fits, and a quarter turn bayonet style lock. Preferably, as exemplified in
Depending wall 108 may be a cylindrical wall positioned inwardly of opening 116. Such an embodiment might be utilized if, for example, opening 46 were positioned in rim 38 or in vertical wall 12. Alternately, as exemplified, if a flange 44 is provided, then depending wall 108 may be provided with a recess 120. Accordingly, when opening 116 is aligned with opening 46, recess 120 is aligned such that flange 44 may be received under top member 102 and not interfere with access member 100 being positioned in handwell 10. As exemplified, recess 120 is concave in shape. However, it will be appreciated that recess 120 may be of any particular shape provided flange 44 is receivable therein.
Optionally, as illustrated in
Lower surface 112 of access number 100 is configured to inhibit radial outward migration of wires 154 positioned in handwell 10. In a typical installation, the lower portion of a handwell is filled with dirt, gravel or the like. While conduits 26 may be provided at the lower end of handwell 10, the ends of wires 154 are preferably positioned towards the upper end of handwell 10 so as to facilitate a worker connecting the terminal ends 156 of wires 154 together and being able to service the wires as needed. During installation of access cover 100, the connected terminal ends 156 of wires 154 are preferably positioned adjacent the radial inner centre of handwell 10 and within raised central portion 128, e.g., dome shaped portion, of access cover 100.
By providing raised central area 128, the terminal ends of the wires would have to travel downwardly as well as outwardly prior to contacting vertical wall 12 of handwell 10. It will be appreciated that raised central portion 128 may be of various configurations. For example, it may comprise generally vertical sidewalls, angled sidewalls or, preferably, curved sidewalls. In any such configuration, downward movement of the terminal ends of the wires would be required for outward migration of the wires.
Referring to
As exemplified, radial outer ends 134 of ribs 130 terminate at the lower end of depending wall 108. In alternate embodiments, it will be appreciated that radial outer end 134 of ribs 130 may terminate at a position below depending wall 108 or, alternately upwardly form the lower surface of depending wall 108. Further, in an alternate embodiment, the upper end of ribs 130 may terminate at a distance spaced from lower surface 112 of top member 102. It will be appreciated that in addition to inhibiting the radial outward migration of wires positioned in the handwell, ribs 130 may also be designed to provide structural strength to access cover 100.
Depending wall 108 may of varying lengths. In a preferred embodiment, as exemplified in
The cover and the depending wall are made from an electrical insulating material. Preferably, access cover 100 is made from an electrical insulating material. The electrical insulating material is preferably a thermoplastic or thermoset material. More preferably, these members are constructed from polyurethane or a polyamide. The thermoplastic or themoset materials may include various fillers, such as glass fibres, glass spheres, minerals and other non-conductive fillers. Various manufacturing methods may be utilized to manufacture the access cover, such as injection molding, injection-compression molding, roto-molding, and casting. The access cover is preferably manufactured by molding. Preferably, the depending wall and the ribs are integrally formed, e.g., molded. More preferably, the access cover itself (top member 102, depending wall 104, flange 106 and ribs 130) is integrally formed, e.g., molded.
As exemplified in
In accordance with another aspect of this invention, a method of reducing the instance of electrical shock emanating from a handwell is provided. In accordance with the method, an access cover 100 according to any of the proceeding embodiments is provided. The existing access cover (e.g., access cover 24) is removed (see
In an alternate embodiment, no liner ring 34 may be provided. Alternately, as exemplified in
New liner ring 158 may be secured in position by any means known in the art, such as an adhesive, setting new liner ring 158 in wet concrete and mechanical fasteners 162. Accordingly, if mechanical fasteners 162 are used, optionally holes 160 may be provided for receiving mechanical fasteners 162 that secure new liner ring 158 in position. As exemplified, mechanical fasteners 162 comprise bolts. The bolts may be secured in position by an adhesive (e.g., an epoxy). Alternately, if new liner ring 158 is seated in wet concrete, then the head of the bolts may be set in the new concrete such that the threaded ends extend upwardly through openings provided in new liner ring 158. A threaded nut may then be used to secure new liner ring 158 in position. In a further alternate embodiment that is exemplified in
Finally, new access cover 100 may be set in position and secured in place.
New liner ring 158 may be of any design, preferably, as exemplified in
Various apparatus or methods are described above to provide an example of each claimed invention. No example described above limits any claimed invention and any claimed invention may cover processes or apparatuses that are not described above. The claimed inventions are not limited to apparatuses of processes having all the features of any one apparatus or process described above or to features common to multiple or any of the apparatuses described above.
