Knockout arrangement for molded plastic electrical boxes

Claim 2

In a plastic molded electrical wiring box for use with a nonmetallic, sheathed cable, wherein one end of the cable is to be received in the box, with the box including a side wall structure integrally connected to a back wall, with the side and back wall structures defining a chamber within the box that is open at the front of the box, and the side and back wall structures merging at a marginal corner about the rear of the box, a knockout arrangement therefor through which the cable end is to extend into the box, said knockout arrangement comprising: a corner segment at said marginal corner comprising a first leaf integral with the side wall structure and a second leaf integral with the back wall structure, said leaves being integral with each other and being respectively offset within said chamber and inwardly of tHeir respective wall structures and said marginal corners, and being integrally connected to the respective wall structures by marginal portions of film thickness proportions, said leaves merging into each other at their adjacent ends adjacent but spaced from and inwardly of said marginal corner and having their respective opposite ends extend away from their respective adjacent ends, said leaves being respectively offset within said chamber a distance equivalent to their respective thicknesses minus the thickness of their respective marginal portions, said marginal portions being integral with each other and defining about said corner segment a marginal edge portion that is continuous and uninterrupted about said corner segment and that is indented into the box and integrally connects said corner segment with said wall structures in a continuous and uninterrupted manner thereabout, with each corner segment leaf having a tapered molding spline integral with said opposite end of same and with the box wall adjacent same on the inside of the box, with said splines respectively being tapered to increase in thickness in the direction of the respective leaf opposite ends, said leaves being identical in outline configuration, whereby said corner segment as a whole is recessed within the box and is thereby protected from accidental dislodgement, and said corner segment may be removed from the box to form a knockout opening therein by fracturing said marginal edge portion utilizing a hand tool from either inside or outside the box, and the cable end may be inserted into the box chamber through the knockout opening from either the side or the back of the box in normal relation thereto.

Claim 3

The knockout arrangement set forth in claim 1 wherein: said leaf marginal portions have a thickness of approximately 0.005 inch.

Claim 4

The knockout arrangement set forth in claim 1 wherein: the box has formed integrally therewith on each of a pair of opposed sidewalls thereof a nail receiving passage extending continuously across same for protecting the box from overhammering of nails received in the respective passages.

Claim 5

In a plastic molded electrical wiring box in combination with a non-metallic, sheathed cable, that is to have one end of same received in the box with the box including a side wall structure integrally connected to a back wall structure, with the side and back wall structures defining a chamber within the box that is open at the front of the box, and the side and back wall structures merging at a marginal corner about the rear of the box, and a knockout arrangement therefor through which the cable end is to extend into the box, said knockout arrangement comprising: a corner segment at said marginal corner comprising a first leaf integral with the side wall structure and a second leaf integral with the back wall structure, said leaves being integral with each other and being respectively offset within said chamber and inwardly of their respective wall structures and said marginal corner, and being integrally connected to the respective wall structures by marginal portions of film thickness proportions, said leaves each having a marginal outline, approximately the general transverse cross-sectional marginal outline of the cable end, said leaves merging into each other at their adjacent ends adjacent to but spaced from and inwardly of said marginal corner and having their respective opposite ends extend away from their respective adjacent ends, said leaves being respectively offset within said chamber a distance equivalent to their respective thicknesses minus the thickness of their respective marginal portions, said marginal portions being integral with each other and defining about said corner segment a marginal edge portion that is continuous and uninterrupted about said corner segment and that is indented into the box and integrally connects said corner segment with said wall structures in a continuOus and uninterrupted manner thereabout, with each corner segment leaf having a tapered molding spline integral with said opposite end of same and with the box wall adjacent same on the inside of the box, with said splines respectively being tapered to increase in thickness in the direction of the respective leaf opposite ends, said leaves being identical in outline configuration, whereby said corner segment as a whole is recessed within the box and protected from accidental dislodgement therefrom, and said corner segment may be removed from the box to form a knockout opening therein by fracturing said marginal edge portion utilizing a hand tool from either inside or outside the box, and the cable end may be inserted into the box chamber through the knockout opening from either the side or the back of the box in normal relation thereto and substantially fill the knockout opening.

Claim 6

In a plastic molded electrical wiring box in combination with a non-metallic, sheathed cable, that is to have one end of same received in the box with the box including a side wall structure integrally connected to a back wall structure, with the side and back wall structures defining a chamber within the box that is open at the front of the box, and the side and back wall structures merging at a marginal corner about the rear of the box, and a knockout arrangement therefor through which the cable end is to extend into the box, said knockout arrangement comprising: a corner segment at said marginal corner comprising a first leaf integral with the side wall structure and a second leaf integral with the back wall structure, said leaves being integral with each other and being respectively offset within said chamber and inwardly of their respective wall structures and said marginal corner, and being integrally connected to the respective wall structures by marginal portions of film thickness proportions, said leaves each having a marginal outline, approximately the general transverse cross-sectional marginal outline of the cable end, said leaves merging into each other at their adjacent ends adjacent to but spaced from and inwardly of said marginal corner and having their respective opposite ends extend away from their respective adjacent ends, said leaves being respectively offset within said chamber a distance equivalent to their respective thicknesses minus the thickness of their respective marginal portions, said marginal portions being integral with each other and defining about said corner segment a marginal edge portion that is continuous and uninterrupted about said corner segment and that is indented into the box and integrally connects said corner segment with said wall structures in a continuOus and uninterrupted manner thereabout, with each corner segment leaf having a tapered molding spline integral with said opposite end of same and with the box wall adjacent same on the inside of the box, with said splines respectively being tapered to increase in thickness in the direction of the respective leaf opposite ends, said leaves being identical in outline configuration, whereby said corner segment as a whole is recessed within the box and protected from accidental dislodgement therefrom, and said corner segment may be removed from the box to form a knockout opening therein by fracturing said marginal edge portion utilizing a hand tool from either inside or outside the box, and the cable end may be inserted into the box chamber through the knockout opening from either the side or the back of the box in normal relation thereto and substantially fill the knockout opening.