Electricity: conductors and insulators – Conduits – cables or conductors – Single duct conduits
Patent
1985-05-17
1987-03-10
Grimley, Arthur T.
Electricity: conductors and insulators
Conduits, cables or conductors
Single duct conduits
174 50, 339103R, 220266, H02G 308
Patent
active
046492305
DESCRIPTION:
BRIEF SUMMARY
The invention relates to an electrical connecting box for low voltage installations comprising a lower part having a bottom to be arranged against a fixed support and an upper part adapted for securing to the lower part, said upper part having side walls in at least one of which a number af punch-out blank portions for providing openings for electrical insulation tubes, wires and/or cables are defined by a set of punch lines, one of which forms a common border for the blank portions at one side thereof.
In most known electrical connecting boxes the size of the punch-out blank portions is usually adapted to a single cable dimension, i.e. the maximum cable dimension for which the box in question is intended. Therefore, when using the blank portions for smaller cable dimensions specially designed plugs or bushings will have to be used in such boxes, said plugs or bushings fitting externally into the size of the blank portion and having a through-bore adapted to the desired cable dimension.
In addition to making installation works more expensive, the need for the electrician to hold a storage of a greater selection of boxes and accessories and to take such a selection with him to a given site of installation is a disadvantage is practice.
However, from Norwegian Pat. No. 61678 and German Pat. No. 611474 installation boxes are known, in which the side walls of the housing have blank portions for different wire, cable and tube dimensions defined by a set of punch lines which in the embodiment according to the former publication coincide and form a common border for all the blank portions at one side thereof.
Relative to these prior art designs, in which a set of blank portions are provided in one and the same wall portion of a lid or a cover for the box so that the number of wire dimensions which may be introduced into the box will be limited to the number of blank portions in said set, e.g. three, it is the object of the invention to obtain a further improved flexibility with respect to the number of types of wires, cables and insulation tubes which without any difficulty may be introduced into the box through blank portions and, thereby, further increase the universal applicability of the box to all practically available standard dimensions of insulation tubes, cables and wires of flat and round cross section.
According to the invention such a universal box is characterized in that the lower part has upright side walls on all sides, said side walls having a circumferential shoulder part forming an abutment for edges of the side walls of the upper part, each set of punch lines comprising in the side walls of the upper part a number of punch lines formed substantially as circular arcs and extending to said edges, each of these set of punch lines having a corresponding set of punch lines in the adjoining side wall of the lower part, said latter punch lines being parallel straight lines at right angles to the bottom of the lower part.
With this design blank portions may be punched out in said adjoining side walls of the lower and upper parts adapted to individual cable dimensions with a safe location and without using special accessories. The proportioning of the side wall of the lower part and the set of punch lines therein may advantageously be such that the part of the side wall of the lower part located between the bottom and the circumferential shoulder part suits the smallest cable dimension for which the box is intended, such as flexible wires or flat cables so that these may be introduced without removing any blank portion from the side wall of the upper part.
In preferred embodiments of the invention the universal applicability of the box is further improved for use not only as a wiring box, but also as a switch casing and/or lamp connection box in that additional punch lines are formed in the upper part for defining blank portions adapted to one or more standard designs of electrical interruptors and/or plug-in switches and/or to the passage of wires for lamp suspensions or the like. Thereby, one and the
REFERENCES:
patent: 1148699 (1915-08-01), McWilliams
patent: 2620081 (1952-12-01), Lear, Jr.
patent: 3279014 (1966-10-01), Fischer
patent: 3859454 (1975-01-01), Mann
patent: 3864512 (1975-02-01), Meadow
Grimley Arthur T.
Tone D. A.
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