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A plurality of sub-frame assemblies for assembling a modular frame and injection moulding apparatus for making injection moulded frames Disclosure Number: IPCOM000191340D
Publication Date: 2009-Dec-30
Document File: 14 page(s) / 2M

Publishing Venue

The Prior Art Database


This publication relates to a plurality of sub-frame assemblies for assembling a modular frame for fixing to an electrical mounting box, the modular frame for supporting therein a plurality of electrical accessories for connecting within the mounting box to an electrical supply, each sub frame assembly defining an area within which one or more of the electrical accessories can be supported; wherein, a first of said plurality of sub-frame assemblies comprises a first member and a second of said plurality of sub-frame assemblies comprises a second member, the first and second members being arranged to interlock when the first and second sub-frame assemblies are placed in use side by side to assemble the modular frame, the interlocking being such that at least a portion of the first member overlies a portion of the second member.

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A plurality of sub-frame assemblies for assembling a modular frame and injection moulding apparatus for making injection moulded frames


As is well known in the art, a gang is a set of switches, sockets or other such electrical accessories (or combinations thereof) grouped together, typically side-by-side, vertically and/or horizontally.

Frames for supporting gangs of electrical accessories are well known and typically comprise a rigid four-sided structure, surrounding and defining a space within which the gang is supported. On installation, such a frame is typically screwed to the front of an electrical back box which itself is fixably mounted, often flush, to a wall. The electrical accessories retained in the frame are connected to an electrical supply in the back box. Normally, to provide an aesthetically pleasing finish, a front cover is screwed to the front of the back box/frame assembly to hide the frame and back box from view, the front cover having an aperture through which the electrical accessories are accessible for operation.

Frames come in various sizes commonly referred to as gang sizes. For example, a 1-gang frame would accept one switch module, a 2-gang frame would accept either two switch modules or one switch module (a socket module is twice the length of a switch module), a 3-gang frame would accept either three switch modules or one socket module and one switch module and so on. The back boxes come in corresponding 1-gang, 2-gang, etc sizes. In the

United Kingdom

, the allowable dimensions of back boxes are defined in the Electrical Wiring Standard BS 4662. BS 4662 dictates that a frame must be attached to a back box by screws that are located an integer multiple of 60.3 mm apart on a horizontal or vertical line, as the case may. This means that the frames must also have screw holes located to conform to BS 4662.

A manufacturer typically manufactures and keeps in stock stand alone frames of different sizes to provide for a range of gang sizes. Having to manufacture many sizes of stand alone frames, each size suitable for use with a correspondingly sized back box is inconvenient and expensive.

A frame is typically made by injection moulding, using a rigid plastic material such as polycarbonate. Thus, if a manufacture provides a number of different frame sizes, the manufacturer must also keep a corresponding number of different mould tools for making the different frame sizes. For example, if frames are required for 1-gang, 2-gang, 3-gang, 4-gang, 6-gang or 8-gang sets of devices, six different mould tools would be needed to produce the six different sizes of frames. As is well known, mould tools are expensive, and so having multiple mould tools adds considerable cost to the manufacturing process of the frames.

Therefore, it is suggested to form a plurality of sub-frame assemblies for assembli...