Autodesk 235B1-05A761-1301 User Guide - Page 829

hidden line Portions of an AutoCAD MEP object that can be displayed with a user-definable linetype when obscured by an object at a higher elevation. For example, a hidden line can be shown as dashed. home run The wire segment connecting the end of a circuit to the associated electrical panel. Typically, an arrow is used to represent the direction of the panel's location on an electrical drawing. hose bib (1) A water faucet to which a hose may be attached. hose bib (2) A valve with an external threaded outlet for accepting a hose fitting. hot wire A common type of circuit wire. Hot wire brings the power from the source to a panel or device. HVAC For Heating, Ventilation, Air Conditioning. I.D. For inside diameter. ID For identification. A number or string of characters that you can assign to symbols. The ID can also be used to group symbols for scheduling. in-line symbol An AutoCAD block that can be anchored anywhere along a schematic line. instant sizing A tool used to calculate an object size as you draw it. There are instant sizing tools for ductwork and wiring. insulation thickness The thickness of insulation added to the outside of a part. invert The part of the interior of a drain or a sewer pipe where the liquid is deepest. invert elevation The elevation of the lowest point along the inner diameter of the end of a pipe. invert elevation calculation The invert elevation determined by the resulting value of a mathematical equation. Typically, the invert elevation of one end of a pipe (A), the slope (B), and the horizontal length (C) are known, and a mathematical equation is used to determine the invert elevation of the other end of the pipe (D). For example, if A is higher in elevation than D, the following equation is used: A2(B3C)5D. isometric A drawing or view in which the X, Y, and Z axes are spaced 120 degrees apart and the Z axis is projected vertically. isometric line A line that represents pressure or temperature changes under conditions of constant volume. isometric riser The vertical segments included in an isometric drawing or view. See also isometric. isometric riser diagram The most common riser diagram for plumbing; provides a 3D representation of the plumbing system in a 2D drawing. Generally not drawn to scale, but shown to be correctly proportioned. In other words, a long run of piping in the plumbing plan is shown as a long run of piping in the riser diagram. Includes symbols for the piping and fittings. isometric snap An AutoCAD drafting option that aligns the cursor with 2 of the 3 isometric axes and displays grid points, making isometric drawings easier to create. isometric symbol style Default symbol properties, such as appearance or connection cleanup type, that are assigned to a specific symbol or a group of symbols in an isometric drawing or view. See also isometric. isometric symbols Symbols used to represent components or equipment within a plumbing system included in an isometric drawing or view. See also isometric. isoplane AutoCAD Architecture command that specifies the current isometric plane (left, top, right). joint A method for attaching pipe segments to each other, to fittings, or to equipment such as flanges, couplings, or butt welds. junction box A plastic or metal box used to protect wire connections. Typically, the boxes are fastened to the structural framing, and devices such as receptacles and switches are attached to the boxes. justification The drag point for AutoCAD symbols. See also drag point and justification/offset. Glossary | 811