This sample chapter is for review purposes only. Copyright © The Goodheart-Willcox Co., Inc. All rights reserved. Chapter 5 Wiring Diagrams Objectives cable assembly drawing wire harness assembly drawing harness posts flexible printed wiring reference designation component representation After studying this chapter, you will be able to: • Select wiring methods. • Create a wire list. • Draft a point-to-point diagram. • Draw a highway diagram. • Draw a cable assembly document. • Make a harness assembly drawing. • Select appropriate wire termination method. Terms to Know bus wire spaghetti point-to-point diagram highway wiring diagram baseline diagram interconnection diagram Wiring Methods The majority of electronic equipment needs some kind of flexible wiring for interconnections of systems. Understanding how to document this wiring is important knowledge for the drafter. This chapter will cover the basic methods used. There are many ways to show factory workers, service personnel, and others in the engineering family how to wire electronics equipment. Normally the decision to choose one method over another is based on three different things: • Knowledge of the technician. • Quantity to be built. • Complexity of the equipment to be manufactured. Schematic The simplest method to get a wiring project built is to give a top qualified technician a schematic. The schematic will only supply the “from” and “to” information. This information will describe where the wire will be hooked (the from position) and where the wire is going (the to position). See Figure 5-1. 84 Electronics Drafting Figure 5-1. A schematic being used to wire between components. Note 1: Technician runs wire connecting all the switches. Note 2: Wire is run from the switch S1-2 to TB-1 (terminal block). From a schematic, a drafter can create a wire list or other wiring documents. The wiring list will save the technician time in reading the schematic. Wire List The wire list is another elementary document. It will include the information from the schematic plus some additional information such as: • Color of wire. • Gage of wire. • Length of wire. • Entry in parts list. • Condition at terminals. Figure 5-2 shows how the wire list information is presented. To understand the wire list information, you need to be familiar with wires and their terminations. Wires or Conductors Conductors used in wiring electronics equipment are either solid, stranded, or flexible printed ribbon types of wiring. See Figure 5-3. Solid conductors have traditionally been used where they will not experience bending or flexing. They are less expensive to manufacture so they cost less than stranded wiring. Because they cannot be repeatedly flexed, they have limited areas of use. Solid wiring is used to connect the outlets and switches in our houses. In electronics, solid wiring is used mainly for jumpers (bus wiring) and for wire wrapping. Wire No. 1 2 3 4 5 6 7 1 Column Column Column Column Column Column Column Column Column 1 2 3 4 5 6 7 8 9 Size Awg. 22 22 20 20 18 18 16 Item No. 1 2 3 4 5 10 6 Color R W O Y BK BR Y From XA1-22 XA1-21 XA1-19 XA1-18 XQ1-A XQ1-B XQ1-C Wire List Condition Solder Solder Solder Solder Solder Solder Solder A Parts List Condition #6 Lug #6 Lug #6 Lug Solder Solder Solder Solder 9 Length 20 14 16 14 12 8 10 Chapter 5 Wiring Diagrams To EOT-2 PI-6 P2-20 S3-8 S3-7 TB1-1 TB1-2 8 Qty 36″ 18″ 12″ 15″ 11″ 10″ Description Awg red stranded teflon coated Awg wht stranded teflon coated Orn stranded teflon coated Blu stranded teflon coated Brn stranded teflon coated Blk stranded teflon coated Wire Wire Wire Wire Wire Wire 8 A/R B Lug #6 Crimp Solder 40/60 #22 #22 #22 #22 #22 #22 2 3 4 5 6 7 The wires position in the wire list The size of the wire as it relates to the American Wire Gage Standard The item number in the parts list where a complete description is given The color of the wire Terminal the wire is coming from How that wire is connected to the terminal Terminal the wire is going to How the wire is connected to the terminal Length of the wire between terminals Item No. 1 2 3 4 5 6 7 8 9 85 Figure 5-2. A—The top section shows a wire list with typical information and below it is an explanation of the information in each column. B—This parts list is used to purchase items listed in the third column in the wire list above. Stranded wiring has superior handling and flexing qualities. This makes it the most universally used wire. See Figure 5-4. The endurance of the stranded wire is judged by the number of strands it contains. The larger the number of strands, the greater its bending endurance. The diameter of a wire is determined by its gage, which is determined by the American Wire Gage Standard. See Figure 5-5. Stranded wire will be identified by two numbers. The first number states the number of strands in the wire. The second 86 Electronics Drafting Figure 5-3. A—Solid wire used where the wire will not be flexed. B—Stranded wire is used where flexibility is needed. C—Flexible ribbon cabling, used to connect components inside your computer. Figure 5-4. A table termination on a circuit board saves space on the board. The flexible mounting and stranded wire help reduce stress on the board and connector. A C B number states the gage of each strand. For example, 7/26 means 7 strands of number #26 AWG wire, which is .0159” in diameter. The wire gage goes from #4/0 (the largest commonly used wire) to #44 (the smallest commonly used wire). The table shown in Figure 5-5 has only given the even sizes. It also has been condensed to show the most used wire sizes. Wire length and diameter affect both the resistance and current-carrying ability. The smaller diameter wires have more resistance to electron flow, and therefore less capability to carry current load. See Figure 5-6. Bus Wire Bus wire is solid wire without insulation (bare) normally used to make short terminal-to-terminal connections. It will be used where bending does not take place after installation. Where the bus wire requires insulation a tube-type insulation called spaghetti is slid over it. The reason for using spaghetti is to avoid having to strip both ends of a short wire. Figure 5-5. The American Wire Gage table. The table is condensed for this example. Figure 5-6. Current ranges for wires. Military Standards allow only 60% of these current values. Shielded and Coaxial Cables Awg. Size 10 12 14 16 18 20 22 24 26 28 Chapter 5 Wiring Diagrams Weight Lbs/1000Ft 31.43 19.77 12.43 7.818 4.917 3.092 1.945 1.223 .7692 .4837 .031 .080 .203 .513 1.296 3.280 8.290 20.900 52.900 133.900 Ohms per Lb. Area Sq. In. .008155 .00513 .00323 .00203 .00128 .000804 .000503 .00317 .000199 .000125 American Wire Gage Maximum Current Amperes Area C/R Mils 10,380 6,530 4,110 2,580 1,620 1,020 640 404 253 159 Wire Size Awg. 50 40 30 20 15 11 9 5 2 .5 Diameter Inches .1019 .0808 .0641 .0508 .0403 .0320 .0250 .0201 .0159 .0126 10 12 14 16 18 20 22 24 26 28 Shielded and coaxial wires are used to exclude or contain undesirable radiation. See Figure 5-7. An example for the use of a coaxial wire is in an automobile radio antenna system. The shield around the signal wire keeps the unwanted engine and electrical noise from radiating into the signal wire. Without this shield, we would hear many interfering noises from engine electrical sources. The shield of the coaxial cable is grounded so the interfering electrical energy or radiation will be absorbed and sent to the chassis instead of the radio. Wire Termination In order to make a wire useful, we must be able to electrically secure it where we desire. There are three basic ways to secure or terminate wires: soldering, crimping, and wrapping. The method used is dictated by the terminal to which the wire is to be secured. You can show the method on your drawing by techniques as shown in Figure 5-8. Wrapping is done by a special wire-wrapping tool. Large wire-wrapping projects will be done by an automated wrapping machine. The wrapping tools strip the wire’s insulation and then wrap the wire tightly around the wrapping post. See Figure 5-9. Wire wrapping has an economical advantage over soldering and crimp 87 88 Electronics Drafting A Neoprene insulation Figure 5-7. A—Coaxial cable. B—Multiple-conductor shielded cable. Symbol A B C Copper shield Foil B Physical Part Rubber insulation Conductor Figure 5-8. A—Solder terminal symbol and wire represented after it has been stripped for soldering. B—Lug crimped to the end of a stripped wire. C—Spade lug. Wrapping post Wrapped wire Figure 5-9. A square wire wrapping post with a wire wrapped around it. The wire is stripped and wrapped tightly around the post making a good electrical connection. Chapter 5 Wiring Diagrams terminations. Wrapping can be set up much easier for automated machines. Wire used for wrapping is solid wire. The gages for this wiring method range from #20 to #32 AWG. Point-to-Point Wiring Diagrams A point-to-point diagram is used to show the engineering, manufacturing, and service personnel the wiring between and across components. See Figure 5-10. Point-to-point diagrams contain the information necessary to make or follow all wire connections. This wiring diagram can be shown on the assembly drawing. The diagram on the assembly will be included only if it is practical, and if room is available. The point-to-point drawing will not have a parts list. All the necessary items will be called out on the assembly document. Some point-to-point diagrams show wiring paths on a background of components which are not drawn to scale. The components are drawn out of scale to fit the requirements of a very complex wiring diagram. The wiring is easier to follow when wires are on equal spacing. A second drawing method is to show the components drawn to the true scale. Point-to-point diagrams show the general physical arrangement of the component parts. See Figure 5-11. General rules for wiring diagrams are as follows: • Minimize jogs in lines. • Run lines with a minimum of crosses. • Space lines a minimum of 1/4” apart. Figure 5-10. A complex industrial point-to-point drawing. 89 90 Electronics Drafting Figure 5-11. A correctly drawn point-to-point wiring diagram. Note the misnumbering of TB1 and S1 to keep from crossing and jogging. This is a good practice. • Separate every three of four lines with an extra wide spacing when groups of lines run parallel to each other. This helps the reader’s eye follow the individual lines. • Label component on the right side. This will help the reader when searching over a large drawing to find a specific component. • Letter the components with larger bold letters. Use smaller lettering for internal terminals. • Component numbering will follow the location and identification given to it when mounted in chassis. Pictorial Point-to-Point Drawing T1 Red TB1 Yellow White Occasionally when there is a simple point-to-point drawing to be made, it can often be drawn as a pictorial. Figure 5-12 is a good example of a pictorial point-topoint drawing. However, pictorials should only be attempted when there are only a small number of wires and simple chassis layouts. Figure 5-12. A typical pictorial point-to-point drawing. Black AC input Highway Wiring Diagrams Chapter 5 Wiring Diagrams Highway wiring diagrams group the wires together into major paths called highways. See Figure 5-13. The technique allows you to put many wires on a drawing because this organized method saves room. The drawing shows the physical arrangement of the component parts as we did in the point-to-point. It will be possible to tell each wire’s destination, color, and gage by looking at either of its ends. In Figure 5-13D we see a second method for showing highways. Note that some companies apply a number to each wire and then create a separate table. The wire number in the table will supply destination, color, and gage. Baseline Diagrams Baseline diagrams are like highway diagrams in that they can handle many wires in an organized manner and they bundle the wires together in one main line. See Figure 5-14. They also have a couple of differences. One is the placement of components. The highway diagram is very concerned with physical placement of the components. The baseline diagram just lines them up in a straight line. Another difference is in the way the wires enter the main bundle. The highway diagram shows which way the wire will be running in the bundle. The baseline shows wires going 90° into the bundle without disclosing direction. The method for drawing baseline diagrams is to: • Add a construction line across the middle of the paper. • Line up the components on either side of the line. • Take short lines from each component and run them into the center line at 90°. • Identify the wire destination and color. • Make the center line a dark bold line. A B C Baseline drawings are used mostly for service manuals and maintenance books. They are especially good for this kind of information because they can neatly show many lines on a book-size sheet of paper. These drawings will not normally be used for assembly work because the information is too limited. Figure 5-13. A—Typical highway diagram. This method can handle many wires in an organized manner. B and C—Two methods for routing individual wires into the highway. They both show direction of travel. D—An alternate method for highway diagrams. It uses a table to inform the technician as to where each wire is coming from and where it is going. It also lists the wire’s colors and gage. D 91 92 Electronics Drafting Figure 5-14. A baseline diagram showing another method of controlling many wires in an organized manner. Interconnection Diagrams Interconnection diagrams show the wiring between different electronic units and between subassemblies. See Figure 5-15. This document is similar to the pointto-point wiring diagram. Each cable assembly and electronic unit is called out and assigned a title and drawing number. Note the subassemblies are shown in phantom lines. Internal connections of electronic units are not shown. Cable Assembly Drawings Cable assembly drawings are assembly drawings that contain all the necessary information to manufacture a finished cable. See Figure 5-16. A cable assembly drawing includes the following information: • A complete parts list. • A drawing showing all components. • Reference designations for each component. • A wiring diagram most often is part of the drawing. It will show the internal wires in the cable. • A general note section that will guide the assembler through the assembly. Wire (Cable) Harness Assembly Drawings Wire (cable) harness assembly drawings are the only wiring drawings drawn to exact scale. See Figure 5-17. It is drawn to scale because it is not just a drawing, but it is also a tool. This tool is used in manufacturing so that many identical parts can be created. Harness drawings will be supported by a wiring list and parts list. It is an assembly so it will need to be supplemented with all information needed by the assembler. The benefits of this drawing are as follows: Chapter 5 Wiring Diagrams Figure 5-15. A typical interconnection diagram. This is an assembly drawing and will require a parts list. Subassemblies on an interconnection diagram are shown in phantom lines. Figure 5-16. A cable assembly and a schematic of its wires. 93 94 Electronics Drafting Harness above routing board A Drawing on harness board. Drawing shows routing. B It will support high volume manufacturing. It will not require high priced technicians. Quality control of the wiring is easier. The wire installation is less expensive than installing many separate wires. Figure 5-17. A—Harness being removed from the harness routing board. B—The harness shown installed in equipment. • • • • Before we can begin a harness drawing, we must know the exact placement of all the electrical components to be hooked up. The layout of the drawing and the routing of the harness will be decided by studying this arrangement. See Figure 5-18. Once we know where the harness will run, we can plan the layout on the drawing. Routing of the wires in a harness is accomplished by retaining them between harness posts. See Figure 5-19. Harness posts will be driven into a routing board as the drawing directs. Harness posts will also be used as securing posts for each end of the wire. The wire will be wrapped around the starting post. Once secured, it will be run through the routing posts as described by the wire list. After routing, it will be secured around an ending post or in a clip used for securing wires. Lacing or cable straps will be used to hold the wires together once they are routed. See Figure 5-20. Lacing or strapping will hold the bundle into a permanent unit. Once the wires have been permanently bundled, they can then be lifted up off the routing board. After a harness has been removed, another duplicate harness may be started. Cable strap Figure 5-18. Terminal Block 1 needs to be wired. The right view shows how the wiring will be routed to service TB1. This is to provide a service loop so the wires can be easily hooked and unhooked. Break-out point A B Component to be Wired Harness post Chapter 5 Wiring Diagrams Layout of Harness to Service TB1 C Figure 5-19. A—Wiring being routed through harness posts. B—Picture of a wiring harness being automatically routed. C—Example of a completed wiring harness. (Amphenol North America Division, Bunker Ramo Corp.) 95 96 Electronics Drafting Figure 5-20. An example of lacing to keep the wire bundle in the desired shape. Lacing around harness half-loop knots on bottom After the harness has been manufactured, it will go to a higher assembly level where it will be installed. In order to make the installation easier, we identify each wire in the bundle. There are three methods of identifying wires. See Figure 5-21. The three methods are: color, number, or destination. When using colors, each wire carrying a different electronic signal will have a different color. Numbered wires will be numbered on both ends with the same number tag. A wire identified by destination will have the exact place where it is to be terminated tagged right on its ends. The destination method will eliminate the need for a wire list during installation. Numbered or colored wires must have a wire list with the harness in order to complete installations. Flexible Printed Wiring Whenever it is possible to automate, a process industry chooses that method. Flexible printed wiring allows the wiring to be etched on thin film that can be shaped to fit into the mechanical package. See Figure 5-22. A flexible circuit can be mass-produced very inexpensively. Typical Notes Used on Wiring Diagrams Wire list will state red wire to TB1-1 & etc Blue Red Yellow Green S1 TB1 TB1 There are notes that are used often for wiring diagrams. Examples of these notes are as follows: • This drawing used with: Assembly drawing _____ Schematic drawing _____ Wiring diagram _____ Wire lengths determined by prototype. Wire color coding per MIL-STD-681. Wiring must conform to _____. Soldering will conform to _____. Unless otherwise specified, all wires are _____. Lace harness at each breakout point and every _____” in-between. Apply cable straps at each breakout point and every _____” in-between. • • • • • • • Figure 5-21. Three ways to identify wires to aid in the harness installation. Wire list will state No. 3 wire goes to TB1-2 Wire itself is marked to its destination Figure 5-22. Flexible printed circuitry is being used in place of having many loose wires. It is used in assemblies where many units will be manufactured. Reference Designations Chapter 5 Wiring Diagrams Reference designations are identical to those on the schematic except for component sockets which are prefixed “X”. See Figure 5-23. Component Representation XQ1 Q1 Simplified View Showing Polarity Socket "XU1" Component "U1" Component representation is just a physical outline suggestive of the component’s features. See Figure 5-24. This is meant to be a simplified view as seen from the wiring side. Figure 5-23. Components and sockets and their reference designations. X is used to indicate the socket for the component. Figure 5-24. The actual component, left, and its representation on the right. Note: Pins have been assigned numbers. This is to help the technician during wire installation. Wiring Side Note: Polarity 97 98 Electronics Drafting Terminal Identification E Transistor Emitter Base Collector Battery Anode Cathode Diode Each terminal must be identified. Most components and connectors are marked adequately, but if not, sufficient details must be supplied with a wiring diagram. Leads of components, such as transistors, diode, electrolytic capacitor, batteries, and other devices shall have their terminals identified or polarity marked, as in Figure 5-25. Figure 5-25. Polarized components with their leads or polarity identified. B C Review Questions 1. What three things are considered when choosing a wiring method? 2. What information is normally included in the wiring list? 3. Name two types of wiring. 4. What is the advantage of stranded wiring? 5. What does 7/26 mean when we relate it to wiring? a. 7 strands wrapped around 26. b. 7 gage wire wrapped by 26 gage wire. c. 7 strands of 26 gage wire. d. 7 strands that total 26 circular mills. 6. Gage of wire is determined by the _____ standard. 7. What is affected by wire length and diameter? 8. How do we use bus wire? 9. Shielded or _____ cable reduces interfering radiation. 10. A point-to-point diagram shows the physical arrangement of the components. What other information does it convey? 11. When would we use pictorial point-to-point diagrams? 12. What is the advantage of a highway diagram? 13. Cable assembly drawings will contain what information? 14. Why is the cable harness assembly drawn to scale? 15. What are the advantages of cable harnesses? 16. How are harness posts used? 17. Cable straps or lacing serve what function? 18. What determines the type of termination a wire will make? 19. The most economical termination method with automation is _____(soldering, crimping, or wrapping). 20. Subassemblies on _____ diagrams are shown in phantom lines. Activities Chapter 5 Wiring Diagrams 1. Using the test simulator schematic shown as Figure A, create a wiring list and parts list. Wiring between the printed circuit connectors, switches, test points, and connector need to be listed. For wire list format, refer to Figure 5-2. Wiring shorting the switch (S4-B) has been accomplished in a subassembly, so do not list. μ Figure A. Shown are the connections from the circuit board to the switches, connecctors, and test points. 99 100 Electronics Drafting 2. Draft a point-to-point wiring diagram for Figure B, the test simulator. Check Figure C for component numbering and sizes. Figure D will show panel mounting positions. Use the wiring list generated in Activity 1 in this chapter to aid in this solution. If the wiring list was not complete, use the information indicated in Activity 1. All wire lengths determined at assembly. Note: Wiring is installed with panel turned upside down. See Figure E. Figure B. An exploded view of a test simulator package. This is the final Assembly Drawing. Use this drawing to see how the components are arranged. The arrangement is needed when working on the chapter activities. Note the wiring will be done on the underside of the lid so turn it over so your drawing complements what the wire installer sees. Chapter 5 Wiring Diagrams 101 Figure C. These components used in the test simulator project are important for planning the case mounting hardware. The chapter activities refer several times to this Figure. 102 Electronics Drafting Figure D. The front panel of the test simulator. The switch, test point, and circuit board positions are dimensionally located. Switch information and position settings are silk-screened on the panel. The circuit board is shown in phantom as it sits below the panel. Some of this information is needed in several other chapter problems. Figure E. This is the basic layout of the highway diagram for the test simulator. Complete this highway diagram using wire destinations given on the schematic. 3. Create a highway diagram using information described in Activities 1 and 2. Figure E shows the layout paths for the highway. Use as much information as you can from previous activities. 4. Using all the accumulated information from previous activities, create a wiring harness drawing. Note: This drawing is drafted to a 1=1 scale. It will be a tool for manufacturing. Check Figures A, B, C, and D. 5. Draft a baseline diagram of the test simulator. Use baseline diagram in Figure 5-14 as an example. Assign a color to each wire. Click below to find more Mipaper at www.lcis.com.tw Mipaper at www.lcis.com.tw