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What Are Cable Drawings?

Published Date
Author Cadence PCB Solutions

Key Takeaways

  • Cable drawings are the pictorial representation of cable assembly in an electrical circuit or system. 

  • Cable drawings provide end-to-end connection details. 

  • Cable drawings are very important for reliable cable assembly, which in turn increases the product quality.  

 Schematic drawing

Cable drawings are essential when wiring a complex circuit or making connections to electronic device

Designers often use different types of cables—such as co-axial/RF cables, multi-conductor cables, or flat ribbon cables—to connect electronic boards or devices. Harnessing cables is common for interconnecting printed circuit boards with other boards or electrical sockets. During the design phase, designers must focus on how PCB routing connections are interfaced with cables and where they are going. Cable drawings save designers time by giving all the required information regarding cable assembly. 

Cable Assembly 

Cables are groups of electrical wires assembled together into a single unit that is used in signal transmission or as a power line. Arranging several wires as a single unit makes it easy for installation, replacement, and maintenance. Cables are arranged as a single unit by putting them inside a sleeve made of materials such as vinyl, rubber, or flexible conduit. The sleeve acts as a shield from dust, dirt, smoke, and flames, thereby increasing the durability of the cable. Even though the cable assembly looks like a thick wire, the individual cables inside the sleeve function separately. For example, there might be cables carrying data signals, and in the same sleeve, some other cable may be exclusively used for power supply.

As the functions of wires are different, any wiring mistake can result in circuit board mishaps. It is very important to equip designers with cable drawings while making cable connections.  

Cable Drawings

Cable drawings are a pictorial representation of cable assembly in an electrical circuit or system. The electrical circuit can be one laid on a PCB, wiring connected to electrical machinery, or wiring of a building. Cable drawings associated with a PCB define the cable connections to the PCB or connector pinouts. Here are a few applications where cable drawings are essential.

Wiring Buildings

When wiring a building, cable drawings explain the physical location of the electrical sockets, outlets, and fixtures. In building electrification work, cable drawings help the engineer adhere to building codes, preventing code violations and the waste of money and materials. From the cable drawings for building floors, it is possible to make a good cost estimate and engineers can have more control over the electrical planning and design. 

Electronic Device Connections

Cable drawings are essential when wiring a complex circuit or making connections to electronic devices. A cable drawing serves as work instructions that ensure the right wiring connections are made. From a cable drawing, one can understand the length of the wire required, the associated component types, part numbers, and where it is going on the board. 

Why Are Cable Drawings Useful?

In general, cable drawings demonstrate a clear visual of the cable assembly. They provide end-to-end connection details. The dimensions of the cable are another important piece of information that can be obtained from a cable drawing. Along with the dimensional details of the cable, the location of the heat-shrinkable tubes and internal solder connections, if any, are marked in a cable drawing. The bill of materials (BOM) and assembly notes are usually included in the cable drawing as well to guide make/buy decisions, installation, and repairs. 

What Can You Find in a Cable Drawing?

Cable drawings give the reader the complete necessary information about a cable and how it is harnessed in a given application system. Typically, one can find the following things in a cable drawing:

  1. A mechanical drawing showing all components connected to the cable.
  2. A schematic drawing showing the internal structure of the cable and pinouts.
  3. Reference designation of each component.
  4. Complete list of the parts used (BOM) with part number, quantity, designation, and description.
  5. Assembly notes to guide the assembler while making connections.
  6. Header block and revision table showing the project details and revision history, respectively.

Cable Drawing Applications

In aerospace, marine, automotive, and missile applications, electronic circuits are becoming mechanically, optically, and electrically integrated to an unprecedented level. This kind of integration requires various types of cables in a single system to transmit energy and communication signals. For systems with such a high level of integration, cable drawings are important for reliable cable assembly, which, in turn, increases product quality.

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