Complete, accurate documentation is the foundation of successful wire harness manufacturing. Poor documentation is one of the leading causes of production delays, quality issues, and cost overruns. This guide covers all aspects of wire harness documentation, from basic drawings to comprehensive manufacturing packages that ensure your harnesses are built correctly the first time.
Why Wire Harness Documentation Matters
Wire harness documentation serves as the single source of truth for manufacturing, quality control, and field service. Unlike simple components, wire harnesses have complex relationships between wires, connectors, and routing that must be precisely communicated.
Benefits of Good Documentation
- •Reduces manufacturing errors by 70-90%
- •Enables accurate quoting and cost estimation
- •Speeds up production ramp-up
- •Facilitates supplier transitions
- •Supports quality audits and certifications
- •Enables traceability and recall management
Consequences of Poor Documentation
- •Production delays and missed deadlines
- •Incorrect assembly and rework costs
- •Field failures and warranty claims
- •Difficulty scaling production
- •Knowledge loss when engineers leave
- •Failed quality audits
Essential Documentation Package
A complete wire harness manufacturing package includes several interconnected documents. Each serves a specific purpose in the design-to-production workflow.
Bill of Materials (BOM)
The BOM is the master list of all components needed to build the harness. It serves as the blueprint for sourcing, kitting, and assembly.
Required Fields:
Wiring Diagram / Schematic
Shows the logical electrical connections between components. This is similar to a schematic for PCB design and defines the electrical functionality.
Key Elements:
Assembly Drawing / Layout
Shows the physical arrangement of the harness including dimensions, routing, connector positions, and overall form factor.
Key Elements:
Formboard / Nailboard Drawing
A full-scale dimensional jig drawing used to fabricate harnesses. It shows exact routing, branch points, and enables precise assembly.
Key Elements:
Wire List / Cut List
A tabular list of all wires in the harness with specifications for cutting and preparation.
Required Fields:
Test Specifications
Defines the testing requirements for quality verification including continuity, hi-pot, and functional tests.
Key Elements:
Creating an Effective Bill of Materials
The BOM is arguably the most critical document in your package. A well-structured BOM enables accurate quoting, efficient procurement, and error-free kitting.
| Item | Part Number | Description | Qty | UOM | Ref Des |
|---|---|---|---|---|---|
| 1 | DT04-6P | Deutsch DT 6-pin plug | 2 | EA | J1, J2 |
| 2 | 0462-201-16141 | Deutsch Pin Contact 16AWG | 12 | EA | — |
| 3 | TXL-16-RED | 16AWG TXL Wire, Red | 2.5 | M | W1, W3 |
| 4 | TXL-16-BLK | 16AWG TXL Wire, Black | 2.5 | M | W2, W4 |
| 5 | HS-1/4-BK | Heat Shrink 1/4" Black | 0.3 | M | — |
BOM Best Practices
- • Use manufacturer part numbers, not internal codes only
- • Include approved alternates for critical components
- • Specify revision levels for all items
- • Use consistent units of measure (EA, M, FT)
- • Include consumables (solder, tape, labels)
- • Document any customer-supplied items
Common BOM Mistakes
- • Missing revision control
- • Incorrect quantities or units
- • Obsolete part numbers
- • Missing wire specifications (length, color)
- • No approved alternates listed
- • Inconsistent reference designators
Technical Drawing Requirements
Technical drawings must clearly communicate the physical layout, dimensions, and assembly requirements. Each drawing should include essential elements for unambiguous interpretation.
Drawing Content Checklist
Dimensions & Layout
- ☐ Overall harness size
- ☐ Branch lengths
- ☐ Connector positions
- ☐ Breakout points
- ☐ Bundle diameters
- ☐ Mounting hole locations
Connector Details
- ☐ Connector part numbers
- ☐ Pin/cavity callouts
- ☐ Mating connector info
- ☐ Keying orientation
- ☐ Locking mechanism
- ☐ Sealing requirements
Assembly Notes
- ☐ Workmanship standard (A-620)
- ☐ Material specifications
- ☐ Tolerances
- ☐ Special instructions
- ☐ Labeling requirements
- ☐ Test requirements
Connector Pinout Documentation
Each connector's pinout must be clearly labeled so connections can only be made correctly. Include both the connector view and the mating connector reference.
| Connector | Pin | Signal | Wire | Color | Destination |
|---|---|---|---|---|---|
| J1 (DT04-6P) | 1 | +12V | 16AWG | Red | J2-1 |
| 2 | GND | 16AWG | Black | J2-2 | |
| 3 | CAN-H | 20AWG | Yellow | J2-3 |
Industry Standards for Documentation
Several industry standards govern wire harness documentation requirements. Understanding which standards apply to your application ensures compliance and quality.
IPC-D-620: Design Requirements
IPC-D-620 provides comprehensive design requirements for cable and wiring harness design. It guides engineers on how to create designs that can be reliably manufactured and tested.
IPC/WHMA-A-620: Workmanship & Acceptance
IPC/WHMA-A-620 is the globally recognized standard for how cable and wire harness assemblies should be built and inspected. It defines materials, methods, and quality benchmarks.
- • Class 1: General consumer products
- • Class 2: Dedicated service products (extended life)
- • Class 3: High-performance products (critical applications)
SAE AS50881: Aerospace Wiring
SAE AS50881 (formerly MIL-W-5088) covers wiring for aerospace vehicles. It's an installation and design standard, not a manufacturing standard, but it influences documentation requirements.
Related Standards
Wire Harness Design Software
Modern wire harness design software automates much of the documentation process, ensuring consistency and reducing errors. Here are the leading tools used in the industry.
Altium Designer
Full harness design with automated BOM, wiring lists, connection tables, and manufacturing drawings derived directly from project documents.
RapidHarness
Specialized harness design with auto-generated top level drawings, BOM, wiring tables, and netlists in PDF and Excel formats.
SOLIDWORKS Electrical
3D wire/cable assemblies with form board drawings, BOM, and reports integrated with mechanical design.
Zuken E3.series
Complete formboard solution with automatic wire lengths, packing algorithms for bundle diameter, and connection tables.
TE HarnWare
Materials listings, equipment requirements, and preparation/assembly instructions output from design data.
Autodesk Inventor
Cable and harness nailboards with full BOM support for all harness objects except segments and splices.
Documentation Best Practices
Revision Control
- ✓Use formal revision numbering (A, B, C...)
- ✓Document all changes in revision history
- ✓Include ECO/ECN reference numbers
- ✓Date stamp all documents
- ✓Control distribution of revisions
Identification & Marking
- ✓Mark each harness with part number
- ✓Include unique serial number
- ✓Label connectors with reference designators
- ✓Include mating connector reference
- ✓Specify marking method and location
File Formats
- ✓Provide PDF for viewing/printing
- ✓Include native CAD files for edits
- ✓Export BOM to Excel/CSV
- ✓Use industry-standard formats (DXF, STEP)
Review & Approval
- ✓Engineering review for design intent
- ✓Manufacturing review for producibility
- ✓Quality review for compliance
- ✓Customer approval for final release
"The best documentation package pays for itself on the first production run. When we receive complete documentation—BOM, drawings, wire lists, and test specs—we can quote accurately and start production immediately. Incomplete documentation leads to questions, delays, and sometimes costly rework when assumptions prove wrong."
Frequently Asked Questions
What documents are needed for wire harness manufacturing?
Essential documents include: Bill of Materials (BOM), wiring diagram/schematic, assembly drawing, formboard/nailboard layout, wire list with cut lengths, connector pinout diagrams, and test specifications. Additional documents may include revision history, quality inspection criteria, and customer-specific requirements.
What is the difference between IPC-D-620 and IPC/WHMA-A-620?
IPC-D-620 is the design requirements standard for cable and wiring harness design, while IPC/WHMA-A-620 is the workmanship and acceptance standard. IPC-D-620 guides engineers on how to design harnesses, while A-620 provides criteria for inspecting and accepting finished assemblies. Both standards are complementary.
What information should be included in a wire harness BOM?
A complete BOM should include: item numbers, manufacturer part numbers, descriptions, revision levels, quantities per assembly, units of measure, reference designators, and approved alternate parts. For each wire, specify gauge (AWG), insulation type, color coding, and cut length.
What is a formboard or nailboard in wire harness manufacturing?
A formboard (or nailboard) is a full-scale dimensional jig used to fabricate wire harnesses. It shows the exact routing, branch points, connector positions, and bundle dimensions. Formboard drawings include connection tables, clips, heat-shrink locations, and wire lengths calculated automatically from the layout.
How do I manage revisions to wire harness documentation?
Use formal revision control with sequential letters (A, B, C) or numbers. Document all changes in a revision history table, including date, description, and ECO/ECN reference. Control distribution to ensure all stakeholders have current versions. Consider using PDM/PLM software for complex products.
Sources & References
Need Help With Wire Harness Documentation?
Our engineering team can help you create or review your wire harness documentation package. We ensure IPC compliance and manufacturing-ready specifications.