Wire Harnessing: Techniques, Tools & Manufacturing Best Practices

A hands-on engineering guide covering wire harnessing methods, essential tools, industry standards, and proven techniques for professional-quality results.

What Is Wire Harnessing?

Wire harnessing is the process of organizing, bundling, and routing multiple electrical wires and cables into structured assemblies that can be efficiently installed, tested, and maintained. It transforms loose, disorganized wiring into neat, functional units that improve reliability and simplify manufacturing.

Having spent years on factory floors troubleshooting control panels and production equipment, I’ve seen firsthand how proper wire harnessing separates professional installations from problematic ones. Good harnessing isn’t just about appearance—it directly impacts functionality, safety, and serviceability.

The goals of wire harnessing include:

• Organization – Grouping related circuits for logical routing
• Protection – Shielding wires from physical and environmental damage
• Simplification – Enabling faster installation and maintenance
• Reliability – Reducing stress, movement, and connection failures
• Standardization – Creating repeatable, consistent assemblies

Wire Harnessing vs Wire Harness Assembly

While related, these terms have distinct meanings:

Term	Definition	Scope
Wire Harnessing	The process/technique of bundling and organizing wires	The activity itself
Wire Harness Assembly	The finished product—a complete bundled wiring system	The output
Wire Harness Manufacturing	The industrial process of producing wire harnesses	The production system

Think of it this way: wire harnessing is the craft, while a wire harness assembly is what you produce using that craft.

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Essential Wire Harnessing Tools

Professional wire harnessing requires the right tools. Here’s what you need:

Cutting and Stripping Tools

Tool	Use	Key Features to Look For
Wire Strippers	Remove insulation from wire ends	Adjustable gauge settings, clean cuts
Cable Cutters	Cut cables and large wires	Clean cuts without crushing
Flush Cutters	Trim zip ties, fine work	Precision blades, spring return
Automatic Strippers	High-volume stripping	Gauge sensing, consistent quality

Crimping Tools

Tool Type	Applications	When to Use
Hand Crimpers	All terminal types	Prototypes, low volume, field work
Ratchet Crimpers	Consistent crimps	Moderate volume, quality-critical
Bench Applicators	High-volume crimping	Production environments
Hydraulic Crimpers	Large gauge wire (8 AWG+)	Power cable terminations

Assembly Tools

Tool	Purpose
Wire Insertion/Extraction Tools	Install/remove terminals from connectors
Pin Depressors	Release locking tabs on terminals
Lacing Needles	Apply lacing cord to harnesses
Heat Gun	Apply heat shrink tubing
Cable Tie Guns	Tension and cut zip ties consistently

Measurement and Testing

Tool	Use
Digital Multimeter	Continuity, resistance, voltage
Crimp Height Micrometer	Verify crimp dimensions
Pull Tester	Measure terminal pull strength
Wire Length Gauge	Verify cut lengths
Continuity Tester	Quick circuit checks

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Wire Harnessing Techniques

Bundling Methods

Different applications call for different bundling approaches:

Cable Ties (Zip Ties)

The most common bundling method. Available in various sizes and materials.

Material	Temperature Range	Best For
Nylon 6/6	-40°C to +85°C	General purpose
Heat-stabilized Nylon	-40°C to +105°C	Higher temps
PTFE (Teflon)	-60°C to +260°C	Extreme temps
Stainless Steel	-80°C to +538°C	Extreme environments

Best Practices:

• Space ties every 100-150mm (4-6 inches)
• Use correct size for bundle diameter
• Don’t over-tighten (causes insulation damage)
• Cut tails flush with tie head

Spiral Wrap

Plastic or polyethylene wrap that spirals around the bundle.

Advantages:

• Easy to add/remove wires later
• Good abrasion protection
• Flexible for routing

Disadvantages:

• Can unwind in high-vibration environments
• Not suitable for harsh chemicals

Braided Sleeving

Expandable mesh that slides over cables.

Type	Properties	Applications
PET	Lightweight, flexible	Electronics, automotive
Nomex	Flame resistant	Aerospace, military
Kevlar	High abrasion resistance	Industrial, outdoor
Fiberglass	High temperature	Engine compartments

Corrugated Tubing (Split Loom)

Plastic conduit that protects bundles from crushing and abrasion.

Material	Temperature Range	Features
Polypropylene	-40°C to +105°C	General purpose
Polyamide (PA)	-40°C to +120°C	Higher temp, oil resistant
PVDF	-40°C to +150°C	Chemical resistant

Heat Shrink Tubing

Provides environmental sealing and strain relief.

Shrink Ratios:

• 2:1 – Standard applications
• 3:1 – More accommodation for irregular shapes
• 4:1 – Maximum shrinkage for large transitions

Lacing and Tying

Traditional method using waxed cord or tape—still required in aerospace and military applications.

Advantages:

• Lightweight
• No sharp edges
• Allows wire movement without damage
• Meets MIL-DTL-81381 requirements

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Routing Best Practices

Proper routing prevents many common harness failures.

Bend Radius Rules

Cable Type	Minimum Bend Radius
Standard wire	4× outer diameter (static)
Coaxial cable	6× outer diameter
Shielded multiconductor	8× outer diameter
Continuously flexed	10× outer diameter
Fiber optic	Per manufacturer spec (typically 10-15×)

Routing Guidelines

Do:

• Follow natural wire paths
• Route along structural members where possible
• Provide service loops at terminations
• Allow for thermal expansion
• Separate power and signal wires

Don’t:

• Route over sharp edges
• Create stress points at breakouts
• Route near heat sources
• Create wire traps that prevent removal
• Route where foot traffic or maintenance occurs

Segregation Requirements

Circuit Type	Separation Distance
Power (> 50A) from signal	75mm (3″) minimum
AC from DC circuits	50mm (2″) minimum
Shielded from unshielded	25mm (1″) minimum
High frequency from low frequency	Per EMC analysis

Securing Methods

Clamping

Clamp Type	Application
P-Clips	General purpose, single cable
Cushioned Clamps	Vibration environments
Saddle Clamps	Large bundles
Cable Tie Mounts	Flexible, general use

Clamp Spacing Guidelines:

• Horizontal runs: 150-300mm (6-12″) intervals
• Vertical runs: 100-150mm (4-6″) intervals
• At each direction change
• Both sides of connectors

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IPC/WHMA-A-620: Wire Harnessing Standards

The IPC/WHMA-A-620 standard provides acceptance criteria for wire harnessing workmanship. Understanding this standard is essential for professional-quality work.

Product Classes

Class	Description	Typical Industries
Class 1	General electronic products	Consumer goods, non-critical
Class 2	Dedicated service products	Industrial, telecom, automotive
Class 3	High-performance products	Aerospace, medical, military

Key Workmanship Requirements

Wire Preparation

Attribute	Class 1	Class 2	Class 3
Nicked strands	Some acceptable	Minimal	None acceptable
Scraped insulation	Acceptable if no conductor exposed	Minimal	None acceptable
Clean cut ends	Required	Required	Required

Bundling and Securing

Requirement	All Classes
Bundle not over-tightened	Insulation not deformed
Tie spacing	Per specification or 150mm max
Clamp cushioning	Required for vibration environments
Edge protection	Where wires contact sharp edges

Sleeving and Tubing

Requirement	Specification
Heat shrink centering	Centered over transition
Heat shrink recovery	Fully recovered, no wrinkles
Braided sleeve ends	Terminated or sealed
Spiral wrap overlap	25-50% coverage

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Wire Harnessing in Manufacturing

Form Board Assembly

The form board (also called assembly board or pin board) is the foundation of harness manufacturing.

Form Board Types:

Type	Construction	Best For
2D Board	Flat layout on wood/composite	Simple harnesses, prototypes
3D Fixture	Contoured jig	Complex routing, high volume
Digital (CAD-generated)	Printed full-scale template	Quick setup, frequent changes

Form Board Components:

• Full-scale layout drawing or template
• Routing pegs or posts
• Connector holders
• Breakout locations marked
• Wire identification at each position

Assembly Sequence

A typical wire harnessing sequence in production:

1. Wire Preparation
   1. Cut wires to length
   1. Strip wire ends
   1. Apply terminals
2. Initial Routing
   1. Place main trunk wires on board
   1. Route according to drawing
3. Branching
   1. Create breakouts at specified points
   1. Verify branch lengths
4. Connector Loading
   1. Insert terminals into housings
   1. Verify pin positions
   1. Install secondary locks
5. Bundling
   1. Apply ties, tape, or sleeving
   1. Maintain specified spacing
6. Finishing
   1. Apply labels
   1. Install grommets/boots
   1. Final bundle securing
7. Testing
   1. Continuity check
   1. Isolation test (if specified)
   1. Visual inspection

Quality Control Checkpoints

Checkpoint	What to Verify
Wire preparation	Strip length, strand condition
Terminal crimp	Height, position, pull force
Connector loading	Correct position, seating
Routing	Per drawing, proper radius
Bundling	Spacing, tightness, appearance
Labeling	Correct, legible, positioned
Electrical	Continuity, isolation

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Common Wire Harnessing Mistakes

Learning from common errors improves quality:

Mechanical Issues

Mistake	Consequence	Prevention
Over-tightened ties	Insulation damage, conductor stress	Use appropriate tension
Sharp bend radius	Conductor fatigue, failure	Follow minimum radius rules
Missing edge protection	Insulation abrasion	Use grommets, sleeves at edges
Insufficient strain relief	Connector damage	Proper clamping near connectors

Electrical Issues

Mistake	Consequence	Prevention
Poor crimp	High resistance, intermittent connection	Verify crimp parameters
Wrong terminal	Mismatch, loose fit	Double-check part numbers
Reversed polarity	Equipment damage	Use polarized connectors, verify
No testing	Field failures	100% electrical test

Process Issues

Mistake	Consequence	Prevention
Wrong wire length	Recut, waste	Measure twice, cut once
Missing wires	Incomplete assembly	Use checklists, verification
Wrong label	Installation errors	Verify against drawing
Documentation not updated	Configuration issues	Maintain revision control

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Wire Harnessing Safety

Personal Protective Equipment

Hazard	PPE Required
Wire ends, sharp tools	Safety glasses
Solder fumes	Ventilation, fume extraction
Heat guns	Heat-resistant gloves
Chemical cleaners	Gloves, eye protection
Electrical testing	Insulated tools, proper procedures

Workspace Safety

• Keep work area organized
• Store sharp tools properly when not in use
• Maintain adequate lighting
• Use anti-static precautions when required
• Follow lockout/tagout for live equipment

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Useful Resources and Downloads

Industry Standards:

• IPC/WHMA-A-620 – Cable and Wire Harness Assemblies – shop.ipc.org
• NASA-STD-8739.4 – Crimping, Interconnecting Cables, Harnesses, and Wiring – standards.nasa.gov
• MIL-DTL-81381 – Lacing Cord and Tape – everyspec.com

Tool Manufacturers:

• Ideal Industries – Strippers, crimpers – idealind.com
• Panduit – Cable ties, installation tools – panduit.com
• TE Connectivity – Application tooling – te.com
• Molex – Crimping tools – molex.com

Training Resources:

• IPC Certification Programs – ipc.org/certification
• WHMA Training – whma.org
• NASA Workmanship Standards – Free online access

Reference Materials:

• Wire gauge/ampacity charts
• Connector pinout references
• Heat shrink selection guides
• Cable tie sizing charts

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Frequently Asked Questions (FAQs)

What is the difference between wire harnessing and cable lacing?

Wire harnessing is the general process of bundling wires, using any method (ties, tape, sleeving, lacing). Cable lacing is a specific technique using waxed cord or flat tape, typically required by aerospace and military specifications. Lacing is lighter and allows more wire movement, but requires skilled hand work.

How do I choose between zip ties and spiral wrap?

Factor	Zip Ties	Spiral Wrap
Cost	Lower	Higher
Speed	Faster	Slower
Serviceability	Cut to remove	Easy to unwrap
Flexibility	Rigid points	Continuous flex
Best for	Permanent, simple bundles	Field service, frequent changes

What crimp height should I use?

Crimp height is terminal-specific. Always use the manufacturer’s specification:

1. Consult terminal data sheet for nominal crimp height
2. Set up crimp tooling per manufacturer instructions
3. Crimp sample terminals and measure with micrometer
4. Adjust until within specified tolerance (typically ±0.05mm)
5. Document settings for that terminal/wire combination

How often should I replace wire stripping blades?

Replace stripping blades when:

• Cuts are no longer clean (ragged edges)
• Conductor nicking increases
• Adjustment can’t compensate for wear
• Blade edges are visibly damaged

For production environments, many shops replace blades on a schedule (e.g., weekly for high-volume, monthly for moderate use) rather than waiting for failures.

What documentation should I maintain for wire harnessing?

Document Type	Content	Purpose
Work Instructions	Step-by-step procedures	Consistent production
Inspection Checklists	Quality verification points	Quality assurance
Training Records	Personnel qualifications	Competency tracking
Tool Calibration	Crimp tool verification	Process control
Nonconformance Reports	Defect documentation	Continuous improvement

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Conclusion

Wire harnessing is a fundamental skill that combines attention to detail with practical knowledge of materials, tools, and techniques. Whether you’re building prototypes on the bench or managing production of thousands of harnesses, the principles remain the same: proper planning, correct tools, adherence to standards, and thorough verification.

Key takeaways:

• Invest in quality tools appropriate for your work
• Learn and follow IPC/WHMA-A-620 workmanship standards
• Develop consistent processes and document them
• Test every harness before it leaves your hands
• Keep learning—wire harnessing techniques continue to evolve

For more detailed information on complete assemblies, explore our guides on wire harness assembly, cable harness assembly, and cable assembly types.