Wire Harness Glossary

The maximum current a conductor can carry continuously without exceeding its temperature rating. Depends on wire size, insulation type, ambient temperature, and bundling.

The loss of signal strength as it travels through a cable, measured in dB/length. Higher frequencies attenuate faster. Limits maximum cable length for data applications.

A standardized wire sizing system used in North America. The gauge number inversely relates to diameter - lower numbers mean thicker wire. Each 3-gauge decrease doubles the cross-sectional area.

A mechanical housing attached to the rear of a connector that provides strain relief, cable clamping, and EMI shielding termination. Available in straight, 45 degree, and 90 degree configurations.

A comprehensive list of all components required to build a harness, including part numbers, quantities, descriptions, and suppliers. The foundation of purchasing and manufacturing.

A flexible rubber or silicone cover that protects connectors from moisture, dust, and mechanical damage. Often molded over the cable-to-connector junction.

Expandable woven mesh tubing that provides abrasion protection and a clean appearance. Expands to slide over connectors and contracts for a snug fit. Made from PET, nylon, or Nomex.

A section of wires that splits off from the main trunk of a harness to reach a specific destination. Each branch typically terminates at a connector or splice.

The point where wires separate from the main bundle to go to different destinations. Requires careful design for strain relief and protection at the junction.

An inline connector that joins two wires end-to-end. Wires are inserted from opposite ends and crimped. Used to extend wire length or repair damaged sections.

Two or more insulated wires bundled together within an outer jacket. Cables may include shielding, fillers, and drain wires. Unlike single wires, cables are designed as complete assemblies for specific applications.

A cable with connectors attached at one or both ends, ready for installation. Simpler than a harness - typically a single cable rather than a bundled group of wires.

A device for attaching and securing cables to enclosures while maintaining environmental sealing. Provides strain relief and IP-rated ingress protection.

A fastener for bundling and securing cables. Made from nylon or other plastics with a self-locking mechanism. Quick to install but not reusable. UV-resistant versions available for outdoor use.

An open support structure for routing and supporting cables in industrial and commercial installations. Types include ladder, solid-bottom, and wire mesh. Allows natural cooling.

The impedance that a cable presents to a high-frequency signal, determined by its physical construction. Must be matched to source and load to prevent reflections. Common values: 50, 75, 100 ohms.

A connector with a round, cylindrical housing. Provides 360 degree shielding and strain relief. Common types include MIL-DTL-38999, MIL-DTL-5015, and M12.

The metallic core of a wire that carries electrical current. Most commonly made of annealed copper (for conductivity) or aluminum (for weight savings). Can be solid or stranded.

A tube or channel that protects and routes electrical wires. Types include rigid metal (EMT, IMC), flexible metal, and non-metallic (PVC, HDPE). Sized to allow 40% maximum fill.

A device that joins electrical circuits together, allowing them to be easily connected and disconnected. Includes the housing, contacts (pins/sockets), and mounting hardware.

The conductive element within a connector that carries current. Can be a pin (male) or socket (female). Made from brass, phosphor bronze, or beryllium copper, often plated with gold or tin.

An electrical test verifying that each wire provides a complete path from end to end. Detects open circuits, high resistance, and wrong connections.

A basic test verifying an unbroken electrical path exists between two points. Uses a low-voltage signal to detect opens, broken wires, or bad crimps. The most fundamental harness test.

The threaded or bayonet ring on a connector that locks the mating halves together. Ensures proper alignment and prevents accidental disconnection.

A terminal attached to a wire by mechanical deformation (crimping) rather than soldering. Faster, more reliable, and resistant to vibration. The standard method for automotive and aerospace.

The process of mechanically securing a terminal to a wire by deforming the terminal barrel around the conductor. Requires proper tool selection and die matching for reliable connections.

Unwanted electromagnetic coupling between adjacent wires where a signal in one wire induces noise in another. Mitigated by shielding, twisting, and physical separation.

A detailed list of all wires to be cut, specifying length, gauge, color, and terminal types for each end. Used by production to prepare wire inventory before assembly.

A family of connectors with a distinctive D-shaped shell. Common configurations include DB9, DB15, DB25, and DB37. Widely used for serial ports, VGA, and industrial controls.

A D-shaped connector with pins in two or more rows. Named by shell size (DB9, DB15, DB25, DB37). Historically used for serial ports, now common in industrial and aerospace applications.

Reducing the rated capacity of a wire due to factors like high ambient temperature, bundling with other wires, or altitude. Essential for preventing overheating.

A brand of rugged, environmentally sealed connectors (now TE Connectivity). DTM, DT, DTP series are industry standards for automotive, agricultural, and heavy equipment wiring harnesses.

Two conductors carrying equal and opposite signals. Noise affects both equally and is cancelled at the receiver. Used in USB, HDMI, Ethernet, and CAN bus.

An uninsulated wire in contact with a foil shield, providing a convenient termination point for grounding. Required because you cannot solder directly to aluminum foil shields.

A protective cover placed over unmated connectors to prevent contamination of contacts. Essential for field-serviceable equipment exposed to dirt or moisture.

A metal sleeve crimped onto the end of a stranded wire to prevent fraying and provide a solid termination point. Essential when connecting stranded wire to screw terminals.

Non-conductive material added to cables to maintain a round cross-section and proper spacing between conductors. Can be made of paper, plastic, or cotton.

A table defining each wire's origin and destination connections. Specifies connector, pin number, and wire ID for both ends. Essential for assembly and testing.

A rubber or plastic ring inserted into a hole to protect cables from abrasion against sharp edges. Also provides vibration dampening and environmental sealing.

Insulation and jacket materials that do not release toxic halogen gases (chlorine, fluorine) when burned. Required in public spaces, transit, and marine applications for fire safety.

A flat board or panel with pegs, clips, and guides that holds wires in position during harness assembly. It keeps routing and dimensions consistent across production runs.

High-Definition Multimedia Interface connector for transmitting uncompressed video and audio data. Uses 19 pins (Type A).

A connector mounted directly to a PCB (printed circuit board), typically with through-hole or surface-mount pins. The mating half of a wire-to-board connection.

Plastic tubing that shrinks when heated to provide insulation, strain relief, and environmental sealing. Shrink ratios range from 2:1 to 6:1. Available with adhesive lining for waterproofing.

A high-voltage test (typically 500-3000V AC or DC) verifying insulation integrity. Detects insulation defects, contamination, and inadequate clearances. Essential for safety certification.

The plastic or metal shell of a connector that holds the contacts in position and provides mechanical support. Determines the connector's form factor and mating characteristics.

A connector that pierces through wire insulation to make contact with the conductor, eliminating the need to strip wires. Common for ribbon cables and telecommunications.

The total opposition to alternating current (AC), combining resistance and reactance. Critical for high-frequency signals like USB, Ethernet, and RF. Measured in ohms.

The non-conductive material surrounding a conductor that prevents electrical contact and provides protection. Common materials include PVC, PTFE (Teflon), silicone, and XLPE. Rated by temperature and voltage.

A test measuring the resistance of insulation (typically in megohms) to detect degradation, moisture ingress, or contamination. Lower readings indicate potential failure.

Ingress Protection rating indicating resistance to solid objects and water. Format: IPXY where X = solids (0-6) and Y = water (0-9). IP67 means dust-tight and waterproof to 1m immersion.

The industry standard for cable and wire harness assembly workmanship. Defines acceptance criteria for crimping, soldering, cable routing, and other manufacturing processes.

Deutsch 9-pin circular connector used for diagnostic access in heavy-duty vehicles (trucks, buses). Carries CAN bus traffic.

The outermost protective layer of a cable that provides mechanical, chemical, and environmental protection. Different from insulation, which surrounds individual conductors.

A short wire used to make temporary or permanent connections between two points. Often used for configuration settings or bypassing failed components.

A flat woven tape used to bundle and secure wires in aerospace and military harnesses. Provides excellent vibration resistance and allows visual inspection of wires. Applied in specific patterns per MIL-STD.

Flexible corrugated plastic tubing used to protect wire bundles. The ribbed design allows bending while maintaining an open pathway. Common in automotive and appliance wiring.

A circular, threaded connector with a 12mm locking ring. Standard in industrial automation, sensors, and Ethernet. Available in various pin configurations (3, 4, 5, 8, 12 pins).

Military specifications defining standards for materials, components, and workmanship. Common wire/cable specs include MIL-DTL-16878 (hook-up wire) and MIL-DTL-27500 (cable). Ensures reliability in harsh environments.

A brand name often used generically for various connector types. Known for the 4-pin power connector (Molex 8981) used in computers, but makes thousands of connector types for all industries.

A molded rubber or plastic covering applied over a cable-to-connector junction during manufacturing. Provides superior strain relief and environmental sealing compared to assembled backshells.

A short length of wire with a connector on one end, used for making quick connections or splicing into existing circuits. Common for adding aftermarket accessories.

The male portion of a connector contact that inserts into a socket. Typically a solid or stamped metal piece. The "plug" side of a mating pair.

The process of filling a connector or junction with a solid compound (epoxy, silicone, or polyurethane) to protect against moisture, vibration, and shock. Provides strain relief and insulation.

High-performance fluoropolymer insulation with excellent temperature range (-200C to +260C), chemical resistance, and low friction. Used in aerospace, medical, and high-reliability applications.

A destructive or non-destructive test measuring the force required to pull a terminal off a wire. Validates crimp quality. Minimum values specified by terminal manufacturer.

The most common wire insulation material. Inexpensive, flexible, and easy to process. Temperature range typically -20C to +105C. Not suitable for high-temperature or plenum applications.

A connector with a rectangular housing, allowing higher contact density than circular connectors. Common in automotive (e.g., Molex, JST) and industrial applications.

Opposition to current flow, measured in ohms. Wire resistance depends on material, length, cross-sectional area, and temperature. Copper has lower resistance than aluminum.

The loss of signal power due to reflections caused by impedance mismatch, measured in dB. Related to VSWR. Higher return loss (more dB) is better - means less energy reflected back.

A terminal with a closed circular end designed to be secured under a screw or bolt. Provides the most secure mechanical connection and cannot accidentally slip off.

Standard 8-pin modular connector used for Ethernet networking. Supports Cat5, Cat6, and Cat6a cables. Wiring follows T568A or T568B standards.

Restriction of Hazardous Substances directive limiting lead, mercury, cadmium, and other materials in electronics. Required for products sold in the EU. Affects solder and component choices.

The physical path that wires follow through a harness or system. Good routing minimizes length, avoids interference, and considers maintenance access.

A conductive layer (foil, braid, or spiral) surrounding wires to block electromagnetic interference (EMI) and radio frequency interference (RFI). Essential for sensitive signals and noisy environments.

Flexible insulation with wide temperature range (-60C to +200C) and excellent flexibility at low temperatures. Soft and easily damaged by abrasion. Common in appliances and automotive.

The female portion of a connector contact that receives a pin. Uses spring tension to maintain electrical contact. The "receptacle" side of a mating pair.

A terminal attached to a wire using molten solder. Provides excellent conductivity but is labor-intensive and can crack under vibration. Common in electronics and PCB connections.

Joining metals using a molten filler metal (solder) that wets the surfaces and solidifies. Provides excellent electrical conductivity but is labor-intensive and sensitive to cold joints.

A conductor made from a single piece of metal. Less flexible but easier to terminate and slightly lower resistance. Common in building wiring but rarely used in harnesses.

A terminal with a forked (U-shaped) end that slides under a screw without removing it. Faster installation than ring terminals but less secure. Also called fork terminals.

A helically-cut tubing that wraps around wire bundles for protection. Allows easy access to wires for service without removing the protection entirely.

A connection joining two or more wires together, either permanently or semi-permanently. Types include butt splices, parallel splices, and tap splices.

A mechanical feature that prevents pulling forces on a cable from being transmitted to the electrical connections. Essential for preventing wire fatigue and connection failures.

A conductor made of multiple thin wires twisted together. More flexible than solid wire and resistant to fatigue from vibration. Standard for harnesses in vehicles and moving equipment.

The metal end fitting attached to a wire for connection to equipment or another wire. Includes ring terminals, spade terminals, pin terminals, and butt splices.

The process of attaching terminals, connectors, or splices to wire ends. Methods include crimping, soldering, welding, and IDC insertion.

Copper wire coated with a thin layer of tin to prevent oxidation and corrosion. Essential for marine, aerospace, and high-reliability applications. Easier to solder than bare copper.

The main body or "backbone" of a wire harness from which branches extend. Contains the highest concentration of wires before they split off to destinations.

Two insulated wires twisted together at a specific rate (twists per inch). The twisting cancels electromagnetic interference, making it ideal for data signals. Used in Ethernet, CAN bus, and audio.

Certification by Underwriters Laboratories indicating a product meets safety standards. Required for many electrical products sold in North America. Look for the UL mark.

Universal Serial Bus connector for data and power. Common types include USB-A (host), USB-B (device), and USB-C (reversible).

The reduction in voltage as current flows through wire resistance. Calculated as V = I x R. Excessive drop (>3%) causes dim lights, slow motors, and unreliable electronics.

A measure of impedance matching in RF and high-frequency cables. VSWR of 1:1 is perfect match; higher ratios indicate reflections. Critical for antenna and coax cable testing.

A single conductor, typically made of copper or aluminum, with or without insulation. Wires are the fundamental building blocks of electrical circuits, carrying current from one point to another.

A plastic channel with slots or holes used to organize and route wires inside electrical panels. The "fingers" break off to allow wires to exit at any point.

An organized set of wires, terminals, and connectors bound together to transmit signals or electrical power. Designed to fit a specific application with predetermined routing. The final, ready-to-install assembly.

A label or tag attached to a wire for identification. Types include heat-shrink labels, wrap-around labels, and clip-on markers. Essential for troubleshooting and maintenance.

Term commonly used in the UK and Europe for a wire harness. Also sometimes refers specifically to the protective covering (loom tubing) around a harness.

Insulation with improved temperature rating (90C+) and moisture resistance over standard PE. Common in power cables and underground installations. "Cross-linked" means thermally set.

Circular 3-pin connector standard for professional balanced audio. Provides a locking mechanism and rugged strain relief.