This comprehensive glossary covers the most important terms used in wire harness design, manufacturing, and quality assurance. Whether you are an engineer specifying a new harness, a procurement professional evaluating suppliers, or simply learning about the industry, this reference will help you speak the language of wire harness manufacturing with confidence. For a deeper dive into design principles, see our Ultimate Guide to Wire Harness Design.
A
Ampacity – The maximum amount of electric current a conductor can carry continuously without exceeding its temperature rating. Ampacity depends on wire gauge, insulation type, ambient temperature, and how many conductors are bundled together. Selecting the correct ampacity is a critical step in wire harness design.
AWG (American Wire Gauge) – A standardized system for specifying the diameter of electrically conducting wire. Lower AWG numbers indicate thicker wire with higher current-carrying capacity. Common harness wire sizes range from 28 AWG (small signal wires) to 4 AWG (heavy power cables).
Abrasion Resistance – The ability of a wire’s insulation or outer jacket to withstand rubbing, friction, or mechanical wear without degrading. Abrasion-resistant materials like nylon or PTFE are chosen for harnesses routed through tight spaces or moving assemblies.
B
Backshell – A protective cover that attaches to the rear of a connector to provide strain relief, shielding termination, or environmental sealing for the cable entry point.
Boot – A molded or heat-shrink cover placed over a connector or splice to provide insulation, strain relief, and protection against moisture or contaminants.
Breakout – The point in a wire harness where individual wires or sub-bundles separate from the main trunk to route to different connectors or termination points. Proper breakout design is essential for clean routing and serviceability.
C
Cable Assembly – A group of wires or cables that are cut to specific lengths, terminated with connectors, and assembled as a complete unit ready for installation. Cable assemblies are a core offering in Simkab’s service portfolio.
Connector – A device attached to the end of a wire or cable that allows it to be joined to another wire, cable, or piece of equipment. Connectors come in thousands of types and are selected based on current rating, pin count, environmental requirements, and mating cycles.
Crimp – A method of terminating a wire to a terminal or contact by mechanically deforming the terminal barrel around the stripped wire conductor. Crimping is the most common termination method in wire harness manufacturing and must meet strict quality standards per IPC/WHMA-A-620. Learn more about our crimp quality processes on the Quality & Certifications page.
Cross-Section Analysis – A destructive quality test where a crimped terminal is cut, polished, and examined under magnification to verify proper wire strand compression, crimp height, and the absence of voids. This is a key inspection method referenced in IPC/WHMA-A-620.
Continuity Test – An electrical test that verifies a complete and unbroken circuit path exists between two points. Continuity testing is performed on every wire harness to confirm correct wiring and detect open circuits.
D
DIN Rail – A standardized metal rail used for mounting circuit breakers, terminal blocks, and other electrical components inside control panels and enclosures. Wire harnesses in industrial machinery and energy applications frequently interface with DIN rail-mounted components.
Derating – The practice of reducing the allowable current through a wire based on factors like ambient temperature, number of bundled conductors, or altitude. Derating ensures safe operation under real-world conditions.
E–F
EMI (Electromagnetic Interference) – Unwanted electrical noise that can disrupt signal integrity in nearby conductors. Shielding and proper routing techniques in harness design help mitigate EMI, which is especially critical in telecommunications applications.
Ferrule – A small metal or plastic sleeve crimped onto the stripped end of a stranded wire to hold the strands together and provide a clean termination point for screw or spring terminals. Ferrules improve connection reliability and are required by many European wiring standards.
Flex Life – The number of bending cycles a cable or wire can withstand before failure. High flex life cables are used in applications with continuous movement, such as robotic arms or cable carriers.
G–H
Grommet – A rubber or silicone ring inserted into a hole in a panel or enclosure to protect wires from abrasion and provide a seal against dust, moisture, and vibration as the harness passes through.
Harness Board (Assembly Board) – A flat board or fixture with pins, nails, and guides that define the routing and branching of a wire harness during manual assembly. Harness boards ensure dimensional accuracy and repeatability across production runs.
Heat Shrink – A thermoplastic tubing that shrinks in diameter when heated, used to insulate splices, cover exposed conductors, bundle wires, and provide strain relief. Heat shrink is available with adhesive lining for waterproof sealing.
Hi-Pot Test (High-Potential Test / Dielectric Withstand Test) – A safety test that applies a high voltage between a conductor and its insulation (or between adjacent conductors) to verify that the insulation can withstand the rated voltage without breakdown. Hi-pot testing is a standard step in Simkab’s quality testing procedures.
I–J
IDC (Insulation Displacement Connector) – A type of connector that makes electrical contact by piercing through the wire’s insulation, eliminating the need to strip the wire first. IDC connectors are common in ribbon cable and flat flexible cable assemblies.
IPC/WHMA-A-620 – The globally accepted standard titled “Requirements and Acceptance for Cable and Wire Harness Assemblies.” Published jointly by IPC and the Wire Harness Manufacturer’s Association, it defines workmanship criteria for crimps, soldering, cable ties, lacing, shielding, and more. Simkab operates in full compliance with this standard. See our certifications page for details.
Insulation Resistance – A measurement of how effectively a wire’s insulation prevents current leakage between conductors or between a conductor and ground. Higher insulation resistance values indicate better insulation integrity.
Jacket – The outermost protective layer of a cable or wire harness. Jackets are made from materials such as PVC, PUR, TPE, or LSZH (Low Smoke Zero Halogen) depending on the application’s environmental and safety requirements.
JST – A major Japanese manufacturer of electrical connectors widely used in consumer electronics, automotive, and industrial applications. JST connectors are known for their compact size and reliability.
K–L
Kevlar (Aramid Fiber) – A strong synthetic fiber sometimes used as a strength member in cables to provide tensile reinforcement without adding significant weight.
Lacing – A traditional method of bundling and securing wires within a harness using waxed cord or lacing tape. Lacing offers a flat profile and is preferred in applications where cable ties might snag or where vibration could cause tie fatigue.
Loom (Wire Loom / Split Loom) – A corrugated or braided tubing used to bundle and protect wires in a harness. Looms provide abrasion protection and make it easier to route and manage large wire bundles, especially in agricultural and industrial environments.
M–N
Molex – A global manufacturer of electronic connectors, cable assemblies, and interconnect solutions. Molex products are widely used across automotive, industrial, medical, and telecommunications applications.
Multi-Conductor Cable – A cable containing two or more insulated conductors within a single outer jacket. Multi-conductor cables simplify routing and reduce installation time compared to running individual wires.
O–P
Overbraiding – A mesh of woven metallic or textile strands applied over a cable or harness bundle for electromagnetic shielding, mechanical protection, or both. Overbraiding is common in shielded cable assemblies for sensitive electronic systems.
Pin-Out (Pinout Diagram) – A diagram or table that defines the assignment of each pin or contact in a connector—specifying which wire connects to which pin position. Accurate pinout documentation is essential for manufacturing and field service.
Pull-Force Test (Pull Test) – A mechanical test that measures the force required to separate a crimped or soldered terminal from its wire. Pull-force testing validates that terminations meet the minimum retention strength specified by the terminal manufacturer and IPC/WHMA-A-620.
R
Ring Terminal – A crimp terminal with a circular opening designed to be secured to a stud or screw. Ring terminals provide a secure, vibration-resistant connection and are common in grounding and power distribution applications.
RoHS (Restriction of Hazardous Substances) – A European Union directive that restricts the use of certain hazardous materials—including lead, mercury, and cadmium—in electrical and electronic products. All Simkab products are manufactured with RoHS-compliant materials. See our Declarations page for compliance documentation.
REACH – A European Union regulation on the Registration, Evaluation, Authorization, and Restriction of Chemicals. REACH compliance ensures that substances used in manufacturing are safe for human health and the environment.
S
Shielding – A conductive layer (foil, braid, or combination) applied around one or more conductors to block electromagnetic interference. Shielding is essential in signal-carrying cables for telecommunications and sensitive instrumentation.
Strain Relief – A mechanical feature (such as a boot, clamp, or grommet) that prevents pulling or bending forces on a cable from being transmitted to the termination point. Proper strain relief extends the service life of a connection.
Splice – A connection made between two or more wires, typically by crimping, soldering, or ultrasonic welding. Splices are used to join wires of different gauges, branch circuits, or repair damaged conductors.
T
Terminal – A metal fitting crimped or soldered to the end of a wire that allows it to be connected to a mating terminal, connector contact, or screw/stud. Terminals come in many forms including ring, spade, pin, socket, flag, and quick-disconnect.
TE Connectivity – One of the world’s largest manufacturers of connectors, sensors, and electronic components. TE Connectivity (formerly Tyco Electronics) products are used extensively in automotive, industrial, aerospace, and energy wire harnesses.
Tinning – The process of coating the exposed strands of a wire with a thin layer of solder to prevent oxidation, improve solderability, and hold strands together. Tinning is a common wire preparation step before soldering.
Traceability – The ability to track every component, material, and process step used in manufacturing a specific harness, from raw material lot numbers to final test results. Traceability is a cornerstone of Simkab’s quality management system.
U–W
UL Listing – A safety certification issued by Underwriters Laboratories indicating that a product has been tested and meets specific safety standards. UL-listed wires and components are required in many applications, particularly in North America.
Wire Gauge – A measurement of the cross-sectional area of a wire conductor, typically expressed in AWG (American Wire Gauge) or mm² (metric). Wire gauge determines the conductor’s current-carrying capacity, resistance, and weight.
Wire Marking – The process of printing, stamping, or labeling identification information (such as wire number, function, or destination) onto the insulation of a wire. Wire marking greatly simplifies installation, troubleshooting, and maintenance of complex harnesses.
Wire Harness – An organized assembly of wires, cables, connectors, and protective components bound together to transmit electrical power or signals within a system. Wire harnesses are designed to fit the specific geometry of the equipment they serve and are manufactured using specialized processes.
X–Z
XLPE (Cross-Linked Polyethylene) – A thermoset insulation material known for its excellent resistance to heat, chemicals, and moisture. XLPE-insulated wires are commonly used in high-temperature and high-voltage applications, including energy sector cable assemblies.
Zip Tie (Cable Tie) – A nylon fastener used to bundle wires together and secure them to mounting points. Cable ties are the most common bundling method in wire harness production, available in various sizes, colors, and materials including UV-resistant and metal-detectable variants.
Need help with your wire harness project? Explore our services, read the Wire Harness Design Guide, or request a quote to get started. For questions about terms or standards, visit our FAQ page.