Wire America's Electrical Wire & Cable Glossary

(A-G) Electrical Wire & Cable Glossary

A

• Abrasion Resistance: The ability of a cable jacket or insulation to withstand external scuffing, friction, scraping, and crushing without tearing or rupturing.

• AAC (All Aluminum Conductor): A bare, stranded electrical conductor made entirely of high-purity aluminum, primarily used for overhead power transmission and distribution in urban areas with shorter spans.
  
  

• ACSR (Aluminum Conductor Steel Reinforced): A type of high-strength, lightweight stranded conductor used primarily in overhead electrical power transmission lines. The steel core provides the necessary tensile strength to support the weight of the cable over long spans.

• Ampacity: The maximum current (measured in amperes) that a conductor can continuously carry under specified conditions of use without exceeding its temperature rating. This is the single most critical factor in conductor sizing.

• Annealed Copper: Copper wire that has been softened by heating. This process increases the wire's flexibility and ductility, making it easier to bend and handle during installation (used in most flexible cables).

• AWG (American Wire Gauge): The standard system used in North America to designate the size of electrical conductors. The gauge number is inversely proportional to the diameter; a smaller AWG number indicates a larger, thicker wire.

B

• Bare Conductor: A conductor (wire) that has no external covering or insulation. It is used where insulation is unnecessary or where the atmosphere provides sufficient insulation (e.g., grounding wire or overhead transmission lines).

• Bonding Conductor: A reliable conductor that connects equipment and enclosures to create electrical continuity and conductivity. Its main purpose is to ensure all metal parts are at the same electrical potential, reducing shock hazard.

• Braid Shield: A woven metallic or fibrous material applied over a conductor or cable assembly. It provides superior flexible mechanical protection and/or electrical shielding against low-frequency interference.

C

• Cable Tray: A support system used to securely hold and route insulated electrical cables within commercial and industrial buildings. It replaces rigid conduit and allows for easier installation and maintenance.

• Capacitance: The measure of an electrical system’s ability to store an electric charge. In cables, capacitance affects signal integrity (especially in control or instrumentation cables) and power factor.

• Concentric Neutral: consists of a series of bare copper wires applied helically (wrapped in a spiral) over the insulation shield of a medium-voltage primary underground cable. It serves a dual purpose: acting as the return path for the electrical current and providing a grounded safety layer for the cable.
  

• Conductor: The element within a wire or cable (usually copper or aluminum) that is specifically designed to carry the electrical current.

• Conduit: A durable tube, channel, or pipe (typically metal or plastic) used to protect and route electrical wiring. It is required where cables lack adequate inherent protection

• Copper Tape Shield: thin ribbon of annealed copper—typically 5 mils thick—applied helically (wrapped in a continuous spiral) over the semi-conductive insulation shield of an MV-105 cable. It acts as a grounded "Faraday Cage," containing the electrical field within the cable and providing a safe path for charging and fault currents.

• Corona: A visible discharge of electricity that appears on the surface of a conductor at medium or high voltages (typically 1kV+). It causes power loss and can degrade insulation over tim

• CPE JACKET:  CPE or (Chlorinated Polyethylene) is a premium jacketing material engineered as "chemical armor" for cables in punishing environments. It provides superior resistance to oils, petroleum, and aggressive industrial chemicals while remaining flexible in extreme cold down to -40°C. Naturally flame-retardant and UV-stable, it is the professional choice for Type SOOW, DLO, and Type W Power Cables where standard PVC fails.

D

• Dielectric Constant: A measure of the electrical insulating ability of a material. A lower constant is generally better for transmitting high-frequency signals, but higher constants are needed to manage very high voltages.

• Dielectric Strength: The maximum voltage an insulating material can withstand before electrical breakdown (failure) occurs, leading to a short circuit.

• Direct Burial: The rating of a cable (e.g., URD, UF-B, or certain TC cables) indicating it is designed to be installed directly into the soil without needing continuous conduit protection.

E

• EPR (Ethylene Propylene Rubber): A high-performance, thermoset insulating material known for excellent resistance to heat, ozone, weathering, and its superior flexibility across a wide temperature range.

• EGC (Equipment Grounding Conductor): The conductor that connects non–current-carrying metal parts of equipment, raceways, and enclosures to the system ground. It provides a path for fault current, tripping the circuit breaker.

• Extrusion: The manufacturing process where the insulating material (like PVC or XLPE) is melted and pushed through a die to form a continuous, uniform layer around the conductor.

F

• FEP (Fluorinated Ethylene Propylene): A high-performance fluoropolymer (a type of Teflon) used as insulation. It is highly valued for its non-stick surface, excellent chemical immunity, and very high temperature rating (often up to 200°C).

• Flame Resistance: The cable's ability to prevent combustion or to self-extinguish once the ignition source is removed. This is a critical safety feature mandated by the NEC.

• Flexibility: A measure of how easily a cable can be bent. It is determined by the conductor material (annealed copper is best) and the stranding (more strands = more flexibility).

• Foil Shield: is a thin layer of aluminum or copper foil, typically laminated to a polyester backing (like Mylar®), wrapped around the conductors of a cable. Its primary purpose is to provide 100% electromagnetic interference (EMI) coverage, protecting sensitive signals from high-frequency "noise" and crosstalk.

G

• Gauge: The numerical size designation of a conductor (see AWG).

• Ground Fault: An unintentional electrical path between an ungrounded conductor (hot wire) and the grounded path (like a metal conduit, the earth, or the equipment ground). This condition requires immediate protection from breakers/GFCI devices.

(H-M) Electrical Wire & Cable Glossary

H

• Halogen-Free: A designation for insulating or jacketing materials that do not contain the halogen elements (fluorine, chlorine, bromine, etc.). When these materials burn, they produce less toxic, less corrosive smoke, which is essential for protecting sensitive electronic equipment (like in data centers) and personnel safety.

• Hard Drawn Copper Wire: Copper wire that has not been subjected to annealing after the final drawing process. This results in a higher tensile strength and lower ductility (flexibility), making it primarily used for overhead line applications where strength is paramount.

• Harness: An assembly of multiple wires, cables, and components (often with many connection points) bundled together or pulled into a protective sheath. Its function is to efficiently interconnect an electric circuit within equipment.

• Hertz (Hz): The standard unit of frequency, equal to one cycle per second. It is used to express the rate at which alternating current (AC) reverses its direction.

• Hi-Pot (High Potential Test): A common quality control test designed to determine the highest voltage an insulated wire or cable can withstand before the insulation breaks down (puncture).

• Hook-Up Wire: A single insulated conductor, usually rated for 600 volts or less, used for internal wiring within enclosed electronic equipment, appliances, or control panels.

• Hybrid Cable: A multi-conductor cable that contains two or more different types of components, such as power conductors, fiber optic strands, and coaxial cables, all bundled under a single jacket.

• Hypalon: DuPont’s trade name for chlorosulfonated polyethylene, a type of synthetic rubber known for excellent resistance to ozone, chemicals, and abrasion. Often used for heavy-duty cable jackets.

I

• ICEA (Insulated Cable Engineers Association): A non-profit professional organization that develops and publishes technical standards and specifications for electrical, electronic, and fiber optic wires and cables.

• IEEE 1580: The primary industry standard for the construction and testing of marine cables (Type P) used on shipboards and offshore facilities. It establishes requirements for cable performance in harsh environments, covering power, control, and signal cables rated from 300V to 35kV.
  

• Impedance: The total opposition (measured in ohms) that a circuit offers to the flow of alternating current (AC). It is a combination of resistance and reactance, and it is critical for maintaining signal integrity in data and control cables (e.g., VFD cable).

• Inductance: The property of an electrical circuit or component that opposes a change in current flow. It is measured in Henrys. In AC power cables, high inductance can cause voltage changes to lag behind current changes.

• Insulation: The non-conductive material (PVC, XLPE, Silicone Rubber, etc.) that surrounds the conductor. Its primary role is to provide dielectric strength, preventing shorts and electrical shock.

• Insulation Screen (or Shield): A layer of semiconductive material placed directly over the insulation layer of medium or high-voltage cables. It helps maintain a uniform electric field and prevents damaging corona formation.

• Interlocked Armor (MC Cable): A continuous, flexible metal sheath (usually aluminum or steel) wound in a spiral around the cable core. It provides mechanical protection against crushing or abrasion.

J

• Jacket: The non-metallic, outermost protective covering applied over an insulated wire or cable assembly. Its primary job is mechanical and environmental protection (against UV, moisture, and abrasion).

• Jumper Cable: A short, often temporary, cable used to connect two devices or terminals. (Also refers to the heavy cables used to start a vehicle).

K

• Kilovolt (kV): A unit of voltage equal to 1,000 volts. Used to rate medium and high-voltage cables.

• Kilo-ohm (kΩ): A unit of electrical resistance equal to 1,000 ohms.

L

• Lay: The length measured along the axis of a wire or cable required for a single strand (in stranded wire) or conductor (in cable) to make one complete spiral turn around the axis of the conductor or cable. Lay direction is typically S (left-hand) or Z (right-hand).

• Lead Wire: A general term for any wire used to connect an electrical device (like a motor or transformer) to a power source. Often refers to high-temperature or flexible hook-up wire (e.g., SRML).

• Low Voltage (LV): Generally refers to cables rated for less than 1,000 volts (1kV), such as standard residential and commercial power (600V).

• LSZH (Low Smoke, Zero Halogen): A designation for specialized jacket materials that emit limited smoke and no toxic or corrosive halogen gases when burned. Essential for data centers, tunnels, and ships.

M

• Mastic: A meltable, sometimes viscous, compound used as a coating or filler inside connectors, splices, or cable terminations. When heated, it flows to create a waterproof and airtight seal.

• MC Cable: Abbreviation for Metal-Clad Cable, a type of armored cable (see Interlocked Armor) commonly used for power and control wiring in commercial and industrial buildings.

• MDPE (Medium-Density Polyethylene): A plastic compound often used for cable jacketing, offering a good balance of durability and flexibility. Used in some direct burial and communication cables.

• Medium Voltage (MV): A class of electrical power system voltage ratings generally between 1 kV and 35 kV. Cables in this class (like 13.2kV TRW) require specialized shielding and insulation techniques.

• Messenger Wire: A metallic supporting member (solid or stranded) integrated into an aerial cable assembly. It bears the weight of the cable and provides physical support between poles.

• MI Cable (Mineral Insulated): A high-temperature cable where conductors are insulated with highly compressed refractory minerals (like magnesium oxide) and enclosed in a seamless metallic tube. Used where extreme heat and fire resistance are required.

• Mil: A unit of length equal to one-thousandth of an inch (0.001"). Used in measuring the diameter of small wires or the thickness of insulation.

• Moisture Resistance: The ability of a cable's insulation and/or jacket to resist the penetration and damaging effects of water or humidity.

(N-S) Electrical Wire & Cable Glossary

N

• NEC (National Electrical Code): A set of standards and regulations (published by the NFPA) that governs the design, installation, and inspection of electrical wiring and equipment in the United States. Compliance with the NEC is mandatory and ensures safety.

• NEMA (National Electrical Manufacturers Association): A key trade association in North America that develops technical standards for electrical products, including specific standards for wire and cable constructions and jacket compounds.

• NM-B Cable (Non-Metallic Sheathed Cable): Commonly known by the trade name "Romex," this is the most common cable type used for indoor residential wiring. It consists of two or more insulated conductors and a bare grounding wire, all encased in a non-metallic (PVC) jacket.

• Nominal Diameter: The stated or theoretical diameter of a conductor, wire, or cable, which is generally slightly different from the actual measured diameter due to manufacturing tolerances.

• Non-Halogen: See Halogen-Free.

O

• OEM (Original Equipment Manufacturer): A company that produces parts or components (like wire harnesses or electronic devices) that are then sold under another company's brand. For wire and cable, this refers to specialized internal wiring used in appliances and machines.

• Ozone Resistance: The ability of an insulating or jacketing material to withstand the damaging effects of ozone, an electrically generated form of oxygen. High ozone resistance is critical for cables used outdoors or near high-voltage equipment where corona discharge occurs (e.g., EPDM and Silicone Rubber).

• Overall Shield: An electrical shield (braid, foil, or spirally wrapped wires) placed around the entire group of insulated conductors within a multi-conductor cable. Its purpose is to protect the whole assembly from external electromagnetic interference (EMI).

P

• Paracourse: Refers to the parallel path of conductors, often used in flat, ribbon, or flexible parallel cord construction.

• PE (Polyethylene): A thermoplastic polymer widely used for insulation and jacketing due to its excellent moisture resistance and low cost. It is often the base material for XLPE.

• PFC (Power Factor Correction): Methods or equipment used in electrical systems to improve efficiency by reducing the phase difference between voltage and current.

• PLTC (Power Limited Tray Cable): A classification of multi-conductor cable used for instrumentation and control applications. It is rated for 300V and can be installed in cable trays, often used in industrial environments.

• Pliability: The measure of how easily a cable can be folded or bent without damage. Flexibility is related, but pliability often refers to the readiness of the cable to bend or yield.  
  

• PTFE (Polytetrafluoroethylene) PTFE is a high-performance fluoropolymer insulation—often referred to by the brand name Teflon™—engineered for extreme thermal and chemical environments. It is the industry standard for applications requiring a 250°C temperature rating, superior "thin-wall" dielectric strength, and total resistance to acids, oils, and fuels. 
  

• PVC (Polyvinyl Chloride): The most common thermoplastic material used for both insulation and jacketing due to its low cost, good flexibility, and inherent flame resistance. Used heavily in building wire and power cords.

• PV Wire (Photovoltaic Wire): Specialized, heavy-duty cable designed for connecting solar panels. It is required to have superior UV resistance and temperature stability, often utilizing XLPE insulation.

Q

• Quad: A cable construction consisting of four conductors twisted together. Used in signal transmission to improve noise cancellation (common in control and data cables).

R

• RHW (Rubber Heat & Water Resistant): A thermoset rubber insulation rating used in building wire (like RHW or RHW-2). It signifies a high resistance to heat and moisture, often used in wet or underground environments.

• RoHS (Restriction of Hazardous Substances): A European Union directive that restricts the use of specific hazardous materials in electrical and electronic products. Compliance is often a global requirement for OEMs.

• Riser Cable: Any cable specifically designed for vertical runs between floors in a building. It must meet less stringent fire codes than Plenum cable but still needs good flame-retardant characteristics (e.g., CMP or CMR ratings).

S

• SC (Semi-Conducting Layer): A thin layer of material with specific resistance characteristics placed between the conductor and the main insulation in medium and high-voltage cables. Its purpose is to smooth out electrical stress and prevent damaging corona discharge.

• SEOOW/SJOOW/SOOW: A set of designations for Heavy Duty Flexible Portable Cords. The letters define the cable's construction:

  • S: Severe Duty

  • J: Junior (300V rating vs. 600V)

  • OO: Oil-resistant outer jacket AND oil-resistant insulation

  • W: Weather/Water resistant

• SE Cable (Service Entrance Cable): Cable used to transmit power from the utility service drop or transformer to the customer's service panel (meter base). Governed by standards like UL 854.

• Shielding: A conductive layer (foil, braid, or tape) wrapped around conductors or an entire cable core. It prevents electromagnetic interference (EMI) from disrupting the transmitted signal or protects nearby electronics from the cable’s own noise.

• SIS (Stranded Insulated Switchboard): SIS is a specialized power and control wire insulated with Cross-Linked Polyethylene (XLPE), designed for tight-clearance environments like switchboards and panelboards. It is rated for 125°C (257°F) and 600V, offering superior resistance to moisture, chemicals, and oils while passing the rigorous UL VW-1 vertical flame test for enhanced fire safety.
• SRML (Silicone Rubber Motor Lead): SRML is a high-temperature industrial conductor featuring flexible Silicone Rubber insulation and a protective fiberglass braid. Rated for continuous use up to 200°C (392°F), it is prized for its "wet-noodle" flexibility and resistance to thermal cycling, making it the primary choice for motor leads, high-heat lighting fixtures, and heavy-duty industrial machinery.
  

• Stranded Conductor: A conductor composed of a group of smaller wires twisted or laid together. This increases the cable's flexibility compared to a Solid Conductor of the same gauge.

• Stranding: The process of twisting or spiraling the wires together to form a conductor or cable core.

(T-Z) Electrical Wire & Cable Glossary

T

• TC Cable (Tray Cable): A classification for multi-conductor control, power, or signal cable (often 600V rated) specifically designed and certified for installation in cable trays in industrial and commercial environments.

• TC-ER (Tray Cable - Exposed Run): A special rating indicating that the TC cable can be run from the cable tray (raceway) to the connection point of the equipment without needing continuous conduit, saving significant installation time and cost.

• Teflon: DuPont's trade name for the fluoropolymer PTFE (Polytetrafluoroethylene) or related compounds like FEP. Used as a high-performance insulation known for extreme heat and chemical resistance.

• Tensile Strength: The maximum pulling stress or force a material (like a conductor or cable jacket) can withstand before permanently stretching or breaking.

• Termination: The mechanical or electrical process of connecting the end of a wire or cable to a device, terminal, or piece of equipment. Proper termination is vital for safety and reliability.

• THHN (Thermoplastic High Heat-Resistant Nylon): A common rating for single-conductor building wire. It features a PVC insulation layer and a thin nylon jacket that provides low friction (easy pulling) and heat resistance (up to 90°C).

• THWN (Thermoplastic Heat & Water Resistant Nylon): Same construction as THHN, but tested and rated for installation in wet locations. Most modern THHN is dual-rated THHN/THWN.

• TPE (Thermoplastic Elastomer): A rubber-like, flexible compound often used for cable jackets. It offers superior flexibility in extreme cold and good abrasion resistance, making it an excellent alternative to PVC for portable cords.

• Triad: A cable construction consisting of three insulated conductors twisted together. Used in instrumentation and control cables to aid in noise cancellation (common mode rejection).

• TR-XLPE: a specialized form of insulation designed for medium-voltage underground cables. It is a "Tree-Retardant" version of standard Cross-Linked Polyethylene (XLPE) that contains a chemical additive to inhibit the growth of water trees—microscopic, tree-like branch patterns that can eventually cause electrical breakdown and cable failure.
  
  

• Twisted Pair: Two insulated conductors twisted together to create a common mode rejection effect. Used heavily in data and telecommunications to minimize electromagnetic interference (EMI).

U

• UL (Underwriters Laboratories): A globally recognized independent testing and certification organization. A UL Listing on a cable means samples have been tested to meet the defined safety standards for that product type (e.g., UL 854 for Service Entrance Cable).

• URD Cable (Underground Residential Distribution Cable): Aluminum Direct Burial cable used primarily by utilities to distribute secondary power from transformers directly to residential service entrances.

• USE-2 (Underground Service Entrance Cable): A specific UL rating for single-conductor power cables certified for direct burial and rated for high moisture and heat resistance. Often used as a Mobile Home Feeder cable.

• UV Resistance: The ability of a cable's outer jacket or insulation to withstand degradation, cracking, or fading caused by prolonged exposure to the sun's ultraviolet (UV) radiation. Critical for all outdoor cables (e.g., PV Wire).

V

• VFD Cable (Variable Frequency Drive Cable): Specialized cable designed to connect a VFD to a motor. It features heavy insulation and multi-layered shielding (foil and braid) to mitigate electrical noise (Common Mode Voltage) and high-voltage spikes (Reflected Wave Voltage) that can damage motors.

• Voltage: The measure of electrical potential difference (measured in Volts). It is the electrical force or "pressure" that causes current to flow.

W

• Water Treeing: A chemical and electrical phenomenon where microscopic, tree-like channels form within cable insulation (especially polyethylene) when it is subjected to high electrical stress and moisture over time. This leads to insulation breakdown and failure.

• Wire: A single, usually round, metallic conductor (solid or stranded).

X

• XLPE (Cross-Linked Polyethylene): A high-performance, thermoset insulation material. Its molecular structure is chemically cross-linked, giving it superior thermal stability (it won't melt), excellent UV resistance, and a long service life.

Z

• Z-Stranding: A method of stranding multi-conductor cables where the components are laid in a spiraling, "Z" formation. Used to maintain mechanical stability.