Garrie AI: Your Cable Guide
20 Popular Types of Electrical Wire and Their Uses
This guide covers 20 types of electrical wire and cable, from the NM-B cable found in most homes to the medium voltage cable used in utility distribution. Each entry includes the typical voltage rating, common applications, and the key construction features that distinguish it from similar products.
1. NM-B Cable (Romex)
Category: Residential | Voltage rating: 600V
NM-B, commonly called Romex after its most common brand name, is the most widely used wire type in residential construction. It is a nonmetallic sheathed cable that contains two or more individually insulated conductors plus a bare copper ground, all wrapped in a flat plastic jacket.
NM-B is rated for use in dry indoor locations only. It is used for branch circuits throughout a home, including outlets, lighting, and appliances. The outer sheath is color-coded by gauge: white for 14 AWG (15A circuits), yellow for 12 AWG (20A circuits), and orange for 10 AWG (30A circuits).
NM-B is not approved for use in wet or damp locations, conduit fill, or commercial construction. For those applications, THHN/THWN or MC cable is required.
Common gauge range: 14 AWG to 6 AWG
Common configurations: 2-conductor with ground, 3-conductor with ground
2. THHN / THWN-2
Category: Building Wire | Voltage rating: 600V
THHN and THWN-2 are single-conductor insulated wires designed for installation inside conduit. They are the standard building wire for commercial and residential construction where individual conductors are run through rigid metal conduit (RMC), intermediate metal conduit (IMC), or PVC conduit.
The letter codes describe the insulation properties: T = thermoplastic; H = heat-resistant (75°C); HH = highly heat-resistant (90°C); W = wet-location rated; N = nylon jacket. THWN-2 carries a 90°C rating in both wet and dry locations, making it the current standard.
Conductors are colour-coded by function: black or red for hot, white or grey for neutral, and green or bare for ground. THHN/THWN-2 is available in copper and aluminium, with aluminium commonly used for larger feeder conductors (4 AWG and above) where weight and cost savings matter.
Common gauge range: 14 AWG to 1000 kcmil
Common configurations: Single conductor; copper or aluminum; available on spools and in pull boxes
3. UF-B Cable
Category: Residential | Voltage rating: 600V
Underground Feeder (UF-B) cable is the direct-burial version of NM-B. Unlike NM-B, which has a separate plastic jacket around the conductors, UF-B encases each conductor in solid thermoplastic insulation, then encases the entire assembly in another layer of UV-resistant plastic. This construction gives it the moisture and sunlight resistance needed for burial and outdoor exposure.
UF-B is used to feed outdoor subpanels, detached garages, outbuildings, and landscape lighting circuits from the main panel. It can be buried without conduit, though depth requirements vary by application under NEC Table 300.5. It is not rated for use in conduit or raceway systems.
Gray outer sheathing is standard. Like NM-B, it is colour-coded by conductor size.
Common gauge range: 14 AWG to 4 AWG
Common configurations: 2-conductor with ground, 3-conductor with ground
4. USE-2 / URD Aluminum Cable
Category: Utility / Distribution | Voltage rating: 600V
USE-2 (Underground Service Entrance) and URD (Underground Residential Distribution) cables are aluminium-conductor cables used for utility secondary distribution and service-entrance applications. They are the standard product for connecting utility transformers to residential and commercial metering points underground.
URD cable is most commonly sold in triplex and quadruplex configurations: two or three insulated phase conductors helically wrapped around a bare neutral conductor. The bare neutral serves both as a current-carrying conductor and as a messenger for mechanical support.
Aluminum is the standard conductor material for these cables because the large sizes required for feeder and service applications make copper cost-prohibitive. USE-2 insulation is rated for direct burial and wet locations. Triplex service drop and secondary distribution cables in this family are a core product for utility contractors and electric cooperatives.
Common gauge range: 6 AWG to 1000 kcmil (aluminum)
Common configurations: Single, duplex (1 neutral +1 phase), triplex (1 neutral + 2 phase), quadruplex (1 neutral + 3 phase)
5. XHHW-2
Category: Building Wire | Voltage rating: 600V
XHHW-2 is a single-conductor wire insulated with cross-linked polyethylene (XLPE) rather than the thermoplastic PVC used in THHN/THWN-2. XLPE insulation is more heat-, moisture-, and mechanical-stress-resistant than PVC, and it maintains its dielectric properties over a wider temperature range.
XHHW-2 is rated 90°C in both wet and dry locations, matching the top rating of THWN-2, but its XLPE insulation provides better performance in high-temperature environments, such as near motors, in direct sunlight, or in conduit runs with significant heat buildup. It is commonly used for large service entrance conductors, feeder runs, and branch circuits in commercial and industrial construction.
Available in copper and aluminum. Like THHN/THWN-2, it is a conduit-installed wire and does not include an outer jacket.
Common gauge range: 14 AWG to 1000 kcmil
Common configurations: Single conductor; copper or aluminum
6. MC Cable (Metal-Clad Cable)
Category: Commercial | Voltage rating: 600V
Metal-clad (MC) cable is a factory-assembled multi conductor cable enclosed in a flexible, interlocked aluminium or steel armour. It contains individually insulated conductors, a full-size green-insulated ground wire, and, in some versions, an aluminium bonding strip.
MC cable is the commercial equivalent of NM-B. It is widely used in commercial, institutional (schools, hospitals, etc), and light industrial construction where running individual conductors in conduit is not practical or cost-effective. The metal armor provides mechanical protection and allows the cable to be installed in exposed locations, plenum spaces, and wet or damp locations when rated accordingly.
MC cable is also used in data centers and healthcare facilities. In homes, it is commonly used when wiring runs through exposed locations like unfinished basements, attached garages, or attic spaces, where NM-B would require conduit for protection. An MC-AP (aluminum clad, PVC jacketed) version is available for outdoor and corrosive environments.
Common gauge range: 18 AWG to 1000 kcmil
Common configurations: 2-conductor, 3-conductor, 4-conductor with ground; standard and MC-AP (PVC jacketed)
7. DLO Cable (Diesel Locomotive Cable)
Category: Industrial / Portable Power | Voltage rating: 2000V
DLO cable is a heavy-duty flexible power cable originally developed for locomotive traction motor circuits. Today it is used broadly in portable power applications that require high current capacity and extreme flexibility, including generator connections, mining equipment, substations, industrial machinery, and welding-grade power feeds.
DLO cable is constructed with Class K fine-stranded bare copper for flexibility, EPR or XLPE insulation, and a CPE or neoprene outer jacket, and is rated 2000V. It features a heavy-duty jacket built for conditions that would degrade standard building wire or flexible cord.
It is not a substitute for standard building wire and is not used in conduit or permanent raceways. DLO is a portable power cable designed for repeated flexing, dragging, and exposure to oils and chemicals.
Common gauge range: 2 AWG to 500 kcmil
Common configurations: Single conductor; EPR or XLPE insulation with CPE or neoprene jacket
8. Tray Cable (TC-ER)
Category: Industrial | Voltage rating: 600V
Tray cable is a multi conductor power and control cable designed for installation in cable tray systems, conduit, and direct burial. TC-ER (Exposed Run) is a specific listing that allows tray cable to be installed in exposed runs between tray sections without conduit, reducing installation issues in industrial facilities.
Tray cable contains multiple conductors individually insulated and twisted or laid parallel, with an overall PVC or thermoplastic elastomer jacket. It is used for power distribution to motors and equipment, lighting circuits, and control wiring throughout manufacturing plants, refineries, and water treatment facilities.
TC-ER must meet UL 1277 and pass a vertical flame test. Conductors are typically 18 AWG to 1 AWG, with pairs, triads, and larger multi conductor counts available depending on the application.
Common gauge range: 18 AWG to 1 AWG
Common configurations: 2 to 37 conductors; shielded and unshielded; PVC or LSZH jacket
9. Instrumentation Tray Cable (ITC)
Category: Industrial | Voltage rating: 300V
Instrumentation tray cable (ITC) is a shielded multiconductor cable used to transmit low-level analog and digital signals in process control systems. It connects field instruments (transmitters, sensors, analyzers) to control room panels, PLCs, and distributed control systems (DCS).
ITC differs from standard tray cable in that it is designed for signal integrity rather than power delivery. Each conductor pair or triad is individually shielded with an aluminium-polyester foil and a drain wire to prevent EMI interference from nearby power cables or variable frequency drives. An overall shield is often added for additional noise rejection.
Common applications include refineries, chemical plants, power generation facilities, and any process industry where reliable signal transmission from field devices to control systems is critical.
Common gauge range: 16 AWG to 12 AWG
Common configurations: Individually shielded pairs or triads with overall shield; 2 to 24 pairs
10. VFD Cable (Variable Frequency Drive Cable)
Category: Industrial | Voltage rating: 600V to 2000V
VFD cable is a shielded power cable engineered for the demanding electrical environment between a variable frequency drive and the motor it controls. Standard THHN or tray cable is not well-suited for VFD applications because the high-frequency switching of VFDs generates voltage reflections and common-mode noise that can damage motor insulation and create interference in nearby control circuits.
VFD cable addresses this with a symmetrical three-ground-conductor construction, an overall copper tape or braid shield, and insulation rated to withstand reflected-wave voltages. The symmetrical ground arrangement helps cancel common-mode currents and provides a low-impedance path for high-frequency noise.
Proper VFD cable selection reduces motor bearing damage, extends insulation life, and minimizes EMI problems in the facility. It is specified for all VFD motor lead applications where the cable run exceeds the drive manufacturer's recommended distance for standard wire.
Common gauge range: 16 AWG to 2/0 AWG
Common configurations: 3-conductor power with 3 symmetrical ground conductors; overall copper braid or tape shield
11. SER / SEU Cable
Category: Residential Service | Voltage rating: 600V
Service entrance cable comes in two types. SEU contains two insulated conductors with a bare neutral wrapped around them and is used for service entrance runs from the meter base to the main panel. SER contains three insulated conductors plus a bare neutral and is used for subpanel feeders and appliance circuits — including electric ranges and dryers where a four-wire configuration (two hots, a neutral, and a ground) is required under NEC 250.140
The aluminum construction of most SER/SEU keeps material cost lower than copper for the large AWG sizes required at 100A to 200A service levels.
Common gauge range: 6 AWG to 4/0 AWG
Common configurations: SEU (2 insulated + bare neutral wrap), SER (3 insulated + bare neutral wrap)
12. Welding Cable
Category: Specialty | Voltage rating: 600V
Welding cable is a single-conductor, ultra-flexible cable used in welding equipment, battery connections, and other high-current DC applications. It is built with extremely fine stranded bare copper (Class K or M stranding), which gives it the flexibility to coil and uncoil thousands of times without conductor fatigue.
The outer jacket is typically EPDM or neoprene rubber, chosen for its ability to resist cuts, abrasion, oils, and temperature extremes common in welding environments. Welding cable is not rated for permanent installation as building wire and is not intended for AC power distribution. It is a portable, flexible cable for high-current applications where the cable will be repeatedly moved.
Common uses include welding machine leads, battery interconnects in industrial equipment, and temporary power runs to portable tools and generators on job sites.
Common gauge range: 6 AWG to 4/0 AWG
Common configurations: Single conductor; EPDM or neoprene jacket; black or red
13. PV Wire (Photovoltaic Wire)
Category: Renewable Energy | Voltage rating: 600V to 2000V
PV wire is the standard conductor for wiring solar photovoltaic arrays. It is listed under UL 4703 and meets the requirements of NEC Article 690 for use in solar systems, including installation in exposed outdoor locations, direct sunlight, and wet environments.
PV wire is built with a cross-linked polyethylene (XLPE) or EPR insulation rated for 90°C in wet locations and 150°C in dry locations, with an outer jacket resistant to UV, ozone, and moisture. It is typically single-conductor and available in red and black for positive and negative polarity identification.
The 2000V rating accommodates the higher open-circuit voltages present in larger utility-scale string configurations. PV wire is not interchangeable with USE-2 or standard building wire for solar applications, though USE-2 is permitted in some PV wiring configurations under NEC 690.
Common gauge range: 10 AWG to 2 AWG
Common configurations: Single conductor; red (positive) and black (negative); 600V and 2000V listings
14. Automotive Wire (GPT / GXL / TXL)
Category: Automotive | Voltage rating: 12V to 48V
Automotive wire is single-conductor stranded copper wire used in vehicle wiring harnesses and electrical systems. The three common SAE J1128 types differ primarily in insulation thickness and temperature rating: GPT (General Purpose Thermoplastic) is the standard grade for general interior use; GXL (Cross-linked, Extra Thin) uses thinner XLPE insulation for weight savings; TXL (Cross-linked, Thin) is the thinnest and lightest, used in high-density harness applications.
Automotive wire is not interchangeable with building wire. It is designed for the specific demands of vehicle environments: resistance to oils, gasoline, and hydraulic fluids, flexibility at low temperatures, and compatibility with the crimp terminals and connectors used in automotive assembly.
AWG sizing follows the same scale as building wire, but the current ratings differ because automotive wire operates in different thermal conditions. Common applications include engine compartment wiring, body and chassis harnesses, trailer wiring, and marine applications.
Common gauge range: 20 AWG to 8 AWG
Common configurations: Single conductor; GPT (PVC), GXL (thin XLPE), TXL (extra-thin XLPE); available by the spool in multiple colors
15. Coaxial Cable (RG-6 / RG-11)
Category: Communications | Voltage rating: Low voltage (signal)
Coaxial cable is a shielded RF transmission cable used to carry television, broadband, satellite, and antenna signals. It consists of a center conductor (solid or stranded copper), a dielectric insulating layer, a tubular braided or foil shield, and an outer PVC or flooring jacket.
RG-6 is the standard coaxial cable for residential TV and cable internet distribution. RG-11 has a larger conductor and thicker dielectric, resulting in lower signal loss over long runs, which makes it appropriate for distribution trunk lines and runs over 100 feet where RG-6 attenuation would be excessive.
Coaxial cable is identified by its threaded F-type connectors in most residential applications. The signal voltages involved are low enough that coaxial cable does not present a shock hazard under normal conditions, but it should not contact power conductors.
Common gauge range: 18 AWG center conductor (RG-6) to 14 AWG center conductor (RG-11)
Common configurations: RG-6 (residential distribution), RG-11 (long runs and trunk lines); quad-shield versions available for high-interference environments
16. Cat5e / Cat6 / Cat6A Cable
Category: Communications | Voltage rating: Low voltage (PoE up to 90W)
Ethernet cable, standardized under TIA-568 and commonly called Cat5e, Cat6, or Cat6A, is the standard cabling infrastructure for data networks. Each cable contains four twisted pairs of 24 AWG or 23 AWG copper conductors. The twist rate of each pair is varied to reduce crosstalk between pairs.
Cat5e supports up to 1 Gbps at 100 MHz bandwidth. Cat6 supports 10 Gbps at distances up to 55 meters with a 250 MHz bandwidth. Cat6A extends that to 100 meters at 500 MHz and is the current minimum recommendation for new structured cabling installations.
Jacket ratings matter for installation location: CM is general purpose, CMR (riser) is rated for vertical runs between floors, and CMP (plenum) is required in air-handling spaces because it has lower smoke and flame characteristics. Power over Ethernet (PoE) allows Cat cable to carry up to 90W (PoE++) to power devices like IP cameras, access points, and phones.
Common gauge range: 24 AWG (Cat5e, Cat6) to 23 AWG (Cat6A)
Common configurations: UTP (unshielded), STP/FTP (shielded); CM, CMR, and CMP jacket ratings
17. Speaker / Audio Cable
Category: Audio / AV | Voltage rating: Low voltage
Speaker cable is a two-conductor stranded cable used to connect amplifiers and receivers to loudspeakers. Both conductors are electrically identical. One is typically marked (by a tracer stripe, ribbing, or printed text) to indicate polarity, which must be maintained consistently to avoid phase cancellation in multi-speaker systems.
Unlike most other wire types, speaker cable selection involves impedance matching and run length calculations. For longer runs or lower-impedance speakers (4-ohm systems), a heavier gauge is required to keep resistance losses below the threshold that audibly affects output. A commonly used rule is that wire resistance should not exceed 5% of the speaker's nominal impedance.
Speaker cable is typically bare copper or oxygen-free copper (OFC). It is not rated for power distribution and should not be used in conduit systems with building wire.
Common gauge range: 16 AWG to 10 AWG
Common configurations: 2-conductor unshielded; bare copper or OFC (oxygen-free copper)
18. Medium Voltage Cable (MV-90 / MV-105)
Category: Utility / Industrial | Voltage rating: 5kV to 35kV
Medium voltage cable is used for primary power distribution in utility, industrial, and large commercial applications. MV-90 and MV-105 designations refer to the maximum conductor temperature rating (90°C and 105°C, respectively) and are listed under UL 1072.
Construction includes a stranded copper or aluminum conductor, a semiconducting conductor shield, XLPE or EPR primary insulation, a semiconducting insulation shield, a metallic shield (tape or wire), and an outer PVC or LLDPE jacket. The semiconducting shield layers are critical for controlling the electric field around the conductor and preventing partial discharge at the insulation surface.
MV cable is used for utility feeder circuits, substation connections, industrial plant distribution, wind and solar farm collection systems, and underground residential distribution at primary voltage levels. Selection requires knowledge of the system voltage, fault current level, and installation environment.
Common gauge range: 1/0 AWG to 1000 kcmil
Common configurations: Single conductor and three-conductor; voltage classes of 5kV, 15kV, 25kV, and 35kV; copper or aluminum conductor
19. Power-Limited Tray Cable (PLTC)
Category: Industrial | Voltage rating: 300V
Power-limited tray cable is a low-voltage multi conductor cable used in industrial automation and control systems. It is listed under UL 13 and is specifically designed for power-limited circuits as defined in NEC Article 725, Class 2 and Class 3.
PLTC is used to wire PLCs, relay panels, distributed I/O systems, motor starters, and other automation components in manufacturing and process industry environments. Like ITC, it is installed in cable trays but differs in that it carries control circuit power as well as signals, whereas ITC is exclusively for instrumentation signals.
PLTC can be used in the same tray as Class 2 and Class 3 circuits without separation from power cables of 600V or less, provided the cable is listed for that application. Shielded versions are available for applications with significant EMI exposure.
Common gauge range: 22 AWG to 12 AWG
Common configurations: 2 to 12 conductors; shielded and unshielded; individual and overall shielded versions
20. Flexible Cord (SOOW / SJTW)
Category: Portable Power | Voltage rating: 300V to 600V
Flexible cord is the broad category covering portable power cables used for temporary equipment connections, extension cords, and movable appliance leads. The two most common types for industrial and commercial use are SOOW and SJTW.
SOOW (Service, Oil-resistant, Weather-resistant) is a heavy-duty portable cord with an oil-resistant EPDM jacket rated for both indoor and outdoor use. It is used for portable tools, welding equipment, compressors, and temporary power distribution. SJTW (Service Junior, Thermoplastic, Weather-resistant) is a lighter-duty version with a PVC jacket, commonly used for general-purpose extension cords and light equipment.
Flexible cord is not a substitute for permanent wiring. NEC Article 400 defines where flexible cord is and is not permitted. It cannot be run through walls, ceilings, or floors, used as a substitute for fixed wiring, or concealed behind building structures.
Common gauge range: 18 AWG to 10 AWG
Common configurations: 2, 3, and 4 conductors; SOOW (rubber, heavy-duty), SJTW (PVC, light-duty)
How to Choose the Right Electrical Wire
Selecting the correct wire type comes down to four factors:
Voltage and amperage. The wire must be rated for the circuit voltage and sized to carry the load current without exceeding its ampacity. NEC Tables 310.16 and 310.17 provide ampacity values for common conductor types and installation conditions.
Location and environment. Dry interior locations allow NM-B. Wet or damp locations require THWN-2, UF-B, or other moisture-rated insulation. Direct burial requires USE-2 or UF-B. Corrosive environments may require special jacket materials.
Code compliance. NEC Article 300 covers wiring methods in general. Specific cable types are governed by their own articles: NM cable (Article 334), MC cable (Article 330), tray cable (Article 392), and so on. Local amendments may apply.
Application requirements. Some applications impose additional requirements beyond the basic NEC rules. VFD motor leads require VFD-rated cable. Solar arrays require UL 4703-listed PV wire. Instrumentation circuits in Class I hazardous locations have specific cable requirements under NEC Articles 501 and 504.
When in doubt, consult the NEC, the equipment manufacturer's wiring specifications, and the local authority having jurisdiction (AHJ) before specifying wire for a project.
Nassau National Cable supplies the full range of wire and cable types covered in this guide, including:
Contact us for bulk pricing and availability.
