General purpose wiring
Electrical wire comes in a ton of options and cryptic types. But how do you know what makes one type different from another? Our friends at Encore wire helped us with this resource to make it a little easier to navigate the sea of wire choices.
Our goal is to give you a reference so that when you're getting a quote for the wire on your next project you can picture and know the difference between MC-AL and MC-AL LED or SE-U and SE-R.
Electrical wire types are designed for specific applications. Wiring for power coming in from the mains is going to look very different from wiring to power light fixtures and other devices in your building.
We explain the different types of electrical wires below:
- General purpose wiring
- Residential building wiring
- Armored/Metal clad wire
- Underground or direct burial wire
- Service entrance wire
- Photovoltaic wire
- Equipment and appliance wiring
- Tray cable power & control cable
- Underground service
- Overhead service
- Tracer wire
- Bare wire
General purpose wiring
THHN / MTW / THWN-2 / T90 Wire
THHN / MTW / THWN-2 / T90 is intended for general purpose applications as defined by the NEC. Permitted appropriate use at temperatures not to exceed 90°C or not to exceed 75°C in oil or coolant and for new construction or rewiring for 600-volt applications.
THHN / MTW / THWN-2 / T90 wire can be made with copper or aluminum conductors.
TFFN / TFN / TEWN Copper Building Wire
Type TFFN (stranded) or TFN (solid) conductors are primarily used as fixture wire as defined by the National Electrical Code (NEC) at temperatures not to exceed 90°C in dry locations. For applications requiring Type MTW, the conductor is permitted for use in dry locations at 90°C or not to exceed 60°C in wet locations or where exposed to oils or coolants. It's also permitted for new construction or rewriting for 600-volt applications.
TW-#8 Solid Green
Type TW is suitable for use in conduit or other recognized raceways for services, feeders, and branch-circuit wiring. Type TW is suitable for use in wet or dry locations where temperatures do not exceed 75°C. Type TW is only available in size 8 AWG.
XHHW-2 / RW90
XHHW-2 / RW90 is intended for general purpose application used in raceways and underground in raceways for service, feeders and branch-circuit wiring in accordance with the NEC. It is permitted for 600-volt and 1000-volt applications and suitable for applications requiring low-leaking circuits and a dielectric constant of 3.5 or less.
XHHW-2 / RW90 wire can be made with copper or aluminum conductors.
USE-2 / RHH / RHW-2
Type USE-2 / RHH / RHW-2 conductors are suitable for use in raceways installed underground in wet locations, and where condensation and moisture accumulations within the conduit do not exceed 90˚C. Applications requiring direct burial are permitted for Type USE-2 / RHH / RHW-2 per UL-854. For applications requiring Type RHH or RHW-2, conductor temperatures shall not exceed 90˚C in wet or dry locations.
USE-2/RHH/RHW-2 wire can be made with copper or aluminum conductors.
Residential building wire
NM-B ("Romex") Building Wire
Type NM-B (Non-Metallic Sheathed Cable) is commonly used for residential wiring of light fixtures, devices, and appliances. Type NM-B may be installed or fished in air voids and joints and in masonry block or tile walls where such walls are not exposed to, nor subject to, excessive moisture or dampness.
Type NM-B ampacity limitation must be in accordance with the 60ºC conductor temperature rating, as specified in the NEC. Type NM-B is rated 600-volt for both exposed and concealed work in normally dry locations.
The outer PVC jacket is color-coded to the gauge of the wire: 14 AWG is white, 12 AWG is yellow, 10 AWG is orange, 8 AWG and 6 AWG are black.
NM-B PCS Building Wire
NM-B PCS is a standard non-metallic sheathed cable constructed with one cabled pair of 16 AWG signal wires for 0-10v lighting control. The multiple signal/control bundles eliminate the need for additional independent signal cables and reduce dependence on Wi-Fi controls which can be intermittent and are subject to security concerns.
Armored/Metal clad wire
MC Steel Armor (MC-SL) Cable
MC-SL is a bundled wire with an interlocked, flexible steel metal conduit on the outside. MC-SL cable is permitted use for services, feeders and branch circuits in residential, commercial, industrial, and non-patient care areas/spaces of health care facilities and is acceptable for power, lighting, control, and signal circuits.
The inner wiring can be THHN/THWN-2 type or XHHW-2 type. MC Steel Cable can include copper or aluminum conductors. Some types include a copper ground wire, and other types can include a bare aluminum or insulated aluminum ground wire.
MC Aluminum Armor (MC-AL) Cable
MC-AL is a bundled wire with an interlocked, flexible aluminum metal conduit on the outside. MC-AL cable is permitted use for services, feeders, and branch circuits in residential, commercial, industrial, and non-patient care areas/spaces of health care facilities and acceptable for power, lighting, control, and signal circuits.
The inner wiring is typically THHN/THWN-2 type or XHHW-2 type. MC Aluminum Cable can include copper or aluminum conductors. Some types include a copper ground wire, and other types can include a bare aluminum or insulated aluminum ground wire. Isolated ground versions are also available where two grounding conductors are distinguished by color code. Finally, multiple neutral options are available with oversized neutral conductors or one neutral per phase.
MC Fire Alarm & Control Cable
MC Fire Alarm and Control Cable is used for fire alarm and fire safety controls. Internal wires can be TFN or type THHN/THWN-2 and include a green insulated grounding conductor. All conductors are cabled together with separator tape containing the identification print legend to form the cable core.
MC-LED Cable
MC-LED (Type MC-PCS) cable is designed for use with LED and Fluorescent dimming systems and smart building technology that offers optimal control over the building’s lighting systems including outdoors, such as parking decks, sporting arenas and parking lots where PVC jacketed. MC-LED eliminates the need to install a separate low-voltage cable and traditional lighting/power MC Cable to a single luminaire and is UL Listed.
AC HCF Aluminum/Steel Armor (HCF-AL) Cable
HCF-MC wiring is a type of MC Armor cable specifically designed for healthcare applications. To meet standards, insulated conductors are typically individually wrapped with a moisture-resistant covering with flame retardant properties. A solid aluminum bond wire is also runs underneath the armor and remains in contact with the armor throughout the entire length.
The inner wiring is typically THHN/THWN-2 type and can have aluminum or steel armor.
MC-LED Healthcare Cable
Type MC-LED Healthcare (Type MC-PCS) cable is designed for use with LED and Fluorescent dimming systems and power management systems in smart building technology for patient care areas of healthcare facilities to aid in optimal control over the building’s lighting management systems. The additional control wires eliminate the need to install a separate low-voltage cable and traditional lighting/power MC Cable to a single light fixture or other permitted device.
PVC Jacketed MC Cable
PVC Jacketed Metal Clad cable can be used for service, feeders and branch circuits in residential, commercial, industrial, and non-patient care areas/spaces of health care facilities. A flame retardant, sunlight-resistant black PVC jacket is applied over aluminum or steel armor.
Used in both indoor or outdoor applications, and allowable for concealed or exposed systems, PVC Jacketed MC Cable is versatile in power, lighting, control, and signal circuits. Some applications include use in theaters, audience areas of motion pictures, television studios, and similar locations (NEC 520.5). This cable is also permitted as aerial cable on a messenger and allowable installations in approved raceways and cable trays (NEC 392) or installation under raised floors for IT equipment (NEC 645.5(E)). This cable is also permitted in Class I Division II, Class II Division II, and Class III Division I Hazardous Locations.
The inner wiring is typically THHN/THWN-2 type or XHHW-2 type. PVC Jacketed MC cable can include copper or aluminum conductors.
Underground or direct burial wire
UF-B Wire
Type UF-B (Underground Feeder and Branch-Circuit Cable) is generally used in underground, direct burial installations as branch circuits and/or feeders to outside floodlights, sewer pumps and motors, electric gates and other loads typically supplied from a distribution system. UF-B is typically used as a replacement for NMC.
Service entrance wire
SE-Style R
Type SE-Style R (Service Entrance Cable - Style R) is used from the main service distribution panel as a feeder to other remote distribution panels. Under special conditions as permitted by the NEC, SE-R can also be used for branch circuits to ranges, ovens, cooking units, or clothes dryers. SE-R is manufactured in accordance with Article 338 of the NEC and approved for installation in accordance with Article 230 of the NEC.
SE wire can be made from copper or aluminum conductors. Aluminum wire is primarily used for above-ground electrical service use from the electric utility power service point to the meter or service entrance panel.
SE-Style U
Type SE-Style U (Service Entrance Cable - Style U) is used from the electric utility service point to the meter or service entrance panel. SE-U is installed in accordance with Article 230 and 338 of the NEC. Also used as branch circuits for HVAC systems and other installations where a grounded conductor is not required.
SE wire can be made from copper or aluminum conductors. Aluminum wire is primarily used for above-ground electrical service use from the electric utility power service point to the meter or service entrance panel.
Photovoltaic wiring
USE-2 / RHH / RHW-2 (Photovoltaic)
Type Photovoltaic / RHH / RHW-2 is suitable for outdoor rooftop PV source and output circuits without raceways and for use in raceways installed underground in wet locations, and where condensation and moisture accumulations within the raceway do not exceed 90°C. PV Source and Output conductors that are listed and labeled as Photovoltaic (PV) wire, of any size, are permitted in cable trays located outdoors when installed in accordance with NEC 690.31(C)(2).
USE-2/RHH/RHW-2 wire can be made with copper or aluminum conductors.
Equipment and appliance wiring
MTW / AWM / TEW Machine Tool & Appliance Wire
Type MTW or TEW conductors are primarily used in control cabinets, in machine tool applications, and in appliance wiring applications at temperatures -25°C to 105°C. For use in accordance with the National Electrical Code (NEC) and NFPA Standard 79.
Tray Cable Power & Control Cable
Tray Cable Power & Control Cable
TC Power & Control Cable is primarily used for connecting power devices in an industrial environment. Suitable for installation in channels, ducts, wireways, cable trays, and conduits. Approved for direct burial in wet or dry locations and outdoors in cable trays where a sunlight-resistant rating is required. Some options are approved for use in Class I Division II Hazardous Locations.
This cable can be available with or without a ground wire. Internal wire can be type THHN/THWN-2 or type XHHW-2. TC cable can include copper or aluminum conductors.
Underground Service
URD / RDC Wire
URD / RDC is an XLPE-insulated wire primarily used in utility underground applications, including direct burial, or for installation in electrical ducts or raceways. URD / RDC cable has an aluminum conductor and is available in single conductor, two-conductor (duplex), three-conductor (triplex), or four-conductor (quadruplex) configurations.
Other configurations of URD / RDC wire use USE-2 / RHH / RHW-2 conductors for added applications and uses.
Overhead Service
ACSR Bare Overhead Supporting Neutral
ACSR Overhead Supporting Neutral is suitable for overhead transmission and distribution applications that require rated strengths for steel support.
Overhead Service Drop
Type Duplex is primarily used for delivering power from utility power lines or transformers to the service point of a building or structure.Overhead Service Drop cable is constructed with an ACSR Supporting Neutral.
Type Duplex delivers single-phase power and is suitable for 120-volt aerial service for outdoor lighting or for temporary service at construction sites.
Type Triplex delivers single-phase power and is also suitable for 120/240-volt aerial service for outdoor lighting or for temporary service at construction sites.
Type Quadruplex delivers single- and three- phase power and is also suitable for 120/240-volt, 120/208-volt and 277/480-volt aerial service for outdoor lighting or for temporary service at construction sites.
Tracer Wire
Tracer Wire
Available in solid and stranded uncoated copper conductors, tracer wire is primarily used in the detection of underground piping and other underground utility installations. Constructed of High Molecular Weight Polyethylene (HMWPE) insulation which has excellent moisture, chemical, oil, crush, and abrasion resistance. Rated 90 ̊C wet or dry. Carries -40 ̊C rating. Colors for the American Public Works Administration Uniform Color Code: yellow for gaseous materials; red for electrical lines; orange for communications; blue for potable water; green for sewers and drain lines.
Bare Wire
Soft-Drawn Bare
Soft-drawn bare wire is used in overhead electrical and distribution systems for grounding electrical systems, and where high-conductivity and flexibility are required for equipment, circuit-grounding and bonding.
Finding the right electrical wire
When you're ready for your next building project, contact us to help you with project. Our team of experts know electrical wire inside and out, and can offer the best solution to fit your needs, while also keeping your budget in mind.
