Southwire 500-ft 12 -AWG White Solid Copper THHN wire ( By-the-roll )

The Southwire 12 AWG white THHN 500 ft solid copper wire is the NEC-mandated neutral (grounded) conductor color used in every residential and commercial electrical circuit that includes 120V loads. As a 12 AWG white THHN wire, this product delivers the 20-amp circuit capacity required for typical residential and small commercial branch circuit applications, with white insulation providing the universally-recognized neutral conductor identification per NEC. As white THHN neutral wire, this conductor color is the ONLY code-compliant choice (along with gray) for insulated neutral conductors per NEC 200.6, making it a universal companion conductor pulled alongside hot conductors (black for Phase A, red for Phase B on 240V circuits with neutral loads) and the equipment grounding conductor (green) in every code-compliant conduit installation that requires a neutral return path. As a 12 AWG neutral conductor, the Southwire 12 AWG white THHN handles the return current for 20-amp circuits at the same gauge as the hot conductors, completing the standard four-conductor pull for 240V circuits with 120V loads (range hood, range accessory outlets, dryer accessory outlets) or the three-conductor pull for 120V circuits. As white THHN 500 ft by the roll, the standard 500-foot spool length matches typical electrician inventory pace for active electrical installation work. Every Southwire 12 AWG white THHN 500 ft roll ships nationwide from IB Lighting with free freight. Manufacturer specifications are available at the official Southwire website.

Southwire 12 AWG White THHN Key Highlights

Why White Specifically: NEC 200.6 Mandates the Color

The Southwire 12 AWG white THHN is white for a specific and mandatory reason rooted in NEC code requirement. Understanding why white is mandated (rather than just conventional) helps clarify why white THHN cannot be substituted with another color even when no other color would create electrical interference.

NEC 200.6 specifically requires that insulated grounded conductors (the technical NEC term for what most people call “neutrals”) be white, gray, or have three continuous white or gray stripes along the entire length. For 12 AWG and smaller insulated grounded conductors, this means the conductor must be solid white or solid gray throughout its length. Any other color is a code violation.

The rule applies universally to:

• Residential 120V branch circuit neutrals: Every 120V circuit requires a neutral in white or gray.
• Residential 240V circuit neutrals (where present): 240V circuits with 120V accessory loads (range, dryer, some water heaters) require a neutral.
• Commercial circuit neutrals: Same requirement applies regardless of voltage or system size.
• Three-phase wye system neutrals: Commercial 277V/480V three-phase wye systems use neutrals in white or gray.

The reason for the strict color mandate is safety. The neutral conductor carries return current at a voltage that is normally near ground potential (zero volts to earth), but if the neutral becomes disconnected or compromised, the neutral side of any active circuit can rise to dangerous voltages. Consistent color identification ensures the neutral is correctly identified during installation, maintenance, and troubleshooting. Misidentifying the neutral by using the wrong color creates the risk that someone working on the circuit later will treat it as a hot conductor or vice versa, creating shock or electrocution hazards.

Hot conductors specifically must NOT be white, gray, or green (which is the equipment grounding color). The NEC reserves these three color families for grounded (neutral), grounded (neutral with stripes), and grounding (equipment ground) conductors respectively. Any other color (black, red, blue, brown, yellow, orange, and others) can be used for ungrounded (hot) conductors.

The Neutral Conductor’s Role in 120V Circuits

The Southwire 12 AWG white THHN serves a specific electrical role in residential and commercial 120V circuits. Understanding how the neutral functions helps clarify why white THHN is required in every 120V circuit installation.

In a 120V single-phase circuit, the hot conductor (typically black THHN) carries current at 120 volts above ground potential from the panel to the load equipment. The current passes through the load equipment and must return to the panel to complete the circuit. The neutral conductor (white THHN) provides this return path, carrying the same amount of current as the hot conductor but at a voltage near ground potential (zero volts to earth).

The neutral connects to the grounded neutral bar in the electrical panel, which is bonded to earth ground via the grounding electrode conductor at the service entrance. This grounding connection establishes the neutral as the reference point for the 120V supply, ensuring that the actual voltage at any point in the circuit corresponds to the nominal 120V difference between hot and neutral.

The current flow pattern in a 120V circuit:

• Current flows OUT from the panel on the hot conductor: The black THHN at 120V relative to neutral.
• Through the load equipment: Where the electrical energy is consumed.
• Returns to the panel on the neutral conductor: The white THHN at approximately 0V relative to ground.
• Completes the circuit at the neutral bar in the panel: Where the neutral connects to the supply’s grounded conductor.

This circuit configuration requires both the hot and neutral conductors in every 120V installation. Omitting the neutral or substituting it with a non-NEC-compliant color creates a code violation and a safety hazard. The Southwire 12 AWG white THHN is the universally-correct neutral specification for typical 20-amp residential and commercial 120V circuits installed in conduit.

When the Neutral Is Required (And When It Isn’t)

While the Southwire 12 AWG white THHN is required for every 120V circuit, not every circuit needs a neutral conductor. Understanding when the neutral is required helps clarify the conductor count for each specific circuit type.

Circuits that REQUIRE the white neutral conductor:

• All 120V circuits: Lighting, general receptacles, kitchen countertop circuits, bathroom circuits, AFCI-protected circuits in habitable spaces, GFCI-protected circuits, smoke detector circuits.
• 240V circuits with 120V accessory loads: Electric ranges (which have 120V accessories like timer, light, igniter), electric dryers with 120V control circuits, some water heaters with 120V controls. The white neutral serves the 120V portions of these circuits.
• Three-phase wye 277V circuits: Commercial 277V circuits using the wye configuration’s neutral.
• Multi-wire branch circuits (MWBC): The shared neutral that carries the imbalance current between two hot conductors on opposite phases.

Circuits that do NOT require a neutral conductor:

• 240V-only loads with no 120V accessories: Air conditioning condensers, electric water heaters with no 120V controls, well pumps with 240V-only operation, electric vehicle chargers (most are 240V-only), pool pumps and heaters.
• Three-phase delta system loads: Some commercial 240V delta systems do not use a neutral.
• Some specific industrial loads: Certain motor circuits and process equipment.

For 240V-only loads, the conductor pull through conduit includes only the two hots (black for Phase A, red for Phase B) and the equipment ground (green). The white THHN is not required in these specific circuit types. For all other 240V applications and every 120V application, the white THHN neutral is required.

White THHN in 240V Circuits: Optional but Common

The role of the Southwire 12 AWG white THHN in 240V circuit pulls is sometimes confusing. Understanding when the white neutral is included in 240V conduit pulls helps clarify the conductor count requirement.

240V circuits fall into two categories:

Pure 240V-only circuits: The connected equipment operates ONLY at 240V with no 120V accessory loads. Examples include simple air conditioning condensers, electric water heaters with no 120V controls, pure 240V motors, and EV chargers. For these circuits, the conductor pull is three conductors: black (Phase A hot), red (Phase B hot), and green (equipment ground). The white THHN neutral is NOT included because no 120V load needs the return path.

240V/120V combined circuits: The connected equipment operates partially at 240V (the main heating elements, motors, or other high-current loads) and partially at 120V (accessory loads like control electronics, lights, timers, igniters). Examples include electric ranges (240V heating elements plus 120V oven light/timer), electric dryers (240V heating element plus 120V controls and accessory outlet), some water heaters with 120V controls. For these circuits, the conductor pull is four conductors: black, red, white (this product), and green. The white THHN neutral serves the 120V accessory loads.

When specifying the cable order for a 240V circuit installation, verify whether the connected equipment has 120V accessory loads. The equipment’s nameplate or installation manual will indicate whether a neutral is required. Standard residential ranges, dryers, and water heaters with 120V controls require the white neutral; pure 240V-only equipment does not.

For the typical 240V residential installation (range, dryer, water heater with 120V controls), the four-conductor pull includes the Southwire 12 AWG white THHN as the neutral, paired with red THHN (Phase B hot) for the second hot conductor.

Universal Application: Every 120V Circuit in Conduit

Similar to green THHN’s universal grounding application, white THHN is consumed on every conduit installation that includes 120V loads. Because nearly all residential and small commercial circuits include 120V loads in some form, white THHN is one of the highest-volume single colors in any electrical contractor’s inventory.

The Southwire 12 AWG white THHN consumption pattern for a typical electrical contractor:

• Every standard 120V residential circuit: Black + white + green = 3 conductors. White is required.
• Every 20A small appliance circuit: Black + white + green. White is required.
• Every dedicated 120V appliance circuit: Black + white + green. White is required.
• Every range or dryer circuit: Black + red + white + green = 4 conductors. White is required for 120V accessories.
• Every multi-wire branch circuit: Two hots (black + red) + shared white neutral + green. White is required.

This universal application makes white THHN the second-highest consumption color in any contractor’s inventory, behind only green THHN (which is consumed on every conduit installation regardless of voltage). A typical electrical contractor’s inventory ratio is approximately 1:1 between green and white THHN, with both colors significantly outpacing red, blue, yellow, and other single-color rolls.

For inventory planning: most electrical contractors stock white THHN at the same volume as green THHN, with red, blue, yellow, and brown stocked at lower volumes proportional to their specific use case frequency.

Common Applications for the Southwire 12 AWG White THHN

The Southwire 12 AWG white THHN serves residential and commercial 20-amp circuit neutral applications across nearly every installation type. The breadth of applications reflects the universal demand for neutral conductors in 120V circuit work.

Residential applications requiring white THHN as the neutral:

• Kitchen countertop receptacle circuits: 20A small appliance circuits per NEC requirements.
• Bathroom GFCI circuits: 20A bathroom receptacle circuits requiring GFCI protection.
• Laundry receptacle circuits: Dedicated 20A laundry circuits for washing machines.
• Garage receptacle circuits: 20A GFCI-protected garage receptacles.
• Outdoor receptacle circuits: 20A weather-resistant GFCI receptacles in conduit installations.
• General-purpose 15A and 20A receptacle circuits: Bedroom, living room, dining room, and similar habitable space receptacles.
• Lighting circuits with switched controls: Both 15A and 20A lighting circuits require white neutrals.
• Electric range circuits (4-conductor): 240V/40-50A range circuits with 120V oven light and timer accessories.
• Electric dryer circuits (4-conductor): 240V/30A dryer circuits with 120V controls.
• Smoke detector and CO detector circuits: Hardwired interconnected 120V detector circuits.

Commercial applications:

• Three-phase wye 277V/120V circuit neutrals: Commercial buildings using three-phase wye service.
• Commercial 20A receptacle circuits: Office and retail general-purpose receptacles.
• Commercial lighting circuits: 20A switched lighting circuits in commercial spaces.
• Small equipment circuits: Dedicated 120V circuits for point-of-sale, refrigeration, and similar equipment.

For larger circuit applications (30A, 40A, 50A circuits with neutrals), step up to 10 AWG white THHN (30-40A circuits) or 8 AWG white THHN (50A circuits). The 12 AWG specification matches 20-amp circuit applications specifically.

White THHN vs Gray THHN: Both NEC-Permitted

NEC 200.6 permits insulated grounded (neutral) conductors to be white or gray. Both colors are equally code-compliant, though white is significantly more common in residential and standard commercial applications. Understanding when gray might be preferred helps clarify the rare cases where gray substitutes for white.

White THHN (this product) is the standard choice for:

• Residential 120V branch circuits: The dominant residential application.
• Standard commercial 120V circuits: Office, retail, and small commercial applications.
• Most general electrical work: The instinctive choice for the neutral color.

Gray THHN is sometimes preferred for:

• Industrial installations: Some industrial conventions favor gray for the neutral in 480V/277V three-phase wye systems, with white reserved for separate distribution voltages.
• Multiple voltage systems in one building: Gray can identify one voltage system’s neutral while white identifies another, providing visual differentiation.
• Specific design standards: Some specifications and design standards specify gray for neutrals in certain applications.

For typical residential and standard commercial work, white THHN is the universal default and the choice that meets nearly all installation requirements. Gray THHN is available for the specific applications where it is preferred but is not stocked by most contractors as part of standard inventory.

Can White THHN Be Re-Identified as a Hot Conductor?

NEC 200.7 establishes specific rules for re-identifying white-jacketed conductors as hot (ungrounded) conductors in limited circumstances. Understanding these rules clarifies why electricians sometimes apply colored tape to white conductors and when this practice is code-compliant.

White conductors can be re-identified as hot ONLY in specific applications:

• Cable assemblies (NM-B Romex) where the white conductor is used as a hot: In switch-loop configurations within NM-B cable, the white conductor may be used as the hot conductor connecting the switch to the load. The white must be permanently re-identified at both terminations by painting, taping, or another permanent marking method that is visible at the termination.
• Three-way switch travelers in cable assemblies: Similar to switch loops, the white conductor in some three-way switch configurations may serve as a traveler when re-identified.

Re-identification is NOT permitted in conduit installations like those using the Southwire 12 AWG white THHN. For conduit installations, the rule is simpler: pull the correct color for each role. Don’t pull white THHN intending to use it as a hot. Instead, pull a hot color (black, red, blue, brown, yellow) for hot conductors and white THHN for neutrals.

The practical takeaway for conduit installations using the Southwire 12 AWG white THHN: this conductor is ALWAYS the neutral. Use red or yellow THHN for second hot conductors on 240V circuits and three-way switch configurations rather than re-identifying white. The conduit installation has the flexibility to use any color the design requires.

White THHN in Multi-Wire Branch Circuits

Multi-wire branch circuits (MWBC) are a specific 240V circuit configuration where the Southwire 12 AWG white THHN plays a critical role. Understanding the MWBC configuration helps clarify how the shared neutral works.

A multi-wire branch circuit consists of two hot conductors on opposite phases of the residential split-phase service, sharing a single common neutral. The two hots are typically black (Phase A) and red (Phase B). The shared neutral is white THHN. The configuration delivers two 120V circuits from a single cable pull, with each hot conductor providing its own 120V circuit referenced to the shared neutral.

MWBC code requirements per NEC 210.4:

• Two hots on opposite phases: The two hot conductors must connect to OPPOSITE phases at the panel, not the same phase. Connecting to the same phase would cause the neutral to carry the SUM of both circuits’ current rather than the difference, potentially overloading the neutral.
• Single shared neutral: The white THHN serves both 120V circuits, carrying only the imbalance current between them.
• Handle-tied breakers: NEC 210.4(B) requires that all ungrounded conductors of a multi-wire branch circuit be disconnected simultaneously. This is accomplished using handle-tied breakers or a two-pole breaker.

The MWBC configuration is electrically efficient because the two 120V circuits share the neutral cable, reducing the total conductor count compared to running two separate 120V circuits (which would need two neutrals). However, the configuration has specific code requirements that make MWBC installations more complex than standard branch circuits.

For typical MWBC installations using the Southwire 12 AWG white THHN as the shared neutral, the conductor pull through conduit includes black (Phase A hot), red (Phase B hot), white (shared neutral), and green (equipment ground). This is the same four-conductor pull as a 240V circuit with 120V accessory loads, but used differently: the MWBC delivers two independent 120V circuits, while the 240V/120V circuit delivers one 240V supply with 120V accessories.

Conduit Fill Including the Neutral Conductor

The neutral conductor counts toward the total conductor count for NEC conduit fill calculations. The Southwire 12 AWG white THHN takes up the same conduit space as the equivalent gauge in any other color.

Typical conductor counts per 120V and 240V circuit:

• Standard 120V circuit (3 conductors): Black hot + white neutral + green ground.
• 240V circuit with neutral (4 conductors): Black hot + red hot + white neutral + green ground.
• 240V-only circuit (3 conductors): Black hot + red hot + green ground. No white neutral.
• Multi-wire branch circuit (4 conductors): Black hot + red hot + white shared neutral + green ground.
• Three-phase wye 277V circuit (5 conductors): Black + red + blue (three hots) + white neutral + green ground.

For 1/2-inch EMT conduit at the maximum 40% fill for 3+ conductors, the typical capacity for 12 AWG THHN is approximately 9 conductors. A standard 240V circuit with neutral (4 conductors) fits comfortably in 1/2-inch EMT with substantial fill capacity remaining. For installations anticipating future conductor additions or multiple circuits sharing conduit, 3/4-inch EMT provides additional capacity.

Southwire 12 AWG White THHN Specifications

Southwire 12 AWG White THHN FAQs

Who the Southwire 12 AWG White THHN Is Built For

The Southwire 12 AWG white THHN serves the broadest buyer base in residential and commercial electrical work because of the universal application of neutral conductors. Every electrical contractor doing conduit installations with 120V loads consumes white THHN as part of normal operations.

The primary buyer is the residential electrical contractor handling conduit installations for new construction, remodels, and major equipment circuit work. For these contractors, the Southwire 12 AWG white THHN is the neutral conductor for every 120V branch circuit they install, paired with the hot and grounding conductors. The 500-foot roll matches typical contractor inventory pace.

The secondary buyer is the commercial electrical contractor handling commercial 120V receptacle and lighting circuits, three-phase wye 277V neutrals, and general commercial 20A circuits. For these contractors, the 12 AWG white THHN is the neutral conductor for the dominant commercial circuit configurations.

The tertiary buyer is the appliance circuit installer handling electric range and dryer rough-ins, where the four-conductor pull (red, black, white, green) is the standard configuration for circuits with 120V accessory loads. For these installers, the white THHN serves the 120V portion of the 240V/120V combined circuits.

The quaternary buyer is the industrial electrician handling control circuits, instrumentation, and small motor circuits where neutral conductors are required. Browse the broader IB Lighting electrical wire collection for related products.

White THHN vs Green, Red, Yellow THHN: The Universal Pair

Within the THHN color family, white THHN occupies a position similar to green: a universal-application color with mandatory NEC color identification. Together, white (neutral) and green (ground) form the universal pair of conductors required for nearly every conduit installation.

The complete THHN color comparison:

• Black THHN: Phase A hot conductor. Used on EVERY circuit.
• Red THHN: Phase B hot conductor. Used on 240V circuits only.
• Blue THHN: Phase C hot conductor. Used on three-phase commercial circuits only.
• White THHN (this product): Neutral conductor. Used on EVERY circuit with 120V loads.
• Green THHN: Equipment grounding conductor. Used on EVERY conduit installation.
• Yellow, Brown, Orange THHN: Alternative identification colors for specialty applications.

For a typical residential 120V circuit, the conductor set is black + white + green = three colors. For a typical 240V circuit with 120V accessories, the set is black + red + white + green = four colors. The Southwire 12 AWG white THHN (this product) is the neutral portion of these universal sets, paired with companion Southwire 12 AWG red THHN for Phase B hot conductors and Southwire 12 AWG green THHN for equipment grounds.

For comparison shoppers also browsing the yellow alternative identification color, browse the Southwire 12 AWG yellow THHN for those specialized applications.

Installation Best Practices for the Southwire 12 AWG White THHN

Installing the Southwire 12 AWG white THHN follows standard practices for THHN conductor pulls through conduit, with neutral-specific considerations that ensure code-compliant safety performance.

Verify neutral requirement first: Confirm the circuit requires a neutral before including white THHN in the conductor pull. 120V circuits and 240V circuits with 120V accessories require the neutral; 240V-only circuits do not.

Match neutral gauge to hot conductor gauge: The neutral carries the same return current as the hot, so the neutral gauge must match. For 20A circuits, 12 AWG white THHN (this product) pairs with 12 AWG hots.

Connect neutrals only to the neutral bar: At the panel, the white THHN terminates ONLY at the neutral bus bar, never at a breaker terminal or the equipment ground bar. Mixing neutrals with hots or grounds is a serious code violation.

Maintain neutral continuity: A broken neutral can cause connected equipment to see dangerous voltage. Verify the neutral path is continuous from the source through every device terminal to the load equipment. Pigtail neutrals at junction boxes rather than relying on device terminals for downstream continuity.

Watch for multi-wire branch circuit configurations: If installing an MWBC, ensure the two hots connect to OPPOSITE phases at the panel and use handle-tied breakers per NEC 210.4(B). Connecting both hots to the same phase can overload the shared neutral.

Never re-identify white in conduit: Re-identification of white as a hot is permitted only in specific cable assembly situations (NEC 200.7), not in conduit installations. Pull the correct color for each role.

Test for proper neutral operation: After installation, verify neutral continuity and confirm no voltage exists between the neutral and ground at connected devices. Use a multimeter to verify the neutral operates at near-zero voltage to ground under load.

Browse the complete IB Lighting electrical wire and cable collection, pair with companion Southwire 12 AWG red THHN for Phase B hot conductors on 240V circuits, pair with Southwire 12 AWG green THHN for equipment grounding conductors, compare with Southwire 12 AWG yellow THHN for alternative identification applications, consider Southwire 10/3 UF-B for direct-burial alternative to outdoor conduit installations, pair with a Tesla Universal Wall Connector for EV charging circuits, explore other Southwire products, or visit our customer FAQ hub. Manufacturer technical sheets are available at the official Southwire website.