Short answer: Article 200 covers the grounded conductor, usually the neutral, and how it is identified (NEC 200.1). For 6 AWG and smaller, the insulation itself must be identified: a continuous white or gray outer finish, or three continuous white or gray stripes on insulation that is not green (NEC 200.6(A)). For 4 AWG and larger, a distinctive white or gray marking that encircles the conductor at its terminations, applied at the time of installation, is also permitted (NEC 200.6(B)). A white or gray conductor may be used as an ungrounded conductor only in the specific cases Article 200 allows, such as a re-identified conductor in a cable assembly (NEC 200.7). Each section lists exceptions, so read them in your 2026 NEC.
PSI’s content outline lists Branch Circuits and Conductors as a subject area of the Texas Journeyman exam: 10 scored NEC Knowledge questions. PSI does not name Article 200 or say how many questions cover conductor identification. The Texas Journeyman Practice Pack has 1,000 original questions and 10 timed mock exams in the real two-part format, with step-by-step solutions for every calculation. Try free practice questions without signing up. Get the full pack for US$39 with one payment.
Tsai Electro is an independent learning site. Not affiliated with TDLR, PSI or NFPA. We explain the ideas in our own words and do not reproduce NEC text. Check every rule and table value in your own 2026 NEC, and follow your supervisor and the local inspector.
Grounded, grounding and ungrounded: three different wires
Exam questions often turn on the name. The grounded conductor is a circuit conductor intentionally connected to ground, usually the neutral, and it carries current in normal operation. The equipment grounding conductor provides the path for ground-fault current and is not intended to carry normal load current. It is commonly bare or green; its identification rules are in Article 250, not Article 200. Ungrounded conductors are the hot conductors. Article 200 is about the first one. For the grounding side, see NEC 250 grounding and bonding mistakes.
How the grounded conductor is marked, by size
| Conductor size | Permitted identification of the grounded conductor |
|---|---|
| 6 AWG and smaller | Continuous white or gray outer finish, or three continuous white or gray stripes on insulation that is not green (NEC 200.6(A)) |
| 4 AWG and larger | Any of the above, or a distinctive white or gray marking that encircles the conductor at its terminations, applied at the time of installation (NEC 200.6(B)) |
So a black 8 AWG conductor with white tape at both ends does not meet the general rule for a grounded conductor; at that size the insulation itself must be identified. A black 2 AWG conductor with white tape encircling it at each termination does meet 200.6(B). Both sections have exceptions for specific cable types and conditions, so check them before you answer a question that names one.
Where grounded conductors of different systems are in the same raceway, box or enclosure, such as a 120/208 V system and a 277/480 V system, each system’s grounded conductor needs its own identification so the two can be told apart. Article 200 sets how that is done and documented; read that rule in your 2026 NEC.
Re-identifying a white conductor as a hot
The default is that white or gray means grounded conductor, and those colors are not used for ungrounded conductors (NEC 200.7). Article 200 then allows limited cases. The two you meet most on the job:
- Cable assemblies. In a cable such as NM, the white conductor may be used as an ungrounded conductor where it is permanently re-identified as ungrounded at each location where it is visible and accessible, for example with black or red tape or marker.
- Switch loops. In a cable used for a switch loop, a re-identified white conductor may serve as the supply to the switch, not as the return to the switched outlet. Check the exact wording and any conditions for 3-way and 4-way loops in your 2026 NEC.
The limits sit in the same section, including the voltage threshold and where the re-identification must appear, so read all of 200.7 before you rely on one sentence of it.
Grouping neutrals in an enclosure
Where grounded conductors of more than one circuit are in the same enclosure, each circuit’s grounded conductor has to be identified or grouped with its ungrounded conductors, for example with a wire tie, so you can tell which neutral belongs to which circuit (NEC 200.4). The section has exceptions, such as for conductors that pass through without a splice or termination; check them in your 2026 NEC.
Terminals and polarity
The terminal intended for the grounded conductor is identified, commonly by a white or silver-colored screw (NEC 200.10). On a screw-shell lampholder, the screw shell connects to the grounded conductor, and the center contact connects to the ungrounded conductor (NEC 200.10). Correct polarity lowers the shock risk when someone changes a lamp, but it does not replace verifying that the circuit is de-energized. A grounded conductor is not to be connected to a terminal or lead in a way that reverses the designated polarity (NEC 200.11).
Worked example: which conductors pass the identification rule
Assume each conductor below is used as a grounded conductor, and no exception in 200.6 applies. For each case, decide whether it passes, then find the rule in 200.6 in your 2026 NEC before you check the answer.
- 12 AWG, gray insulation. 6 AWG and smaller may use a continuous gray finish. Passes.
- 10 AWG, black insulation with white tape at each end. At 6 AWG and smaller, the insulation itself must be white or gray or have three white or gray stripes. Does not pass the general rule.
- 1/0 AWG, black insulation with white tape encircling it at each termination, applied when it was installed. 4 AWG and larger may use that marking. Passes.
- 6 AWG, green insulation with three white stripes. The stripe option is for insulation that is not green. Does not pass.
Check yourself
- What size break separates “insulation must be identified” from “marking at terminations allowed”? 6 AWG and smaller versus 4 AWG and larger.
- In a switch loop in cable, which job may a re-identified white conductor do? Supply to the switch, not the return to the outlet; confirm the conditions in 200.7.
- On a screw-shell lampholder, which conductor goes to the screw shell? The grounded conductor.
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Find Article 200 faster on exam day
NFPA 70, National Electrical Code, 2026 Edition (softcover). Highlight the size break between 200.6(A) and 200.6(B) and the re-identification limits in 200.7, so a color question sends you to the right paragraph. The Texas exam is open book. PSI allows a soft-bound NEC with highlighting, underlining and notes made in advance. Loose-leaf, spiral-bound and ring-bound copies are not allowed, and only permanent index tabs made or supplied by the NEC publisher are permitted; homemade and third-party tabs are not.
FAQ
What colors identify a grounded conductor?
White or gray, as a continuous outer finish, or three continuous white or gray stripes on insulation that is not green. For 4 AWG and larger, a white or gray marking encircling the conductor at its terminations is also permitted.
Can I tape a black 10 AWG wire white and use it as a neutral?
Not under the general rule. At 6 AWG and smaller, the insulation itself must be identified. Check the exceptions in 200.6(A) for specific cable types.
Can a white wire in NM cable be used as a hot?
Yes, in the cases Article 200 allows, where it is permanently re-identified at each location where it is visible and accessible.
Is the grounded conductor the same as the grounding conductor?
No. The grounded conductor is usually the neutral and carries normal current. The equipment grounding conductor is the bare or green fault path covered in Article 250.
Why group neutrals in a panel or box?
So each circuit’s grounded conductor can be matched to its ungrounded conductors, which Article 200 requires where more than one circuit’s grounded conductor shares the enclosure, subject to its exceptions.
Sources checked October 2026
- PSI Candidate Information Bulletin, Texas electrician examinations (updated September 15, 2026): https://test-takers.psiexams.com/api/content/bulletin/1682
- NFPA 70, National Electrical Code, 2026 Edition, Articles 200 and 250
