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Wiring colors vary by jurisdiction, circuit type, and installation era. This quick-reference guide separates a North American branch-circuit excerpt, a common IEC-oriented European/UK AC example, and machinery wiring. These are not interchangeable color keys, and color alone cannot confirm a conductor’s function in a particular installation.
Which wiring color code applies?
Start with the location and the kind of system: building AC, DC, machinery or equipment, and vehicle wiring can use different identification schemes. The examples below cover only the contexts named; they do not establish the current local code for every country or installation. For compliance, consult the applicable local rules and the installation’s documentation.
North American branch circuits: what do the cited colors mean?
OSHA’s electrical-safety material reproduces NEC branch-circuit identification language. In that excerpt, the grounded conductor is identified by continuous white or natural gray, while the equipment grounding conductor is continuous green, continuous green with one or more yellow stripes, or bare. The excerpt is not a complete or necessarily latest version of the NEC.
The excerpt distinguishes the grounded conductor (neutral) from the equipment grounding conductor, which serves a fault-protection role. They are different conductors with different functions, not interchangeable labels.
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- Diagram covers the complete basic car including: interior and exterior lights, engine & engine compartment, firewall, under dash, instrumentation, etc.
- All wire colors (including tracers) and component information is from the original factory service manuals. This means the wire colors on the diagram are the same as what is in your car.
- All text is crystal clear and easy to read, and all colors are easy to distinguish.
- The diagram is laminated in rigid plastic for years of use.
- Large 11" X 17" Tabloid Size.
Colors shown in the North American infographic
The All About Circuits infographic for this topic presents the following chart. Treat it as that page’s chart, not a universal key or a guarantee of present-day requirements in every situation.
| Chart item | Color shown | Scope and qualification |
|---|---|---|
| Phase 1 | Black | North American chart in the All About Circuits infographic; not a universal phase assignment. |
| Phase 2 | Red | North American chart in the All About Circuits infographic; not a universal phase assignment. |
| Phase 3 | Blue | North American chart in the All About Circuits infographic; not a universal phase assignment. |
| Neutral | White | Chart example; OSHA’s reproduced branch-circuit excerpt also permits continuous natural gray. |
| Ground | Green, green with yellow stripe, or bare | Chart example; OSHA’s reproduced branch-circuit excerpt gives these equipment-grounding-conductor identifications. |
| High-leg connection | Orange | Noted by the infographic; the cited material does not establish every applicable installation rule. |
Common IEC-oriented European/UK building AC example
TP-Link’s UK guide, updated June 10, 2026, gives this common AC color example. It is a regional/contextual reference, not a substitute for checking the rules that apply to a specific location and installation.
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| Conductor or phase | Color in the guide | Application shown |
|---|---|---|
| Line in single-phase AC; L1 in three-phase AC | Brown | Common European/UK IEC-oriented AC example |
| L2 | Black | Three-phase AC |
| L3 | Grey | Three-phase AC |
| Neutral | Blue | AC |
| Protective earth (ground) | Green-yellow | AC |
Why this AC chart does not apply to DC or machinery
DC systems
The TP-Link guide shows that DC assignments change with the grounding arrangement: positive and negative colors can differ depending on which side of the circuit is grounded. The cited material does not provide one universal DC mapping, so do not carry an AC chart over to DC. Identify the system’s grounding arrangement and use its applicable documentation.
Machinery and equipment wiring
Machinery wiring has its own context. An IDEC EMEA overview of IEC 60204-1 gives black for AC power circuits and recommends light blue for neutral. This differs from the European/UK building AC example above, which uses brown for line. IEC’s catalog describes IEC 60445:2017 as covering identification and marking of equipment terminals and certain designated conductors, and indicates a later 2021 publication. For a particular machine, consult its documentation and the applicable standard rather than assuming a building-wire chart governs it.
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What about cars and military wiring?
Automotive harnesses and military wire identification are separate systems, not extensions of a household live-neutral-ground chart. Electrical.Design’s cross-standard poster reference names SAE J1128 automotive primary wire and MIL-STD-681, among other references. It describes military color-digit coding as wire-number identification, not a household conductor-function mapping. Automotive colors may depend on the vehicle and system, so use the vehicle’s wiring documentation; the poster reference alone is not a vehicle-specific key.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Can color alone identify a wire safely?
No. These references describe conventions in particular contexts; they do not establish that color alone proves a conductor’s function, condition, or state in an existing installation. Legacy wiring and local requirements may also differ. Do not use this infographic as a diagnostic procedure: when identification matters for work or safety, rely on the applicable rules, installation documentation, and assessment by a competent person.
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- Common Electrical Symbols Poster Wiring Reference Chart
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