The correct wire plug color code depends entirely on your regional standard and the origin of the appliance. In North America (NEC), the standard for AC power cords is Black (Hot), White (Neutral), and Green/Bare (Ground). In Europe and most of the world (IEC), it is Brown (Live), Blue (Neutral), and Green/Yellow (Earth). Mixing these up when repairing an imported appliance or wiring a custom plug is a guaranteed way to trip a breaker, destroy equipment, or cause a fire.
The Master Wire Plug Color Code Table
Use this table to identify the conductors inside an AC flex cord or plug housing. This covers the four major standards you will encounter on the bench or jobsite.
| Function | Symbol | US/Canada (NEC / NEMA) | EU/Intl (IEC 60446) | Old UK (Pre-2004) | AU/NZ (AS/NZS 3000) |
|---|---|---|---|---|---|
| Line / Hot | L | Black (Red/Blue for 3-phase) | Brown | Red | Brown (Active) |
| Neutral | N | White (or Grey) | Blue | Black | Blue (or Black) |
| Earth / Ground | E / G / ⏚ | Green, Green/Yellow, or Bare | Green/Yellow Stripe | Green | Green/Yellow Stripe |
Regional Standards: Which Plug Color Code Applies?
Before you strip a jacket, you must identify the cord's origin. The physical plug shape (NEMA 5-15, IEC C13, BS 1363) is your first clue, but internal wiring dictates the termination.
- North America (NEC/NEMA): Governed by NFPA 70 (NEC Article 250.119 for grounding, 400.23 for flex cords). You will see Black/White/Green. The hot blade on a NEMA 5-15 plug is the narrower blade, and the neutral is the wider blade.
- Europe & International (IEC 60446 / IEC 60320): The global harmonized standard. If you are wiring an IEC C13/C14 (kettle lead) or C5/C6 (cloverleaf) connector, you must use Brown/Blue/Green-Yellow. IEC standards strictly forbid solid green or solid black for mains flex cords.
- United Kingdom (BS 1363 / BS 7671): The UK harmonized with the IEC in 2004. However, millions of pre-2004 appliances with the old Red/Black/Green colors are still in circulation. The UK Health and Safety Executive (HSE) provides specific guidance on transitioning legacy wiring.
- Australia & New Zealand (AS/NZS 3000): Harmonized closely with the IEC (Brown/Blue/Green-Yellow), but older installations and some specific flex cords may still use Red (Active) and Black (Neutral).
Rows People Get Wrong (And How They Cause Fires)
When repairing appliances or building custom power distribution units, these specific color code mismatches cause the most bench failures and field callbacks.
1. Old UK Black (Neutral) vs. US Black (Hot)
If you import a vintage UK appliance and assume the black wire is 'Hot' because you are used to North American NEC wiring, you will wire the 240V line directly to the neutral return path. This bypasses the appliance's internal switching, leaves the chassis or internal components energized even when 'off', and creates an immediate shock hazard. Fix: Always treat black as Neutral in a UK-origin BS 1363 cord.
2. Solid Green vs. Green/Yellow Stripe
In the US (NEC), solid green is a perfectly legal and common equipment grounding conductor. In the IEC world, solid green is strictly forbidden for earth wires in flex cords because it can be confused with low-voltage signaling or telecom wires. IEC mandates the bi-color green/yellow stripe. If you are building an export product or wiring an IEC inlet, using solid green wire will fail CE/IEC safety audits.
3. The 'White' Wire in European Equipment
White is the standard neutral in North America. If you open a European-manufactured power supply or appliance and see a white wire, it is not the AC neutral. In IEC internal wiring, white is often used for low-voltage DC returns or sensor signals. Terminating 230V AC mains to an internal white wire will instantly fry the control board.
Decision Path: Identifying Unmarked or Non-Standard Wires
Use this decision tree to terminate wires safely when the colors don't match your expectations or when dealing with imported equipment.
| Condition / Wire Color | Context / Region | Action / Concrete Pick |
|---|---|---|
| Wire is Black | US/Canada NEMA 5-15 plug | Terminate to Brass (Hot) screw on receptacle. |
| Wire is Black | Old UK BS 1363 appliance cord | Terminate to Blue (Neutral) pin. Sleeve the wire with 3M 1/8" Blue Heat Shrink (Part: EPS-200-1/8-BU) to update the visual code. |
| Wire is Solid Green | IEC C13/C14 appliance cord | REJECT. IEC requires Green/Yellow. Replace the cord with an IEC 60320 C13 compliant cord (e.g., Schurter 4300.0101). |
| Wire is White | EU/IEC internal appliance wiring | STOP. Do not connect to mains. Trace with a multimeter; it is likely a low-voltage DC return. |
| All wires are identical (e.g., all black or all brown) | Any region, unmarked or custom cord | Perform continuity test (see below). Label wires with Brady B946 vinyl tape in corresponding regional colors before termination. |
Safe Interpretation When Markings Are Faded or Missing
Sun exposure, heat from appliance exhausts, and cheap manufacturing can fade wire jacket colors until Brown looks identical to Black, or the Green/Yellow stripe is invisible. Never guess. Use this exact multimeter procedure to map the plug pins to the stripped wire ends.
- De-energize and Isolate: Ensure the cord is completely unplugged from both the wall and the appliance. If the cord is hardwired to a PCB, desolder or disconnect the spade terminals so you are testing the cord in isolation.
- Set the Multimeter: Turn your DMM to the Continuity/Diode setting (the one that beeps). Set the range to measure Ohms (Ω) if your meter doesn't have a dedicated continuity beep.
- Map the Ground (Earth): Place one probe on the grounding pin of the plug (the round pin on NEMA, the top rectangular pin on BS 1363, the center pin on Schuko). Touch the other probe to each stripped wire end. The wire that reads < 1.0 Ω (and beeps) is your Ground. Mark it immediately with green/yellow tape.
- Map Hot and Neutral (If colors are totally faded): For a polarized plug (like NEMA 5-15), probe the narrow blade (Hot) and the wide blade (Neutral) against the remaining two wires. Map them accordingly. For non-polarized plugs (like Europlug CEE 7/16 or Schuko CEE 7/4), the Line and Neutral pins are reversible; you can assign either of the remaining two wires to L and the other to N, provided the Ground is correctly identified.
- Verify Insulation Integrity: Switch your DMM to the Megaohm (MΩ) range. Place one probe on the Hot wire and the other on the Ground wire. The reading should be OL (Over Limit) or >10 MΩ. If it reads low resistance, the cord's internal insulation is compromised and it must be destroyed and replaced.
By relying on physical pin mapping and continuity testing rather than trusting faded PVC jackets, you eliminate the guesswork that leads to reversed-polarity faults and chassis energization. Always default to the IEC Brown/Blue/Green-Yellow standard when building new custom cords for international use, and sleeve legacy wires to match modern expectations.
