When wiring a replacement plug, hardwiring an appliance, or troubleshooting a faulty IEC cable, misidentifying the ground, neutral, and hot conductors can cause immediate shock hazards or equipment failure. The 3 wire power cord color code is not universal; it shifts dramatically depending on your region, the voltage of the circuit, and the governing electrical standard. Below is the definitive, table-forward reference to identify your conductors safely and accurately.
| Conductor Function | US / Canada (NEC Art. 250/400) | EU / International (IEC 60446) | UK (BS 7671 Post-2004) | AU / NZ (AS/NZS 3000) |
|---|---|---|---|---|
| Line 1 (Hot/Active) | Black (or Blue for 277V) | Brown | Brown | Red (or Brown) |
| Neutral (Grounded) | White (or Grey) | Blue | Blue | Black (or Blue) |
| Earth (Ground/EGC) | Green, Green/Yellow, or Bare | Green/Yellow (Striped) | Green/Yellow (Striped) | Green/Yellow (Striped) |
| Line 2 (240V Hot)* | Red (or Orange for High-Leg) | Black (or Brown L2) | Black (or Brown L2) | White (or Black) |
*Note: Line 2 applies to 3-conductor 240V cords (e.g., NEMA 6-15 or NEMA 10-30) which feature two hot legs and a ground, but lack a neutral conductor.
Decoding the Standards: What Each Color Means in Practice
The colors in a standard 3 wire power cord (Line, Neutral, Earth) dictate the physical path of current and the safety mechanisms of your electrical system. Understanding which standard applies to your region prevents catastrophic miswiring.
North America (NEC / CEC)
In the US and Canada, the National Electrical Code (NFPA 70) governs cord colors under Articles 250 and 400. The black wire is your ungrounded 'hot' conductor, carrying the full 120V potential from the panel. The white wire is the 'grounded' neutral conductor; it completes the circuit back to the transformer and carries the exact same current as the hot wire under normal operation. The green or bare wire is the Equipment Grounding Conductor (EGC). It carries zero current during normal use and exists solely to provide a low-impedance fault path to trip the breaker if the hot wire touches the appliance chassis.
Europe and International (IEC 60446)
The International Electrotechnical Commission standardizes colors across most of the globe. Here, brown is Line (Hot), blue is Neutral, and green/yellow is Earth. Unlike the NEC, which permits bare copper for grounding in flexible cords, IEC standards strictly mandate the green/yellow bi-color stripe for the protective earth. If you are importing a 230V appliance with an IEC C13/C14 inlet, you will exclusively see these colors.
The Australia/New Zealand Anomaly
AS/NZS 3000 uses red for Active (Hot) and black for Neutral. This is a massive trap for North American electricians: in the US, black is hot and white is neutral. If you are wiring an Australian-exported appliance in a US shop, swapping the red and black based on US assumptions will reverse the polarity, leaving the appliance's internal switching on the neutral side and creating a severe shock hazard during maintenance.
Never assume wire colors on unbranded, imported, or salvaged power cords. Counterfeit cords frequently violate regional color standards. Always verify conductor identity with a multimeter before energizing the circuit.
The 'Rows People Get Wrong' and Faded Wire Recovery
Even experienced makers and electricians stumble on specific edge cases within the 3 wire power cord color code. Here are the most common failure points and how to resolve them.
Mistake 1: The 240V 'White Wire' Trap
Look at Row 4 in the table above. If you are wiring a 240V-only appliance (like a heavy-duty compressor or welder) using a 3-wire cord (Hot, Hot, Ground), there is no neutral. In North America, if you use a standard 3-conductor cable (Black, White, Bare), the white wire must be re-identified as a hot conductor using black or red electrical tape at both terminations. Leaving it white implies it is a neutral, which will confuse future troubleshooters and violate NEC 200.7(C).
Mistake 2: Old UK vs. New EU Harmonization
If you are working on vintage UK equipment (pre-2004), the colors were Red (Live), Black (Neutral), and Green (Earth). In 2004, the UK harmonized with the IEC (Brown, Blue, Green/Yellow). If you open an old British appliance and see a black wire, it is the neutral, not the hot. Swapping it with the new IEC brown wire will cause a dead short or reverse polarity.
Mistake 3: Swapping Neutral and Ground
The most dangerous error is connecting the white (neutral) wire to the green (ground) terminal on a plug. While the appliance might turn on, this creates a parallel neutral path through the grounding system. It will immediately trip a GFCI/AFCI breaker, and if the ground wire breaks upstream, the appliance chassis will become energized at 120V.
Safe Interpretation for Faded or Missing Markings
Flexible cords (like SJT or SOOW) degrade. Heat and oil can turn a white neutral wire yellowish-brown, or a green ground wire black. OSHA electrical safety guidelines dictate that you must never guess conductor identity based on faded insulation.
- De-energize the cord completely. Unplug it from the wall.
- Set your multimeter to Continuity/Ohms (the setting that beeps when probes touch).
- Identify the Ground: Place one probe on the exposed copper of the suspected ground wire and the other probe on the round, U-shaped ground pin of the plug. A reading of less than 1.0 ohm confirms the ground.
- Identify the Hot and Neutral: Place a probe on the flat, narrow blade (Hot) of the plug and test the remaining two wires. The one that shows continuity (< 1.0 ohm) is your Line/Hot. The remaining wire is your Neutral (which will show continuity to the wide blade).
- Mark them immediately with colored heat shrink or vinyl tape before making your terminations.
Pinout and Terminal Mapping for 3-Prong Plugs
Knowing the wire colors is only half the job; you must map them to the correct physical terminals on your replacement plug or appliance inlet.
North American NEMA 5-15P (Standard 120V 15A Plug)
- Brass (Gold) Screw: Connects to the Black (Hot) wire. This aligns with the narrow blade on the plug face.
- Silver Screw: Connects to the White (Neutral) wire. This aligns with the wide blade on the plug face.
- Green Screw: Connects to the Green/Bare (Ground) wire. This aligns with the U-shaped pin.
Pro-Tip: When stripping an SJT cord for a NEMA plug, leave the green ground wire slightly longer than the hot and neutral wires. If the cord is yanked from the wall, the ground connection should be the last one to break.
IEC C13 / C14 Appliance Inlets (Computer/Server Power)
For the ubiquitous 'kettle lead' or computer power supply inlet (IEC 60320 C14):
- Pin 1 (Left, looking at pins): Neutral (Blue / White)
- Pin 2 (Center, protruding): Earth/Ground (Green-Yellow / Green)
- Pin 3 (Right, looking at pins): Line/Hot (Brown / Black)
Always verify the pinout stamped into the plastic of the specific IEC inlet you are using, as some high-current variants (like the C19/C20) rearrange the physical orientation of the ground pin to prevent mating with lower-amperage cords.
