AC Wiring Color Codes Chart: NEC, IEC, and UK Standards Explained

In North America (NEC), standard 120V AC wiring uses Black for hot, White for neutral, and Bare/Green for ground. In Europe and regions following IEC 60446, the standard is Brown for live, Blue for neutral, and Green/Yellow for earth. If you are opening a panel or wiring a new branch circuit, guessing the color code is a fast track to a short circuit or a failed inspection. Below is the definitive reference to keep your wiring legal and safe.

AC Wiring Color Codes: The Master Reference Table

This table covers the primary single-phase and split-phase residential standards. Keep this bookmarked on your phone when you are on the jobsite or at the supply house.

Regional Variants: Which Standard Applies to Your Panel?

Wire colors are strictly governed by regional electrical codes. Applying the wrong regional standard in your home will result in an immediate fail from your local Authority Having Jurisdiction (AHJ).

• North America (NEC / CEC): Governed by the NFPA NEC guidelines (specifically Articles 200, 210, and 310). The US and Canada share nearly identical color codes for residential single-phase and split-phase systems. White and Grey are strictly reserved for grounded (neutral) conductors.
• Europe & International (IEC): Governed by IEC 60446. Most of the world, including Australia and New Zealand, uses the Brown/Blue/Green-Yellow scheme. If you are importing a European appliance or machine to the US, you must re-identify the internal wiring or use a properly configured transformer; you cannot simply wire IEC brown to a US white neutral.
• United Kingdom (Harmonization Shift): The UK harmonized its colors with the IEC in 2004. However, millions of UK homes still contain pre-2004 legacy wiring (Red=Live, Black=Neutral, Green=Earth). When extending a legacy UK circuit, you must use modern Brown/Blue wire but place a permanent warning label at the consumer unit stating that both old and new color codes are present.

The "Gotchas": Rows People Consistently Miswire

Even when you know the chart, real-world jobsite conditions introduce exceptions. Here are the most common code violations I see when tearing out DIY electrical work.

1. The Switch Loop "White Wire" Trap

In older homes (pre-NEC 2011), electricians often ran a 2-wire cable (Black and White) down to a light switch. The Black wire brought constant hot down to the switch, and the White wire was used to carry the switched hot back up to the light fixture.
The Rule: Per NEC 200.7(C)(1), if a white wire is used as an ungrounded (hot) conductor, it must be permanently re-identified with black tape or paint at both ends. If you see a white wire connected to the brass (hot) screw on a switch, do not assume it is a neutral.

2. The 240V "No Neutral" Misidentification

Older 240V appliances (like baseboard heaters or older AC compressors) only require two hots and a ground. Installers would sometimes use 2-wire NM-B (Black and White) to save money, using the White wire as the second hot leg (Line 2).
The Fix: If you are replacing an old 240V heater and find a white wire wire-nutted to a red or black pigtail, verify it with a meter before touching it. Modern code requires a dedicated 3-wire setup (Black/Red/White) for 240V circuits that also need 120V for control boards (like dryers and ranges).

3. Bonding Neutral and Ground Downstream

Because both the White (Neutral) and Bare (Ground) wires ultimately terminate at the same bus bar in the main service panel, DIYers often assume they are interchangeable. They are not.
The Rule: Per NEC 250.142, the neutral and ground buses must be bonded only at the main service disconnect. In any subpanel, downstream outlet, or junction box, the white neutral and bare ground must remain strictly isolated. Mixing them creates a parallel path for return current, energizing your grounding system and creating a severe shock hazard.

Faded, Missing, or Tape-Wrapped: How to Safely Identify Unknowns

If you are working in a house built between the 1930s and 1950s, you will likely encounter cloth-covered wiring. The white insulation degrades into a dirty brown or grey, making it visually identical to the black hot wire. Furthermore, you may open a junction box to find someone used red electrical tape to wrap a white wire, leaving you guessing.

Never trust visual identification on old or modified wiring. Use this exact bench-tested verification sequence:

1. Initial Sweep: Use a Non-Contact Voltage Tester (NCVT) to identify which wires are energized. The NCVT will beep on the Hot wire, but it can sometimes give false positives on neutral wires due to capacitive coupling.
2. Multimeter Verification (AC Volts, 200V+ range): Place your black probe on a known, verified ground (like a bare copper wire or a metal junction box that you have confirmed is grounded). Touch the red probe to the suspect wire.
   • Reads 114V - 126V (or 220V-240V in EU/UK): This is your Hot/Live conductor.
   • Reads 0V: This is either your Neutral or your Ground.
3. Distinguishing Neutral from Ground: If you have two wires reading 0V to ground, you must identify which is the neutral. Turn on the load (e.g., plug in a hair dryer or space heater to the circuit). Measure the voltage between the two 0V wires.
   • The Neutral carries return current and will exhibit a slight voltage drop due to wire resistance, typically reading 0.5V to 3.0V relative to true ground.
   • The Ground carries no current under normal operation and will read exactly 0.0V.

Decision Tree: Picking the Right Wire Color for Your Next Branch Circuit

Stop guessing at the hardware store. Use this decision matrix to select the exact cable type and color configuration for your next rough-in. All picks assume standard US/Canada NEC residential copper wiring in dry, indoor locations.

For deeper code references and international variations, consult the international wiring color standards database. Always verify your local AHJ amendments before pulling wire, as some municipalities strictly prohibit NM-B cable in certain commercial or multi-family dwelling applications, requiring you to pull individual THHN conductors in conduit instead.