Quick answer: Lighting wire colors depend on the country: according to Wikipedia’s North American wiring reference, hot wires commonly use black, red or other colors (black is the usual hot in NM cable), neutrals use white or gray, and grounds use green or bare wire. According to Wikipedia’s IEC color reference, the IEC convention uses brown for a single AC phase, blue for neutral and green/yellow for the protective conductor.
This guide covers color identification in lighting supply wiring, older UK installations and US lamp cords. It does not identify a particular circuit from a photograph. For mains wiring, use a qualified electrician to verify conductor functions with a tester; never rely on color alone. If you meant the color of the light itself, see the color temperature guide.
What do lighting wire colors mean in each country?
There is no universal color chart: wiring conventions vary by country and region, and national differences remain despite efforts to harmonize them. Start with the installation’s location before interpreting the insulation. Wikipedia: electrical wiring
The table separates the US convention from the IEC convention and older UK fixed wiring. According to the Wikipedia references linked in each row, the same color can have a different role across these schemes.
| Wiring context | Hot or live | Neutral | Ground or protective conductor |
|---|---|---|---|
| North American wiring (typical) | Often black or red; other phase colors are possible | Typically white or gray | Typically green or bare (North American wiring reference) |
| IEC preferred colors, single AC phase | Brown | Blue, preferably light blue | Green/yellow (IEC color reference) |
| Older UK fixed wiring | Red in the old red/black scheme | Black in the old red/black scheme | Earth green/yellow since 1976 and green before that, so the wiring’s age matters (UK wiring reference) |
Read the entire row rather than matching a color across rows. For example, according to Wikipedia’s North American wiring reference, blue can be a US phase-wire color, while according to Wikipedia’s IEC color reference, blue identifies neutral in the IEC scheme. A blue wire therefore cannot be interpreted without the installation context.
US lighting: black and red are common hot colors
According to Wikipedia’s North American wiring reference, phase wires may use colors other than green, gray or white; common choices include black, red, blue, brown, yellow and orange. This is why a chart that calls blue, brown and yellow “neutral colors” gives the wrong answer for US wiring.
Red is not a universal code for a switched live. The same reference lists red among common phase colors, without making it an exclusive switched-wire identifier. A red wire’s color alone does not establish whether it is switched or what it supplies. Wikipedia: North American wiring
Why a white wire may be hot
According to Wikipedia’s North American wiring reference, a white conductor can serve as hot in a switch loop and should then be re-identified, commonly with black tape. White insulation is therefore a usual neutral identifier with an important exception, rather than a guarantee of function.
For a conceptual example, suppose an existing switch cable contains a white conductor with black marking. That observation is consistent with the re-identification described by Wikipedia’s North American wiring reference. It does not supply enough information to decide which fixture terminal it belongs on. Treat this as an identification question, not a connection recipe.
IEC and UK lighting: wiring age changes the answer
According to Wikipedia’s IEC color reference, the preferred neutral color is blue, with light blue preferred, and green/yellow identifies the protective conductor. The same reference explicitly allows different neutral and protective-conductor colors in the United States, Canada and Japan: white or natural gray for neutral and green for protection. “International” does not mean identical everywhere.
For UK fixed wiring, the brown/blue scheme belongs to newer, post-2004 installations; older red/black wiring remains in existing buildings. The adoption of harmonized colors did not replace every older cable, so old and new schemes can coexist. Wikipedia: UK wiring and IEC color reference
That makes black a particularly poor color to interpret in isolation. According to Wikipedia’s UK wiring reference, black occurs as neutral in historical fixed wiring; according to Wikipedia’s North American wiring reference, black is a common US hot color. Applying a US chart to an older UK ceiling connection can reverse the intended interpretation.
US lamp cords: ribbed and smooth identify different conductors
According to Wikipedia’s North American wiring reference, a US lamp cord uses a ribbed conductor for neutral and a smooth conductor for hot. With transparent cord, the reference describes the hot conductor as copper-colored and the neutral as silver-colored.
These are lamp-cord identification conventions, a different context from the colored insulation in the supply-wiring table. According to that same North American wiring reference, the useful comparison is ribbed versus smooth, or silver-colored versus copper-colored for transparent cord. Do not transfer the cord convention to an unrelated cable just because its conductors look similar.
Checklist for interpreting a lighting-wire color chart
A useful chart must explain exceptions as well as typical colors. The white-wire switch-loop exception described by Wikipedia’s North American wiring reference is a practical test: a chart saying “white always means neutral” leaves out a relevant case.
Use this checklist when comparing a diagram or guide with an existing installation:
- Country: Does the guide explicitly name the jurisdiction or convention it describes?
- Wiring context: Does it distinguish fixed supply wiring from a lamp cord?
- Age: Does it account for older wiring where the color scheme changed?
- Exceptions: Does it discuss re-identified conductors rather than treating insulation as conclusive?
- Purpose: Is the question conductor identification, cable sizing or voltage drop?
Keep that last distinction clear when planning lighting. The wire gauge calculator and voltage drop calculator address sizing and voltage-drop questions. Neither calculation determines the function of an unidentified conductor, and this color guide supplies no cable-size recommendation.
FAQ
Is a red lighting wire always switched live?
No. According to Wikipedia’s North American wiring reference, red is a common phase-wire color, not an exclusive identifier for a switched live. The color alone does not establish the switching arrangement.
Can a white lighting wire be live?
Yes. According to Wikipedia’s North American wiring reference, a white wire can be used as hot in a switch loop and should be re-identified, commonly with black tape.
Is a blue wire neutral?
According to Wikipedia’s IEC color reference, blue is the preferred neutral color in the IEC scheme. According to Wikipedia’s North American wiring reference, blue is also a common US phase-wire color, so the country and scheme matter.
What color is the ground wire?
According to Wikipedia’s North American wiring reference, US grounding conductors are green or bare. According to Wikipedia’s IEC color reference, the protective conductor uses green/yellow in the IEC scheme.
Do current UK colors apply to an old house?
Not necessarily: older red/black fixed wiring can remain alongside the newer, post-2004 brown/blue scheme. The house’s age alone does not tell you which scheme is present at a particular light. Wikipedia: UK wiring
Which side of a US lamp cord is neutral?
According to Wikipedia’s North American wiring reference, the ribbed conductor is neutral and the smooth conductor is hot. For transparent cord, that reference identifies silver-colored as neutral and copper-colored as hot.
Jack Shi
Founder & editor, LEDaskJack Shi builds and writes LEDask, an independent LED-lighting tools project operated by clooms. He designs the calculators, checks their formulas and reference values against published engineering data, and writes the guides across the site.
