Wire Color Conventions
The one-line answers: DC systems are red (positive) and black (negative). US AC is black/red/blue for hots, white for neutral, green for ground — and 480V three-phase runs brown, orange, yellow. Those conventions carry real safety weight, and they also lie to you in exactly the places people get hurt: old buildings, vehicle harnesses, and DIY conversions. The codes first, then the caveats.
DC color conventions (12V, 24V, 48V)
Red is positive, black is negative. Vehicles, boats, RVs, solar, battery banks — the convention holds across all of them. Marine practice (ABYC) adds a wrinkle worth knowing: yellow is preferred for DC negative on boats so black can't be confused with AC hot in the same chase. In a camper van carrying both 12V and shore-power AC in the same walls, that confusion is precisely the danger the conventions exist to prevent.
US AC color codes — 120/240V and 480V
Residential and light commercial (120/208/240V): black first hot, red second, blue third; white neutral; green or bare ground. Higher-voltage commercial (277/480V): brown, orange, yellow phases with a gray neutral. The caveat that keeps electricians alive: color is a convention, not a guarantee — decades of renovations, re-tapes, and shortcuts mean the meter, not the jacket color, is the final word. Test before you touch.
Automotive wiring: the code that isn't
Vehicle harnesses follow each manufacturer's scheme, not a universal standard. Red or yellow usually means battery or accessory power and black usually means ground — usually. The only trustworthy reference is the wiring diagram for your exact model year, and the only trustworthy verification is a multimeter. This matters in conversions because house-system wiring has to tap vehicle circuits (ignition sensing, alternator charging) without disturbing the chassis harness — the most expensive wiring mistakes we repair started as a confident guess about a wire color.
How a professional van build wires it
Consistent DC colors (red/black), proper AC colors on the shore-power side, every circuit fused at the source, conductors sized to load with real crimps — and labels at both ends of every wire, because colors run out long before circuits do. That documentation is what makes the system serviceable by any competent shop later, and it is standard in every power and electrical system we build. If you are planning the electrical side of a build — battery bank, inverter, solar, shore power — start there, or see how the electrical package fits the whole van in our interior packages.
Frequently asked questions
What are the color conventions for DC systems?
Red and black: red is positive (+), black is negative (−). That is the standard for 12V/24V/48V DC in vehicles, boats, RVs, and solar. In some fixed DC installations under NEC practice you may also see white used as the grounded conductor, but red-positive/black-negative is the convention DC questions are asking for.
What is the 480V wire color code?
In the US, 480/277V three-phase commonly uses brown, orange, and yellow for the three phases, gray for the neutral, and green (or green/yellow) for ground. The lower-voltage 208/120V counterpart uses black, red, blue with a white neutral.
What are American automotive wiring colors?
Automotive harnesses do NOT follow one universal code: red or yellow typically feed battery/accessory power, black is usually ground (but not always — some grounds are brown or body-colored). The only trustworthy source is the vehicle’s wiring diagram; verify with a meter before cutting anything.
Do camper van conversions follow a wiring color standard?
Professional builds do: red/black (or red/yellow per ABYC marine practice for DC negative) on the 12V side, US AC colors (black hot, white neutral, green ground) on the shore-power side, every circuit fused at the source, and every conductor labeled at both ends. The label matters more than the color — colors run out long before circuits do.