Editing Electronic color code (section)

==Wire==

===Transformer===
Power [[transformer]]s used in North American vacuum-tube equipment were often color-coded to identify the leads. Black was the primary connection, red secondary for the B+ (plate voltage), red with a yellow tracer was the [[center tap]] for the B+ full-wave rectifier winding, green or brown was the heater voltage for all tubes, yellow was the filament voltage for the rectifier tube (often a different voltage than other tube heaters). Two wires of each color were provided for each circuit, and phasing was not identified by the color code.

Audio transformers for vacuum tube equipment were coded blue for the finishing lead of the primary, red for the B+ lead of the primary, brown for a primary center tap, green for the finishing lead of the secondary, black for grid lead of the secondary, and yellow for a tapped secondary. Each lead had a different color since relative polarity or phase was more important for these transformers. Intermediate-frequency tuned transformers were coded blue and red for the primary and green and black for the secondary.<ref name="ARRL77"/>

===Other===
Wires may be color-coded to identify their function, voltage class, polarity, phase or to identify the circuit in which they are used. The insulation of the wire may be solidly colored, or where more combinations are needed, one or two tracer stripes may be added. Some wiring color codes are set by national regulations, but often a color code is specific to a manufacturer or industry.

[[Building wiring]] under the US [[National Electrical Code]] and the [[Canadian Electrical Code]] is identified by colors to show energized, neutral, and grounding conductors, and to identify phases. Other color codes are used in the UK and other areas to identify building wiring or flexible cable wiring.

Mains electrical wiring, both in a building and on equipment, was once usually red for live, black for neutral, and green for earth, but this was changed as it was a hazard for color-blind people, who might confuse red and green; different countries use different conventions. Red and black are frequently used for positive and negative of battery or other single-voltage DC wiring.

[[Thermocouple]] wires and extension cables are identified by color code for the type of thermocouple; interchanging thermocouples with unsuitable extension wires destroys the accuracy of the measurement.

Automotive wiring is color-coded but standards vary by manufacturer; differing [[SAE International|SAE]] and [[DIN]] standards exist.

Modern [[personal computer]] peripheral cables and connectors are [[PC connector colors|color-coded]] to simplify connection of speakers, microphones, mice, keyboards and other peripherals, usually according to coloring schemes following recommendations such as [[PC System Design Guide]], [[PoweredUSB]], [[ATX]], etc.

A common convention for wiring systems in industrial buildings is: black jacket – AC less than {{val|1000|u=volts|fmt=commas}}, blue jacket – DC or communications, orange jacket – medium voltage {{val|2300|fmt=commas}} or {{val|4160|u=V|fmt=commas}}, red jacket {{val|13800|u=V|fmt=commas}} or higher. Red-jacketed cable is also used for relatively low-voltage [[fire alarm]] wiring, but has a much different appearance.

Local area network cables may also have non-standardised jacket colors identifying, for example, process control network vs. office automation networks, or to identify redundant network connections, but these codes vary by organization and facility.