Wire Code Identification Color – USA

NEC Wires’ Color Identifications

  • Neutral wire – White or grey color
  • The ground wire – green or green with yellow strips
  • Hot or live wire – black color
  • Second live or active wire – Red color

Any colors rather than those mentioned above can be helpful for other power lines. Thus, according to the local practice, the standard wiring color codes are divided into two main categories –

  1. USA wire color codes for A.C. and
  2. USA wire color codes for D.C.

Electrical Wiring Color Coding

Black wire

This wire is mainly utilized to transfer power to outlets and switches in all sorts of circuits. Black cables are often found as switch legs in circuits, building the connection to link a button to a load. Also, Black wires are live at all times.

The Red wire

known as secondary active wire in 220-volt circuits, just like black wires. And similarly, they are also used in some sorts of switch legs. For example, red wires can connect hardwired smoke detectors to the home’s power system. Two red wires or red wire to a black wire link is also possible.

Blue and yellow wire

These colors carry power as they are not used in the typical wiring of an outlet. Instead, they are used as live wires pulled via conduits such as switching legs to fans, outlets with light switches, and structural lights. Blue cables are often called travelers for three and four-way switches.

White and Gray wire

If you find grey and white colors, then these are neutral wires. White is mainly used, but gray also serves the same purpose. The purpose of the neutral wire is to make a connection to the neutral bus bar. Both cables can only be connected and carry a current even if they are neutral, especially if the current load is unbalanced.

Green wire

The use of green wire is to ground the electrical circuit connecting to the ground terminal in the outlet. The green wire acts as a failsafe wire, providing electricity a space to escape to the ground if any live wire in a circuit touches any metal or any conductive object.

Thus, you got a fair idea about what various colored wires do with this wire color coding guide.

What Are Wiring Color Codes?

Wiring color codes identify the type and purpose of electrical wires. It is also a part of standardization followed in many regions and countries for easy traceability and understanding.

The governing body finalizes the wiring colors with their particular functions. Thus, the significance of the given color of wire may vary in different countries. Here is a brief guide explaining different shades of cables used in the USA for common types of A.C.

When talking about wiring color coding, the first question that comes to your mind is: which colors indicate neutral, ground, and hot wires, right? However,

A Brief Overview of U.S. Electrical Wiring Codes

Apart from those mentioned above, primary wire color coding of neutral, ground, and active wires, the following colors are used for power wires in branch circuits.

120/208/240 Volt A.C. Wire Coding

Such systems are ubiquitous in houses and offices, so other than active, ground, and neutral-

  • Black color for phase 1
  • Red color for phase 2
  • Blue for phase 3

If the wiring system has any of the one phases at high voltage compared to others using high-leg connectivity, you must mark the wires of phases with orange according to the NEC article 110.15. But, such high-leg delta systems are not familiar with new installations there.

277/480 Volt A.C. Wiring Colors

These high voltage systems are quite common for equipment and industrial motors keeping black as active.

  • Brown color for phase 1
  • Orange color for phase 2
  • Gray for neutral
  • Green or green with yellow stripes or bare wire for the grounding

For such higher voltage conditions, it becomes essential to have a documented wire coding system. Detailed labels must have information such as circuit identification, disconnection point for a tag out, or locking out.

D.C. Power Wire Colors

When there is a use of solar power systems and any battery systems, it uses D.C. power. So, for D.C., standard colors of wires go like this-

  • Red color for positive
  • Black for negative
  • And white or gray color for ground

So here, every color with its significance is clear, but every color’s purpose and function is not.