House Wire Color Code

House Wiring Color Code

When wiring a house, there are many types wire to choose from, some copper, others aluminum, some rated for outdoors, others indoors. In general however, there are only a couple varieties used for wiring a residential home

How Wires Are Sized

Wire is sized by the American Wire Gauge (AWG) system. Wire gauge refers the physical size of the wire, rated with a numerical designation that runs opposite to the diameter of the conductors—in words, the smaller the wire gauge number, the larger the wire diameter. Common sizes include 14-, 12-, 10-, 8-, 6-, and 2-gauge wire. The size of the wire dictates how much current can safely pass through the wire.

Electrical current is measured in ampacity, and each wire gauge has a maximum safe carrying capacity. For standard non-metallic (NM) cable, these amperage capacities are:

Amperage Capacities for Standard Non-Metallic (NM) Cable

14-gauge wire 15 amps White
12-gauge wire 20 amps Yellow
10-gauge wire 30 amps Orange
8-gauge wire 45 amps Black
6-gauge wire 60 amps Black
4-gauge wire 70 amps Black
3-gauge wire 85 amps Black
2-gauge wire 95 amps Black

These ratings are for standard copper NM sheathed cable, but there are instances where these amperage ratings vary. For example, there is aluminum wiring in some homes, and aluminum wires have their own ampacity-carrying capacity. Aluminum wiring was once widely used, but because it was found that aluminum had a greater expansion profile under load, it often loosened wire connections and sometimes caused electrical fires. That is not to say you are necessarily at risk just because you have aluminum wiring, because those connections may work forever if not overloaded. But an evaluation and replacement with copper wiring may be a good idea.

Shown to the right - [Fig. 1] is your standard 12g - 20A house wire. Note: the color is white. This is the old color, although you might find some places still carrying it. The new color for 12g is yellow.

Types Of Wire

Solid
Stranded
Copper
Aluminum
Romex
UF
AC or BX
Metal Clad
Cat 5,6, 6e
Coaxial: RG59, RG6, RG6-Q
Audio
Video

Although THHN is primarily used for commercial or industrial this can also be used for residential. The letters below are substituted for the last letter above. This describes the type of wire:

T – Thermoplastic insulation
H – Heat resistance
HH – High heat resistance up to 194 degrees Fahrenheit
W – Rated for wet locations
N – Nylon-coated to resist damage from oil or gasoline

Outer Sheath Color Coding - [Fig. 5]

The color of the outer sheath tells you the gauge of the wire inside as well as the current rating for the circuit.

WHITE = 14g wire - 15A Circuit
YELLOW = 12g wire - 20A Circuit
ORANGE = 10g wire - 30A Circuit
BLACK = 8g or 6g wire - 45A or 60A Circuit - Check sheath for labeling for rating
GRAY = Underground Cable. Check sheath labeling for rating

Romex 12-2 and 12-3 Wire [Fig. 1]

Solid Vs. Stranded Wire [Fig. 2]

Aluminum Service Wire [Fig. 3]

Copper Service Wire [Fig. 4]

Wire Types From 14g - UF [Fig. 5]

HOW TO FACTS AND INFO

HOUSE WIRE COLOR CODES

House Wiring Color Code

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