Few concerns when building or remodeling a home are as critical as home wiring safety. A professional electrician is required when any type of electrical work is done but it can be helpful and interesting to homeowners to understand the principle of electrical wire color codes.
Following is an outline to help you understand the tangle of wires inside your electrical box and the ones that snake their way through your home’s walls. Each has a specific industry standard use, so that any electrician working on a system at a later date can understand the setup at a glance, can safely make repairs, changes or additions.
Here’s another reminder, though (we can’t stress it often enough): It’s great to be able to understand what the color of each wire means, but it’s never ok to try to tackle a wiring project on your own. It’s not only illegal, it’s extremely dangerous. Professional electrical contractors are here for your protection.
Basic Principles of Electrical Cables
Non-metallic electrical cable that carries 120 or 240 volts comes in two main parts. The outer plastic sheathing (jacket) binds the inner color-coded wires together. Markings on the outside of the sheathing tell how many wires, (and what size gauge of wire) are contained within the sheathing. The color of the sheathing indicates its recommended usages.
White sheathing shows the inner wires are 14 gauge.
Yellow sheathing contains wires that are 12 gauge.
Who Determines Wire Colors?
The National Electrical Code (NEC) dictates that white or gray wire be used for neutral conductors, bare copper or green wire for ground wires. General industry accepted wire colors are used for remaining purposes.
Wire Colors That are Always Hot
A hot wire is one that carries power from the service panel to a destination where it will be utilized such as an outlet or light.
Black wire is always used for hot wires. Most standard household circuit wiring is contained within black insulation. Black wire is never permitted to be used as a neutral or ground wire.
Black insulation is always used for hot wires and is common in most standard household circuits.
Red wires are always used to designate hot circuits. They are sometimes used as the second hot wire when 240 volt service is installed. They can also be used for interconnected items, such as alarms, so that if one is triggered, all identical alarms activate simultaneously.
White Wires With Black or Red Tape
Typically, when a white wire is used as a hot wire, it bears a band of black or red electrical tape wrapped around its insulation (other colors may be used in some cases). A white wire may be used for the second hot wire on a 240-volt appliance hookup or household circuit leading to an outlet or light. The white wire should be looped several times with black electrical tape to alert future electricians working on the system that it is not being used for a neutral application.
Wire Colors That are Sometimes Hot
Blue and yellow wires are sometimes used as hot wires inside conduit or for three or four way switches.
Wire Colors for Neutral Uses
White or gray indicates a neutral wire unless it has been wrapped in electrical tape. If it is wrapped in electrical tape, the wire is hot. Old wiring has sometimes lost its tape wrapping, so check for loose tape that has been detached to try to make certain if the wire is hot or not.
Remember, though, to never touch any wire. Neutral does not mean a wire is not carrying power. Neutral wires carry power back to the electrical box (service panel). A neutral wire could give you an unexpected shock.
Ground Wire Colors
Grounding gives electricity a safe pathway in case of a fault. Every electrical device must be grounded. Grounding takes the current to the ground (earth). Bare copper wires attach to electrical devices like switches, outlets, metal appliance frames. Metal electrical boxes must be grounded as they are made of conductive material, but plastic boxes are nonconductive so don’t require grounding.
This type of wire is the type most commonly used for grounding.
Wire with green outer insulation (sheathing) is sometimes used for grounding. Green wire should never be used for any other purpose.
Need help making certain your wiring system is safe? Planning a building or remodeling project? Be certain to obtain the help of a professional electrician like Wiring Pros LLC. Contact us today for a free quote.