How to Understand 120/240V Wiring Color Code

A non-double phase electricity service of 120/240V is made available to various homes in North America. The inbound power of 240V is divided into two branches. Either of the branch has the capability of providing 120V hot to neutral which makes it possible for the two branches to supply a combined power of 240V which is utilized for cook stoves and air conditioning compressors.


Each home has a circuit which is responsible for providing electricity for the lights, built-in appliances and receptacles. The circuits have wires and conductors which are grouped with respect to color, wiring type and size. The color of the wire’s insulation determines the work to be done by the wire. Proper knowledge of the message being communicated by these colors will greatly assist you in working safely and without stress whenever you are faced with the challenge of correcting an electrical fault or implementing enhancements or repairs in your electrical systems. You must also ensure that the connections are properly done and organized. For a wire to be used in the United States, the color must be in accordance with the National Electrical Code (NEC) requirements.

A Word of Warning: Consistently make use of a line voltage meter or circuit tester to find out whether a cable is “hot” or “live.” Never rely on the color of the wires alone.

Types of Wiring

Where you live determines if your home’s circuit wiring will be done with either individual conductors which passes via a hollow metal conduit or any of the three cable types. A wire is a factory product of an assembly of conductors in either a sheath or an outer coat. Plastic sheathed or The Type NM (NonMetallic) cable is extensively used for house wiring circuits. Modern Type NM cables have distinct color sheathing which signifies the size of the conductors: Yellow for 12 AWG conductors, White for 14AWG (American Wire Gauge) conductors, and Orange for 10 AWG conductors. The Type NM cable may also have a mark on the cable sheath of the cable. This indicates the size as well as the form of the conductors inside, also as well as other info “14-2/G,” for instance, reveals that that cable got two insulated, current-carrying conductors plus one grounding conductor, size 14 AWG.

Type MC (Metal Clad) and Type AC (Armor Clad) are the other two forms of cable which are always used in the extension of a system wired with metal conduit. Type MC and Type AC are sheathed in a metal coil which is flexible. Type AC cable, usually called BX, and doesn’t possess a grounding conductor. And also a thin aluminum bonding wire and the metal sheath all supply the path that is necessary. Type MC Cable has a grounding conductor. Recently, producers commenced the practice of spraying on color codes. The colored symbols matches with that of the conductors which conveys current in the cable.

Black and Red Wires

With regards to NEC’s requirement, an ungrounded conductor or hot cable must be made with a red or black wire must be utilized as hot cable or an ungrounded conductor. However, any color wire aside green, gray or white can be utilized in conduit for the carriage of ungrounded electricity power. Any wire which has any one of the colors cannot be used for creating and implementing a neutral or ground connection.

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These wires are utilized to link the second branch of the electrical system because a reddish colored wire additionally functions as an ungrounded conductor. A red wire can also be frequently utilized wire in a circuit that demands that, as an interconnection, or communicating, just like a smoke detector circuit.

Blue, Yellow, as well as Other Shades Colors

In electrical systems where wires, or individual conductors, are made to run via a hollow conduit, wires which are yellowish or blue, or any color except white, gray or green are occasionally installed to assign a particular use. For instance, if electricity must be run from a ceiling box all the way down to a box with three switches and then returned to the ceiling to power three distinct sets of lights, a black wire may be utilized to take the electricity down to the switches along with three wires with other colors. Say red, blue, and yellow–could be utilized to bring the power up from all the switches. That makes it easier to identify in a glimpse, which switch is used to control each set of lights.

White Wires

A white wire is usually utilized to serve a vital purpose; neutral or grounded conductors. For conductors, as little as those present in home leg circuits, a gray or white wire can only be utilized for that particular function.

Prior to now, a white wire was given a nod to be used in the converging of underground potential, which is to serve as a hot wire in either a switch branch or when initiating and implementing the connections of 3-way switches. This changed together with the adherence to the 2011 cycle of the NEC, which states the need for the existence of a grounded conductor in every switch box, to ease the setup of motion detectors, lighted switches, timers, and related energy-saving controls. In a new work, the white wire in a cable assembling is unable to be utilized to carry electricity that was ungrounded. Though, a homeowner might discover that this is the method that is used in the current setup because that change was just embraced in 2011. In those instances, the white cable needs to be marked with a permanent marker or any color besides green or gray or black or reddish electrical tape to reveal that it is carrying ungrounded potential and is used as a hot wire. However this is not consistently done, so be mindful of wires that are white in switch boxes. Since a neutral should never be changed, presume that any white cable which you discover is linked to a switch is a hot wire before you find out that it isn’t with a suitable meter.

The White Wire in a 240V Circuit

There is a situation where a white wire can be utilized in converging ungrounded potential which still abides with the latest cycle of the NEC. This is the time a cable can be used to feed a 240V load. When an appliance doesn’t want or use 120V power, but simply needs and uses 240V power, a typical 2-conductor cable, which has a bare, white and black pair of wires, can be utilized to link that appliance. If so, the black cable is connected to a terminal of the two-terminal 240V breaker in the panel. The white cable is reassigned as an ungrounded conductor through the use of black or reddish (or some color except gray or green) electrical tape or permanent marker, and linked to another terminal of the breaker, as well as the bare ground wire is connected to the ground bus. In the appliance end, the white wire is marked again as well as the two insulated cables are joined to the two input terminals for ungrounded power on the appliance, or on its disconnect switch, as well as the ground wire is joined to the framework of the appliance or the box the disconnect is in.

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This wiring system-two hots as well as a ground–was not unusual for a long time to provide most of the bigger appliances in our houses, so it’s nevertheless uncovered in place, and in service, now. Together with the increased usage of electronic and electric controls in several appliances, however, a four wire service including a neutral conductor will be demanded to get a fresh circuit. New cooking appliances like, Cook tops, Wall Ovens, and Ranges are being constructed to make use of that wiring. Thus are the electrical driers that are newer. They may, nevertheless, be effective at working with either kind of wiring. If you’re replacing drier or an older cooking appliance, the instructions may let you know which you are able to by replacing the cord link it to a current three-cable 240V circuit.

You can find 240V appliances that only require two hot wires and a ground. Compressors, or the outside condensing unit along with an electrical water heater, for central air conditioning, are two of those.

The key thing to remember here is a white wire in a 240V circuit may be carrying the power that is ungrounded. Also, it could not happen to be marked to demonstrate it is. Do not suppose that because it is not white; you cannot shock. Ensure you test it, to be safe

Green and Bare Wires

Wires with green colored insulating material and non-insulated wires are ground wires or equipment grounding conductors. The equipment grounding conductor, or EGC, is a significant improvement to residential wiring that became widely embraced in the 1970s. This different pair of conductors is linked straight to the ground. No electricity is carried by the EGC wiring whatsoever when everything is functioning normally. But when there is a fault, where it might damage an appliance or shock someone and ungrounded power is present, a correctly joined EGC supplies a low-resistance path to that electricity to earth. Because the electricity is looking to go back to its source, that route will be taken by it. This could trip a circuit breaker or blow a fuse; fire appliance damage or a shock to some human being is going to have been averted. For the EGC to work correctly, bare and green wires should be linked to any metal electrical box, and to devices like switches and receptacles.

Identify Electrical Wire Color Coding Video

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