4 Wire Cable4 wire cable may refer to a cable with 4 conductors or 4 current-carrying conductors. Our 4 wire cable has four conductors: 1 white (neutral), 1 black (hot), 1 red (hot), and 1 green (equipment ground), but only three carry current for the circuit. Please see our 3 wire cable page for an explanation of current-carrying conductors and color codes for multiconductor cables for an explanation of the purpose of conductor insulation colors. |
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Why Use 4 Wire Cable?
A very common application of 4 wire cable is to provide both line-to-line 240V and line-to-neutral 120V AC power to appliances such as electric dryers and stoves. This is because they have components that require more power (e.g. heating elements) as well as components that run on 120V AC circuits (e.g. digital timer, lights, etc.). The higher voltage (240 volts) reduces the conductor size required for components that would otherwise draw more current at 120V.
"Line-to-neutral" and "Line-to-line" Voltage
Voltage is the electromotive force that exists between two charged particles (i.e. electrons and protons) when they are separated. Voltage is what moves charged particles along a circuit in order to return to a state where the net charge is neutral.
Though not entirely accurate, for the purposes of this explanation it helps to think of voltage as a measure of height. Since height is a measurement of distance, when you measure the height of something you need two points of reference. Thus, I am 6 feet tall if I measure from the top of my head to the ground, but if I were to measure from the top of my head to say the center of the Earth the measurement would be different. Line-to-neutral and line-to-line voltages refer to different sets of reference points.
With line-to-neutral voltage you are measuring the voltage from one of the phases (i.e. “lines”) coming off of a step-down (voltage reduction) transformer and the connection to the earth ground at the transformer. With line-to-line voltage you are measure the voltage between any two phases, or lines, in a 3-phase power system.
What is the fourth wire used for?
If a single load appliance ONLY required 240 volts, then 3 wire cord with 2 hots and a ground would be fine. 4 wire cable with a neutral would not be needed, since there is only one load so there is no chance of imbalanced loads. The two hots (typically with black and red insulation) would conduct the 240 volt power, while the ground wire is required to ground the equipment for safety purposes.
However, since so many of today's electric stoves, dryers, ovens, and other large household appliances or industrial equipment come with smaller accessories, the fourth wire is used as a (common) neutral to provide the required 120V AC power.
Note that there is 240V AC between black and red (the two “hot” lines, with a range of plus or minus 12 volts). Both the white neutral and green equipment ground are 120V AC when referenced to either black or red. However, the white neutral (the circuit ground) provides 120V AC power to devices in addition to carrying the difference in current between imbalanced loads, while the ground carries no current under normal operating conditions.
Product Selection
View our full selection of 4 wire cable here.