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IN THIS ARTICLE
1Wire Colors for DC Power
2Wire Colors for AC Power
3Speaker Wiring
4Appliance Plugs or Power Cords
5Extension Cords
6Testing with a Multimeter
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Co-authored byRicardo Mitchelland Amber Crain
Last Updated: October 25, 2022References
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When you're dealing with electrical wiring, it's important to know which is positive and which is negative—but how are you supposed to tell them apart? The easiest way to tell is by looking at the color, but the colors mean different things depending on what kind of power is being used. Don't worry, it's not as confusing as it sounds! We're going to explain everything you need to know so you can correctly identify positive and negative electrical wires no matter what you're working on.
Things You Should Know
- For DC power, the red wire is positive and the black wire is negative.
- For AC power, the black wire is the phase 1 hot wire, which means it's positive. The red wire is a phase 2 hot wire, and the white wire is neutral.
- For exposed wire, the copper strands are positive and the silver are neutral.
1
Wire Colors for DC Power
- (Video) How to find positive and negative wires || The Insider
DC (direct current) powered devices usually have 2-3 electrical wires. DC power is common in batteries, solar cells, fuel cells, and small electronics. It’s called “direct current” because the electrical current only flows in 1 direction.[1] Here’s how to tell the wire colors apart:
- The red wire is positive.
- The black wire is negative.
- The white wire (if present) is ground (sometimes called neutral in DC).
- If both wires are black but one has a white stripe, the striped wire is negative, while the plain black wire is positive.
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2
Wire Colors for AC Power
AC (alternating current) power usually has 3 or more electrical wires. AC power is what comes out of power outlets and ceiling light fixtures in standard home and office settings in the United States.[2] Typically, AC power handles currents of 120, 208, or 240 volts.[3] This type of wiring has multiple phases in place, but here's what you need to know:
- The black wire is a phase 1 “hot” wire, which means it’s a positive or live wire. This wire usually runs to the electrical outlet from the switch.
- The red wire is a phase 2 “hot” wire, which means it’s also a live or positive wire (but the black is the primary positive wire).
- The blue wire (if present) is a phase 3 “hot” wire.
- The white wire is neutral. Neutral is distinct from ground in AC wiring.[4]
- The green wire (if present) is the ground wire.
3
Speaker Wiring
The copper wire is the positive wire in a speaker. On a standard wire used for things like speakers and amps, the silver strand is the negative wire and the copper-colored strand is the positive wire. These wires are often held together by a clear casing, but you can see through that (or look at the exposed wiring on the end).[5]
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4
Appliance Plugs or Power Cords
Power cords have hot and neutral wires rather than positive or negative. You don’t necessarily have to inspect the wire colors to tell these apart. For modern 2-strand appliance cords with 2-prong plugs, the longer prong connects to the neutral wire.[6] If you're looking at exposed wires:
- The neutral wire is identified by a white stripe, ribbing or white insulation.
- The hot (live) wire has no ribbing or stripe; it may have black or red insulation.
- If the cord has a green wire (rare), it’s a ground wire.
5
Extension Cords
For extension cords, the ribbed wire is usually the negative wire. If you have a wire where both sides are the same color, which is typically copper, the strand that has a grooved texture is the negative wire. Run your fingers along the wire to determine which side has the ribbing.[7]
- The smooth wire is the positive wire.
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6
Testing with a Multimeter
If all else fails, use a digital multimeter to figure out which wire is which. The multimeter will have 2 leads with small alligator clips on the end. Attach 1 lead to each wire. Clip the small alligator clip on the red lead to the end of 1 wire and the clip on the black lead to the end of the other. Look at the reading on the screen—you'll see a number and either a + or – sign.[8]
- The number is the voltage reading.
- The + indicates positive current.
- The – indicates negative current.
Expert Q&A
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Question
If two wires are black, how can I tell which is negative and which is positive?
Ricardo Mitchell
Electrician & Construction Professional, CN CoterieRicardo Mitchell is the CEO of CN Coterie, a fully licensed and insured Lead EPA (Environmental Protection Agency) Certified construction company located in Manhattan, New York. CN Coterie specializes in full home renovation, electrical, plumbing, carpentry, cabinetry, furniture restoration, OATH/ECB (Office of Administrative Trials and Hearings/Environmental Control Board) violations removal, and DOB (Department of Buildings) violations removal. Ricardo has over 10 years of electrical and construction experience and his partners have over 30 years of relevant experience.
Use a multimeter to test each one. Put the red side on the terminal to one black wire and the black side of the terminal to the other wire. If the tester shows voltage, the wire touching the red terminal is the one that has power.
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Warnings
The electrical wiring colors and standards in this article are for the United States. Colors and standards vary in other countries.
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Live wires are dangerous. It's best to shut down the circuit breaker or power down/unplug devices before touching the wiring to prevent electrical shock.[9]
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References
- ↑ https://www.creativesafetysupply.com/articles/wire-color-codes/
- ↑ https://www.power-and-beyond.com/whats-the-difference-between-ac-and-dc-power-a-915187/
- ↑ https://www.creativesafetysupply.com/articles/wire-color-codes/
- ↑ https://www.creativesafetysupply.com/articles/neutral-wire-color/
- ↑ https://www.allaboutcircuits.com/textbook/reference/chpt-2/wiring-color-codes-infographic/
- ↑ https://sciencing.com/pin-plug-work-4571446.html
- ↑ https://inspectapedia.com/electric/Electrical-Wall-Plug-Wire-ID-Connections.php
- ↑ https://www.youtube.com/watch?v=xoUHbf_bRxw&t=58s
- ↑ https://www.cpsc.gov/s3fs-public/518.pdf
About This Article
This article was co-authored by Ricardo Mitchell and by wikiHow staff writer, Amber Crain. Ricardo Mitchell is the CEO of CN Coterie, a fully licensed and insured Lead EPA (Environmental Protection Agency) Certified construction company located in Manhattan, New York. CN Coterie specializes in full home renovation, electrical, plumbing, carpentry, cabinetry, furniture restoration, OATH/ECB (Office of Administrative Trials and Hearings/Environmental Control Board) violations removal, and DOB (Department of Buildings) violations removal. Ricardo has over 10 years of electrical and construction experience and his partners have over 30 years of relevant experience. This article has been viewed 905,843 times.
54 votes - 69%
Co-authors: 9
Updated: October 25, 2022
Views:905,843
Categories: Electrical Wiring and Safety Switches
Article SummaryX
If you want to identify positive and negative wires, keep in mind that appliance plugs have hot wires and neutral sites, rather than positive and negative sides. However, if you're using an extension cord, the positive wire will be the smooth one, while the negative wire will have a ribbed or grooved texture. To find the right wires on a speaker, check to see which colors you have. For example, negative silver wires are paired with positive gold wires. Alternatively, if you have a black wire, it'll be negative if the other wire is red, or positive if the other wire is striped. For more tips, like how to use a digital multimeter to identify positive and negative wires, scroll down!
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中文:分辨正极引线和负极引线
العربية:تحديد الأسلاك الموجب والسالب
Bahasa Indonesia:Mengidentifikasi Kabel Positif dan Negatif
Nederlands:Positieve en negatieve draden identificeren
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FAQs
How do you know which wire is positive and negative DC? ›
In the world of DC electronics, the accepted wiring convention is that the red wire carries the positive voltage, and the black is circuit ground. Usually the red is marked as + (plus) and the black is marked as – (minus). Notice that in both AC electricity and DC electronics, there is a black wire.
How do I tell which wire is positive? ›The positive wire, also commonly called the hot wire, will typically be black in color. It is the source of the electricity. The electrical current travels from the outlet or other power source on the positive wire, so if it is plugged in anywhere, it should be considered a live (and dangerous) wire.
What color wire is negative and positive? ›| Function | label | Color |
|---|---|---|
| Positive | L+ | no recommendation (red) |
| Negative | L- | no recommendation (black) |
| 2-wire grounded DC Power System | ||
| Positive (of a negative grounded) circuit | L+ | red |
When wiring for DC power, there are typically going to be either two or three wires. The coloring is as follows: The positive current must be red. The negative current must be black.
Does DC have a positive and negative? ›The converse of Alternating Current, is Direct Current. DC refers to whenever the voltage isn't alternating between positive and negative, but stays either positive or negative, as shown in the first two graphs. Note that DC can be positive or negative.
How do you tell which wire is hot and which is not? ›The black wire is the "hot" wire, it carries the electricity from the breaker panel into the switch or light source. The white wire is the "neutral" wire, it takes any unused electricity and current and sends it back to the breaker panel.
Which cable is positive which cable is negative? ›Each battery has two metal terminals. One is marked positive (+), the other negative (-). There are also positive and negative cables in the jumper cable set. The red one is positive (+), the black one is negative (-).
How do I know if my wire is AC or DC? ›You may use an oscilloscope to determine whether a signal is AC or DC. If the output when the output wires are connected to the oscilloscope has a sinusoidal waveform, it is AC. An output of direct current (DC) is represented as a straight line.
Which is positive on DC cable? ›Usually* the wire with the white stripe or the dashed lines carries the "positive" (+) end, while the other, unmarked wire carries the "negative" (-) end.
Is DC current always positive? ›Direct Current (DC) always flows in the same direction, but it may increase and decrease. A DC voltage is always positive (or always negative), but it may increase and decrease.
Is white or black positive on DC? ›
If you encounter wiring from a DC power device, such as in solar cells or batteries, the colors of the sheath in the wires differ from AC wiring. Red: The red wire is positive. Black: The black wire is negative. White: The white wire is neutral or ground.
How can I tell which wire is hot without a multimeter? ›- Get a voltage detector screwdriver. ...
- Turn on the screwdriver by pressing the power button.
- Touch the probe of the screwdriver to the wire.
- If the detector lights up, then there is electricity running through the screwdriver.
A DC motor is a motor that runs using a DC power supply. As shown in the preceding picture, it has two terminal wires. We can call one of these terminal wire positive and the other one negative. Usually, these wires are marked red and black where red is positive and black is negative.
What happens if you wire DC backwards? ›Reversed polarity can damage or short-circuit your electronics, including TVs, radios, phones, and computers. Electronic equipment controls voltage in one direction; thus, the internal components can overheat or short-circuit when you reverse the electrical flow.
How can you tell if a cable is AC or DC? ›With AC current, as supply flows through the cables, the current's polarity (negative versus positive) changes, alternating as it flows in one direction, and then changing as it flows the other direction. DC current, however, does not change polarity.
How do you identify the terminals of a DC motor? ›DC motor terminal leads are labeled for easy identification in the motor's terminal box. For example, leads labeled "A1" and "A2" are connected to the armature through the motor's brushes; leads labeled "S1" and "S2" are the ends of the series field; and leads labeled "F1" and "F2" are the ends of the shunt field.
What direction does current go in a DC motor? ›Simply put, DC motors can turn in either direction (clockwise or counter-clockwise) and can be easily controlled by inverting the polarity of the applied voltage. Strictly speaking, the motors can actually create a force in either direction.
Is negative terminal on left or right? ›positive on left and negative on the right corner on the long side of the battery.