Is the Black Wire Positive or Negative?

Maintaining a proper wire color code system ensures safety and ease of wiring. Sometimes it can prevent a fatal accident. Or sometimes, it can help keep you safe during a project. That is why today, we choose a simple topic that has two answers. Is the black wire positive or negative?

In general, the polarity of a black wire depends on the circuit type. If you are using a DC circuit, the red wire is for the positive current, and the black wire is for the negative current. The ground wire should be white or grey, given that the circuit has a ground connection. In an AC circuit, the black wire is positive, and the white wire is negative. The ground wire is green.

The Straight Answer

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If you are still confused about the polarity of the black wire, here is a simple explanation. In DC circuits, the black wire represents the negative wire. In AC circuits, black wire represents the positive wire. So, it is important to determine the circuit system before determining the polarity of the black wire. However, most people get confused quickly. It can lead to electrocution or damaged electrical devices.

Various Types of Wire Color Codes

Depending on the circuit types, you might encounter several different wire color codes. Identifying these wire color codes will benefit you in many ways. Most importantly, it will ensure safety. Here, I’m hoping to discuss DC and AC wire color codes.

Wire Color Codes for DC Power

DC, aka Direct Current, travels in a straight line. However, DC power cannot travel a long distance like AC power. Batteries, fuel cells, and solar cells are the most common sources that use DC power. Also, you can use a rectifier to convert AC to DC power.

Here are the wire color codes for DC power.

The red wire is for the positive current.

The black wire is for the negative current.

If the DC circuit has a ground wire, it should be white or gray.

insulated red and black wire with coil stripped at the tips
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Keep in mind: Most often, DC circuits have three wires. But, sometimes, you’ll only get two wires. The missing wire is the ground connection.

Wire Color Codes for AC Power

AC, aka Alternating Current, is commonly used in homes and businesses. AC power can change its direction from time to time. We can label the AC as a sinusoidal wave. Because of the waveform, the AC power can travel further than DC power.

With different voltages, the AC power type will vary. For instance, the most common voltage types are 120V, 208V, and 240V. These different voltages come with multiple phases. For this post, we are going to talk about three-phase power.

Three-Phase Power

Three-phase power wires
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This AC power type has three hot wires, one neutral wire, and one ground wire. Because power comes from three different wires, this three-phase system can supply more power with excellent efficiency. (1)

Here are the wire color codes for AC power.

The Phase 1 wire should be black, and this is the black hot wire that we mentioned earlier in the article.

The Phase 2 wire should be red.

The Phase 3 wire should be blue.

The white wire is the neutral wire.

The ground wire should be green or green with yellow stripes.

Keep in mind: The black, red, and blue wires are hot wires in a three-phase connection. However, in a single-phase connection, you can only find four wires; red, black, white, and green.

Wrapping Up

According to the National Electrical Code (NEC), the above wire color codes are the standards for electrical wiring in the US. So, follow those guidelines whenever you are doing a wiring project. It will keep you and your home safe. (2)

Take a look at some of our related articles below.

(1) excellent efficiency –
(2) NEC –

Video References



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About Sam Orlovsky

b1d87d2ee85af3e51479df87928bdc88?s=90&d=mm&r=gCertifications: B.E.E.
Education: University Of Denver - Electric Engineering
Lives In: Denver Colorado

Electrical engineering is my passion, and I’ve been in the industry for over 20 years. This gives me a unique ability to give you expert home improvement and DIY recommendations. I’m not only an electrician, but I also like machinery and anything to do with carpentry. One of my career paths started as a general handyman, so I also have a lot of experience with home improvement I love to share.

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