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Is it red to red and black to black?

Is it red to red and black to black?

The colors red and black have been associated with electrical wiring for decades. The common mnemonic phrase “red to red, black to black” refers to the standard color coding used for electrical connectors, specifically when connecting a car battery or installing electrical appliances. But why are red and black the chosen colors for positive and negative wires respectively? And is it always red to red and black to black when dealing with electrical work? Let’s take a closer look at the history and purpose behind this color coding system.

Purpose of Color Coding Wires

The primary reason for color coding electrical wires is safety. Distinguishing between wires with different colors allows for quick identification and prevents dangerous mix-ups. Red wire is universally used to denote the positive side, while black is used for the negative. This color scheme enables anyone working on electrical systems to instantly recognize which wire they are handling. Pairing the same colors together (red to red, black to black) maintains a consistent system that minimizes wiring errors.

Additional colors like green, white, and blue are sometimes used as well in advanced systems. But red and black remain the standard for basic positive and negative connections. There is no technical reason why red and black were originally chosen over other colors. However, the high contrast between these two hues undoubtedly helps with fast visual identification in complex wire configurations.

When the Mnemonic Applies

The “red to red, black to black” rule specifically applies when:

Connecting a car battery Attaching the positive and negative battery cables to the corresponding terminals on the battery
Jumping a car battery Connecting jumper cables from a running car’s battery to the dead battery
Installing new light fixtures and appliances Attaching the power supply wires, often with wire nuts or terminal screws
Connecting solar panels and generators Attaching the outgoing positive and negative wires to each other when wiring in parallel

So whenever you are handling exposed positive and negative wires, it is critical to follow the “red to red, black to black” rule. This ensures the proper flow of electricity through the system. Making incorrect connections can result in short circuits, damaged equipment, or even electrical fires and shock hazards.

Exceptions to the Rule

While using red for positive and black for negative is the standard in most electrical systems, there are some exceptions:

DC power connectors – Some DC power connectors like barrel plugs have the center positive and outer sleeve negative, opposite of the red/black coding.

Bare copper grounding wires – These have no insulation and are not red or black. They connect to earth ground.

Older wires – In antique lighting systems, the color coding may not follow modern conventions.

Low voltage wiring – Doorbells, thermostats, alarm systems may have unconventional color schemes since they are low voltage.

European wiring – Europeans sometimes use brown for hot and blue for neutral wires.

Temporary connections – When jump starting a car, if the battery cables don’t follow red/black coding you need to check polarity first.

So there are certainly exceptions to the general “red to red, black to black” directive. One should always verify wiring colors and polarity before making connections, especially in unfamiliar systems. Safety remains the priority.

Verifying Connections

To avoid any doubt about proper wiring, there are a few methods to double check connections:

– Use a multimeter to test for voltage and confirm positive and negative terminals.

– If available, consult wiring diagrams to match up colors and polarity.

– Trace wires back to their sources if necessary to identify their purpose.

– Refer to any labels on wires, connectors, or equipment.

– When in doubt, seek assistance from a qualified electrician.

Taking these extra steps verifies that “red to red” and “black to black” is correct before making the final connections.


While the “red to red, black to black” mnemonic provides a helpful rule of thumb when dealing with electrical wiring, it does have exceptions. The key points to remember are:

– Red and black are the standard colors denoting positive and negative respectively.

– This color coding enables quick identification and safety when making connections.

– Polarity and wire colors should always be verified before connecting.

– There are some cases where wiring does not follow the red/black scheme.

– When unsure, use a multimeter, wiring diagram, labels, and qualified help to confirm.

With safety as the number one priority, taking the extra time to double check connections helps avoid polarity mistakes even when the wiring colors deviate from the norm. While “red to red, black to black” is a handy guideline, making sure of the actual positive and negative wires is the key to preventing electrical mishaps. Proper wiring is about more than just wire color.

How to Remember the Mnemonic

Here are some tips to help remember the “red to red, black to black” mnemonic:

– Imagine the red wires kissing each other and the black wires kissing when connected.

– Associate red with “hot” and black with “ground” as a memory cue.

– Chant or sing the phrase repeatedly when working with wires to cement it in memory.

– Visualize red berries and blackberries when seeing red and black wires.

– Use mnemonic devices like “roses are red, licorice is black” to link the colors.

– Draw the wires together with red and black markers while repeating the phrase.

– Quiz yourself by looking away from a wire configuration and then saying the phrase.

– Explain the meaning of the mnemonic to someone else to reinforce it.

– Post sticky note reminders about the phrase on your electrical box.

Turning the phrase into songs, chants, visualizations, or physical movements can help boost retention and recall. With practice, the pattern of “red to red, black to black” when connecting positive and negative wires will become second nature. This assists in safely completing electrical work.


In summary, the mnemonic phrase “red to red, black to black” refers to the standard practice of connecting red wires to other red positive wires, and black wires to other black negative wires. This color coding system enables quick visual identification of polarity to prevent dangerous wiring mix-ups. While red and black are the most common Scheme, exceptions exist in certain types of connections and non-standard applications. It remains critical to always verify that red is positive and black is negative before completing the circuit. With electrical work, safety should be the top concern. Memorizing and applying the “red to red, black to black” directive helps reinforce proper wiring technique as long as precautions are taken to confirm polarity first. Pausing an extra moment to check connections, consult diagrams, and utilize testing equipment can prevent shocks, fires, or gear damage. For both novice DIYers and experienced electricians, diligently adhering to wiring fundamentals – including color-coding – makes electrical work safer and more efficient.