Understanding the basics can help guide copper cable selection
Whether you want to ensure proper handling, determine whether a cable will work in a specific environment or enable quick diagnosis and resolution of network issues, everyone involved in a technology project must understand how copper cables work.
Often, being familiar with their inner workings means going back to the basics—a fundamental step that informs smarter technology decisions, enables better copper cable selection and installation, and supports network resilience.
When I left the world of power distribution to join Belden a few years ago, I quickly realized that many industry professionals—regardless of experience level—had common questions that needed clear, accessible answers. (Admittedly, I sometimes had to do research before I could respond correctly.) I’m sharing those insights here to help others access the information they need.
Consider this your reference guide to mastering copper cable basics with confidence.
What’s the difference between a wire and a cable?
Wires and cables are closely related, but they aren’t the same—even though it’s not uncommon to hear industry professionals use one term when they should be using the other.
What’s the difference?
- Wire: a single conductor of electricity
- Cable: a bundle of wires that work together and are generally enclosed in the same jacket
How do copper cables work?
Copper cables rely on conductive metal materials to transmit data. Copper is used most often because of its excellent conductivity, durability and reliability.
There are two types of Ethernet cables (a form of copper cables) found in most network environments:
- Permanent link cables: fixed cables that run through ceilings or walls to form the network backbone. Most people never see or interact with these cables. In a 100 m channel, defined as the maximum allowable length for Ethernet cabling by TIA 568 standards, 90 m is dedicated to the permanent link.
- Patch cables: shorter cable lengths that are used to connect devices to jacks. The remaining 10 m of the 100 m channel length is allocated to patch cables. Most people do see and interact with these cables (to connect their computer to the network, for example).
What does gauge size mean?
Gauge size measures the diameter of electrical wires inside a cable. When it comes to copper cables, a large gauge numeral does not mean a large gauge size. For example, a 1 AWG or 2 AWG cable is large in diameter, while a 24 AWG or 26 AWG cable is small in diameter.
What’s inside a copper cable?
Once you understand how a copper cable is constructed, your copper cable selection will be more informed. You’ll also have a better understanding of where and how it can be used, as well as how it should be terminated and maintained.
Every copper cable is made up of:
- A conductor that transmits electrical current to allow data or power to flow from Point X to Point Y
- Insulation that protects the conductor and maintains signal quality
- A jacket that ensures durability and protects the components inside
Depending on copper cable selection, the cable may also include shielding, armor, a drain wire and/or a ground wire.
Conductor basics
Common copper cable types include coaxial cables (a single conductor surrounded by insulation, shielding and an external jacket, sometimes with duo or quad shields for added protection) and Category cables (four twisted wire pairs around a spline, which is surrounded by insulation, covered by a protective jacket and sometimes shielded or armored).
Insulation basics
Insulation keeps electrical current within the cable as it flows from one end to the other. It can be made from a thermoplastic material (PVC, FEP, LSZH, etc.) or a thermoset material (CPE, EPR, etc.) to maintain signal integrity and quality.
While cables with thermoplastic insulation are common in installations with moderate environmental demands, cables with thermoset insulation work well in harsh environments.
Jacket basics
The cable jacket is a determining factor in copper cable selection. It determines where the cable should be installed. As the only visible component of the cable, it surrounds the insulation to protect internal components from external threats like water, oil, harsh cleaners and even rodents.
In some cases, armor is used as another layer of protection over the jacket to guard against physical damage from crushing or abrasion.
What’s the difference between a plug, jack and coupler?
Jacks, couplers and plugs can be easy to mix up—even for those who have been in the industry for a while. Although they work together to enable connections, the terms aren’t interchangeable.
Here’s how these components are defined:
- Jacks: stationary connection points, such as Ethernet ports in patch panels or on walls, used to terminate a permanent link. The back of the jack is where wires from the permanent link are punched down (unless you’re using Belden’s REVConnect®) and terminated. Jacks are considered a female interface.
- Couplers: double-sided jacks that allow you to plug into both sides. Think of them as two back-to-back jacks.
- Plugs: connectors on cable ends that plug into jacks and couplers. By inserting a plug into the front of a jack, you create a connection. Plugs are considered a male interface.
Patch panels often act as centralized hubs where jacks, couplers and plugs connect. On the back of a patch panel, permanent cables are terminated into jacks. On the front of a patch panel, plugs connect to devices.
Making the right connections
While these questions may seem basic, they come up regularly in conversations about copper cable selection. Starting a project with this level of foundational knowledge not only builds trust and credibility but also ensures that you make the right connections every time.
Beyond understanding how copper cables function, it’s equally important for installers, technicians, owners and consultants to understand the project environment and specific requirements for the cables being installed. Cable construction plays a critical role in determining how these requirements are met.
Have other questions we didn’t cover in this list? Send us a note; we’ll be happy to answer them!
Get answers to your copper cable questions.
Related links:
About the Author
Ike Sachse joined Belden in 2022, working in Chicago alongside one of Belden’s Customer Innovation Centers. As a solution consultant, he partners with customers, contractors, consultants and other professionals—asking them the right questions to better understand their needs and align Belden’s solutions with their business objectives. Before joining Belden, Ike studied electrical engineering at Iowa State University. He’s also working toward his Fundamentals of Engineering Certification.