7 Layers of Copper Cable Construction: Why Each Layer Matters
When you want to move power or information from one place to another—whether you’re sending data, video, audio or control signals—the journey often takes place on a copper communications cable.
Copper cables are a market-proven technology that enables reliable, cost-effective data and power transmission along with easy termination.
Each layer of a copper cable’s construction is critical in order to get signals and/or power where they need to go. These layers heavily influence how well data and power are transmitted throughout the lifetime of the cable. They also impact:
- Safety in terms of the ignition and spread of fire, as well as the amount and toxicity of smoke released
- Downtime and system performance
- A cable’s ability to perform in harsh environments
- Ease of cable installation
Every copper cable includes the following layers:
- Conductor, which enables signal and/or power transfer
- Insulation, which protects the conductor and separates it from other conductors
- Jacket, which protects the cable
Depending on the cable type, a copper cable may also include these layers:
- Shield, which prevents interference that could disrupt signal transfer
- Armor, which provides physical protection for the cable overall
- Drain wire, which serves as a path to ground
- Ground wire, which diverts current away from the circuit and into the ground
High-performance cables are made with high-quality materials within each layer, which promotes safety and uptime. This level of performance is crucial if you want to optimize the return on investment (ROI) of your systems and technology.
The conductor: at the center of it all
Located in the center of the cable, with the other layers protecting it, is a copper cable’s conductor. It transfers data signals and/or electricity from Point A to Point B.
There are two types of conductors to consider: solid and stranded. They differ in terms of construction and performance.
Made up of a single round wire, solid conductors are cost-effective to produce and can be bare or coated in metal. They’re typically used in permanent applications because they don’t bend easily. Solid conductors also carry more current than stranded wire of the same diameter.
Stranded conductors are made of strands of twisted or braided copper wires. Due to their construction, they offer a longer flex life and withstand bending. As a result, they’re more flexible than solid conductors, which makes them easier to route around obstacles and install in tight spaces.
The insulation: safeguarding signal transmission
Wrapped around conductors, a copper cable’s inner layer of insulation is positioned between the conductors and the shield (when available) or jacket. That insulation is called the “dielectric” on cables that have high-frequency performance parameters.
It protects the conductor from environmental threats and electrical currents and is a critical part of ensuring data transmission at high frequencies, playing a major role in preventing capacitive loss. It also separates conductors from each other to reduce electrical interference. It does not guard against electromagnetic interference (EMI).
Two types of insulation are used in copper cables: thermoplastic (PVC, nylon, PE, PP, LSZH, etc.) and thermoset (XLPE, EPR, etc.), also known as crosslinked materials. Where the cable is installed and the type of environment it will operate in helps determine the best type of insulation.
Where the cable is installed and the type of environment it will operate in helps determine the best type of insulation.
Compared to thermoplastic insulation, thermoset insulation has a higher temperature rating. As a result, it can be more durable because it resists cracking, abrasion, corrosion and water.
Thermoplastic insulation softens when heated.
The shield: protecting against interference
In a copper cable, the shield is a metallic layer that surrounds the conductor(s). Not all copper cables have shielding. To optimize the effectiveness of the cable and ensure reliable signal transmission, it limits signal interference from external sources. It also prevents the cable from becoming a source of interference for nearby systems or components. For copper cables that carry high-frequency signals or have multiple conductors, inner and individual shields are used.
There are two types of shielding to consider for copper cables: foil and braid shielding. Some cables use both to guard against low- and high-frequency EMI.
Foil shields are often made of a thin, lightweight aluminum layer. While copper foil is sometimes used, it’s more expensive. Belden uses aluminum and polyethylene compounds to improve durability. Compared to a braided shield, foil shields can be more cost-effective. They’re best suited to guard against RFI and EMI at higher frequencies.
Braided shielding is made up of copper or aluminum strands (depending on the cable) that are “braided” together to offer excellent mechanical strength and withstand flexing. A braided shield protects against low-frequency EMI best.
Some cables use both types to guard against low- and high-frequency EMI.
The drain wire: ensuring proper grounding in shielded systems
Shielded copper cables have a drain wire to establish proper grounding in a shielded system. In these cases, the drain wire completes an electrical circuit from the shield and moves electrical noise away from the circuit to ground. Generally made of tinned copper, drain wires are designed to ensure proper conductivity and corrosion resistance.
Whether your copper cable needs a drain wire depends on factors like the probability of noise interference and whether the cable runs alongside power cables or other sources of EMI.
The ground wire: offering electrical safety
Some cables have a ground wire, which is a dedicated conductor that connects electrical systems to the earth and provides a safe path for excess electricity to dissipate. For example, multi-conductor cables sometimes feature a ground wire to minimize noise and improve signal quality.
The armor: preventing physical cable damage
Some copper cables have an extra layer of protection called armor, which is wrapped around the cable to guard against physical damage from crushing or abrasion. Armor is often made of steel or aluminum.
Armor becomes a priority when copper cables are installed in harsh environments that could put the cable at risk of physical damage (a forklift driving over it, something heavy falling on it or a rodent chewing through it, for example).
The jacket: guarding everything inside
The cable jacket serves a few purposes. It maintains the inner structure of the cable and protects it from environmental conditions. It also helps prevent the spread of fire and the release of smoke.
The jacket prevents deterioration and damage and provides a buffer between shielding and outside conductors.
Jackets can be designed to resist specific environmental factors, such as oil, sunlight or moisture, and possess different fire safety ratings.
A cable jacket also tells you everything you need to know about the cable: where it can be installed, who manufactured it and how easy it may be to handle (based on gauge size).
Similar to a copper cable’s insulation, there are two primary types of cable jacket material to consider:
- Thermoplastic (PVC, FEP, LSZH, etc.)
- Thermoset (CPE, EPR, etc.)
The cable jacket material should be selected based on the application and where the cable will be installed.
Copper cables for all types of connections
These seven layers must work together to create a high-performance copper cable. Just one inferior material can negatively impact what your cable can do.
Belden knows exactly where, when and how all its products are made. Our inspection testing and factory acceptance tests ensure quality and functionality of mission-critical networks before they are deployed.
Over the last several decades—and still today—Belden has proven itself to be the top choice for high-performance cabling and complete connection solutions.
Learn more about our high-performance copper cables.