What is Shielded Cable? Types, Benefits & EV Applications (2026 Guide)

What is Shielded Cable? Types, Benefits & EV Applications (2026 Guide)

A wire wrapped with a conductor outside the conductor is called a shielded cable. The wrapped conductor is called a shielding layer, which is usually a braided copper mesh or copper foil (aluminum). The shielding layer needs to be grounded, and external interference signals can be guided into the earth by this layer.

Function of Shielded Cable:

Prevent interference signals from entering the inner layer and conductor interference while reducing the loss of transmission signals.

Structure of Shielded Cable:

1. Ordinary Shielded Cable

Insulation layer + shielding layer + wire

2. Advanced Shielded Cable

Insulation layer + shielding layer + signal wire + shielding layer ground wire

Note: When selecting a shielded wire, the insulation layer of the shielded ground conductor has a conductive function and can be connected to the shielding layer (has a certain resistance).

The Principle of Shielded Cable

The shielded wiring system originated in Europe. It adds a metal shielding layer to the outside of the ordinary unshielded wiring system. It uses the reflection, absorption and skin effect of the metal shielding layer to prevent electromagnetic interference and electromagnetic radiation. The shielding system comprehensively utilizes The balancing principle of the twisted pair and the shielding effect of the shielding layer have very good electromagnetic compatibility (EMC) characteristics.

Electromagnetic compatibility (EMC) means that electronic equipment or network systems have a certain ability to resist electromagnetic interference and cannot produce excessive electromagnetic radiation.

That is to say, the equipment or network system is required to be able to work normally in a relatively harsh electromagnetic environment. And at the same time, it cannot radiate excessive electromagnetic waves and interfere with the normal operation of other surrounding equipment and networks.

The main reason why shielded cables resist external interference is that the integrity of signal transmission can be guaranteed to a certain extent through the shielding system. Shielded cabling systems can prevent transmitted data from being affected by external electromagnetic interference and radio frequency interference.

Electromagnetic interference (EMI) is mainly low-frequency interference, and motors, fluorescent lamps and power lines are common sources of electromagnetic interference. Radio frequency interference (RFI) is high-frequency interference, mainly wireless frequency interference, including radio, television broadcasts, radar and other wireless communications.

For resisting electromagnetic interference, braided shielding is most effective, that is, metal mesh shielding because of its low critical resistance.

When addressing radio frequency interference, the most effective approach involves a metal foil layer for shielding. This choice is driven by the capability of metal foil to permit the unimpeded passage of high-frequency signals, owing to the gaps in the metal mesh shield.

For mixed interference fields of high and low frequencies, a combined shielding method of metal foil layer and metal mesh should be used, that is, a double-layer shielded cable in the form of S/FTP. This can make the metal mesh shielding suitable for interference in the low frequency range, and the metal foil shielding Suitable for interference in the high frequency range.

Why is EMI Shielding Critical for Electric Vehicles?

Unlike traditional internal combustion engines, Electric Vehicles (EVs) rely on high-voltage systems (400V to 800V) and high-frequency switching devices like DC-DC converters and Inverters. These components generate significant Electromagnetic Interference (EMI).

Without proper shielded cables, this EMI can disrupt sensitive onboard electronics, such as:

• BMS (Battery Management Systems): Causing inaccurate state-of-charge readings.
• Infotainment & Sensors: Creating noise in audio systems or errors in autonomous driving sensors.

Therefore, high-quality HV shielded cables act as a Faraday cage, grounding the noise and ensuring the Electromagnetic Compatibility (EMC) of the entire vehicle.

Grounding Methods for EV High-Voltage Shielded Cables

Shield Grounding and 360-Degree EMC Termination

In electric vehicles, high-voltage power cables connect major components such as battery packs, inverters, and electric motors. These systems generate high-frequency electromagnetic interference (EMI), making effective cable shielding and grounding essential for electromagnetic compatibility (EMC).

Unlike some low-frequency signal applications where single-point shield grounding may be preferred to minimize ground-loop currents, EV high-voltage cable shields are commonly bonded to the vehicle chassis or equipment enclosures at both ends. The actual grounding configuration depends on the vehicle’s electrical architecture and EMC requirements.

For effective high-frequency shielding, 360-degree circumferential shield termination is widely recommended. This method provides continuous electrical contact between the cable’s braided shield and the connector’s metal shell or EMC gland, creating a low-impedance path for interference currents. Compared with conventional pigtail connections, 360-degree termination generally offers better high-frequency shielding performance and helps reduce electromagnetic emissions and susceptibility, supporting compliance with automotive EMC requirements such as CISPR 25.

Electrical Safety and Fault Protection

Beyond EMC performance, the cable shield can also contribute to electrical fault protection when properly bonded to the vehicle chassis and designed to withstand the expected fault current.

According to ISO 6469-3:2021, accessible exposed conductive parts of voltage class B electrical equipment must be bonded to the vehicle’s electric chassis to achieve equipotentiality. This bonding provides a defined electrical fault path and helps reduce the risk of electric shock if an insulation fault occurs.

The vehicle’s insulation monitoring system (IMD) can detect reductions in insulation resistance and trigger appropriate warnings or high-voltage de-energization measures, depending on the vehicle’s safety architecture. The High Voltage Interlock Loop (HVIL) serves a separate function by monitoring designated high-voltage connection and interlock conditions, helping prevent unsafe operation when monitored connections are disconnected or improperly engaged. For a full high voltage interlock loop guide, please read HVIL in Electric Vehicles.

What Industries Use Shielded Cables Except for EV?

Industrial Automation and Control Systems: On modern factory floors, heavy machinery, motors, and variable frequency drives (VFDs) generate immense electromagnetic noise. Shielded cables are vital for connecting sensors, actuators, and programmable logic controllers (PLCs). They guarantee that low-voltage control signals and feedback loops remain highly accurate, preventing erratic machine behavior and costly production downtime.

Medical and Healthcare Equipment: High-precision medical instruments are exceptionally sensitive to external electrical noise. Life-saving devices such as electrocardiograms (ECGs), ultrasound scanners, and MRI machines rely on heavily shielded cables to protect delicate physiological signals. This shielding prevents data distortion, ensuring that healthcare professionals receive accurate, reliable diagnostic results.

Telecommunications and Data Centers: In the era of high-speed digital communication, signal integrity is paramount. Shielded data cables (such as Cat6a/Cat7 Ethernet, USB, and high-fidelity audio/video cables) prevent data packet loss, attenuation, and internal crosstalk. They are extensively deployed in server farms, satellite broadcasting, and telecommunications infrastructure to maintain high-quality, uninterrupted data streams.

Power Generation and Energy Storage: In high-voltage environments like power substations, smart grids, and modern Battery Energy Storage Systems (BESS), electromagnetic fields are intense. Shielded cables are crucial here to isolate and protect the low-voltage control, metering, and monitoring circuits from the disruptive interference of high-power transmission lines, ensuring the safe and stable operation of the energy grid.

Commercial Aviation and Aerospace: Flight control systems, avionics, and navigation equipment demand absolute reliability. Shielded cables protect these mission-critical communication networks from both internal electronic noise generated by other onboard systems and external atmospheric interference, ensuring safe and precise flight operations.

Comparison: Shielded vs. Unshielded High Voltage Cables

Feature	Shielded HV Cable	Unshielded HV Cable
Structure	Conductor + Insulation + Braided Shield/Foil + Sheath	Conductor + Insulation + Sheath
Primary Use	High-power lines (Inverter to Motor, Battery to Charger)	Low-power auxiliaries or inside metal enclosures
EMI Protection	Excellent (Reduces radiation & susceptibility)	Poor (Transparent to EMI)
Flexibility	Lower (Due to metal braid layer)	Higher (Easier to route in tight spaces)
Cost	Higher	Lower
Renhotec Recommendation	Must-have for main traction circuits.	Suitable for auxiliary heaters or pumps.

The Role of Shielded Wire

The function of the shielded wire is to isolate the electromagnetic field noise source from sensitive equipment and cut off the propagation path of the noise source.

Shielding is divided into active shielding and passive shielding. The purpose of active shielding is to prevent the noise source from radiating outward and to shield the noise source. The purpose of passive shielding is to prevent sensitive equipment from being interfered by noise sources and is a shield for sensitive equipment.

The shielding layer of shielded cables is mainly made of non-magnetic materials. Such as copper and aluminum, and its thickness is very thin, which is much less than the frequency of use of metal materials. The effect of the shielding layer is not mainly caused by the reflection and absorption of the electric field and magnetic field by the metal body itself, but by the grounding of the shielding layer.

Different forms of grounding will directly affect the shielding effect. The grounding methods for electric field and magnetic field shielding layers are different. Can be ungrounded, single-ended grounded or double-ended grounded.

3 Key Criteria for Selecting EV Shielded Cables

Choosing the right high-voltage cable is critical for suppressing electromagnetic interference (EMI) in 800V electrical architectures. When sourcing, prioritize the following three parameters:

• Shielding Coverage: Ensure the optical coverage is >85% (braiding + foil) to guarantee signal integrity.

• Flexibility: Look for XLPE or Silicone insulation (Class D/E) to withstand tight routing in battery packs without cracking.

• Certification: Verify compliance with ISO 6722 or LV 216 standards for automotive safety.

Renhotec’s Solution: Engineered for Performance

Based on the stringent standards outlined above, Renhotec has developed and launched its EV High-Voltage Cable Series, including shielded cable and unshielded cable.

Boasting an impressive 85% shielding coverage and featuring a highly durable orange insulation layer, this cable series achieves an optimal balance between flexibility and safety.

Browse our full range of our shielded and unshielded cable products.

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