What is the difference between concentric cable and coaxial cable?

Concentric Cable vs Coaxial Cable

Concentric cable and coaxial cable look very similar, which often leads non professionals to confuse them during procurement, or even assume they are different names for the same product. في الحقيقة, they are two completely different technical routes:

Concentric cable is a power cable, mainly used to transmit electrical power (على سبيل المثال, service entrance cables under the UK BS 7870 معيار). Coaxial cable is a signal/communication cable, mainly used to transmit high frequency signals (على سبيل المثال, cable TV and antenna feeders).

Although their appearance may be similar, their internal structure, materials and physical principles are completely different. Below we break down and compare the structures of concentric cable and coaxial cable to help you distinguish them thoroughly.

Structure of Concentric Cable

The “concentric” in concentric cable means that the neutral conductor (neutral/earth) is helically wrapped concentrically around the insulated phase conductor.

Central phase conductor: The material is usually soft annealed copper, الألومنيوم, aluminum alloy or copper clad aluminum. It is solid or stranded and is responsible for carrying large currents.
طبقة العزل: XLPE, PVC or EPR is mainly used. It isolates the phase conductor from the outer neutral conductor.
Concentric neutral conductor: This is usually bare copper wire or bare aluminum alloy wire, wrapped around the insulation layer in SZ helical or alternating fashion. It serves as both the neutral return path and mechanical protection.
Filler and tape (for multicore cables): Polyester tape or filler rope is used for shaping, isolation and moisture protection.
غمد الخارجي: The outermost layer is usually PVC, LSZH (low smoke zero halogen) or PE, and some cables have armor.

Structure of Coaxial Cable

The “coaxial” in كابل متحد المحور means that the inner conductor, insulating dielectric and outer conductor shield share the same geometric center (axis). The signal is transmitted in the space between the inner and outer conductors.

موصل داخلي (center conductor): The material is usually copper, النحاس المعلب, silver plated copper or even copper clad steel. Its diameter and material directly determine signal attenuation and characteristic impedance.
Insulating dielectric layer: Foamed PE, solid PE or PTFE is mostly used. It not only isolates the inner and outer conductors but also fixes the spacing. The dielectric constant directly determines the impedance (50 Ω or 75 أوه).
Outer conductor (shield): Materials include copper braid, aluminum foil plus copper braid, corrugated copper tube, إلخ. It is the signal return ground and also shields external electromagnetic interference and prevents signal leakage.
غمد الخارجي: بولي كلوريد الفينيل, PE or LSZH. Black weather resistant PE is commonly used outdoors, and light colors are used indoors.

Concentric Cable vs Coaxial Cable: How to Choose for Different Scenarios?

Types of Concentric Cable

By core number: جوهر واحد (neutral wire wrapped directly outside the phase conductor) و multicore (multiple phase conductors stranded together, with neutral wire wrapped outside).
By neutral form: split concentric (phase and neutral separated, common in UK standard service entrance cables) و concentric neutral (overall wrapping, common in US standard underground power supply).
By voltage: الجهد المنخفض (600/1000 الخامس) has a simple structure; medium voltage (15 كيلو فولت, 25 كيلو فولت, إلخ.) requires an added semiconductive screen and semiconductive sheath.
By standard: اللجنة الانتخابية المستقلة 60502-1, بكالوريوس 7870, ASTM B881, إلخ., with strict requirements on wrapping method and dimensions.

أنواع الكابل المحوري

By characteristic impedance: 50 أوه (تواصل, RF, antenna feeders) و 75 أوه (cable TV, video surveillance).
By shielding strength: single braid (basic), aluminum foil plus braid double shield (mainstream surveillance), multilayer shield (high interference resistance) and corrugated copper tube (fully shielded RF).
By insulating dielectric: foamed PE (خسارة منخفضة) and PTFE (high temperature and high frequency resistance).

Comparison of Concentric Cable and Coaxial Cable

To help engineers and procurement staff check quickly, here is a direct comparison of concentric cable and coaxial cable:

البعد	Concentric Cable	كابل محوري
Core function	Transmit power	Transmit signal / RF
Structural logic	Phase conductor inside, neutral conductor concentrically wrapped outside	موصل داخلي, insulation and outer shield share the same axis
Function of outer conductor	Serves as neutral (ن) or earth (بي) return path, with protective function	Serves as signal return ground, with electromagnetic shielding function
Parameters	Cross sectional area, ampacity, الجهد المقنن	Characteristic impedance (50/75 أوه), shielding attenuation
التطبيقات	Service entrance power lines, low voltage distribution networks, street lighting	تلفزيون الكابل, video surveillance, antennas, RF communication

Installation Environment and Construction Constraints

Concentric cables and coaxial cables have vastly different requirements for their installation environments; incorrect placement or improper handling can lead to immediate failure:

الكابلات متحدة المركز (توزيع الطاقة):
Primarily used for direct underground burial, building service entrances, or outdoor conduits. Construction constraints: The outer layer of bare copper neutral wires is susceptible to damage during pulling; if the outer sheath is compromised, the cable becomes highly vulnerable to moisture and corrosion once buried. Rough handling or forceful pulling is strictly prohibited; an adequate bending radius must be maintained.

الكابلات المحورية (Signal Transmission):
Primarily used in indoor low-voltage cable trays, on surveillance poles, or for outdoor antennas. Construction constraints: The internal foamed insulation layer is extremely sensitive to pressure. Sharp bends or “kinks” at corners can cause impedance fluctuations and signal loss. بالإضافة إلى, outdoor connectors must be rendered strictly watertight; the ingress of water will effectively destroy the high-frequency signal.

خاتمة

كابل متحدة المركز is designed to deliver “power” safely and economically to homes and businesses; coaxial cable is designed to deliver “signals” to terminals cleanly and with interference resistance. The two cannot replace each other and cannot be mixed. In overseas projects, whether for power distribution or communication surveillance, ZMS Cable can provide high quality cables that meet international standards.

We provide concentric cables compliant with BS 7870 واللجنة الانتخابية المستقلة 60502, as well as various 50 Ω/75 Ω coaxial cables (such as the RG series), meeting full scenario requirements from power to signal. فضلاً عن ذلك, the ZMS Cable engineering team will recommend the correct model strictly according to your application scenario (power supply circuit or low voltage signal), avoiding project rework caused by selection errors.

Need to purchase concentric cable or coaxial cable for your project? Please send your specification requirements to our technical team, and we will provide an accurate quotation and technical support.

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