Multicore cables play a vital role in modern electrical and communication systems, combining multiple insulated conductors within one protective sheath for efficient performance. By understanding how these cables are constructed, you’ll be able to make an educated choice and find the right specification for your environment, whether you’re an engineer or an installer.
This guide explains the key elements of multicore cable construction, the different types available, and how custom designs can meet demanding technical requirements across industries.
What is a multicore cable?
A multicore cable contains two or more individually insulated conductors enclosed within a single protective sheath. Each conductor carries power, data, or audio signals depending on the application type.
The bundled design reduces space, improves organisation, and simplifies installation compared to running multiple single-core cables. In industries like telecoms, control systems and live audio, multicore cables are essential for reliable signal transfer in compact form.
Multicore cables follow international standards such as EN 60228, EN 50525, and EN 60332, ensuring safety and performance in demanding environments.
Multicore cable types
Different cable types exist to suit different conditions and electrical demands.
- Flexible cable – Uses a Class 5 flexible tinned copper conductor with silicone rubber insulation and silicone rubber sheath. Ideal for high-temperature or moving equipment.
- Armoured cable – Includes steel wire armour (SWA) or galvanised steel wire braid for mechanical protection. Common in industrial or underground installations.
- Audio cable – Carries multiple audio signals between a mixing console and stage box. Often uses twisted pairs or star-quad constructions with aluminium foil shields to reduce interference.
- Telecoms and data cable – Built with twisted solid copper conductors, polyethylene jackets, and UV-stable outer sheaths. Some feature a petroleum jelly moisture barrier for outdoor or duct grade use.
- Control and instrumentation cable – Designed for control panels and industrial systems, using PVC or low smoke zero halogen (LSZH) materials for enhanced safety and compliance.
How are multicore cables constructed?
The construction of a multicore cable ensures electrical integrity, flexibility, and long-term performance.
1. Conductors
The build begins with stranded copper wires, usually Class 5 flexible tinned copper conductors. These allow flexibility without sacrificing conductivity. Each layer serves a specific purpose in protecting signals and maintaining reliability under operating conditions. Below is a step-by-step look at how a multicore cable is built.
Each conductor is tested for continuity and compliance with EN 60228.
2. Conductor insulation
Every core is coated in an insulating layer to prevent short circuits and interference.
- Common materials include PVC, polyethylene, or silicone rubber insulation.
- Heat-resistant cables use silicone rubber compound for temperature stability.
- Colour-coded insulation helps with identification during installation and continuity testing.
3. Core grouping and laying
Insulated cores are then twisted and grouped into bundles.
- Engineers use planetary stranding machines to form uniform concentric lays.
- The lay length and lay direction are optimised to maintain flexibility and reduce electromagnetic interference.
- For multi-signal cables, twisted pair or triple/quad constructions ensure consistent signal integrity.
Cores are often bound with polyester melinex tapes or lantor tapes to hold shape and add mechanical strength.
4. Shielding and armour
For applications sensitive to noise or mechanical stress, additional layers are added:
- Aluminium foil shields or braided copper screens reduce electromagnetic interference.
- Galvanised steel wire braid or steel wire armour provides mechanical strength and grounding.
- A petroleum jelly moisture barrier may be included for protection against water ingress.
5. Outer sheath or jacket
The assembly is then covered by a protective outer sheath:
- PVC for general use.
- LSZH variants for fire-safe indoor environments (tested to IEC 60754-1, IEC 60754-2, IEC 61034-2).
- UV-stable Polyethylene for outdoor or telecoms applications.
- Silicone rubber sheath for high-temperature and flexible applications.
This sheath provides protection from UV, abrasion, and chemicals, ensuring long-term reliability.
6. Testing and Quality Assurance
Manufacturers like Custom Designed Cables (CDC) perform rigorous tests for:
- Continuity and insulation resistance
- Flexibility and tensile strength
- Compliance with ISO 9001:2015 and relevant EN and UL/CSA standards
Where are multicore cables used?
Multicore cables appear across almost every modern sector:
- Audio and Broadcast – Used in sound reinforcement systems, digital mixing consoles, and microphone splitters with XLR or TRS phone connectors.
- Industrial Automation – Links control panels and machinery for seamless communication.
- Telecommunications – Transmits data and signals across duct grade telecoms cables and network installations.
- Military and Aerospace – Built to withstand vibration, temperature extremes, and meet tight standards.
- Stage and Event Production – Powers lighting rigs, video multicore lines, and SCHILL Kabeltrommel cable spools for mobility.
What is the difference between single core and multicore cable?
A single-core cable contains one conductor with insulation and a jacket. It is simple, robust, and used for high-current or fixed installations.
A multicore cable combines several insulated conductors in one sheath. This reduces clutter, speeds up installation, and allows multiple circuits or signals to run in parallel.
The primary distinction between the two is that single-core cables prioritise current capacity, while multicore cables prioritise convenience and system organisation.
Advantages of multicore cables
Multicore cables offer several performance and practical benefits that make them a preferred choice across industries, from simplified installation to enhanced signal protection:
- Space saving – Multiple conductors in one sheath simplify routing and reduce bulk.
- Improved signal integrity – Twisted pairs or shielded cores prevent crosstalk and interference.
- Faster installation –Single sheath design means fewer individual runs.
- Enhanced protection – Armour, shields and jackets guard against physical and electrical hazards.
- Design flexibility – Can include custom core counts, insulation materials, and outer jacket options.
Custom multicore cable design
At Custom Designed Cables, we design, test, and manufacture cables to your exact specification.
You choose:
- Core count and conductor size
- Shielding and armour type
- Insulation and outer sheath materials
- Required standards or approvals (EN 50525, UL/CSA, ISO 9001:2015)
Our in-house team uses advanced design software to produce drawings for design approval. Every cable is built to order, continuity-tested, and backed by reliable customer service and manufacturer warranties. Get in touch today to see how we can help.