Comprehensive Guide to Buying Aerial Bundled Cables: Technical Comparison of 5-Core and 6-Core Systems

Introduction: The Dilemma of Choice in Modern Power Distribution Networks

In recent years, replacing old and worn-out copper wire networks with Aerial Bundled Cables (ABC) has created a true revolution in the country’s power distribution industry. This technological change has brought undeniable advantages, including a significant reduction in energy theft, increased public safety, reduced illegal connections, and ultimately improved urban aesthetics and cityscape.

However, moving from theory to project execution, contractors, supervising engineers, and employers constantly face a very important technical and economic question: *”Should we use the 5-core system, which is more common and cheaper, or invest more in the 6-core system which offers higher safety standards?”*

The precise answer to this question defines the fine line between building a “merely economic network” and a “fully stable and safe network.” Unfortunately, in many distribution projects, decision-makers choose the 5-core version solely to reduce initial costs. In doing so, they overlook hidden and highly destructive risks such as the “floating neutral” phenomenon and “severe voltage fluctuations” that threaten network health and customer equipment.

In this analytical article prepared by the technical and engineering unit of “Sim Rad Sama Company,” we intend – without any bias and relying solely on precise electrical engineering principles and approved Tavanir standards – to thoroughly dissect both cable structures. Our goal is to enable you to make the best and safest decision for your project with a completely open and engineered perspective.

Part One: Anatomy of the 5-Core Aerial Bundled Cable (Economic Structure)

To deeply understand the differences, we must first know the basic structure of these cables. The 5-core aerial bundled cable is a product that has been used as the default standard for many years in many electrification projects in rural areas and low-density urban areas in Iran.

Internal Structure of the 5-Core Combined System

In this engineering configuration, we have 5 aluminum conductors neatly stranded together:

Three phase conductors: These three strands are responsible for three-phase current transmission and are covered with resistant XLPE insulation. Their cross-sections are typically manufactured in standard sizes of 35, 50, 70, or 95 mm².

One lighting conductor: This strand is dedicated to supplying power to the public lighting system and is typically placed in the cable with a cross-section of 16 or 25 mm².

One combined critical conductor (PEN – Protective Earth Neutral): This strand is precisely the key point and Achilles’ heel of the 5-core system.

In this cable structure, a single strand must simultaneously perform two completely different and demanding tasks: carrying the neutral electric current and bearing the mechanical load of the entire cable’s weight.

Technical features and material of the combined conductor: Since this combined conductor must bear the weight of tens of meters of suspended cable between two utility poles, from a materials engineering perspective, it cannot be made of pure aluminum because pure aluminum is a soft metal and has insufficient tensile strength. Therefore, manufacturers necessarily make this strand from a high-strength aluminum alloy (such as AAAC – All Aluminum Alloy Conductor) to provide the necessary tensile strength for hanging between poles.

Part Two: Anatomy of the 6-Core Aerial Bundled Cable (Safety Standard)

Here, safety engineering steps in to address the shortcomings. The 6-core aerial bundled cable is a fully engineered response to the inherent weaknesses and potential hazards of the 5-core model.

Internal Structure of the 6-Core Separated System

Unlike the economic model, in this structure we encounter 6 completely separate and distinct conductor strands:

• • Three phase conductors: Their structure and function are exactly the same as the 5-core model.

  • One lighting conductor: The function of this strand is also exactly the same as the previous model.

  • One independent neutral conductor: In this structure, the neutral strand has gained a completely independent identity and has only one electrical task (carrying return current). Since there is no mechanical weight or stress on the neutral wire in this design, it can be made from pure aluminum (AAC), which has much higher electrical conductivity than alloys.

  • One independent messenger or supporting strand: This sixth strand has only a mechanical task: to bear the cable’s weight. The material of this critical strand is typically high-carbon galvanized steel or a very hard aluminum-magnesium-silicon alloy. This strand is often uninsulated or has an insulation layer distinct from the other strands so that installers can easily identify it.

Part Three: The Hidden and Devastating Risk of “Floating Neutral”

You may wonder why the 5-core cable can be dangerous. In answer, one of the most important technical issues in comparing these two cable types is directly tied to the safety of customers’ electrical equipment.

To understand this risk, let us imagine a real scenario: Suppose the aerial bundled cable network of a neighborhood experiences severe stretching and eventually breaks due to incidents such as a severe storm, a tree falling on the lines, or a truck bed hitting the cable.

Scenario A: Breakage in a 5-core cable network (a technical disaster)

As mentioned earlier, in the 5-core cable structure, the supporting wire is exactly the neutral wire. When the cable is subjected to excessive mechanical stress, the first wire to lose its resistance and break is usually the supporting (messenger) wire.

With this wire breaking, a terrible event occurs in the network: the neutral connection to the transformer is completely severed. The result of this disconnection in a three-phase network, which typically has unbalanced loads, is a dangerous phenomenon called neutral point displacement. This phenomenon, known in electrical engineering as “floating neutral,” causes the voltage on the loads to change severely and uncontrollably. In such a situation, a customer’s electrical outlet may suddenly deliver 380V instead of the standard 220V to household appliances. The damage is immense: immediate and irreversible burnout of expensive devices such as refrigerators, televisions, computers, and all sensitive electrical equipment connected to the network at that moment in that neighborhood.

Scenario B: Breakage in a 6-core cable network (a safe solution)

Now let us examine the same incident in a network with a 6-core cable. In this structure, the messenger wire is completely separate from the neutral wire. From a safety perspective, if mechanical stress from a storm or accident breaks the messenger wire, the cable may hang from the pole, but the neutral wire does not break. (The reason is that during manufacturing and installation, no tension is applied to the neutral wire, and its length is usually slightly longer than the messenger to prevent it from breaking in such events.) The result of this intelligent design is that the power does not go out, or in the worst case, no severe voltage fluctuation occurs. Thus, all people’s electrical devices in their homes remain completely safe.

A technical recommendation from Sim Rad Sama: If your electrification project is located in areas with special weather conditions (such as windy regions, forested environments, or mountainous areas), using a 6-core cable is no longer a luxury choice but a definite “safety requirement.”

Part Four: Electrical Resistance and Voltage Drop (Alloy vs. AAC)

Beyond the mechanical aspects, another subtle technical difference that experienced contractors and network design engineers pay close attention to is the neutral conductor material and its direct impact on the quality of power delivered to customers.

• • In the 5-core cable: As stated, the combined conductor (serving as both neutral and messenger) must bear the cable’s weight, so the manufacturer is forced to make it from aluminum alloy (Alloy). The downside is that the electrical resistance of aluminum alloy is on average about 15-20% higher than pure aluminum. This increased resistance means greater energy losses in the network and higher voltage drop along the return (neutral) path.

  • In the 6-core cable: Since the neutral wire bears no mechanical load, it can easily be made from pure aluminum (AAC). Pure aluminum offers the best and highest electrical conductivity among all aluminum grades used in cable manufacturing, which greatly improves the network’s power quality.

Technical Performance Comparison Table

Part Five: Economic Analysis and Installation Challenges (Cost vs. Investment)

There is no doubt that the 6-core cable, due to having an additional conductor strand (an independent steel or alloy messenger), has a higher upfront purchase cost. But as an engineer or project manager, you must ask yourself: Is paying this initial cost justifiable?

Let us break it down:

• • Cable purchase cost: Typically, a 6-core cable is about 10-15% more expensive in the market than a 5-core cable with similar specifications.

  • Hardware and installation cost: The hardware used for 6-core cables (such as suspension clamps and jumpers) is somewhat different and more specialized than that for 5-core cables, and naturally their installation requires greater precision and technical skill from linemen.

But why does this higher cost ultimately benefit you? If you work as a contractor for the power distribution company, you should know that in the event of an accident and neutral break in a 5-core network, paying compensation for burnt electrical appliances of customers in a neighborhood can be tens of times greater than the price difference you did not pay for a 6-core cable. In fact, purchasing a standard 6-core cable from a reputable industrial brand like “Sim Rad Sama” is a form of lifetime insurance policy for the health of your distribution network.

Part Six: Final Selection Guide (Engineering Purchasing Checklist)

If after reading the above you still have doubts about choosing the right model for your project, we suggest using this practical engineering checklist for your final decision:

✅ You can purchase the 5-core Sim Rad Sama aerial bundled cable if the following conditions apply to your project:

• The project budget is extremely tight, and your employer strongly insists on using the lowest possible price.

• The distance between poles (called span) is short and within urban standards (i.e., less than 30-35 meters apart).

• The network construction site is in low-risk urban areas, and operational teams have easy access for quick repairs.

• The main purpose of the project is temporary electrification or supplying power for small, auxiliary rural projects.

✅ However, you must purchase the 6-core Sim Rad Sama aerial bundled cable if your project conditions are as follows:

• Ensuring electrical power quality and maintaining voltage stability for consumers is a red line for you and your employer.

• The network under construction is long (you are dealing with a long feeder), and you are worried about severe voltage drop at the end of the line.

• The geographical area of the project has harsh weather conditions such as strong winds, risk of heavy ice loading on the cable, or a high risk of tree branches falling on the network.

• You wish to hand over the network to the operator with complete peace of mind after completion, and have no concerns about receiving complaints from customers regarding harmful voltage fluctuations.

FAQ about Aerial Bundled Cables

1. Is it technically possible to install a 6-core cable on old utility poles? Yes, it is possible, but before installation, precise mechanical calculations of the pole (especially top load calculations) must be redone. The reason is that the 6-core cable is slightly heavier than the 5-core model due to the additional strand, and when installed over long spans, it may require foundation reinforcement or more precise sagging operations.

2. What exactly is the messenger strand material in 6-core cables? In the standard product range manufactured by Sim Rad Sama factory, the messenger strand of 6-core cables is typically made of high-carbon galvanized steel or a very hard aluminum-magnesium-silicon alloy – materials that exhibit extremely high tensile strength against mechanical stresses.

3. Can hardware for 5-core cables be used to install 6-core cables? No, absolutely not. The dead-end clamps and suspension clamps designed for 6-core cables must have the technical capability to engage the bare (or separately jacketed) messenger strand alone, so their structure is completely different from clamps for 5-core cables. Using incorrect or mismatched hardware can cause the cable to slip off the poles and lead to serious accidents.

Conclusion: Sim Rad Sama – Your Reliable Partner in Safe Power Distribution Projects

Ultimately, the final choice between 5-core or 6-core systems depends entirely on your project’s technical priorities and financial constraints. But there is a fundamental principle that never changes: the paramount importance of “cable manufacturing quality.” It does not matter whether you choose the 5-core system or the 6-core system; if the cable you purchase does not have valid Tavanir approvals, does not use standard XLPE insulation, and its conductor lacks sufficient purity, your distribution network will never remain stable and safe.

At Sim Rad Sama factories, we proudly manufacture both types of aerial bundled cables according to the strictest national Iranian standards as well as IEC international standards. Using the highest quality raw materials, we are always ready to meet the technical needs of your large and small projects. Do not forget that the quality of our products guarantees the credibility of your engineering projects.

[For completely free technical consultation and to get a current price quote for various types of aerial bundled cables, contact the sales specialists at Sim Rad Sama today.]