Top 10 Mistakes When Selecting Power Cables
Created on 08.19
Selecting the right power cable is an important decision for any electrical project. A cable that is incorrectly specified may lead to overheating, excessive voltage drop, premature insulation aging, installation difficulties, or unexpected system failures.
However, cable selection is not simply about choosing a larger conductor or finding the lowest price. The correct cable must match the electrical system, installation environment, mechanical requirements, applicable standards, and expected operating conditions.
In this guide, we discuss the 10 most common mistakes when selecting power cables and explain how to avoid them.
1. Selecting the Cable Based Only on Price
Price is an important consideration in any project, but choosing a cable solely because it is cheaper can create problems later.
Low-priced cables may not provide the required:
- Conductor quality
- Insulation performance
- Mechanical protection
- Manufacturing consistency
- Testing and quality control
A cable with a lower initial purchase price may result in higher installation, maintenance, replacement, or downtime costs.
Instead of comparing price alone, buyers should evaluate the complete value of the cable, including quality, specifications, service life, and supplier reliability.
2. Choosing the Wrong Conductor Size
One of the most common cable selection mistakes is choosing a conductor that is too small for the required load.
An undersized cable may experience excessive temperature rise and voltage drop.
Cable sizing should consider:
- Design current
- Installation method
- Ambient temperature
- Cable grouping
- Voltage drop
- Short-circuit conditions
- Future load requirements
The largest available conductor is not automatically the best choice either. The cable should be selected according to the actual project requirements.
3. Ignoring the Installation Environment
The same cable construction may perform differently under different installation conditions.
For example, a cable installed:
- Directly underground
- In a cable trench
- On a cable tray
- Inside a conduit
- In open air
may have different current-carrying capacities.
For underground cables, soil thermal resistivity and installation depth may also affect heat dissipation.
Therefore, cable selection should always be based on the actual installation environment.
4. Choosing the Wrong Voltage Rating
The cable's rated voltage must be compatible with the electrical system.
For example, low-voltage and medium-voltage distribution systems require different cable constructions and insulation systems.
Common power cable voltage ratings include:
- 0.6/1kV
- 3.6/6kV
- 6/10kV
- 8.7/15kV
- 12/20kV
- 18/30kV
- 19/33kV
Using a cable with an unsuitable voltage rating can compromise system safety and reliability.
Always confirm the system voltage and applicable standard before placing an order.
5. Ignoring Voltage Drop
A cable may have sufficient current-carrying capacity but still produce excessive voltage drop, especially over long distances.
Voltage drop can affect:
- Motors
- Pumps
- Lighting systems
- Industrial equipment
- Control systems
For long cable runs, voltage drop should be checked during the design stage.
In some cases, increasing the conductor cross-sectional area may be necessary to maintain acceptable voltage at the receiving end.
6. Choosing Armoured or Unarmoured Cable Incorrectly
Not every installation requires an armoured cable, but some environments require additional mechanical protection.
Armoured cables are commonly considered for applications such as:
- Underground installation
- Industrial plants
- Mining projects
- Outdoor installations
- Areas exposed to mechanical impact
On the other hand, installing unnecessary armour may increase cable weight, diameter, and project cost.
The correct choice depends on the installation environment and project requirements.
7. Ignoring Environmental Conditions
Environmental conditions can have a major impact on cable performance.
Before selecting a cable, consider whether it will be exposed to:
- High temperatures
- Water or moisture
- UV radiation
- Chemicals
- Oil
- Salt or coastal environments
- Mechanical stress
- Rodents or other external hazards
For projects in hot-climate countries, ambient temperature should receive particular attention because higher temperatures can reduce the cable's allowable current-carrying capacity.
The sheath and insulation materials should also be selected according to the environmental conditions.
8. Focusing Only on the Cable Standard Without Checking the Complete Specification
A cable may comply with a recognized standard but still not meet the specific requirements of a project.
For example, a project may require specific:
- Conductor material
- Insulation thickness
- Armour construction
- Sheath material
- Fire performance
- Water-blocking characteristics
- Testing requirements
Standards such as IEC, BS, ASTM, and other national or international specifications provide important technical requirements, but buyers should also review the complete project specification.
Before ordering, confirm both the applicable standard and the detailed cable construction.
9. Forgetting About Cable Accessories
Selecting the cable itself is only part of the electrical system.
Cable accessories such as:
- Cable joints
- Terminations
- Glands
- Lugs
- Connectors
must be compatible with the selected cable.
For medium-voltage cables in particular, cable accessories should match the cable's voltage class, conductor size, insulation system, and construction.
A high-quality cable combined with unsuitable accessories can still result in poor system performance.
10. Not Considering Future Load Requirements
Electrical systems often expand after the original project is completed.
Additional motors, equipment, buildings, or production lines may increase the total electrical load.
If the original cable was selected only for today's load, future expansion may require expensive cable replacement.
Where appropriate, engineers should consider expected future capacity during the design stage.
A slightly larger cable investment today may sometimes reduce future modification costs.
How to Select the Right Power Cable
Before purchasing a power cable, it is useful to prepare a complete technical specification.
At minimum, consider:
Electrical Requirements
- System voltage
- Design current
- Frequency
- Short-circuit current
- Voltage drop
Cable Construction
- Copper or aluminum conductor
- Number of cores
- Conductor cross-sectional area
- XLPE, PVC, or other insulation
- Armour requirements
- Sheath material
Installation Conditions
- Underground
- Cable tray
- Conduit
- Direct burial
- Outdoor
- Indoor
Environmental Conditions
- Ambient temperature
- Moisture
- UV exposure
- Chemicals
- Soil conditions
- Mechanical risks
Standards and Testing
Confirm the required standard and testing requirements before production.
Commonly referenced standards for power cables include IEC and BS standards, as well as applicable national or project-specific specifications.
Power Cable Selection Checklist
Before placing a purchase order, ask the following questions:
- Is the voltage rating correct?
- Is the conductor size sufficient?
- Has voltage drop been checked?
- Is the cable suitable for the installation method?
- Is armour required?
- Is the sheath material suitable for the environment?
- Has ambient temperature been considered?
- Are cable accessories compatible?
- Does the cable meet the required standard?
- Has future load growth been considered?
If these questions are clearly answered, the risk of selecting an unsuitable cable can be significantly reduced.
Why Work With an Experienced Cable Manufacturer?
Cable selection can involve many technical factors, especially for medium-voltage, industrial, mining, infrastructure, and utility projects.
An experienced cable manufacturer can help customers review the required:
- Cable construction
- Conductor size
- Insulation system
- Armour
- Sheath
- Applicable standards
- Testing requirements
At NINGLAN Cable, we manufacture copper and aluminum power cables for low-voltage and medium-voltage applications, with customized constructions available according to project requirements.
Our product range includes power cables up to 35kV and various cable constructions for industrial, utility, infrastructure, and other electrical applications.
Conclusion
Choosing the right power cable requires more than comparing conductor sizes and prices.
The cable must be selected according to the electrical load, voltage, installation method, environmental conditions, mechanical requirements, applicable standards, and expected service life.
By avoiding these 10 common mistakes, project owners, engineers, contractors, and cable buyers can reduce installation risks, improve system reliability, and achieve better long-term value.
If you are unsure which cable construction is suitable for your project, providing the voltage, conductor material, conductor size, number of cores, installation method, applicable standard, and project environment to the cable manufacturer is a good starting point for technical evaluation.
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