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When selecting a busway system, many project teams begin with one simple question:
“What current rating do we need?”
But in modern electrical systems, current capacity alone does not tell the whole story.
Data centers, automated factories, commercial buildings and EV infrastructure increasingly rely on power-electronic equipment such as UPS systems, computer power supplies, variable-frequency drives and rectifiers.
These devices are often non-linear loads, meaning they can draw current in a distorted waveform rather than a perfect sine wave.
The result is harmonic current.
For engineers and facility owners, harmonics can affect conductor loading, temperature rise, neutral current and overall power quality. That makes harmonic conditions an important consideration when planning modern busway systems.
In a standard AC system, power operates at a fundamental frequency such as 50 Hz or 60 Hz.
Harmonics are electrical currents or voltages that occur at integer multiples of this fundamental frequency.
Common sources include:
As the number of electronic loads increases, harmonic content can become more important in electrical system design.
Harmonic currents contribute to RMS current flowing through conductors.
Higher current means additional electrical losses and heat.
If harmonic conditions are not considered during design, conductors, transformers and other electrical components may experience higher operating temperatures than expected.
This is particularly important in high-density installations that operate continuously.
In a balanced three-phase system with linear loads, neutral current can be relatively low.
However, third-order harmonics and their multiples behave differently.
Instead of cancelling in the neutral conductor, they can add together.
This means that in systems with a high concentration of single-phase non-linear loads, the neutral conductor may carry significant current even when the three phases appear balanced. Schneider Electric specifically notes that non-linear loads can cause substantial neutral loading because of third-order harmonics.
For this reason, some high-harmonic installations require a neutral conductor sized differently from a conventional system.
Harmonics do not affect only busway.
They can also influence:
For example, transformers designed for environments with significant non-linear loads may require additional thermal consideration or harmonic-rated solutions.
Eaton notes that harmonic currents generated by non-linear loads can increase heating and neutral current, which is why specialized transformer designs are used in such applications.
Modern data centers contain thousands of electronic power supplies.
Server power supplies, UPS systems and other IT equipment can contribute to harmonic distortion.
For high-density data halls, engineers should therefore consider not only total kW or current demand, but also power quality and load characteristics.
Modern manufacturing increasingly depends on:
These loads can introduce harmonics into the electrical network.
For plants expanding automation, power quality should be reviewed together with busway capacity.
Office buildings often contain a large number of:
Even when each individual load is relatively small, the combined effect across a large building can become significant.
EV charging systems rely heavily on power electronics.
As more chargers are added to commercial and industrial facilities, engineers may need to consider harmonics, transformer loading and electrical distribution capacity together rather than as separate issues.
Consider a commercial facility planning a new electrical distribution system.
The calculated operating current appears to fit comfortably within the selected busway rating.
However, most of the connected equipment consists of:
UPS systems + IT equipment + electronic lighting + variable-speed HVAC drives.
If the design considers only fundamental current, the engineering team may miss the impact of harmonic loading.
A more complete review would consider:
Load Type → Harmonic Content → Phase Current → Neutral Current → Thermal Performance → Protection → Busway Configuration
This is why professional busway selection should begin with an understanding of the actual loads, not only the total connected power.
Before finalizing busway specifications for installations with significant electronic loads, project teams should consider:
Load Characteristics
Are the loads linear or non-linear?
Total Harmonic Distortion
What level of harmonic current is expected?
Neutral Loading
Could triplen harmonics increase neutral current?
Operating Duty
Will the system run continuously at high load?
Ambient Temperature
Will the busway operate in a hot or enclosed environment?
Future Expansion
Will more electronic loads be added later?
Power Quality Requirements
Does the facility include sensitive equipment that requires tighter voltage or waveform quality?
Modern electrical systems increasingly use digital monitoring equipment to track:
Power quality meters can measure harmonic content and help operators determine whether non-linear loads are affecting the electrical system.
This allows facility teams to move from simply measuring energy consumption to understanding how the electrical system is actually performing.
There is no single busway configuration that is ideal for every project.
A manufacturing plant dominated by motors has different electrical characteristics from a data center dominated by electronic power supplies.
That is why busway design should consider:
Current Capacity + Harmonics + Neutral Requirements + Temperature + Environment + Expansion
rather than relying on current rating alone.
Ohory Electric provides customized busway solutions for industrial, commercial, data center and infrastructure applications.
Our engineering team can review project information such as:
This allows the busway system to be configured around the actual operating requirements of the project.
As electrical systems become more digital and power-electronics-driven, power quality will play an increasingly important role in electrical distribution design.
For EPC contractors, consultants and facility owners, evaluating harmonic conditions early can help reduce thermal stress, improve system reliability and avoid unexpected limitations after commissioning.
Planning a project with UPS systems, servers, VFDs or other non-linear loads?
Send Ohory Electric your load information and electrical drawings. Our engineering team can help evaluate a suitable busway solution for your application.
