Why Copper Is Superior to Aluminium in Coil Windings

Published: 2026-01-13

In low-voltage coils and transformer windings, both copper and aluminium are technically usable. However, for compact switchgear, control panels and demanding industrial duty, copper remains the preferred material because it offers lower losses, better thermal behaviour and stronger long-term reliability.

1) Electrical conductivity and losses

Copper has significantly higher electrical conductivity than aluminium. For the same current and winding geometry, a copper coil will usually have lower resistance. Lower resistance means lower I²R losses, which translates into lower temperature rise and better efficiency. This matters especially in enclosed LV switchgear, where every degree of temperature margin counts.

2) Thermal performance and life of insulation

Most premature failures in coils are driven by thermal stress on insulation. If a winding runs cooler, insulation life is extended. Copper’s ability to carry the same current with lower losses helps reduce hotspot temperatures and provides more margin relative to the insulation class limits. Over years of operation, this margin is what separates stable products from nuisance failures.

3) Space utilisation in compact designs

LV switchgear panels are often very space-constrained. Designers need to fit coils into tight envelopes while still meeting current and temperature-rise targets. Because copper allows achieving the required performance in a smaller cross-section, it can enable more compact designs or free space for other components.

4) Mechanical robustness and terminations

Coils see mechanical stress during handling, transport and in service due to vibration and thermal cycling. Copper windings and terminations have a long track record in switchgear applications and are well understood by panel builders and maintenance teams. This familiarity reduces the risk of connection issues and makes field service easier.

5) When would aluminium still be considered?

Aluminium can be attractive in large power applications where cost and weight dominate and there is sufficient physical space for larger conductors. In compact LV coils and control windings, those advantages are usually outweighed by copper’s better conductivity and thermal performance.

Practical takeaway for LV coils

• Use copper when temperature rise and reliability are critical.
• Specify current, duty cycle, ambient temperature and space clearly to your coil supplier.
• Ask for guaranteed temperature-rise data at your operating conditions.