In the electrical industry—especially in industrial, commercial, and facilities maintenance environments—mounting hardware isn't just about holding things in place. Rather, it's about making reliable, conductive connections that ensure optimal electrical performance and safety. When mounting circuit breakers, switches, or other electrical equipment into distribution boards, the choice of material for mounting hardware is crucial. It must not only provide physical support but also, in many cases, serve as a conductive pathway to the bus.
In this article, we will outline the correct materials for mounting circuit breakers, focusing on conductivity, compatibility with bus bars, structural needs, and durability in harsh environments.
Mounting Hardware: It's More Than Just Support
Mounting circuit breakers into panels isn’t just about screwing something into place. In fact, the hardware often plays a critical role in conducting electricity directly to or from the breaker. Especially in designs where strap kits (i.e., bus connectors) or clips contact energized bus bars, conductivity becomes essential. As a result, choosing the wrong material can cause resistance, overheating, and system failure over time.
- Conducting ability matters – hardware in the current path must be highly conductive.
- Corrosion and temperature stability are essential in industrial settings.
- Mechanical vibration and structural loads are secondary but still important.
Copper Mounting Hardware: The Gold Standard
Copper is by far the best material when conductivity is critical. Whenever mounting hardware must connect directly to a bus bar, copper remains the top choice. Therefore, whenever mounting hardware must connect directly to a bus bar, copper remains the top choice.
✅ Advantages:
- Excellent electrical conductivity (nearly 100% IACS).
- Low resistance ensures minimal heat generation.
- Naturally corrosion resistant, especially when tinned.
⚠️ Considerations:
- Higher cost, but justified where performance and reliability are paramount.
- Softness means it may need reinforcement in high-vibration applications. Nevertheless, its superior conductivity makes it the preferred choice whenever current flow is critical.
🔧 Best Use:
- Direct connections to bus systems.
- Additionally, copper components simplify maintenance because they resist oxidation more effectively than many other metals.
Aluminum Mounting Hardware: The Acceptable Alternative
Aluminum is a common second choice. While it doesn't match copper's conductivity, it offers a good balance of electrical performance and weight savings. Therefore, it is often used in breaker bus connectors, mounting brackets, and backplates, especially when cost or weight are constraints.
✅ Advantages:
- Good conductivity (about 61% IACS).
- Lighter than copper, easier to handle in large assemblies.
- Naturally corrosion resistant, though it forms a resistive oxide layer.
⚠️ Considerations:
- Oxidation is a concern: aluminum rapidly forms an oxide layer that is non-conductive, which can increase resistance at connection points.
- To prevent this, aluminum strap kits and bus bars are often tin-plated, providing a conductive, corrosion-proof surface that better fits copper connections.
- Requires anti-oxidant compound when mating raw aluminum to copper.
- Heating and cooling can loosen connections over time.
- Consequently, periodic inspections and torque checks become even more important in facilities using aluminum hardware.
🔧 Best Use:
- Bus bar, and bus connectors that tie into bus.
- Backplates or connectors not under extreme mechanical stress.
- For this reason, tin plating remains a common industry practice for aluminum components used in critical current paths, ensuring better long-term performance and compliance with code.
Steel Mounting Hardware: For Structure, Not Current
Steel is not a suitable conductor (2-3% IACS) and should never be used where a conductive path is required. Nevertheless, it's excellent as a support material — think side rails, mounting frames, or filler plates that bear mechanical loads rather than carrying current.
✅ Advantages:
- High structural strength, excellent for supporting heavy apparatus.
- Cost-effective and readily available.
- Durable under vibration and mechanical stress.
❌ Disadvantages:
- Terrible conductor, generates heat under load.
- Prone to corrosion if uncoated or scratched. On the other hand, using galvanized or powder-coated steel can improve corrosion resistance significantly.
- Incompatible with copper bus connections.
🔧 Best Use:
- In contrast to copper and aluminum, steel’s role is purely mechanical and never electrical.
- Covers, filler plates, and cabinet reinforcements.
Plastic Mounting Hardware: Insulating and Corrosion-Proof
Plastic, usually in the form of nylon or strong polymers, plays a minor but important role in mounting. Although it cannot bear heavy electrical loads, it excels in applications where insulation, corrosion resistance, and lightweight materials are top priorities.
✅ Advantages:
- Non-conductive, excellent for insulating brackets.
- Won’t rust or corrode, ideal for harsh or chemical environments.
- Lightweight and easy to install.
⚠️ Considerations:
- Not load-bearing for heavy breakers.
- Heat-sensitive, can warp in high-temp areas.
- UV degradation in outdoor use unless stabilized. Therefore, selecting UV-stabilized plastics is critical for outdoor panels or rooftop installations.
- UV degradation in outdoor use unless stabilized. Therefore, selecting UV-stabilized plastics is critical for outdoor panels or rooftop installations.
🔧 Best Use:
- Mounting spacers, insulating brackets, filler pieces in non-load-bearing positions.
Summary: Choosing the Right Mounting Hardware Material
| Material | Conductivity | Structural Use | Best For |
| Copper | ★★★★★ | ★★ | Direct bus-mounted breakers, live hardware |
| Aluminum | ★★★★☆ | ★★★★☆ | Breaker backplates, lightweight bus interfaces |
| Steel | ★☆☆☆☆ | ★★★★★ | Frames, filler plates, supports (non-current) |
| Plastic | ☆☆☆☆☆ | ★★ | Insulating components, corrosion-prone zones |
If you would like deeper technical discussions on mounting hardware, bus connections, or conductivity issues, visit the Eng-Tips Electrical Engineering Forum, where electrical professionals and engineers share real-world advice on ensuring safe, compliant, and durable installations in commercial and industrial environments.
Conclusion: Electrical Reliability Starts with the Right Hardware
In the electrical industry, hardware is never just “hardware.” Instead, it serves as a foundation for safety, performance, and code compliance. When mounting circuit breakers or related equipment, your material choice can directly impact these critical factors. If the hardware connects to bus, copper is king. Similarly, tin-plated aluminum provides a cost-effective option when properly installed and maintained. Aluminum works where weight and cost are a concern, and steel is strictly for support — never conduction. Plastic plays a useful, limited role in insulating and corrosion resistance.
Ready to apply the right materials in your next project? Check out our step-by-step guide to selecting the right circuit breaker mounting hardware kit for secure, code-compliant installations.
Consequently, choosing appropriate hardware materials can significantly extend the lifespan and efficiency of the entire system., selecting the right hardware is essential. In each case, choosing appropriate materials ensures your installation is built to last — both electrically and structurally.
By taking the time to understand each material’s unique advantages, you can make an informed decision that ensures your mounting hardware not only stands the test of time but also provides optimal safety and performance for your commercial or industrial operations.