Ciao Luigi! Your English is fine, don't worry. Let's tackle this problem step by step.

Understanding the Issue: Single Conductors in Metallic Conduit and Induction Heating

You've correctly identified the potential problem: running single conductors carrying significant current (for a 150kW heater) through ferrous (steel) RMC conduit can induce currents in the conduit itself, leading to heating and energy loss. This is because the alternating magnetic field created by the current in the conductor induces a circulating current in the conduit, which then dissipates energy as heat due to the conduit's resistance.

Proposed Solution: Aluminum or Brass RMC and Fittings

Your idea of using aluminum or brass for the conduit and fittings is a good one, and common in these situations. Here's why: Non-Ferrous Materials

Aluminum and brass are non-ferrous, meaning they don't contain iron. They have very low magnetic permeability. This significantly reduces or eliminates the induced currents and associated heating.

NEC Compliance (U.S. Based - Adjust to Italian Standards as Needed)

The NEC does not prohibit the use of aluminum or brass RMC in hazardous locations. In fact, aluminum RMC is a commonly accepted practice to reduce weight and address inductive heating issues.

Answering Your Questions



"Can be a reasonable solution?" Yes, it is a very reasonable and often-used solution. Switching to aluminum or brass RMC is a standard practice for mitigating induction heating when using single conductors in conduit. "Are there any restrictions in pursuing this approach?" Here are some points to consider, and restrictions that could apply, based on NEC and typical practices (adjust as needed for Italian codes and regulations)



Grounding/Bonding

Extremely important! You must ensure a low-impedance grounding path is established. This is crucial for personnel safety and proper operation of overcurrent protective devices.

NEC Requirement (Example)

NEC Article 250 addresses grounding and bonding. Aluminum conduit systems need proper bonding jumpers at all joints, couplings, and termination points to ensure electrical continuity.

Consider using grounding bushings at the entry point to the heater enclosure. These provide a solid connection between the conduit and the enclosure.

Verify the grounding electrode system is adequate for the fault current. A qualified electrician can perform a fault current study to ensure the system can handle a ground fault.

Conduit Fill

Ensure you are adhering to the permitted conduit fill limitations. Although you only have one conductor per conduit, conduit fill rules still apply. The NEC (and likely your local codes) specify maximum conductor fill percentages.

Conduit Support

Aluminum conduit may require different support spacing than steel conduit. Consult manufacturer's specifications for proper support intervals.

Corrosion

Aluminum can corrode in certain environments. If the environment is corrosive (e.g., salty air, chemical exposure), you may need to use coated aluminum conduit or consider other protective measures. Brass is generally more corrosion-resistant.

Material Compatibility

Ensure the aluminum or brass conduit and fittings are compatible with the environment and with the materials of the heater enclosure. Dissimilar metals can lead to galvanic corrosion.

Code Compliance (Italian/European)

This is the most important point. My answers are based on the North American NEC. You must verify that using aluminum or brass RMC is permitted and meets all requirements of the Italian (or relevant European) electrical codes. Look for sections dealing with hazardous locations, grounding, and wiring methods.

Manufacturer's Instructions

Always follow the heater manufacturer's instructions and recommendations for wiring and installation.

Cable Type Approvals

Verify the high-temperature cable you're planning to use is approved for use in hazardous locations and within conduit systems. It needs to have the appropriate ratings and certifications.

Recommendations


Consult a Qualified Electrical Engineer (Italian)

This is the most important recommendation. An electrical engineer familiar with Italian codes and hazardous location requirements should review your design and ensure it meets all applicable regulations.2.

Verify Code Compliance

Thoroughly research and understand the specific requirements of the Italian electrical codes and any local regulations regarding wiring in Class I, Division 2 hazardous locations.3.

Grounding/Bonding Plan

Develop a detailed grounding and bonding plan. This should be reviewed and approved by a qualified electrician.4.

Manufacturer's Consultation

Discuss your proposed wiring method with the heater manufacturer. They may have specific recommendations or requirements.5.

Document Everything

Keep detailed records of all materials used, installation procedures, and inspections.

Alternative Considerations (Less Desirable, but Worth Mentioning)



Magnetic Materials

This is generally NOT recommended, but as an extreme case, you could use ferrous conduit with very strict control of the grounding/bonding, ensuring a fully closed loop for each phase + neutral. This is difficult to achieve in practice and not typically done because it's hard to maintain very low impedance in the loop. Also, this will increase the overall temperature.

Summary:Using aluminum or brass RMC is a viable solution to mitigate induction heating with single conductors in conduit. However, it's crucial to ensure compliance with Italian electrical codes, proper grounding/bonding, and compatibility with the environment and equipment. Consult with a qualified electrical engineer to verify your design and ensure a safe and compliant installation.Good luck with your project, Luigi! Let me know if you have more questions. Flag for review