Understanding NEC Article 669: Electroplating

NEC Article 669 provides safety standards for the electrical systems used in electroplating, anodizing, electropolishing, and electrostripping processes. These systems involve high currents and low voltages, requiring specialized wiring methods and equipment for safe operation.

Scope of Article 669

This article applies to:

• Electrical components and accessory equipment supplying power and controls for electroplating, anodizing, electropolishing, and electrostripping.

Key Note: The term electroplating in this article encompasses all these processes.

Key Requirements for Electroplating Systems

1. General Requirements
   • All equipment used in electroplating processes must be identified and listed for this specific service​.
2. Branch-Circuit Conductors
   • Conductors must have an ampacity of at least 125% of the total connected load.
   • Busbars must follow ampacity guidelines as per 366.23​.

Wiring Methods

1. Systems Not Exceeding 60 Volts DC
   • Insulated conductors may be used without insulated supports if protected from physical damage.
   • Bare copper or aluminum conductors are allowed when supported on insulators​.
2. Systems Exceeding 60 Volts DC
   • Insulated conductors must use insulated supports and be guarded to prevent accidental contact.
   • Bare conductors are allowed if supported on insulators and protected up to the termination point in compliance with 110.27​.

Warning Signs

• Warning signs or labels must indicate the presence of bare conductors.
• Signs must comply with the marking requirements in 110.21(B)​.

Disconnecting Means

1. Multiple Power Supplies
   • Systems with more than one power supply must have a disconnecting means on the DC side of each power source​.
2. Removable Links or Conductors
   • Removable links or conductors are permissible as disconnecting means​.

Overcurrent Protection

Direct-current conductors must include one or more of the following protections:

• Fuses or circuit breakers.
• Current-sensing devices that activate disconnecting means.
• Other approved overcurrent protection methods​.

Applications

Article 669 is critical for ensuring safety in:

• Electroplating Facilities: Coating metals for corrosion resistance or aesthetics.
• Anodizing Operations: Enhancing aluminum surface durability.
• Electropolishing Systems: Smoothing and shining metallic surfaces.
• Electrostripping Processes: Removing coatings or contaminants from metals.

Conclusion

NEC Article 669 establishes robust guidelines for the safe operation of electroplating and related processes. These standards address the unique electrical challenges of high-current, low-voltage systems, ensuring safety and efficiency in industrial applications.