Cathodic Protection Junction Boxes (Cathode Boxes)

Cathodic protection (CP) junction boxes, also known as band boxes or test boxes, are essential components in CP systems. They serve the critical function of connecting various elements within the system, ensuring its proper operation and effectiveness in preventing corrosion.


  • Connection point: Junction boxes provide a central point for connecting multiple cables, including those from individual anodes, structure cables, and other system components.
  • Test point creation: These boxes act as convenient test points for measuring crucial electrical parameters like voltage, current, and others within the CP system. This allows for system monitoring and performance evaluation.
  • Protection: Junction boxes safeguard the CP system components from environmental hazards like water, dust, and corrosion.

Types of Junction Boxes:

  • Anode Junction Box (AJB): This type connects anode cables together and to the system’s output cable.
  • Cathode Junction Box (CJB): This box connects structure cables together and to the system’s input cable.
  • Combined Junction Box (ACJB): This combines the functionalities of both AJB and CJB in a single unit.
  • Current Control Box (CCB): This box regulates the current output from the CP system to the protected structure.
  • Cathodic Bond Junction Box (CBB): This type connects pipelines or other metallic structures to reduce galvanic corrosion.
  • Resistor Junction Box (RBB): This box connects a resistor between the structure cable and ground.

Design Considerations:

  • Size: The size of the junction box should be appropriate for the number of cables it needs to accommodate.
  • Materials: Corrosion-resistant materials are essential for the box’s construction to withstand harsh environmental conditions.

Benefits of Using Junction Boxes:

  • Reliable Connections: Junction boxes provide secure and watertight connections for CP system cables.
  • Simplified Maintenance: These boxes offer easy access points for testing and maintaining the CP system.
  • Enhanced System Protection: They safeguard the CP system components from environmental damage.
  • Extended System Lifespan: By protecting the system from corrosion, junction boxes contribute to its longevity.


Cathodic protection junction boxes are employed in various applications, including:

  • Pipelines: Protecting underground pipelines from external corrosion.
  • Marine Structures: Safeguarding piers, docks, and other metallic structures exposed to seawater.
  • Storage Tanks: Protecting steel storage tanks from both internal and external corrosion.
  • Bridges: Preventing corrosion of the steel reinforcement in bridges.
  • Water Pipes: Protecting metallic water pipes from corrosion.

Selecting the Right Junction Box:

Choosing the appropriate junction box for a specific application depends on several factors, including the system’s size, the type of structure being protected, and the environmental conditions. Consulting with a cathodic protection specialist is crucial to select the most suitable junction box for your specific needs.

This revised text incorporates the following improvements:

  • Conciseness: Unnecessary phrases have been removed while maintaining clarity.
  • Technical Accuracy: The information remains accurate and reflects technical standards.
  • Additional Information: While not explicitly included, mentioning the importance of consulting with cathodic protection specialists provides valuable guidance.

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