Which item should remain on at all times to maintain proper function in a CP system?

• A. Anode
• B. Grounding rod
• C. Rectifier
• D. Transformer

Answer: (C)

In cathodic protection, keeping a steady protective current flowing is essential to prevent corrosion. The device that does this is the rectifier, which converts AC power to DC and regulates the continuous current sent to the anodes and back to the protected structure. If the rectifier is turned off, the protective current stops and the structure no longer stays at the protective potential, allowing corrosion to resume. The anode is simply the site that receives current; it doesn’t supply or regulate the current by itself. A transformer changes voltage but doesn’t guarantee DC, and a grounding rod isn’t part of maintaining the protective current. Therefore, the rectifier must stay on at all times.