Getting to grips with cathodic protection here.

If someone had a 12, 24 or 48VDC system, say solar PV and batteries, and the battery negative is earthed, this means the earth is the cathode, and the positive rail of the electrical system becomes the anode.

Is it right that in moist conditions only, that the copper of the +ive rail is now more likely to corrode than the -ive?

Is it correct that this copper +ive can be protected by attaching a zinc or magnesium block to the copper itself?

I've seen the effects of a corroded anode in old 12V solar systems, the black copper oxide is difficult to clean up.

  • \$\begingroup\$ The answer is yes and yes. \$\endgroup\$ – Dmitry Grigoryev Apr 11 '19 at 12:52
  • \$\begingroup\$ It is quite common to use nickel plated copper electrodes in this situation. \$\endgroup\$ – Peter Smith Apr 11 '19 at 12:59
  • \$\begingroup\$ @PeterSmith Re NPCEs - yes - but if I recall correctly Nickel is the 'wrong side' of copper electrochemically and the protection relies on the coating not being breached. If there is a scratch / nick / chip in the coating then corrosion can occur at the breach and will be accelerated due to the smaller exposed area handling the same corroding current. Zinc coated / galvanised protection avoids this problem. \$\endgroup\$ – Russell McMahon Apr 11 '19 at 13:21

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