Davethsparky
Well-known member
Secondary CPC's or Overlays as they are commonly known are another belt and braces practice set by the DNO about 30 years ago. They weren't convinced that the steel armouring was capable of taking the fault current. There is only one cable that I've come across where this was possibly the case and that was 185 mm 3 core.
Interesting, what influence did the DNO have over installations at the time? I don't suppose you've got any information relating to this?