Is it safe to paint Metal-Clad/armored electrical cables?
Yes. If it is bare and unpainted then it needs an oil-based primer (Red Oxide unless it is galvanised or other non-ferrous), you could get away with any oil-based undercoat however. Do not put water-based wall emulsion straight on it as the water would react with the metal and rust/stain. Fine to emuslion after sealing or priming with oil-based paint though.