Replies to two questionnaires concerning lead and copper-jacketed cables are summarized Seventeen power companies, 10 communication companies and one electrolysis committee sent replies.
Cathodic protection criteria: Negative potentials used ranged from .05 to 0.5 volt negative, with some preference for 0.2 to 0.3 volt negative. Currents used to protect steel tape or wire armored cable were in the vicinity of 0.85 volt negative to a copper-copper sulfate electrode near the cable. On copper-jacketed cable a potential of 0.1 to 0.25 volt negative is used.
Ground Bed Design and Location: Scrap steel, iron and cable are used either in point or distributed beds. Some inert anodes are used in point beds and a few installations of magnesium galvanic anodes are reported.
Power Source: Selenium rectifiers are preferred but other kinds, including vacuum tube types are reported on.
Protection Coordination: Most users of rectifiers report some kind of protection coordination among plant operators.
Interference Filters: Used to prevent noise on telephone circuits.
Surge and Lightning Protection: Some operators provide means of grounding surges or lightning charges.
Insulating Joints: Some use is reported, especially on cables entering office buildings, between aerial and underground cables and in stray current areas. Numerous uses for, insulating joints on power cables are reported.
Protective Coatings: Some use is reported and no user reports damage from cathodic protection currents. 7.7
