CATHODIC PROTECTION CABLE

[zayed78]

Hi every body. AS you know we are using the Copper cable for DC power (Negative and positive cables)in the cathodic protection system and this good practice. But I was wondering if possible to use Aluminum cable instead of Copper and this due to theft cables out side our plant. Moreover, would you please tell me any previous experience with this practice and what is the Specification Data for Aluminum cable I mean standards ( ASTM,....) will be used.

Thank

Zayed

 

[bmoorthy]

From ISO 15589-2
Cables should be copper-cored, and shall be insulated and sheathed to withstand the prevailing chemical and mechanical conditions. The minimum conductor size for measurement cables shall be 4 mm2. Cables shall be sized such that no excessive voltage drops occur which reduce the capacity of the system.

As per DNV B 401

electrical continuity shall be ensured by a stranded cable (typically copper). Cables for electrical continuity shall have a minimum cross section of 16 mm2 and are to be attached by brazing, friction or explosion welding, or by a mechanical connection using e.g. serrated washers to provide a reliable electrical connection at bolt heads or washers. Any cable shoes shall have a brazed connection to the cable.

As per MIL-HDBK-1004/10
6.7.1.3 Recommended Cables for Specific Applications. Because of similarities in required characteristics of the various connecting cables in many impressed current cathodic protection systems, general specifications for cable sizes and types for many cathodic protection system requirements have been established and are given

a) Test Wires: These wires carry only very small currents and, as they are themselves cathodically protected, insulation requirements are not critical. Solid copper wires, No. 12 gauge AWG with type TW, RHW-USE or polyethylene insulation should be used for this application unless otherwise indicated by experience.

b) Bond Wires: These wires carry more current than test wires. No. 4 AWG, 7-strand copper cable with Type TW, RHW-USE or polyethylene insulation is recommended for all bonds unless a larger wire size is required for current carrying capacity.

c) Power Supply to Structure Cables: The power supply is HMWPE insulated 7-strand cable, usually in the size range of No. 2 or No. 4 AWG. The actual wire size should be determined by economic analysis as described in para. 6.7.1.4 but wire no smaller than No. 4 AWG should be used because of mechanical stength required.

d) Power Supply to Anode Cable:The insulation in these cables is critical. HMWPE insulation, 0.110 inches thick, as a minimum, is required on these cables. The anode connection wire is usually No. 8 AWG with HMWPE insulation. The wire used to interconnect the anodes and to connect the anode bed with the power supply is commonly in the range of No. 2 AWG or larger. The actual wire size should be selected based upon the economic analysis but should not be smaller than No. 4 AWG because of
strength.



My view :: Aluminum cables are not recommended. Under certain circumstances, Aluminum may become anodic and may get consumed.