The Notices on Electrical Installation for Cathodic Protection System

The Notices on Electrical Installation for Cathodic Protection System

All electrical installation works shall be undertaken in accordance with international (or other applicable national) electrical safety standards. Below are some notices on electrical installation for cathodic protection system.

Note 1: The electrical power supply for the cathodic protection system may be provided by transformerrectifier(s) powered by an electrical supply from a mains voltage distribution system.

The direct current and monitoring cables of a cathodic protection system are all classified as “extra low voltage” (ELV) in accordance with IEC 61140.

In addition to the particular requirements of the cathodic protection system, the following electrical safety measures shall be applied to all installations:

a) mains voltage cables shall be electrically isolated and separated from low voltage direct current cables in accordance with local regulations;

b) cables shall be uniquely identified at the direct current power supply, at any junction box and at their point of connection;

c) cables shall be adequately supported and protected from environmental, human and animal damage;

Note2: In locations where there is high risk of damage, cables may be embedded into concrete or may be protected by steel wire armouring.

d) except for the cable connections covered in item f), cable connections shall only be made at locations in enclosures or junction boxes;

e) connections inside boxes, whose construction and/or installation renders their environmental protection rating below the worst case external environmental exposure, including boxes with
non-sealed conduit entries, shall be made by methods suitable for long-term water immersion;

Note 3: Connections inside water resistant or sealed boxes constructed and installed with an environmental protection rating above the worst-case external environmental exposure may utilize copper
or brass threaded or proprietary connection assemblies.

f) it shall be permissible for anode/cable connections for anodes, e.g. activated titanium mesh, which are to be permanently embedded in an overlay material to be installed without junction boxes if the anode/cable connection and its method of electrical/mechanical/moisture sealing can be demonstrated by trials or past projects to enable the requisite performance to be achieved;

g) anode systems for which there is no overlay or electrical barrier to prevent direct human or animal contact, e.g. conductive coating, shall be limited to a supply voltage of 24 V DC with a maximum ripple content of 100 mV RMS;

h) equipment shall be marked with all relevant electrical safety/testing/maintenance markings in accordance with national and International Standards.

Note4: The electrical characteristics required of the low voltage direct current circuits of cathodic protection systems may render full conformity to European (or national) electrical safety standards inappropriate in one respect; the normal requirement for isolation between all power circuits and the safety earth. This is due to the negative pole of the cathodic protection circuit (the steel reinforcement or embedded steel) often being electrically earthed (connected to the safety earthing or lightning protecting system), thus, preventing the normal requirement for isolation between all power circuits and earth.