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 TM 5-684/NAVFAC MO-200/AFJMAN 32-1082
Section IX - UNDERGROUND CORROSION CONTROL
5-32. Importance of corrosion control.
conductors, in which moisture serves as the electro-
lyte.
As corrosion often results in deteriorated equipment
leading to electrical outages, its control is necessary.
5-34. Prevention of corrosion.
While corrosion can occur because of many reac-
Maintenance personnel must be alert to minimize
tions, underground corrosion of metallic cable
the effects of corrosion inherent in exposure to the
sheaths and grounds is the most common and costly
elements or resulting from installation methods
type of corrosion found in electrical distribution sys-
that did not properly address galvanic effects.
tems.
a. Chemical corrosion. Prevention of chemical
5-33. Types of corrosion.
corrosion is relatively easy to accomplish by proper
painting or other surface protection.
There are two basic types of corrosion. One is purely
b. Galvanic corrosion. In electrical systems, gal-
chemical in nature and is the reaction between ele-
ments, such as water and iron to cause rust. The
vanic corrosion is caused primarily by protective
other is galvanic corrosion and is an electro-
metallic cable coverings, such as lead or steel; by
chemical reaction between dissimilar metals in an
the grounding system, which is usually copper or
electrolyte. An example of the first type is rusting of
copper coated; and by metal conduit, either galva-
a steel nail in a glass of water with no other metal
nized or ungalvanized. TM 5-811-7, MIL-HDBK-
involved in the reaction. An example of the second
1004/10 and AFI 32-1054 cover galvanic corrosion
type is corrosion between copper and aluminum
in detail.
5-18
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