Environmental deterioration of aluminum-aluminum connections

Wire splice connections are investigated for deterioration due to environmental factors. The tested splices of solid aluminum and copper wires are made using twist-on connectors. Some specimen groups are exposed in a chamber at 35 degrees C and 90% relative humidity. Additional groups are exposed for ten years to a normal application environment. There is no current flow except when potential drop measurements are taken. Deterioration of the connections is indicated by increasing connection potential drop at normal circuit current levels. Splices involving aluminum wire made using a conventional installation technique deteriorate in both environments. Splices made with copper wire only do not deteriorate in these environments, nor do aluminum splices made utilizing corrosion inhibitor, abrasion of the aluminum wire surface, and pretwisting the wires. The results demonstrate that normal environmental factors can contribute to the failure of connections involving aluminum wire. The failure process starts and progresses without current flow. It is concluded that any projection of safe aluminum wire connection life that is based on current cycling without effective environmental testing may be seriously in error.<
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