Terminating Aluminum Wire
April 1, 2006
Q: Is there a requirement in the National Electrical Code (NEC) for the use of an oxide inhibitor on aluminum conductor terminations? Some lugs are provided with an antioxidant paste supplied by the manufacturer and some are not. Some cable and wire terminal manufacturers that do not provide a compound in the lug suggest that an antioxidant paste be used but do not require it.
A: There is no rule in the NEC that requires an oxide inhibitor at all aluminum wire terminations. In fact, this sentence appears in Section 110.14 of the Code: “Materials such as solder, fluxes, inhibitors and compounds where employed, shall be suitable for the use and shall be of a type that will not adversely affect the conductors, insulation or equipment.”
This information appears in the General Information for Electrical Equipment Directory (White Book) published by Underwriters Laboratories Inc. under the title Wire Connectors and Soldering Lugs (ZMVV): “Some connectors are shipped prefilled with conductor termination compound (antioxidant compound). For non-prefilled connectors, conductor termination compound may be used if recommended by the connector manufacturer as preliminary preparation of the conductor. Wire brushing of the conductor may also be performed if recommended.”
Underwriters Laboratories listed conductor termination compounds are available. These compounds retard oxidation at the connector-conductor interface, and they do not have an adverse effect on the conductor metal, insulation or equipment.
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