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Is antioxidant paste code required for aluminum wire lug connections?
Saturday, January 29, 2022
There is no specific code requirement for antioxidant paste at the lug connections of multi-strand aluminum wires in electrical panels. Also, some aluminum wire manufacturers and panelboard manufacturers now no longer require antioxidant paste for aluminum wire connections using their products.
The only National Electrical Code (NEC) reference that could be considered as requiring antioxidant paste is at NEC 110.3(B): Installation and Use. Equipment that is listed, labeled, or both shall be installed and used in accordance with any instructions included in the listing or labeling.
This seems to mean that sometimes it’s required, and somtimes it isn’t, and you many have to do some research to determine which it is. But if a building official insists that 110.3(B) means you need antioxidant paste, well…just do it.
We do not call out the lack of antioxidant paste at lug connections for a modern panel because of the uncertainty of whether the requirement applies. But all older panels and wiring required antiox paste at the lug connections, and for a good reason. The first photo below is of a 1970s era panel that has had no antiox paste at the wire connections for many years, with wires coated in a layer of non-conductive aluminum oxide. The second photo is an infrared of the same panel, showing how hot the service wires and adjacent breakers were getting.
This is definitely one way an electrical fire can start. So we do check for the paste at multistrand aluminum wires in older panels.
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