Wetting current

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In <a href="/facts/Electrical_and_electronics_engineering/YYXW1KLW">electrical and electronics engineering</a>, wetting current is the minimum <a href="/facts/Electric_current/Dc1xdnUX">electric current</a> needing to flow through a contact to break through the surface film resistance at a contact. It is typically far below the contact's nominal maximum current rating.
</p><p>A thin film of oxidation, or an otherwise passivated layer, tends to form in most environments, particularly those with high <a href="/facts/Humidity/Nwb28VlT">humidity</a>, and, along with surface roughness, contributes to the <a href="/facts/Contact_resistance/m0D7MTpj">contact resistance</a> at an interface. Providing a sufficient amount of wetting current is a crucial step in designing <a href="/facts/Electrical_circuit/zt94kTW0">circuits</a> that use <a href="/facts/Switch/vqbNDgYm">switches</a> with low contact pressure. Failing to do this might result in switches remaining electrically "open" when pressed, due to contact oxidation.
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Wetting current open-in-new

Wetting current