Tin plated lugs to silver plated busbar 1

Should not be a problem as far as UL listing is concerned as some heavy duty fusible swithes on the market use silver plated busbars connected to tin plated aluminum lugs.

However, silver plating develops a nonconductive black tarnish over time. The lugs should be installed with Ilsco Deox or Penn Union CuAl Gel on both flat surfaces of the lug, the flat surface of the silver plated busbar, and on the machine screw threads. DO NOT use Penetrox or Noalox for a flat-to-flat connection because these products contain metallic grit that will actually interfere with electrical contact. Tighten the nut for the busbar stud or bolt to full torque and that will squeeze out all excess electrical grease.

Electrical greases are purposely formulated so that lubrication failure ( metal to metal contact ) will occur when a connection is properly tightened. Electrical greases ( with the exception of Noalox ) also containe fire inhibitors as well.

Mike Cole