UL UL 20 ⑧ Underwriters Laboratories Inc . Standard for Safety General-Use Snap Switches COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL This PDF Standard downloaded from . . DECEMBER 12 .2008 UL 20 Underwriters Laboratories Inc .( UL) 333 Pfingsten Road Northbrook .IL 60062-2096 UL Standard for Safety for General-Use Snap Switches ,UL 20 Twelfth Edition ,Dated September 22 ,2000 Revisions :This Standard contains revisions through and including December 12 ,2008 . Summary of Topics This revision of ANSI /UL20 includes the following changes in requirements : Clarification of 347 V Endurance Test Contact Sticking AC Switches Grounding Symbol With or Without the Circle Text that has been changed in any manner is marked with a vertical line the margin . The revised requirements are substantially in accordance with UL's Proposal (s)onthis subject dated June 27,2008. The revisions dated December 12 ,2008 include a reprinted title page ( page1)for this Standard As indicated on the title page ( page1 ),this UL Standard for Safety is an American National Standard Attention is directed to the note on the ti...