I was wondering if anyone could provide me with information on the research used to determine the conductor spacing requirements of IPC-2221. More specifically, why is it not material dependent and is there a safety factor provided in the spacing determination? Any help would be greatly appreciated. Thanks in advance, Craig Hillman University of Maryland Dr. Craig Hillman CALCE Electronic Products and Systems Consortium University of Maryland College Park, MD 20742 (301)-405-5316 [log in to unmask]