Michael Royer wrote: > Doug, > Part 68 makes no minimum clearance. > UL 1950 3rd edition requires clearances much greater than what you have > written. The path to your exact clearance is complicated, and there are > exceptions for permanently earth grounded hosts and pluggable type B > equipment. > These exceptions are often used by rack mounted commercial gear. > > For most PCB's UL 1950 requires creepage and clearance of 2mm = 0.079" T-G, > R-G, T-GSELV, R-GSELV. > > Michael Royer > Senior Agency Compliance Engineer > BABT Approvals Liaison Engineer > N.E.T. (Network Equipment Technologies) > 800 Saginaw Drive > Redwood City, CA 94063 > Voice: 415-780-4218 > Fax: 415-780-5004 > [email protected]
Ouch! Thanks Michael. That makes sense now. I've done creepage calculations by using 3M volts = 1 meter for air breakdown. Therefore, 3,000V = 1mm, or, 1mm = roughly 0.040". To be doubly safe, 2mm = roughly 0.080" through air! Funny how that science stuff works. ******************************************************* Doug McKean [email protected] ------------------------------------------------------- The comments and opinions stated herein are mine alone, and do not reflect those of my employer. ------------------------------------------------------- *******************************************************
