Doug McKean's answer is sound, but another theory might contend that it is preferable to put the equipment switch first, to help assure that the fuse will not be carrying current when it is pulled. Remember, we are dealing with lay consumers here, who might assume everything is safe when the switch is off. I think that the original question was wondering if there is some official standard or commonly accepted practice. I, too, wonder if one theory is more prevalant.
-------------------------------------- Jackson, William L wrote: > > Good Morning List, > > Does anyone know of any standards that provide guidance on where in-line > fuses must be located in relation to the power switch; 1) before the > switch, that is connected to the EMI filter or line, or 2) after the switch > ( to the load side)? The power switch and and fuses (LN) are both on the > front panel of an electronic drawer which primary power is 115VAC. We have > researched both the IEC 950 standard and the 1990 National Electrical Code > book and found no clear guidance. Also I would be interested in your > thoughts on the rationale or justification for location. > > TIA > Bill Jackson > Product Safety > Harris Corp > RF Communications Div > [email protected] The location of primary fuses has always been more of a common sense thing for me. It should be the first device in the product that is connected to the hot ac line. The fuse is a sfaety device and connecting anything that could "fail" before a fuse is defeating its intended purpose. Just my two cents. ******************************************************* ------------------------------------------------------- The comments and opinions stated herein are mine alone, and do not reflect those of my employer. ------------------------------------------------------- *******************************************************
