> From: Doug Beckwith > Sent: Friday, December 03, 2004 6:56 AM > > I suspect that 100% of people in the engineering > profession have > experienced it because we tend to ask "I wonder > what happens > when......?" > > Doug >
And some inadvertently. Product safety engineers seem to take many chances with their persons. No matter how wary we think we are or how careful we believe ourselves to be, we commit the very acts we intend to protect others from. Another anecdote of a _one_finger_ electric shock: While working on a product, I was demonstrating to a safety agency engineer that a product had an accessibility issue that was a risk of electric shock. The product was sitting on an static dissipative bench top, with a 1-? in. tall fan module (otherwise secured with knurled thumbscrews) removed. Mains voltages were accessible through the opening on a PWB mounted, right-angle connector. The unit was connected to a 120V source, with power switch on the power supply in the OFF position. What I neglected to consider in that moment of glory, was that the very accessibility issue I was demonstrating with my finger was that the power supply switch did not disconnect mains voltages from the entire product. To receive this shock, I had to bridge phase and neutral, so the current path through my body was very limited. I consider myself lucky that my reaction did not do more than take a little skin off my finger, by scraping it along a sheet metal edge at high velocity. A phantom shock anecdote: At another time and working with another product with the same agency engineer, I reached out to adjust a potential on a power converter sourced by a test sample when my cell phone range. The cell phone (at my hip) was set to vibrate. In retrospect, I'm not sure which was more precious: my reacting (which was identical in gesture to the above real shock scenario, though without injury) or the look on the agency engineer's face when he saw my reaction. Regards, Peter L. Tarver, PE [email protected] This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] Instructions: http://listserv.ieee.org/listserv/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Ron Pickard: [email protected] Scott Douglas [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
