There is another phenomena that seems to be world wide. It’s what I call the “Find a choke point and fill it” syndrome. Have you ever noticed that if there is a narrow(er) spot in a passageway that people just naturally stop there to converse, think about what they’re going to do next, or whatever? It has nothing to do with the increased difficulty of transiting that narrower spot, they stop and block it. Never mind that there was plenty of room not 10 feet away.
Human nature. Got to love it. Ghery ________________________________ From: [email protected] [mailto:[email protected]] On Behalf Of Kunde, Brian Sent: Wednesday, December 10, 2008 6:03 AM To: [email protected] Subject: RE: Cables On The Floor I am so glad you posted this. I have seen this phenomenon but didn’t have the guts to tell anyone in fear of being labeled crazy (again). Where I really notice this affect is when I am doing radiated immunity Calibration and I have my bright orange fiber optic cable running to my Field Probe. When people come in the chamber, I have literally seen a person try to take a step when their entire body starts to vibrate and kind of hovers just slightly off the floor moving closer and closer to my cable until “crack”. You all know what I’m talking about; the sound that is made when someone steps on a duplex fiber optic cable and it has to rotate under the weight of their foot being forced to lay flat against the floor with that scary sound. Did they break it? If not this time, surely the next. The Other (Crazy) Brian ________________________________ From: [email protected] [mailto:[email protected]] On Behalf Of Price, Edward Sent: Tuesday, December 09, 2008 8:45 PM To: [email protected] Subject: Cables On The Floor Although I am naturally pessimistic, I am not superstitious. However, how else to explain the near magical capabilities of a cable laying on the floor to attract human feet? If I lay a BNC or SMA cable (assuming 1/4" cross section by 10 foot exposure length) onto the working area (about 16' by 12'), the cable occupies only 30/27,468, or only about 0.11% of the floor area. The typical human feet cover 4" by 12" by 2, or 96 square inches. So there are 27,468/48, or 286, places where you can step in the room. You would think that the odds of stepping on the cable would be 285 to 1. But >from experience, as you talk with a visitor in the chamber, how many times have you looked down to see one of their feet planted squarely across a cable? Indeed, it's not all that remarkable for a visitor to managed coverage with both feet. Or to amble along the cable as if it were some kind of guidance wire! Some programs attract a disproportionate amount of official (management) visitors, and it was during one of those that I implemented my experiment with sacrificial cables. After walking each visitor into my chamber, while repeating the mantra of "please be careful not to step on a cable" and pointing at a cable so that they understand what a cable looks like, I began to notice the mathematical anomaly of non-random foot placement. I decided to test my suspicions, so, as we moved into conducted susceptibility testing, I laid four BNC cables around the chamber working area. (These were cables accumulated during the radiated emission test; cables which had endured numerous verified foot stomps.) Then I began watching the visitor pattern. I wish I had kept accurate data, for I'm sure that I could have produced a very important and controversial paper (that could have given me a decent vacation for its presentation). However, I am left with only the subjective memory of those trials. I concluded that cables have some kind of unexplained power to strongly direct the human mind to place a foot over a cable whenever the physical opportunity is available. Although I never conducted further trials, I have speculated as to the attractive mechanism that causes this. I wonder if it may somehow be related to the technique by which cows are kept off of a roadway (cows will not cross a couple of parallel painted stripes on the ground). True, this would be an inverse relationship, as cables attract the foot, but I think I'm really onto something important here. BTW, the test cables were all later found to be in acceptable condition, and were returned to service. I must assume that either I am being too alarmist about the dangers of stepping on a cable, or, my management just leaves no lasting impression on physical reality. More studies are needed! Ed Price [email protected] <blocked::mailto:[email protected]> WB6WSN NARTE Certified EMC Engineer Electromagnetic Compatibility Lab Cubic Defense Applications San Diego, CA USA 858-505-2780 Military & Avionics EMC Is Our Specialty _________________________ LECO Corporation Notice: This communication may contain confidential information intended for the named recipient(s) only. If you received this by mistake, please destroy it and notify us of the error. Thank you. - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. 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