Timeline for Anti-static mat connected to earth directly or 1E6 ohm resistor?
Current License: CC BY-SA 3.0
8 events
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| Dec 15, 2016 at 8:14 | comment | added | LorenzoDonati4Ukraine-OnStrike | @Lundin Well, I guess my previous comment still applies, in a sense: it's all about knowing a definite lower bound for the resistance in the fault current path. Without that resistor a faulty device on the mat could create a connection with a live wire which could end up in an excessive fault current through the mat and the user (if he is connected to ground in any other way). | |
| Dec 14, 2016 at 13:37 | comment | added | Lundin | Well this picture isn't all that pedagogical, as there is a resistor between the wrist strap and the ESD table, which in turn has another resistor to ground. The resistor to the wrist strap seems superfluous (but harmless) - I'm guessing it is only there to protect some nutto from connecting the wrist strap directly to the ground. | |
| Dec 14, 2016 at 13:25 | comment | added | Chris H | @Marty grounding cords are also used when there's no mains present. An easy example is adding RAM to a PC, where the PC chassis acts as the antistatic table mat, and is disconnected. A field technician can connect directly to the case. Another example -- testing battery-powered devices, or those fed off an isolating power supply | |
| Dec 14, 2016 at 11:17 | comment | added | LorenzoDonati4Ukraine-OnStrike | @Marty: please, read the answer from FakeMoustache. Not everything companies sell is, by itself, something that provides adequate safety margins. The resistance of the mat might be a sufficient mean of limiting ground faults currents, but you cannot predict exactly what resistance will be on the current path during a fault event. The difference between 10mA and 2mA through your heart muscle could mean death vs life! | |
| Dec 14, 2016 at 10:58 | comment | added | user127725 | Then why would a company sell grounding cords without resistor and why would they sell common ground point with no internal resistor between the mat and the ground point? | |
| Dec 14, 2016 at 10:53 | review | Suggested edits | |||
| Dec 14, 2016 at 11:02 | |||||
| Dec 13, 2016 at 22:00 | comment | added | Bimpelrekkie | +1 exactly the point I want to make in my answer. Thanks for backing that up with with info from a book. | |
| Dec 13, 2016 at 20:58 | history | answered | LorenzoDonati4Ukraine-OnStrike | CC BY-SA 3.0 |