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| Subject - GFCI BREAKER, HOW IT WORKS? | |
| bobo |
hello, Just exactly how does a GFCI function, compared to a standard breaker? Does the GFCI breaker more closely monitor the circuit for arcs, shorts to ground? Would a start up draw/load of a the GFCI circuit be more prone to trip the GFCI breaker, than a standard breaker? bobo |
| Electricman | A Gfci device monitors the current imbalance between the grounded and ungrounded conductors. In a class A device the trip range is between 4 and 6 miliamperes, as soon as the current in the ungrounded(hot) conductor is not equal to the return current the device will open. For example: we have an appliance drawing 3 amps, under normal operation the current will be the same in both conductors, but if we have a faulty appliance and the imbalance exceeds 6 miliamps the device will open. So, good device, 3amps on ungrounded conductor, 3amps on grounded conductor. Bad device , 3.006 amps on ungrounded conductor 3 amps on grounded conductor. The Gfci does not monitor arcs that is what AFCIs are for, A Gfci breaker will not trip if the arcing fault does not exceed the devices rating. |
| Wirenutz |  hopefully a pix is worth more words than i can type... quote: Electricman, next time your in the shop try hooking an afci up in series with a steel plate, i can weld my co name without it tripping... ~W~ |
| John A. Peters | S.F. Chief inspector told me to try dragging the arc across something like hardware cloth with 1/2 in squares. Using a file will not do it. I guess it monitors pulsing arcs. Let me/us know. I never did the test. |
| Wirenutz | we've used afci's since 99' John, most of us here get around to doing an 'arc test' , sometimes on the job within an installation imo, these afci's don't mitigate a series arc as well as they claim they do, and it's the series arc that the most common culprit, as well as the firestarter the white book stats 'cabonized' & 'noncarbonized' ,thier lingo for parralel and series i wonder what good @ 75A and/or whatever funky parameters these magic widgets employ will really do, if only because contractors are the final salepeople for this product would you pose to your customers that they would never have an electrical fire with these? seems quite a few of us have already been sold on that idea eh? ~W~ |
| Electricman | ~W~ You dont test your GFCIs with a toaster and a bathtub do ya? I am just joking of course, I never tried the test with an AFCI though, sounds interesting.Great picture by the way.
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