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  • Writer's pictureNathanSpeir

What is all this new fault protection? GFCI? AFCI?



If you have had a recent house inspection or service visit from an electrician, there is a good chance you have heard of terms like ground fault, arc fault, GFCI, AFCI, and so on.

If you are still looking for a better explanation about those things, look no further, this brief article is it - I hope.

Simple explanations for common current leak/fault protection:

Ground Fault: When electricity goes somewhere it was not intended to go...good chances are that someone/something will get shocked unless a GFCI device interrupts that fault. Example: electricity starts going across the bare earth or a pool of water.

GFCI = Ground Fault Circuit Interrupter

Arc Fault: When electricity starts moving towards another conductor intermittently...good chances are that a fire might result unless an AFCI device does not interrupt that fault. Example: nail driven through/next to a conductor.

AFCI = Arc Fault Circuit Interrupter


Well there it is - in short. Now to back up a bit and elaborate on this a little further would probably make for a better article then a brief text that would almost fit well in a social media post. GFCI is not that new at all and AFCI, by my standards, is still - kinda - new.


First off, the context of electricity we are discussing here is alternating current that is designed to go from point A to point B. Point A would be the power source (like a circuit breaker) and point B would be the thing that is supposed to work when it gets power (like a switch or light or receptacle). In the ideal installation, electricity safely moves between those two points without interruption and without fail.


Second, current leakage is when that electrical current gets off of its intended path for one reason or another. Think about water dripping out of the faucet when it is supposed to be off already or a hole in a garden hose that spits out water continuously as water simultaneously runs through the hose end. Using the illustration of a dripping faucet, we can create a rough parallel to the current leakage that happens during an arc fault. In an arc fault a momentary amount of current is "leaking" or arcing out beyond the path that the electrical current was intended to encompass. Likewise, the hole in a garden hose can roughly illustrate the "leakage" that is happening when a ground fault occurs and electricity continuously pours out into some other conductive field that it was never supposed to in the first place.


Third, either additional fault protections described here (GFCI or AFCI) is often advised to and/or required to have installed in applicable situations in both dwelling places (homes) and other buildings (including businesses). The fine line between "advised" and "required" greatly depends on the area you live or do business in and what National Electrical Code edition that local jurisdiction has adopted to enforce. Licensed electricians are supposed to be informed and up to date on how these rules apply so that they can determine the best course of action for installing GFCI or AFCI protection on a circuit. There are some situations when both GFCI and AFCI are required on a circuit and a dual function protective device might be installed to achieve that. Often, in situations of new wiring installations and even some repairs, an electrical permit will be part of the electrical service process, and in that situation, if there is still confusion (but hopefully NOT) on that matter by the time there is an inspection for work done, the electrical inspector will be the one to rule out any confusion on that matter and enforce the interpretation of the NEC as best as he or she can.


Fourth, the way the fault protective devices are installed, at this time, are either by means of a receptacle or circuit breaker that provides the applicable fault current interrupting device. On average, the receptacles can be a more economical choice, but in other cases, the circuit breaker might cost more itself but take less labor to install by a capable electrician. Both receptacles and circuit breakers that provide either GFCI or AFCI protection will have some identification, in small writing, with at least the abbreviated protection that it provides on it. There will also be a test button where you can push to test that the device actually works. Testing your GFCI or AFCI receptacles or circuit breakers once in a while is a good practice...like testing your smoke alarms...to ensure that they will actually work in the moment you need them to the most. If you choose to do the tests, please note that the receptacles have a reset button, and the circuit breakers will trip when tested (which means that it works still). Turning the circuit breaker handle of the circuit breaker all the way to the OFF position first (if it is not already) will reset the mechanism and allow you to restore power when you turn the handle back to the ON position.


Finally, there are some good reasons to both love and hate these devices. On one hand, the whole intent of these things is to help save lives and equipment from damage and or fatality. These devices are designed to interrupt within a small fraction of a second in response to a specific pattern of imbalance across the circuit within a small fraction of one ampere. It is impressive and very important, because beyond those measures, heart filtrations and/or fires can occur under the right circumstances. Ok. On the other hand, these devices are far from perfect, extra special intuitive AI, or anything close to sentient beings watching out for the salvation of mankind (sorry overkill there). GFCI and AFCI devices respond to patterns that are indicative to current leaks that USUALLY ARE, but, other non-linear equipment with motor loads and other inefficient imbalances in a circuit can cause these device to trip when they really do not need to. One example I have seen, several times over, is a freezer or refrigerator plugged into a GFCI receptacle in a garage that already operates a few other things as well like battery chargers. As soon as that compressor in the fridge kicks on, the GFCI trips - not because there is a ground fault or because there is an overload on the circuit (which if that was the case, the circuit breaker would have tripped) - it trips because the momentary spike of current from the compressor reads like the pattern of a current leak to the GFCI receptacle. GFCI receptacle does not know the difference. Another brief example in AFCI devices, when a bare ground wire is tucked away in an outlet box and the conductor gets too close to the a live terminal screw it will trip the AFCI device not because any arcing has occurred yet, but because that bare ground wire crossed the magnetic field of a live conductor and it automatically created the pattern of a current leak indicative to an arc fault. There was no blow out or arcing...yet, and in that situation it could almost be called a nuisance rather then a life saver. So the flip side is that these device can cause nuisance trips if the right precautions are not taken both : 1)during the installation 2) during the life usage of that fault current device.


I realize some additional illustrations or photos would truly take this article to another level and it is possible in the future I may just revisit this posting and add some of my own. I do hope this has been been a helpful or at least amusing read if you made it this far. Please always consider consulting or just outright hiring a licensed electrician to help you with your current fault protection and other electrical projects at your home and business. If nothing else, consider that a little common sense and humility will help you make the right call before you have to make the hard call.


Until next time, be safe out there.


~ Nathan S. Speir


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