Teardown: Leviton Ground fault circuit interrupter

[@Siniverisyys]

I was just installing some GFCIs and was curious what was inside and how they worked exactly. I got a lot more than what I bargained for with this video. Good stuff thanks!

[@roshanrewane7125]

High quality and most underrated video

[@Kamel419]

ngl, by the thumbnail i thought this video was going to be useless. very impressed by the technical detail, great job

[@dimtraveler589]

Nice presentation... The way how ground/neutral path causes oscillations needs better explanation. In fact, it only works because ground and neutral are connected on electrical panel on the source side, and shorting it on the load side creates a coupling winding between coils, and thus enabling positive feedback. This circuit may also trip if some high-frequency current is present in the load (as with modern switch mode power supplies). To fix that, many recent GFCIs have a capacitor in parallel to sense coil to reduce sensitivity to high frequency noise.

[@hoodhomesgardens]

Loved the advanced description.

[@mcdouche2]

The man in this video looks like he is constantly holding back laughter from and inappropriate joke he recently heard.

[@kenbrown7963]

Very good presentation, but an error in the beginning saying Neutral current is sensed to trip the GFCI. Of course you know it is unbalanced Hot and Neutral currents NOT Neutral current by itself. Of course there should be Neutral current.

[@andysamsung3140]

Amazing flow of information, thanks!

[@peppermintt5979]

The wire set GFCI I have installed in my car for the Tea Engine is triggering. It's very useful for me to understand fully how they work. It will help me track down the problem -- I need to have tea brewing in my car again!

[@gaad7938]

At 0:17 you said that GFCI's trip if they sense "current flowing in the neutral wire". THIS IS INCORRECT! GFCI's detect the DIFFERENCE in current between hot and neutral, not the presence of current in the neutral.

[@bobflannagan7262]

Very fine video. Thanks!

[@wilgo45]

Good video. Very informative

[@mrrodneyalong]

With this particular gfci receptacle would I need to ground the metal box it was placed in. I was told that simply installing it into the metal box would ground the box with out attaching any additional wires to the box itself.

[@xtrchessreal]

I kinda figured it was a NAND and XOR type logic but wasn't sure how it was applied. Thanks for the video.

[@theblinkstykrab3106]

🤓🤓🤓

[@billybudd340]

Any ideas why my gfi trips when a fountain pump is turned off? It trips about every 20th time that the pump is turned off. I've replaced the plug and the pump.

[@colinellicott9737]

It may be due to leakage current anywhere in the circuit due to water and or humidity in the environment.

[@lampoyo]

wow, thanks for an awesome video!

[@aubreyroche5080]

Are we Protected from Electrical shock from a Two wire Outlet down stream of a GFCI ?

[@hawkwind769]

Yes. One GFCI can protect anything downstream... Ground wire isn't necessary, but recommended.

[@dimtraveler589]

You are partially protected - if you touch the live wire and stand on the ground or touch metal enclosure of grounded equipment. You are NOT (!) protected if you decide to hold live and neutral wires and not touch anything else (eg. insert two nails in the outlet and touch them both). That is because your body will be a normal electrical load, and no current path to ground. Use tamper-proof outlets for physical protection against kids as required now by the code for anything installed below 6ft from the floor.... 🙂

[@Coldbrookdangee]

What’s the difference between the line and load side on GFCI? Why can we not join the neutrals together?

[@dimtraveler589]

The interrupter coil is powered from the line side. There will be not enough energy to complete disconnection if the power in solenoid disappears mid-way. On the second question: if you connect neutrals externally, the GFCI will trip because of both the current through sensor coil will be unbalanced, and (!) because the circuit will start oscillations as the coils now have common winding (see above). So it will immediately tripped when powered.

[@okaro6595]

On the load side you can connect other outlets that are also protected. Line is where the current comes. You do not join the neutrals as the GFCI needs to be able to break the connection.

[@Intense_Cloud]

Great!

[@tedlahm5740]

Test button function. Load side hot to line side neutral?

[@Sastas]

I'm curious if someone wire the GFCI wong(swap hot and neutral) will it work or trip instantly or not working at all? As it is a "simple" electromagnetic sensor I believe it should be okay, but I'm not sure. I'm not an electrician, but an engineer, and in the office it lead to quite an argument what will be the resoult.

[@dimtraveler589]

IMHO, it will work exactly the same (given that you did not switch input and output ports) - because schematic is symmetric wrt the pass-through wires. It will even detect ground and neutral shorts. This part is not clearly described, but eventually this short creates a common winding loop between two coils and thus it will create positive feedback between "sense" (input of the amplifier) and "grounded" (output) transformers. This feedback results in oscillations whose swing will trigger detector. It will be clear once you notice that pin 1 is output of the amplifier and the "grounded" coil is actually NOT sensor, but rather a transformer. The fact that both phase and neutral wires run through it makes design symmetric wrt swapping wires.

[@xtrchessreal]

IMHO if you thought you were smart enough to wire it but didn't double check your work with a simple outlet wiring tester, you know the one with three lights, then you deserve the mess that will be created later by your incompetence. Thus your engineering buddies should consider it moot. Humans that cannot overcome their environment will eventually either suffer a genetic devolution that leads their new branch toward a death or die outright, before spawn preferably.

[@disabledvet5127]

I need some info. I had a 35 dollar gfci plug in my kitchen and all of a sudden it just starts rapidly clicking. I tried the test and reset button and neither one would click. Then it starts clicking again really fast and then it starts spitting smoke. I had to flip the main house breaker cause all the lights were dimming and surging. So I open the plug up and inside at the top of the plug is a plastic spool with lots of copper wire spun around it. That's what caught fire. Does anyone know what that spool is , what it does , and how it failed ? And why I couldn't reset the plug or why it didn't trip the 20 amp breaker it's on?

[@notsure1232]

3:00, toroid sensor arcing? Once it arcs out the rest of the chip probably fried, along with the solenoid function of disconnecting power. Check for correct wiring, humidity (if applicable), or possibly an overdraw on the circuit (motor, dryer, fluorescent lamp?). Breaker stays on unless tripped by a higher current

[@donaldlee6760]

I'm curious if the circuit is normally open or closed. If normally open, and the circuit must actively close the circuit to power the receptacle, then if the gfci is broken then would if fail in the open (no power) state. I'd assume this is desirable.

[@stefanslaw1140]

This example is not exactly correct. If the GFCI in a test circuit I setup is unplugged open, then it will be open when plugged in again. If it is closed and unplugged, then it will be closed when plugged in again. Why? The open or close state is mechanically done by either pushing the reset button or the test button. So, how the failure happens, determines the On or Off state, even if broken. Of course, if the mechanical latch part has failed, who knows what the failure state will be when the mechanical part is broken? JMO.

[@donaldlee6760]

@@stefanslaw1140 - thanks for the explanation. This is slightly different than what Mike Holt mentions (about Levition smartlock gfci's only), but your idea about setting up a test circuit to actually test the function is brilliant! I am going to turn off and then on the breaker to my kitchen and bathroom circuits (bathroom uses the Leviton with black/red buttons and kitchen has Leviton with white buttons) and see if I must then manually turn the gfci's back on. According to Mike Holt, the Leviton must actively close the circuit, and additionally will perform a self-check on first power up, which is unique to the Leviton gfci's. Here's the video at 7:23 where he mentions this - kzbin.info/www/bejne/poDFpIalfplgr6c

[@purpleidea]

Does anyone know what value the Rtest resistor has?

[@stefanslaw1140]

Assuming the Metal Oxide Varistor, MOV, is not in the circuit; the value would be 120 V divided by 5 or 6 mas. That's calculated as about 24,000 ohms as simulated in this test circuit setup as Rb. Stefan

[@mjr.3st116]

what's the difference between gfci outlet and gfci breaker?

[@cannonbrooker515]

Same thing ones in a outlet the other is in the panel

[@lilcanada273]

This was helpful info. But the presentation would be better if the woman was coached in speaking as if she was actually talking to students, rather than so obviously reading a script, using a flat monotone. The male presenter was much better at his presentation, with voice inflection rising and falling at appropriate times.

[@Jessebaldwin-cp1hl]

who's here after tibees

[@barrysoklofske4221]

These two are simply reciting (far too rapidly) from a script and probably know little about electronics. Still interesting to see the innards.