what burns out in a gfci outlet?

Discussion in 'General Electronics Chat' started by sdowney717, Apr 5, 2015.

  1. sdowney717

    Thread Starter Member

    Jul 18, 2012
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    I managed to to destroy two GFCI outlets today by shorting neutral to ground when run off a schumacher 750 watt inverter. They reset a few times but then nothing, they can not be reset. I was deliberately doing that to see if they would trip off, and they did not trip. The inverter did overload a few times before finally blowing a mosfet, which I replaced and it works again.
    The GFCI did trip off with the test button, but a direct short killed them both. Both GFCI mechanically look fine.

    I took apart the Leviton and it has a small PC board. About the only thing I could replace is a transistor.
    Do those devices have an onboard fuse soldered in?

    Over the years I have had maybe 10 of these just fail for no good reason, one day they worked, another they did not. So I would like to know are they mostly junk and designed to trip off break and not work well after some age is on them?
     
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  2. tcmtech

    Well-Known Member

    Nov 4, 2013
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    Why would you want one on anything anyway and why are you deliberately shorting your power inverter common and ground lines together?

    As far as I am concerned they are nothing more than a nuisance device I typically disable after the first time or two they tripout for no definable reason. .
     
  3. Hypatia's Protege

    Distinguished Member

    Mar 1, 2015
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    I expect the damaging 'agent' was a "voltage" transient -- in the absence of specific stipulation to the contrary, they are not intended for MSW operation... Moreover, please be advised that the output of most MSW inverters is 'balanced' about ground -- hence N-G connection is abusive to the inverter and an over-current 'stressor' to the GFCI...

    Best regards
    HP
     
    Last edited: Apr 5, 2015
  4. Reloadron

    Active Member

    Jan 15, 2015
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    We covered this in your other thread. Some will work with a MSW and some will not and there were a few "maybe". To test a GFCI you do not short anything, you use a high value resistor to give a small amount of current flow to ground causing a current imbalance to trip the GFCI. This link was part of the other thread, did you read it? GFCIs were never fully intended for use with MSW inverters, as was mentioned before and just revisited by Hypatia's Protege.

    Ron
     
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  5. sdowney717

    Thread Starter Member

    Jul 18, 2012
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    Well I ordered a Hubbell GF20L off Ebay as they seem to have a better chance of maybe surviving with GFCI on MSW inverters.
    I am more interested in preserving the inverter versus preserving the GFCI outlet, hence the wasteful testing. I think though the MSW waveforms, some are better on some inverters.
    I never had trouble with the GFCI on the large 3000 watt peak power inverter or on the 1500 watt go power inverter, this little 750 watt schumacher maybe the waveform is not as good.
    I wanted to see if the GFCI would trip off if shorted to ground and protect the inverter, and so far it wont and not willing to test that on the two better inverters I plan to use.

    I have done some searching and there is not much info out there.

    http://www2.schneider-electric.com/resources/sites/SCHNEIDER_ELECTRIC/content/live/FAQS/229000/FA229516/en_US/gfci compatabilities output.pdf

    I ran for years using the Leviton on the 3000 watt Peak Power inverter without a hiccup.
    But that devastating short to generator has me more concerned about now destroying it again if one of the lines shorted to ground. So I still don't know if a GFCI will prevent inverter shorts to ground, but I have my doubts.
    Both of the gfci outlets i destroyed were old and the buttons were somewhat sticky.
     
    Last edited: Apr 5, 2015
  6. sdowney717

    Thread Starter Member

    Jul 18, 2012
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    1 out of 8 gfci have failed on average in a home. Pretty poor really, amd mirrors my experience over the years.


    On the circuit board of the Leviton gfci, there is a tiny smd zener 4E that I think failed. It reads 23 ohms either way.
     
  7. Hypatia's Protege

    Distinguished Member

    Mar 1, 2015
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    Connection of either output line to ground is highly abusive to the inverter inasmuch as such is, in essence, 'shorting out' half of the output bridge while, effectively, bypassing the overload protection... Also such a test is not a reliable assay of GFCI suitability. If you insist upon such 'testing' please use a resistor!, you'll get the same results sans equipment damage -- but, again, unless so certified, the GFCI is not reliable in your application! I don't know how else to say it!:rolleyes:

    Best regards
    HP
     
    Last edited: Apr 6, 2015
  8. WBahn

    Moderator

    Mar 31, 2012
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    Boy, I'm sure not average, then. Over the last twenty years I've owned three homes with numerous GFCIs in them and I have yet to have one fail. I've had a few trips, but I'm pretty sure I know what caused each of them. Just as I'm pretty sure I know what caused each of the occasional circuit breaker trips over the years. This house is almost twenty years old and has at least a dozen GFCIs in it and, to the best of my knowledge, they are all original to the house.
     
  9. Hypatia's Protege

    Distinguished Member

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    That's what you get for using the test button instead of a jumper lead!;)

    If it doesn't snap, crackle, pop, burn or just plain explode you're not tryin' hard enough!;););)

    Best regards
    HP
     
    Last edited: Apr 5, 2015
  10. sdowney717

    Thread Starter Member

    Jul 18, 2012
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    Here is a pic of the GFCI board showing a diode marked 4E. It definitely says 4E, not 4F
    I think it is a zener diode? It has a bar on one side, and board says Z1

    What can cross this to with leads, can anyone link me to what this component is right above the C8?
    It reads the same 23 ohms either way, so if it is a diode then it is shorted. I checked all the other smd items including the diodes down lower not being shown and they seem normal, but I cant do much with the little IC, although it is not shorted.
    [​IMG]

    http://www.faidatepc.it/images/articolo_componenti/smd_code_book.pdf
    I see several 4E at that web site, but none are diodes?
     
    Last edited: Apr 6, 2015
  11. WBahn

    Moderator

    Mar 31, 2012
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    Unless you are taking it out of the circuit, measuring the resistance if meaningless. How is it that your meter is supposed to distinguish between that component and the entire rest of the circuit that is in parallel with it?
     
  12. sdowney717

    Thread Starter Member

    Jul 18, 2012
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    I think suspicious that it reads the exact same ohms though forward and reverse polarity even in the circuit.
    The other diodes on the board read normal - ok in circuit using diode test function and ohms.
    Still dont know what this component is.
    I cant check the small IC or the smd caps, but they are not shorted.
    Not sure I want to spend any money on it, but I might have a free part here in some other device.
     
  13. WBahn

    Moderator

    Mar 31, 2012
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    What would you expect the reading to be if there is a 23Ω resistor in parallel with that component? Would you expect it to read different forward or reverse? Maybe, maybe not. Depends on the specs of the zener (assuming that's what it is) and of your meter.
     
  14. Hypatia's Protege

    Distinguished Member

    Mar 1, 2015
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    What are you looking to find via your postmortem of the GFCI? Obviously they're not appropriate for your application! Without wishing to appear 'owly' one wonders why you make inquires only to dismiss all responses and proceed regardless?!

    With jaded regards
    HP
     
    Last edited: Apr 6, 2015
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  15. studiot

    AAC Fanatic!

    Nov 9, 2007
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    I must remember this form of words, it could be the mark of a gentleman or woman.

    It is certainly much gentler than the tool room expressions I and other engineers normally use in these circumstances.
     
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  16. Reloadron

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    Jan 15, 2015
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    Classic stuff, truly classic. :)

    Ron
     
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  17. sdowney717

    Thread Starter Member

    Jul 18, 2012
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    Xantrex tested some GFCI outlets and I noticed all the Hubbell worked, so not necessarily true nothing will work with an msw inverter.
    http://www2.schneider-electric.com/resources/sites/SCHNEIDER_ELECTRIC/content/live/FAQS/229000/FA229516/en_US/gfci compatabilities output.pdf

    Maybe Hubbell work better, so anyway I need one so I got one. I wont be deliberately test shorting it. And I did say the Leviton worked for years with the 3000 watt peak power inverter.
    People say I am dismissing all responses-principles, but I think your ignoring what my experience showed me too.
    http://www.hubbell-wiring.com/press/pdfs/H5212.pdf

    And I still think these GFCI outlets are deliberately designed to be throwaway consumables, as the MikeHolt NEC video says, typically 1 in 8 in a home are in failure mode without the home owner knowing so, which mirrors my experience over the years. The first GFCI I cooked, I visited my brothers house and it was very cold so I plugged in the diesel's block heater in his gfci, in the morning the gfci had failed and I had to buy him a new one, so it failed just because it got used?
    It did keep the engine warm overnight, but failed to reset on test.

    The GFCI on my deck, I have replaced twice in about 15 years, they also just stopped working on test. Right now one bathroom GFCI has power, but the test button refuses to push, it is internally stuck.

    I think eventually, I will have another Leviton fail, and maybe can use for parts the little 4E device.
     
    Last edited: Apr 6, 2015
  18. studiot

    AAC Fanatic!

    Nov 9, 2007
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    If you were in the UK, bathroom power outlets of any sort except isolation and saturation limited shaver sockets are illegal anyway.
    Even ordinary switches to fixed devices are illegal unless external to the room. Special switches have to be used.
     
  19. Hypatia's Protege

    Distinguished Member

    Mar 1, 2015
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    He also said that such 'failure' owes primarily to improper wiring or damage corollary to transients -- and, perhaps most importantly, that in any event proper operation may be confirmed via the test button... :cool:

    Best regards
    HP
     
    Last edited: Apr 6, 2015
  20. Reloadron

    Active Member

    Jan 15, 2015
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    Back around post #5 you mentioned:
    A GFCI outlet is not designed to protect a device, they are designed to protect people. Inverters which have various designs should include their own device protection. Well at least well made quality inverters will have their own protection schemes. If you want to test ground fault interrupters there are ways to go about it which do not include:
    So a GFCI outlet is not going to protect an inverter, it was never designed for that purpose. Testing a GFCI outlet which is connected to an inverter is relatively easy with a good DMM and a few resistors.

    Finally if I recall correctly your use of these inverters focus on Marine Applications which are quite different than many for example residential applications, especially when it comes to electrical grounding or bonding. Electrical Grounding on Boats and RVs is a good read on the subject. When it comes to boats this is another very good read of the standards. You as a boat owner should be familiar with the latter linked document.

    As to the use of GFCI outlets on a boat? I suggest you contact the GFCI manufacturer for definitive information regarding their GFCI in Marine applications with MSW Inverter supplied power and stop with the homebrew experiments.

    Ron
     
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