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I noticed my tooth brush wasn't charging one morning and none of the plugs in my bathroom were getting power, I went down to the circuit box and saw a flipped breaker so I flipped it back and it immediately tripped again. I tried it once more with the same result so I started to investigate the plugs in my house to see if anything was obviously wrong.

The external GFI on my deck had obvious signs of smoke on the siding so I disassembled the outlet and the entire back of the GFI blew out.

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Is that a normal failure mode? Could it be a manufacture defect / installation issue?

There was obviously a lot of heat as the wire connectors appear scorched and the box is filled with a thick black soot.

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Do I need to worry about additional damage to the wires beyond what is visible in the box or can I just remove the damaged wires and install a new GFI? Time to call an electrician?

Additional GFI Outlet Images

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    What type of cover did it have? My guess is water went in thru the face and saturated the circuit board inside. The wire insulation (except the crispy ends) remains intact, suggesting the fire came from within the GFCI, not the area beside or behind it. – Tyson Nov 12 '18 at 14:19
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    This is why I don't like putting GFCIs outdoors. Did you disassemble it with the power on? – Harper - Reinstate Monica Nov 12 '18 at 16:30
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    Others have noted that the box is almost certainly not rated for outdoor use. But the thing that no one has mentioned yet that struck me as very odd is: why is your bathroom on the same circuit as your exterior outlet? Bathrooms are supposed to have a GFCI-protected circuit just for the bathroom plugs. This sounds like a good opportunity to review all the wiring in your house, because we've just seen that there are serious fire risks and code violations; there are probably more. – Eric Lippert Nov 12 '18 at 17:30
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    Speaking of which, a common mistake I see is to put the bathroom GFCI on the same circuit as the bathroom lights, which is completely wrong. If the GFCI trips because you got water on the electric shaver plug, you don't want the lights to go out. Make sure you double-check that while you're doing your review of your electrical system. – Eric Lippert Nov 12 '18 at 17:32
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    If you flip a breaker and it immediately flips back STOP! You shouldn't try again - the fact that it's immediately flipped means that something very, very bad is happening somewhere along that path. – Wayne Werner Nov 13 '18 at 0:55
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This happens all the time if an exterior GFCI is not weather-resistant. I've never had a weather resistant GFCI go up in smoke.

Yes, they can be in a metal box, but they still should be marked WR (weather resistant) - this means the electronics inside are coated to reduce the chances of moisture causing exactly what happened with your GFCI.

If it had shorted to the box, the metal screw would have arced and tripped the breaker. If it had shorted on the load side, it would have tripped the GFCI. But, in this case, enough moisture got in and the electronics shorted and let the magic smoke out.

Last item on the list is that it should have an in-use cover or an extra duty cover, that allows a cord to be plugged in with the cover protecting from rain.

In this case, replace your GFCI with a WR rated GFCI and add an in-use cover to greatly reduce the chance of this happening again. In some jurisdictions the local ordinances require the outlet itself to be GFCI so it can be reset (not running cords inside because of tripping the GFCI in wet grass with an electric mower is the "why" the inspector told me).

  • 2
    This exact same situation happened to me with a weather-rated box. As is often the case with catastrophic failures of safety systems, multiple things had to go wrong at once. In my case, the box was properly sealed from the outside but where the wires entered the box from inside the wall was not sealed; the GFCI was near a hose, and the hose fitting had a slow leak inside the wall that dripped onto a wire, that led to the GFCI, and got it wet without ever causing a ground fault. Had I not smelled the burning plastic and immediately turned off the power, bad things could have happened. – Eric Lippert Nov 12 '18 at 17:27
  • Thank you for the advice, do I have any concern of damage to the wires outside of the box? I am comfortable replacing an outlet (using the appropriate rated outlet and in-use cover) but I was concerned that the heat might have cause some damage to the wire further in the wall. – almarshall Nov 12 '18 at 20:26
  • Note that most GFCI outlets can be installed to protect additional "downstream" outlets. On my house the GFCI are all indoors, but then wired to protect the outdoor ones. This is occasionally inconvenient as I don't always remember which ones protect what, but the expensive outlets are safe from water and people driving away without unplugging their block heater. – Perkins Nov 12 '18 at 22:26
  • @almarshall The wires should be rated with safety margin - you'd rather see a faulty device on fire than a wires in your wall. Only the terminals were at risk and the spread of the damage is limitted by heat conductivity of the wire and ambient temperature. – Crowley Nov 12 '18 at 22:39
  • As far as wire damage it would not extend outside the clamps. I would check the insulation at the clamps in the back of the box if it is good there and to the ends of the wires put in a new WR GFCI and in-use cover and power it up. – Ed Beal Nov 12 '18 at 22:49
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Move the GFCI

GFCIs have sensitive electronic components, as you found out the hard way. A regular outlet does not. If you can move the GFCI protection to an indoor location and then replace this with a regular receptacle, that would solve the problem permanently while still protecting against ground faults. Two options:

  • Earlier in the chain. If there are other receptacles as part of this circuit before this outlet (e.g., possibly the bathroom that is on the same circuit), replace one of those with a GFCI receptacle. Just make sure that you use line vs. load correctly so that this receptacle is protected (on load screws).

  • At the breaker. If you have sufficient space in your panel, replace the regular breaker with a GFCI breaker. That will protect the entire circuit.

As already noted, you should have an in-use cover on any outside outlet. This will help prevent nuisance trips due to moisture, though it is not a 100% cure-all and therefore moving the GFCI inside makes sense in any case.

Based on additional comments: It appears that the bathroom receptacle already has GFCI. If that is the case then (a) no need for a GFCI breaker and (b) need to check whether the outdoor receptacle (and any others in the circuit) is pigtailed to share the line connection or is actually using load. If the outdoor receptacle connects via load then it is already protected. Open up the bathroom receptacle box. If there are wires on both line and load, then wire up an ordinary receptacle in the outdoor location. Make sure it works. Then press the TEST button in the bathroom.

If the outdoor receptacle responds to the bathroom TEST button (i.e., when TEST is pressed, both bathroom & outdoor have no power, when RESET is pressed both bathroom & outdoor have power again) then you do not need a GFCI on the outdoor receptacle because it is already protected in the bathroom. Only one is needed but keep in mind that it protects "outward" - i.e., if the sequence is breaker->bathroom->outdoor then a GFCI breaker or a bathroom GFCI will protect bathroom and outdoor, but a GFCI outdoor will NOT protect the bathroom (though as we've discussed, you shouldn't put the GFCI outdoors anyway).

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    Add an in-use cover and this would be a better answer because moisture getting into an exterior outlet can trip the remote mounted GFCI. – Ed Beal Nov 12 '18 at 17:29
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    The in-use cover is required by Code (even though they don't work) and having the indoor GFCI trip is a vastly better outcome than OP. – Harper - Reinstate Monica Nov 12 '18 at 18:24
  • @manassehkatz If I am replacing the breaker is it worth getting a dual function AFCI/GFCI or is the GFCI generally considered suffcient? – almarshall Nov 12 '18 at 20:32
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    An AFCI protects against different types of problems than GFCI. Is it probably a good idea, yes. But the key issue with both an outdoor outlet and a bathroom outlet is to protect against ground faults, which is what GFCI does. AFCI protects primarily against wiring faults, which can happen anywhere - more of a fire prevention issue than a life safety (electrical shock) issue. – manassehkatz-Reinstate Monica Nov 12 '18 at 20:48
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    You might find AFCI functionality to be problematic hair dryers and electric hand tools used outside can cause AFCI's to trip because they think the brushes in the motor are wiring failures. They have gotten better but I would use a GFCI only until they get the bugs out. – Ed Beal Nov 13 '18 at 14:14
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Exploding and burning equipment is not normal at all. Except for cases you are pyrotechnist and it burned/exploded intentionally.

There is no shame to admit limited knowledge about electricity and call an electrician to fix the issue. To be honest, this is the only sane way to go, unless you know what you are doing and why you are doing it bloody well. Shame is when one does not admit lacking knowledge and sets own house on fire accidentaly.

Any receptacle, connection and device shall be tested for a proper IP code to its use. Indoor receptacles are sufficient with code IP30 (protection against tools with diameter greater than 2.5 mm and no protection against water), for outdoor receptacles look for code IP65, IP68 for being sure. Materials are usualy not the concern here - the interior shall be dust-free and dry and the parts are well insulated when dry and clean (IP00).

Your receptacle was IP30 at most - no dust protection and no water protection. What happened to you was crossing the circuits within your receptacle by rainwater mixed with dust. This is conductive enough to shortcircuit anything behind the receptacle while resistant enough to heat significantly.

As other sugested, move the GFCI circuit indoors and use common receptacle outdors. The whole receptacle setup - box, receptacle and wiring - shall be code IP65 and more. If you move the GFCI only your breakers will be down quite often. The only improvement will be not burning the GFCI to ashes.

  • This is a DIY site telling everyone to have it done professionally is not what we are about. As several answers specify in-use covers or extra duty these covers are considered water proof by code. – Ed Beal Nov 13 '18 at 14:18
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    In this case, as someone who used to work as an electrician, I think this should be looked at by a professional. I can't tell from the pictures exactly how bad the damage is, but if I had to guess, the wires inside the box are probably damaged and may need to be replaced. An expert will know better than most people on this site. If I was confident it was just the outlet, then yes, replace the GFCI and the cover. However, I see a melted wire nut in the last picture, which concerns me greatly. Seeing that makes me thing the wires are damaged as well. – blockcipher Nov 13 '18 at 18:17
  • @blockcipher the OP stated he was comfortable doing the repair and asked the right questions about the insulation so I believe he is competent to do the repair, this is what this site is all about no electrician is really needed on site to verify the repair and there are at least 2 responding to this that regularly assist home owners in doing there own repairs. – Ed Beal Nov 13 '18 at 18:35
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    I understand what you're saying and under many other circumstances, I'd be on board with the homeowner doing it themselves, however, in this case I'm highly recommending on the side of caution since I cannot assess the condition of the wires themselves. I do see the other comments related to this and I do agree you have to examine the wires in the connector to assess the damage. I just think that someone with experience would do a better job of assessing the damage to prevent future problems. Ultimately, it is up to the homeowner if they wish to attempt it themselves. – blockcipher Nov 15 '18 at 12:24

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