GFI Caused a Fire!

Do you have a question? Post it now! No Registration Necessary.  Now with pictures!

Threaded View
My neighbor just suffered a serious fire.  His house had an enclosed
porch at the rear, with an open, roofed desk connected to the porch
rear.  He had several GFI breakers out there, including one on the
rear porch wall.  Around one AM, when he and family were asleep,
a fire started at that GFI switch (according to Fire Marshall), and
got going pretty good before their dog started barking.  That saved
their lives for sure.  Almost killed their dog and cat, though.  The
fire badly burned the rear half of the house and sent black soot
throughout the rest of the house.  The house is pretty well totaled.

That's what happened.  I have to wonder how a GFI could do that!
I heard the Fire Marshall actually say that what happened was the GFI
wires arced, but that was not a 'short' to the GFI.  Hence it didn't
trip.  So, the GFI presented no protection did it!  The arcing just
continued until it started the fire!

All this makes me think that my GFIs are not providing me the
protection I always thought they did.  I'm not sleeping as well these

Anyone have an opinion about this?



Re: GFI Caused a Fire!

On Tue, 25 Jun 2013 15:17:33 -0400, a@b.c wrote:

Quoted text here. Click to load it
Put arc-fault circuit breakers in the panel to protect the circuits
you are concerned about.

Re: GFI Caused a Fire!

Quoted text here. Click to load it

I never heard of them. Thank you.  I certainly will check that out.


Re: GFI Caused a Fire!

a@b.c wrote:

Quoted text here. Click to load it

Who installed the GFI/GFCI outlets?  The homeowner?  If so, is he a
qualified electrician?  Were these GFI outlets ever tested
periodically?  Was the home originally wired for 3-wire (grounded)
outlets?  Or was it built circa 1970, or earlier, and wired for
2-prong (ungrounded) outlets?  Although homes built as of 1962, and
later, were required to have both grounded and polarized outlets, I've
seen some homes built as late as 1970 that still just had ungrounded
2-wire outlets (but polarized).  If it's a 2-wire house, how was
ground brought to the outlets?  Was the porch added later and has it
own 3-wire circuit to the breaker box?

Were any devices attached to the GFI outlets (and were left on)?
Maybe one of them shorted.  GFIs snap when sensing ground faults (when
the current differential between the hot and neutral lines is non-zero
because some of the current leaks out elsewhere), not for shorts
across neutral and hot lines (where the current differential would
still be zero so the GFI won't trip).  Your circuit breaker still
handles that overload fault; however, if the device doesn't short so
its current draw exceeds the breaker's rating then the device could be
heating up, like across shorted windings in an abused home-grade drill
used to build the home.  Was any motor connected to the GFI outlet
(and left on)?  

A toaster filled with newspaper won't trip the circuit breaker, has no
cause to generate a ground fault (so hot and neutral currents remain
the same and the GFI doesn't trip), but will still cause a fire when
you heat up the toaster.  GFIs are NOT purposed the same as circuit
breakers or fuses.  GFIs don't regulate the load on a circuit.  They
check for a difference between the currents on the hot and neutral
lines.  If the homeowner sticks in a 30A fuse in a 15A circuit, expect
the wires to heat up in the walls when the homeowner overloads the
circuit while the GFI, like any other outlet, continues allowing the

Did the homeowner ever press the Test button in the GFI outlets to
ensure they were still working, like once a month.  

Did the homeowner use one GFCI to protect the other outlets?  Or did
he have a separate GFI at each outlet?  Was it a closed circuit being
protected by the GFCI?

Re: GFI Caused a Fire!

On Tuesday, June 25, 2013 12:17:33 PM UTC-7, a...@b.c wrote:
Quoted text here. Click to load it

Were they GFI breakers or just GFIs?  Because almost all GFI breakers
are installed in the circuit breaker box, not on porch walls.

GFIs are designed to shut off the current to prevent electric shock.
The ones that mount inside breaker boxes also contain circuit breakers  
to shut off the current if the amp draw is too high.  The arc fault  
preventers that Mr.E mentioned also contain circuit breakers.

The house where we used to live had several push-in wire connections  
that would drop 20-30 volts when loaded down with 15 amps.  That's  
a few hundred watts in a tiny space, enough to make plastic melt and
wood burn.    

Re: GFI Caused a Fire!

On Tue, 25 Jun 2013 17:10:28 -0700 (PDT),

Quoted text here. Click to load it

My misuse of  the term 'GFI breaker' I'm thinking now.  He must have
had a simple GFI in that wall box.  As do I for that matter.  For
example, my garage has several wall outlets, all with GFIs.  The same
is true for the wall outlets in my kitchen and bathrooms.  The
associated circuit breaker boxes just have  normal breakers.  I did
not know there was such a thing as a 'GFI breaker' or 'arc-fault
circuit breaker'.  I am going to Google the terms when I finish with
this post.  I might should consider replacing some breakers, huh?

BTW, I apologize for starting this post in this newsgroup.  In my
haste, I picked the wrong group.  SAT.  I appreciate your responses


Quoted text here. Click to load it

Re: GFI Caused a Fire!

On 06/26/2013 05:58 AM, a@b.c wrote:
Quoted text here. Click to load it

Quoted text here. Click to load it

I , for one and very glad you posted.

Concerning safety I feel the more info, the better.

Though I was aware of the difference between a GFI outlet and a GFI  
breaker, I did not know about the anti-arc breaker. I knew that (other  
than motor start breakers) the trip time is very fast...but never before  
considered an arc situation that could cause a fire yet with current low  
enough as to not trip a "normal" breaker.

Re: GFI Caused a Fire!

On Wednesday, June 26, 2013 3:58:55 AM UTC-7, a...@b.c wrote:

Quoted text here. Click to load it or should have more information  
about GFIs.  Another place that's very authoritative is the "Break Time"
forums at, the company that publishes Fine Homebuilding
and other quality crafts magazines.
Our fire department recommended flipping each circuit breaker  
annually, to clean its contacts, because sometimes they stick, and
I vaguely remember a local fire caused by a stuck breaker (OTOH it
could have been due to a Federal Pacific breaker, a widely hated
brand that was recalled).  

GFIs have a lot of electronic parts in them, and it wouldn't surprise  
me if a surge could cause parts to short out and burn.  Some time
in the 1990s, I had two plug-in GFIs fail due to manufacturing or  
design defects, but neither caused a fire and probably no surge of  
current that could have caused overheating in upstream wiring.  I  
don't know if they were enclosed in fire resistant V-0 rated plastic,  
which can help a lot  to contain fires.  V-0 plastic seems to be more  
common now for all sorts of electrical and electronic devices.

Re: GFI Caused a Fire!

On 06/25/2013 02:17 PM, a@b.c wrote:
Quoted text here. Click to load it

The short was "upstream" from the GFI...viz: The wires going to it.

A GFI only protects from a short to ground of the device plugged into it.

Of course the breaker in the panel should have tripped.

Site Timeline