Thread: FIRE! Electrical fires cuased by backstab outlets

Friend of my wife, owns house was occupied by family members, moved out after not being able to pay power bill, was left unoccupied for months.
She decided to fix the house up and move back in.
Although not doing as a living now agreed to help and check things out before she got power hooked back up.

During the inspection I also discovered two outlets if different rooms that had caught fire, side of plastic box melted. wiring burnt. the previous tenants had tried to bypass by wire-nutting the connections but left the wires burnt and not cleaned or cutback to clean wire.
A few other outlets showed signs of heat at the back-stab connections.
We tried to get as much as we could but no way to go through every outlet right now, but since had these issues I am thinking of doing just that before she moves in.

Other issues at the house, the previous tenants had done some rearranging of circuits in the panel boxes, tried to attach a generator at some point, just a mess, 30 amp breakers on 14 awq wiring, etc. Got all that corrected. Were also a few other surprises with DIY wiring in an attempt to close in a room in the basement that is has to be removed and redone. a couple places that rats ate some of the outer covering in one location and was repairable but all other exposed wiring was OK.


When have done electrical, I never trusted those back-stab connections and always used side screw terminals.
Has anyone run across issues much with the back-stab outlets and/or light switches ?
And I wonder about issues with rats, etc in many of the foreclosed homes being vacant for long period of time, Does anyone see much of a problem when inspecting those houses ?


FYI: The previous idiots when moved out left dogs in the house for a month could not take with, the house was so messed up, dog crap everywhere, horrendous, took them forever to get all that cleaned up and not sure ever will be clean enough for me to live in it :-(
Relatives or not, someone did that to my house, would not be good for them.
Unfortunately did not have my camera to take pictures when was there, forgot it, words just can not describe.
As for the electrical, just amazing the house did not burn down with all the electrical issues.

Mike

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I have never pulled an outlet out on an inspection. I have only removed about 5 outlet covers over the years, just to see if they had pigtailed aluminum wire. But I have replaced around a hundred outlets in fixer uppers over the years and have never seen the back stab melted. (I always called them the "quick connects".)

This is not the first time I have run across issues with the back-stab connections, most of the time light loads, no melting just intermittent connectivity.
There is just not a lot of contact pressure the way they make contact and never have trusted them and always installed all my outlets with the side screw terminals.
Most likely the melting ones are just heavy loads, suspect space heaters were in use.
The ARC fault breakers should help prevent most of the safely issues, a bad connection would cause a breaker trip before that would happen, but most houses built before the requirement most likely will never see an upgrade, just scary.
In fact, my next house if can afford to do so, will be all metal boxes and EMT stranded wiring with commercial type receptacles, just a preference for myself.

Originally Posted by Mike Clarke

In fact, my next house if can afford to do so, will be all metal boxes and EMT stranded wiring with commercial type receptacles, just a preference for myself.

Complete overkill.

Originally Posted by jack davenport

Complete overkill.

Not much if can afford to do so, I have had to repair many wiring chewed through by rats and squirrels, Had a rental burn down once due to rats getting in when empty just four weeks, ate through wiring and shorted.
And this was not the only time have burnt wiring in an outlet box, and a few times required the drywall to be removed in several places to run new wiring when was too short in the box. EMT allows to run new wiring easily, may not be needed often, but once is enough for me. Also if needing to split a branch into two circuits in a future upgrade, easy to make changes.
May not be practical to do for everyone, but as long as have the money, and can, then no amount of being safer is overkill for me personally and just something I prefer.
I have also learned to run flex conduit to all low voltage outlets at least to accessible space so can replace/upgrade all media wiring if/when needed.
And any conduit could satisfy changes but I like EMT since would better contain a shorted conductor, help better prevent nails from hitting wiring, etc.
Maybe end up not but like mentioned if I can then that is what I prefer to do for my own future wiring needs.
And my next house I am hoping not be built stick framed from wood, maybe age the older I get the more paranoid I become with everything with house fires, to the point I will not leave my inside pets home alone more than a few minutes, someone has to be at the house or they have to go somewhere, seen too many house fires where pets were left and could not get out. I would build a fortress for mine, just getting too protective I guess

Originally Posted by Mike Clarke

In fact, my next house if can afford to do so, will be all metal boxes and EMT stranded wiring with commercial type receptacles, just a preference for myself.

Originally Posted by jack davenport

Complete overkill.

Not just overkill, but could also lead to the loss of equipment grounding unless there is a redundant equipment ground wire in the EMT - it is totally pathetic how many loose screws - even missing screws - I find in fittings for EMT and MC cable in commercial work, even broken fittings for EMT runs. And residential work is typically not done to the higher level of workmanship usually reserved for commercial work - sure, the EMT and metal boxes would keep the fire in the boxes and conduit, but it may lead to electrical shock and electrocution - not saying that *it will* lead to that, just that because of the loss of ground from poorly installed EMT and fittings *could* lead to that.

Did an electrical rough at a Pollo Tropical a couple of weeks ago ... screw in the FIRST fitting I tried to turn with my fingers was r-e-a-l-l-y loose, SECOND fitting I walked to and reach for had MISSING screw. The equipment grounding in that place was, I guess, based accidental metal to metal contact between the various parts - 'accidental' contact because there was evidence that such metal to metal contact was 'intentional'.

Originally Posted by Lon Henderson

But I have replaced around a hundred outlets in fixer uppers over the years and have never seen the back stab melted. (I always called them the "quick connects".)

Back-stabbed outlets are indeed a hazard. I had flickering lights in the bedroom. We were cursed with two pendulum lights in our bedroom, a big draw on the light circuit. A back-stabbed receptacle in the wall was overheating and burned a connection.

Billy Bob punches two wires in, two wires out, so the receptacle is in series with the load, not on a pigtail. Now he's drawing maybe 10 amps thru contacts that are shaped like knife blades. They have caused hundreds of fires, no doubt about it. Inspect the whole house, one fixture at a time. Have an electrician install new receptacles with wire nuts and pigtails.

I think some of the earlier back-stabs were the worst. I had a 1989 house about 10 years ago and replaced all the outlets. About 1/2 dozen were totally loose at the back of the outlet and of those two I remember beind scorched really bad. One was at the washing machine and another in a bedroom. It's taken me awhile but I pretty much trust the newer back-stabs. They seem to be a better design. Of course, I still prefer good old fashioned screws on the sides.

On a related note I just did an inspection for a past agent I use to work for and she told me a story of how her house with a Zinsco panel almost burned down a couple weeks ago. 1950s house, outlet shorted out and started to catch fire in the wall. Luckily she was home and smelled something burning. I know it's more of a FPE problem for breakers to not turn off but the Zinsco panel probably didn't help.

Originally Posted by Jerry Peck

but could also lead to the loss of equipment grounding unless there is a redundant equipment ground wire in the EMT '.

YES, I agree with the grounding, I always run a dedicated ground, never trust the conduit to maintain a ground either.

Originally Posted by Mike Clarke

YES, I agree with the grounding, I always run a dedicated ground, never trust the conduit to maintain a ground either.

I thought a dedicated ground wire was required in EMT for the last 10-15 years, just because the EMT isn't a reliable return path. Rewired a couple commercial buildings about 5 years ago, and we'd use the existing 14awg wire to pull in the new 12awg circuits which including a bare ground. Wish I could think of the year, but I'm pretty sure it's in the NEC that EMT is no longer considered a valid ground.

EMT is still accepted as an equipment ground. Numerous local jurisdictions amend the NEC to require a conductor to be added as an equipment ground. When installed in some areas of hospitals a redundant equipment ground is required by the NEC.

I have found the same problem with loose screws in couplings and connectors. It is just something you need to keep after the electricians about. I am sure somewhere in the 10,000's of feet of EMT I have installed I left a screw loose somewhere. It only creates a hazard in a fault condition.....

I was amazed when I first installed EMT with the old connectors and couplings you would impinge (crimp). But it worked....

Originally Posted by Ken Lyons

I thought a dedicated ground wire was required in EMT for the last 10-15 years, just because the EMT isn't a reliable return path. Rewired a couple commercial buildings about 5 years ago, and we'd use the existing 14awg wire to pull in the new 12awg circuits which including a bare ground. Wish I could think of the year, but I'm pretty sure it's in the NEC that EMT is no longer considered a valid ground.

Hello Ken,

I'm not sure where you got that information. EMT is "valid" and is acceptable as an EGC and no additional conductor is required.

Homes that are piped with EMT rarely have an additonal EGC pulled through the pipe. In commercial applications an additional EGC is usually by preference of the electrical contractor or is a spec by the design professional.

On larger commercial jobs "value engineering" is the buzz word and not using an a pulled EGC in an EMT installation is one way to save money and still be in complete compliance with the NEC.

Corey

Originally Posted by John Kogel

Back-stabbed outlets are indeed a hazard. I had flickering lights in the bedroom. We were cursed with two pendulum lights in our bedroom, a big draw on the light circuit. A back-stabbed receptacle in the wall was overheating and burned a connection.

Billy Bob punches two wires in, two wires out, so the receptacle is in series with the load, not on a pigtail. Now he's drawing maybe 10 amps thru contacts that are shaped like knife blades. They have caused hundreds of fires, no doubt about it. Inspect the whole house, one fixture at a time. Have an electrician install new receptacles with wire nuts and pigtails.

I bought this house and over the course of about 3 months changed out every switch and recepticle. The previous owner had "upgraded" them all to backstab. One in a bedroom was dead. Traced that back to where it was feeding from another recepticle. The hot wire had snapped off at the backstab connection.

Of course I also repaired the nice free air splice the guy left in the garage.

-dave

When running extra grounds in EMT commercial property, always used green/greenyellowsrtiped wire, not bare copper due to the different metals. Also used ground isolated outlets so the grounds were not tied at both ends for the ground wire and EMT, only back at the panels.

As for wiring breaking off, bad practice using wire cutters many times to strip the insulation and nicking the wire, seen way too many times, seen some in wire nuts break with new installations due to nicking the wire.

Originally Posted by Ken Lyons

I thought a dedicated ground wire was required in EMT for the last 10-15 years, just because the EMT isn't a reliable return path. Rewired a couple commercial buildings about 5 years ago, and we'd use the existing 14awg wire to pull in the new 12awg circuits which including a bare ground. Wish I could think of the year, but I'm pretty sure it's in the NEC that EMT is no longer considered a valid ground.

Not only is metalic conduit sufficient in ground faults, it is superior! That is of course, all connections are made up tight.
I always refer Soures Book on Grounding by the IAEI. Tests show that conductors enclosed by metallic will work the best when conducting ground faults. Moreover, almost all the fault current will run on the conduit and very little on that redundant grounding conductor. This flies in the face of the old and mostly correct assertion that current will flow/run on all paths and devide according to their impedance.
(Soares) sp? The Wife unit cleaned up and rearanged my office.. cannot find some of my reference material and such

Forgot to address the OP, sorry. 30 plus years has taught me to only 'back stab' when using the device for end-use. That is to say; A receptacle is an end-use device but the load is an unknown for its life expectancy. Therefore I do not back-stab a receptacle but I will use this method on a known lighting circuit not more than, say 5 amps or so.
I will never use any device as a flow-thru using the back-stab connections. My experience both as an electrician & an AHJ has shown me that it is the flow-thru applications that cause the failures.

It is interesting to note, and I have commented here before that both pressure and contact area are the two most important componants in conducting available current (remember our discussions on device mounting screws) and surface condition is another.
The internal back-stab contacts have plenty of initial pressure, until they have been heated = annealed. Also, the contact area might be enough for the device/load itself but the area does not equal that of the cross section of the conductor! I personally do not comprehend how they are rated for feed-thru with this fact in mind.

Originally Posted by bob smit

Moreover, almost all the fault current will run on the conduit and very little on that redundant grounding conductor. This flies in the face of the old and mostly correct assertion that current will flow/run on all paths and devide according to their impedance.

"This flies in the face of the old and mostly correct assertion that current will flow/run on all paths and devide according to their impedance."

Incorrect - and the first part of your post confirms it is incorrect. The electrical current *WILL* "current will flow/run on all paths" which are available to it, and is divided up into circuits based on resistance and impedance (as 'short path' does not necessarily equal a low impedance path, and, likewise, a 'long path' does not necessarily equate to a high impedance path). Electricity will take 'all available paths' - just make sure not to jump to conclusions on what amounts to be 'available' at the time the current flows.

Originally Posted by Matt Fellman

I think some of the earlier back-stabs were the worst. I had a 1989 house about 10 years ago and replaced all the outlets. About 1/2 dozen were totally loose at the back of the outlet and of those two I remember being scorched really bad. . . .

A good practice when doing inspections might be to turn on every light in every room, then come back in a few minutes and shoot each and every (visible) wall switch and receptacle with an infrared thermometer. I found a few "hot" ones that way, with one wall switch in an '80s condo north of Durango registering 163 degrees F. Suspect a back-stabbed switch, as no wires were visible when I removed the (very warm) switch plate. Advised the Realtor/owner by phone, and noted it in my report to the buyer.

Originally Posted by Jerry Peck

"This flies in the face of the old and mostly correct assertion that current will flow/run on all paths and devide according to their impedance."

Incorrect - and the first part of your post confirms it is incorrect. The electrical current *WILL* "current will flow/run on all paths" which are available to it, and is divided up into circuits based on resistance and impedance (as 'short path' does not necessarily equal a low impedance path, and, likewise, a 'long path' does not necessarily equate to a high impedance path). Electricity will take 'all available paths' - just make sure not to jump to conclusions on what amounts to be 'available' at the time the current flows.

Sorry Jerry, there are other physics at play than just available paths and their inherent impedance.
In real world tests, my statement holds true. Conductors enclosed in metallic conduit in which a fault current is imposed: Most of the fault current will return on the conduit as opposed to the grounding conductor inside.

bob smitSorry Jerry, there are other physics at play than just available paths and their inherent impedance.

Quite frankly this is not true, in this world anyway.


In real world tests, my statement holds true. Conductors enclosed in metallic conduit in which a fault current is imposed: Most of the fault current will return on the conduit as opposed to the grounding conductor inside.

Research by the Steel Tube Industry and independent research will verify this statement. And as much as 90% of the fault current will flow on the steel conduit. Good job!

Originally Posted by Roland Miller

In real world tests, my statement holds true. Conductors enclosed in metallic conduit in which a fault current is imposed: Most of the fault current will return on the conduit as opposed to the grounding conductor inside.

Research by the Steel Tube Industry and independent research will verify this statement. And as much as 90% of the fault current will flow on the steel conduit. Good job!

Are you by chance using this investigation and report?
- http://steeltubeinstitute.org/steel-...over_600V5.pdf
- This is from page 6:
- - 120 volts to ground, 40 volts at the arc, and 400% fault clearing current (80 amps) with 256 feet of conduit:
- - - Where E = IR, R = E/I or R = 40/80 or 0.5 ohms for the 256 foot run, or ohms per hundred feet = 0.5 / 2.56 or 0.195 ohms per hundred feet

And the other 10% takes those other paths I am referring to ... just as I said:

The electrical current *WILL* "current will flow/run on all paths" which are available to it, and is divided up into circuits based on resistance and impedance (as 'short path' does not necessarily equal a low impedance path, and, likewise, a 'long path' does not necessarily equate to a high impedance path). Electricity will take 'all available paths' - just make sure not to jump to conclusions on what amounts to be 'available' at the time the current flows.

From the only source I've found so far, 1/2" conduit with 3-#12 conductors on a 20 amp breaker, with a Fault Clearing Current of 500% of the 20 amp breaker with a 50 volt drop at the arc, will give approximately 0.198 ohms per hundred feet.

Let's compare that to the resistance of a #12 equipment ground from Table * Conductor Properties in the NEC which shows #12 has 1.98 ohms per thousand feet, or 0.198 ohms per hundred feet. If we take the same Fault Clearing Current of 500% of the 20 ampere breaker with the same 50 volt drop at the arc, the same current will flow through the #12 conductor where E=IR (E= 50 volts, I= 100 amps, and R= 0.198 ohms).

Let's see, we have 0.195 ohms per hundred feet for the conduit, and 0.198 ohms per hundred feet of conduit, and 0.198 ohms per hundred feet of #12 copper ... hmmm ... E=IR (for plain DC resistance, capacitance and inductive impedance does change the numbers some, but it's been soooo long since I worked with those numbers (back in the late 1960s to early 1970s) that I have forgotten the finer art of working with capacitance and inductive impedance ... which means that I have gone as far as my memory will take me on this ...

Using Conduit and Other Metallic Enclosures for Grounding
http://steeltubeinstitute.org/steel-...over_600V5.pdf
FAQ's | Steel Conduit

Originally Posted by Corey Friedman

.....On larger commercial jobs "value engineering" is the buzz word and not using an a pulled EGC in an EMT installation...... Corey

Round here they call that a cheap contractor........

Originally Posted by jack davenport

Complete overkill.

I agree.. COMPLETE OVERKILL..!