Electrical Fire -a Disaster Averted!

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Yesterday I received a call from one of my last customers while I was still an electrical contractor.
He called to let me know that his building was on fire and the fire chief had told him they already found the cause of the fire - ELECTRICAL. So, like any other contractor who has just been told his work has caused a fire that damaged a multiuse building, I got in my car and calmly drove to the building at 150 MPH. ;)


When I got there, they were just mopping up the fire. There was extensive damage to the building, which is 2 stores on the first floor, and 4 apartments on the second floor.
I met with the owner and the building official, who has a lot of respect for me. He treated me very well and got me permission to enter the building and take pictures. They explained to me what had caused the fire and the progress of the fire. At that time the news woman was trying to interview me and I asked the Building Official if he could get me out the back door, which he gladly did.
I met with the fire marshal who had cut out the portion of the wiring that he determined had started the fire. It was definitely wiring in a location I had worked in and did not look like anyone had added work to the area in the six years since I was there.
The fire marshal put the cable he had removed under lock and key...the BO persuaded him to let me look at it and photograph it, which I did.
I studied the cable and could not see how it was determined that this piece had started the fire. He told me his expertise was better than mine, okay.


Today at 4 pm, the owner of the building called me to let me know the fire investigater from the insurance company had spent 6 hours piecing the fire back together and came up with a positive identification of the cause of the fire...not electrical.
It was caused from a tenant who had emptied an ash tray into a plastic garbage can whch had contained a smoldering cigarette. Case closed, another disaster averted.



Here are two of the pictures of the burnt cable.

BrickOvenFire-3270814.jpg



BrickOvenFire-327089.jpg
 

480sparky

Senior Member
Location
Iowegia
So were you wearing your Captain America x-ray glasses you ordered from the back of the Cap'n Crunch cereal box when you installed that? If not, how could you have seen inside the sheath?

I see no nicked insulation, nor damage in the sheath that would have caused a problem. Looks more to me like someone took a torch to the cable. Of course, that's based on what I see.
 

frizbeedog

Senior Member
Location
Oregon
I started my carreer working on many mobile homes...When they burn they make news, and my ears prick up a little each time....I listen for the adress and wonder.

Strange how they were so sure, so quick.

150 MPH? What are you driving man? :rolleyes:
 

ceb58

Senior Member
Location
Raeford, NC
#1 I am glad for you, that someone who "knew" what they were looking at found the real cause.
#2 Isn't it amazing how every one jumps on the "it was caused by electrical" band wagon before all the facts are in. I guess it would be to hard to wait for expert investigation to determine the real cause.
 

JohnJ0906

Senior Member
Location
Baltimore, MD
Pierre, I'm sure you were releived. :smile:

Did the Fire Marshal just fall back on the old standby? He must not have investigated very well. Found his "cause" while the fire was still going.

Took the other guy 6 hours to actually look for, and find, the real cause.

Did he tell you, "An AFCI breaker would have prevented this"? :rolleyes:
 

SiddMartin

Senior Member
Location
PA
here in PA you'll here the cause of a fire "electrical", then you find out it is an Amish resisdence.... how's that work? ...scapegoat
 
L

Lxnxjxhx

Guest
I'd think nowadays it would be easy to determine if the heat progressed from the inside of the cable out, or from the outside of the cable inward.

The bx armor conducts heat very well, but the inside insulation might give a clue as to which side got hot first, the inside or the outside.

Finding someone who can do this, though, might be difficult. I'd say an insulation specialist.

Let's say the outside of the bx needs to be at fahrenheit 451 to ignite stuff. The conductor temp would need to be above this for the heat to travel outward.
That is, there is thermal resistance from the conductors to the outside of the bx armor. Once this is known, you plug in the 451 to calculate the conductor temp.

On the other hand, if the heat comes from the outside, the insulation would be more charred on its OD than on its ID. The conductor temp would be less than 451.

I don't know how the copper conductors are heat-treated or annealed or whatever, but this new rise in temperature due to the fire may leave telltale marks in the grain boundaries or other structures inside the copper.

Don't let anyone tamper with this evidence.
You may also need a metallurgist, depending on how much money is riding on the outcome.

For someone who does this for a living, they might even be able to tell without a microscope.
The rest of us don't know what to look for.
 

yursparky

Senior Member
Location
WA
I've been in two situations where my work "had caught fire". I know how you feel, Pierre. My knees were shaking for weeks after the news.

First one was very similar. We had just finished wiring a brand new house, way over budget for the homeowner, lots of hassle for us, and bam! the place has a fire around the new kitchen area. Lots of smoke damage, the home is uninhabitable. Of course, the cause of fire - electrical, the two of us working on the house thought we're loosing our jobs if not licenses. Fortunatelly, the 12 year old son confessed to smoking upstairs in his bedroom and tossing the cigarretes out through the window where they must have landed on the roof above the kitchen.

The second time, I guy I was supervising in a big blue box home improvement center, had made a bad splice on a 200A feed to a subpanel. I got a call while 200 miles away from the store that the splice box was smoking profusely and sparks were flying in all directions. By the time I got there, about an hour later ;), the fire department had already closed the store and were on a scissor lift with the IR meter by the box. The fault had cleared itself by then, by the breaker was still on. I don't know how much money the store lost from being closed that night, but I'm sure they still remember us sparkies. They were pretty nice about it, but I felt like a total loser. Did I mention the box was right above the paint isle?
2877703080094545463S600x600Q85.jpg

That chunk of copper sticking out was what was left of the C phase conductor splice. And it was still hot when the FD was checking it out.
 
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e57

Senior Member
yursparky - what was the voltage on that feeder? And man that is a lot of arc welding/plasma cutter type temp to do that.... If still live - it very well could have re-started - to allow the phase conductor to continue to cut through..... Might there have been a screw at the start of all that?
 
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yursparky

Senior Member
Location
WA
e57 said:
yursparky - what was the voltage on that feeder? And man that is a lot of arc welding/plasma cutter type temp to do that.... If still live - it very well could have re-started - to allow the phase conductor to continue to cut through..... Might there have been a screw at the start of all that?

The voltage was 120/208, and there was very minimal load, maybe 10-15A at that point.

From what I figure, the box if you look close, is bear metal and the edges were somewhat sharp. We had to use material that the firm that hired us would send us, and they were from NC and I've never seen that brand of box here on the west coast.
2253223370094545463S500x500Q85.jpg

2404937290094545463S500x500Q85.jpg

I think also the guy that made up the splice had left too much slack so he had to force the conductors into the box probably either nicking the insulation or the tapped splitbolt. And that probably was just slowly arcing over the weekend until it got melted. This is why we should all megger our feeders!!!

Here's some more pics.... Enjoy
2209983350094545463S500x500Q85.jpg


2162691800094545463S500x500Q85.jpg

 

RUWired

Senior Member
Location
Pa.
Pierre C Belarge said:
Pierre, I always wonderd how mc lite was allowed in commercial applications because of the easy melt verses the steel armor of previous years.Seems to me, that piece of cable would have sustained a longer life had it been steel armour.
Rick
 

K8MHZ

Senior Member
Location
Michigan. It's a beautiful peninsula, I've looked
Occupation
Electrician
I used to work at an aerospace casting facility. Metallography would have been able to determine if the outside of the cable was hotter than the inside, if any arcing had been present and if the wiring had burnt the insulation or not (by the reaction of the metal with the insulation and the type of alloy that would occur under such circumstances).

Just looking at the photos even instills some suspicion. It just looks like the cable had been heated from the outside as the sheath is in worse condition than the conductors.
 

peter d

Senior Member
Location
New England
yursparky said:
I think also the guy that made up the splice had left too much slack so he had to force the conductors into the box probably either nicking the insulation or the tapped splitbolt.

Any reason why they used split bolts instead of a Polaris connector? :confused:
 

charlie b

Moderator
Staff member
Location
Lockport, IL
Occupation
Retired Electrical Engineer
Nice job on the photos Pierre. It looks like the kind of photo quality one might get from something like a Canon PowerShot SX100IS. Didn't you recently say you were in the market for a new camera? ;)
 

e57

Senior Member
yursparky said:
I think also the guy that made up the splice had left too much slack so he had to force the conductors into the box probably either nicking the insulation or the tapped splitbolt. And that probably was just slowly arcing over the weekend until it got melted. This is why we should all megger our feeders!!!
I had a simular situation happen in a single flash - the open end side of a split-bolt pushed through the tape while closing a can with conductors of simular size (2/0) - blew a 4" hole in a single BOOM! I opened this can to check something, and there was a piece of wood in there holding all the splices back - I dropped it and did not put it back in. I retrospect I wish I had.

IMO - in your case it may have just been the wieght of the splices or a shift of them inside the can. As well as A, B, and C where in a pig pile with C on the bottom.... C doesn't look as if it were curled back enough not to act as a spring putting pressure on the cover. Just a little vibration, and it made its way through the tape...... Thats my speculative guess... I don't think a megger would have helped - but a little more care to not have the conductors and splices forced into the box would have.
 

Buck Parrish

Senior Member
Location
NC & IN
I wired a 12 unit apt building that burned to the ground a couple of months later.
Luckily some ones X, threw gas on it and lit her up.



I'll tell you though, those remote fan controlls. The part in the fan. They will catch fire easily if hooked up wrong.
 
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