O/T would not believe what I heard on the news

old · Jan 2, 2009

Watching new tonight and they showed where a house had burned. Fire fighter said that you should not have a cord under a rug well ya I agree with that be they said the reason was it did not let the power go through the cord so it made the cord hot and caused fires. How stupid do they think people are?? Fire is caused by damage to the cord under a rug not the bull of it causing the resistance on the cord to go up

RodinNS · Jan 2, 2009

I dunno about that...
I think that you might find the cord is very well insulated under a rug which would cause it to dissapate heat more slowly, or not at all. With an increase in heat there would be an increase in resistance, and then more heat.
I do know that if you look at wire recomendations for buried service, they always derate a given AWG size's current capacity when it's buried over when it's hung out in the open...

Rod

GA Dave · Jan 2, 2009

Old, I think I'll tie a knot in all my drop cords. That'll make them use less electricity. David..............

old · Jan 2, 2009

Well if the rug makes them use more then the knot would make them use even more LOL

Coloken · Jan 2, 2009

Yea, the world is crazy, and dumb. Just saw on the news a fellow at a car dealer adding up rebates. List price on a Tahoo (sp?) was 51 thousand...wonder why the car people are hurting.

Anonymous-0 · Jan 2, 2009

Firemen are no different than anyone else, they say at times say stupid things, and some times have no idea of what they are talking about. No different than a politician, news reporter, or farmer.

I heard my dad once tell off a milk inspector. Seems the milk inspector decide that the milk went through the pulsators, and could pick up a hair that was on the outside of the pulsator.

Prior to that moment my dad had always been soft spoken, and (prior) to that sold grade A milk.

Something interesting to share with everyone here is if times get rough and you want to cash in a insurance policy with a fire loss....If they bring in the dogs, you sure are going to jail, cause those dogs are never going to be fooled if you use any liquid fire starter. They don't miss a trick. Probably one of the most imprerssive demonstrations I have ever seen...made me a believer.

charles todd · Jan 2, 2009

Two things probably were going on with the cord under the rug. The cord can become damaged and go unseen and/or the cord was undersized and overheated.

As for direct bury cable, the ampree rating is derated in open air or conduit. When direct buried, the conductor has full ampacity (the ground is a heat sink). IE: #2 aluminum triplex has a 100 A rating buried, but only like 85 A in free air or conduit.

Charles

oliver power · Jan 3, 2009

You are right on the money Rod. That's exactly how it goes.

Anonymous-0 · Jan 3, 2009

Have you also noticed the price of corn, and wheat products, and beef and pork, and lumber, and wall board, and roofing, and electricity and natural gas, and.......

Anonymous-0 · Jan 3, 2009

Funny thing about electricity is that as the conductor heats up and the electrons in the wire become more active the resistance of the wire increases. One would think that with the electrons moving faster that the resistance would drop.

Not supposed to use romex inside of a conduit either because it will heat up. It must be seperate insulated conductors.

Bus Driver · Jan 3, 2009

Charles writes: "As for direct bury cable, the ampree rating is derated in open air or conduit. When direct buried, the conductor has full ampacity (the ground is a heat sink). IE: #2 aluminum triplex has a 100 A rating buried, but only like 85 A in free air or conduit."

This does not at all agree with my copy of the NEC 2008, Article 310 tables. Could you give us an NEC reference for your claim?

Anonymous-0 · Jan 3, 2009

I wonder if maybe the cord got overheated, not necessarily because it was under the rug, but because it was not big enough to carry the load that was placed on it and ignitied the rug? Not the rugs fault and not the cords fault, just a combination of the two. I know I have used an extension cord that hasn't been big enough at times and it can get prety warm if used long enough and hard enough. Like on an electric heater. I suppose if the cord got hot enough and with the rug not letting the heat escape, it could ignite the rug.

Anonymous-0 · Jan 3, 2009

Just a couple of comments on the electrical portion of this thread. The hazard with extension cords under rugs comes from the fact that they are typically made of fine strand wire in molded on insulation. When people walk on the wire under the rug it abrades the two conductors against each other and the failure mode has been for the wires to start to come in contact with each other and/or break. Since they are so small individually, they can not drop enough current to trip a breaker. They can however catch on fire easily and also overheat due to the decreased effective ampacity of the wire as the strands break.

This is more common than you may think and is the major reason for the new arc-fault circuit breaker requirement. Think of the arc fault as a little guy sitting in front of an osciloscope watching for a wave form that indicates a brief fault and tripping the circuit when that happens. Remember, the NEC is written, in large part, in response to the insurance industry. If they weren't paying losses in significant amounts they wouldn't require the arc faults.

Ground fault requirements started the same way. When enough people with insurance insisted on using their hair dryers in the bath tub, they said find a way to protect these people from themselves.

BTW, Triplex is not listed for installation in conduit. When you see a service done like this it is a sign of a cheap job.

old · Jan 3, 2009

What the new was saying is a cord under a rug causes the flow of power to have problems as in higher resistance which of course doe not happen. It is the fact the under a rug causes wear in/on the cord which then in turn causes it to short out which in turn cause the fire. Whos the smart one here think about it

Bus Driver · Jan 3, 2009

News people have to cover lots of topics, and like each of us, are not experts on everything. But they could verify by internet or calling an expert. Fire officials will often blame fires on electrical if they cannot definitely find the cause.
Sometimes it is quite funny. One young TV talking head was describing a bridge collapse after a gasoline tanker hit the support columns and burned. The TV guy said that the weight of the hot asphalt caused the bridge to collapse. Until then, I did not know that hot asphalt weighed more than does cold asphalt.

Anonymous-0 · Jan 3, 2009

Proving your ignorance making comments like that about firefighters buster! Most firefighters are well trained in arson and causes of fires and if you are a firefighter thinking you know it all and not training you are finished and need to get out of there. We just can't tell the stupid news media or general public anything without them twisting the story around so many times it's best to just tell them it's "under investigation" or "unknown cause" for legal reasons too. Lawyers and dang insurance have limited firefighters to what they can say at most incidents now days! Doesn't matter anyway as most real causes of 99/9% of fires is caused by gremlins

old · Jan 3, 2009

Thats is true but as said in the new the rug is the cause and that in turn causes higher resistance in the cord. Even when the cord is big enough for the load the rug will not change the resistance as they said it did on the news

old · Jan 3, 2009

LOL. Ya one thing that bugs me about news people is they do say so many things that are just plan wrong so then in turn people who believe what they hear on the new then know things but are stupid enough to believe with out checking it out for them self's. I look at it this way the new people should tell the truth not not tell it at all

Anonymous-0 · Jan 3, 2009

Night before last the news reprted on an accident involving a "manure truck". Video showed tractor and manure spreader of course. A while back there was a "farm truck" in an acccident. Video showed a combine. These people have no clue.

Areo

Anonymous-0 · Jan 3, 2009

I call BS on that, the elitist sewage attempt to pass themselves off as "experts" on everything, when in fact, they are knowlegeable about nothing.

Eric SEI · Jan 3, 2009

You ever see the blooper show with the news reporter talking about 2 cattle on the loose, Black and Gus? At least the other reporter caught it.

RAB · Jan 3, 2009

RodInNS is about the only sensible responder (plus the two that replied to his post.

It is just plain stupid to insulate a cable , lead or whatever. They all have resistance so will heat up. Simple physics of I squared R.

If that heat cannot dissipate the lead will eventually melt the insulation and/or burn.

When insulating a roof cavity allwiring must be on the insulation, not under or in it.

Those who ignore that warning are the stupid ones - and sounds like there are a few on this forum.

Regards, RAB

Anonymous-0 · Jan 3, 2009

Hey OLD, don't worry about these other experts, I know what your trying to say. It's like saying throwing a rug over a pipe will cause the fluid inside plug up.

IndianaRed · Jan 3, 2009

What was the source of this fine reporting?

RodinNS · Jan 3, 2009

BINGO!!!!!!!

When you're actually on a fire today, it's just not safe to open your mouth... to anyone, including members of other departments who respond with you.
We've had situations.... where the damn thing was gone before we got called. Long gone. Had trucks piled on top of truck hauling water to drown the damn thing because not much else could be done, and then there's people running with stories that we lost the house, blah, blaht, this and that.
If it wasn't for a reasonably honest homeowner and an insurance adjuster that could see what happened we probably would have had a lot of trouble from that one.
It's just not safe to make an idle comment or crack a joke anymore lest some fool will run with it.
The media tend to just be vultures. They only want to make a story that will sell copy. There's no need to let the facts get in the way of that goal.
Block it off, tape it off, kick them out and shutup...

Rod

old · Jan 3, 2009

KOLR 10 out of Springfield MO

jimva · Jan 3, 2009

Are you sure it wasnt Santa that casued the fire????

RodinNS · Jan 4, 2009

Alas, it doesn't agree with ALCAN's specs either which is what I'd looked at, but there's no need for the truth to get in the way.

As far as I know, open air is the highest rated conductor. I don't recall that they differentiated between conduit and direct burial for ampacity, but I do remember it was significantly less than open air.

Rod

Leroy · Jan 4, 2009

Not only the TV news like that. I work as a rual delievery driver for a newspaper and they blame us drivers for loosing subscriptions when it is that they can never get the facts straight in a story, or only print half of the artical or something simular. Reporters that don't seem to know north-south from east-west as when somethings happen and they say a driver was going north on an east-west road. Go figure.

jimva · Jan 5, 2009

Nope i just wanted to see if you were so into the topics that you comment on that you would dig back 6 pages and leave a response to my comment.
Thats all, have a good day.

FYI, If i were you i wouldnt bother to leave a comment because iam not going past 2 pages on this form to see if you responded.

O/T would not believe what I heard on the news

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