How Electrical Insulation Fails and Causes Fire in a New House?

This could easily happen if the circuit breaker connected to the wires either failed to operate or was of a larger capacity than the wire capacity.

WJMFIRE:

It is assumed that electrical wiring fitting was as per approval and inspected and certified. What can still go wrong?

Fire report says there was spark in the roof wiring.

There was no one in the house so I assume the power consumption must be at low.

Fire Alarm detected fire and turned ON but owner left the mobile in home itself.

Perhaps fire brigade took the picture or traced the smoke and then went for fire fighting job.

old salt:

There is no flame visible from outside so fire must have started inside.

The fire reported that there is spark in the roof wiring; then how it is concluded that there is an insulation failure.

If all the protective devices are designed and installed properly, the fire hazard is very less. If the wiring termination and splices are not done properly, there is chance for sparking; and the protective system do not recognize this spark, unless provided with Arc Flash Circuit Breaker.

Probably the owner might have forgot to switch off the iron box

An electrical fire depend up on circumstances like weather the building is constructed by a Government contractor , private builder , single building , apartment complex ( Multi storied,single storied , concrete / brick , wooden walls and electrical supervision during construction ,quality of wiring material used , surface wirng ,concealed wiring through conduit (steel pipe /PVC pipe ) joints in wiring , type of termination, loose contact in wiring, protective components like MCB , RCCB, Fuse unit, isolators and the back up main protection, service connection and many more factors .Once these information are correctly available we can come to certain possible reasons from the above facts.

Failure to check one's work, incompetence, your pick.

The insulation didn't fail. Somebody didn't do their job properly, and there was a short.

This can happen from running romex in the walls,,,,,one misplaced sheetrock screw....or damaged wire insulation when pulling through conduit....or failure to install plastic hole protectors with romex or other wire....but it would be a longshot....the only electrical house fires I've seen are from safety systems bypassed...or lightning strike...or something left on the stove.....overloaded circuit.....aluminum wire....space heaters....

these go right through romex when hanging pictures

That's for a really big picture eh?

Fredski:

I like that big nail idea and have given you one point up but can't connect the idea as fire investigating agency said there was spark in the roof. You don't hang pictures in the roof or do you?

See #3

If someone has determined that the electrical insulation has failed and caused the fire, there must have been an investigation that determined this.

Otherwise, it must be speculation, and no one here can analyze the evidence and determine the cause. We can't see it.

lyn:

Yes, there was this investigation perhaps by the insurance agency and investigating agency took 3 months and concluded that the fire started in roof insulation by a spark.

Disregard.

If that is the case, then this thread is superfluous.

lyn:

The house owner was away, there were fire alarms and some communication to the fire fighters and by the time owner came to the site, the entire house was on fire and fire fighters were doing their job.
These houses have a lots of wood and then some filler insulation as per law of the land for approval in Australia.
This is while construction of house.

This is after construction is done and approved.

During installation, the wire might have been flexed enough to cause a crack in the insulation. Though rare, a manufacturing defect is also possible. As others have noted, penetration by a nail or the like could occur; I imagine it happens fairly often.

Tornado:

It happened when house owner was away on work so can you explain the delay effect.

Did you mean that spark was there but un-noticed and then after gross delay of several hours it caught fire?

Of course there's always the old rat/mouse in the roof trick, did they find any corpses? Have had to replace cables in walls many times when I was contracting due to rodents chewing through the insulation.

In the UK before an installation is energised it undergoes a regime of inspection and testing, dead testing. The intake will have maximum fault current and earth loop impedance the first live tests. RCD's and RCBO's are ramp tested live to ensure the tripping characteristics are met for its class.

For a fault on a new(ish) install something has been overlooked, or there's been subsequent damage after commissioning.

What we come up with is all supposition.

What is less protected and can cause fire are loose connections: screws that haven't been tightened enough, sometimes wire ends that aren't stripped properly and break off, causing sparking, many wires in a lock nut and one not really.

Had this last week: all wires' isolation in the metal box burned down (about 10) till some real short-out occured and the breaker disconnected.

IMHO it was hot enough to start a fire. There was a lot of smoke and where smoke is, there is......

Here is the picture taken:

If you look well you will see the completely burnt wire nut between the 2 others and all the wires inside, where the isolation (insulation) became ash:

In this particular case the box sat in a concrete environment and nothing else was ignited.

This happened in an installation of 3 years old.

After fire pictures

This scenario is only possible:

1. Fire started in sunlight + 2. Bad connections in the wire connectors? Solar panels come with very typical connectors, that are sealed and locked +3. Roof made of e.g. asphalt shingles or any other "fuel" roof.

One home solar panel is able to produce 8 amperes DC.

The problem seems to be spotted, because a Austrian/Canadian/US prime inverter manufacturer (Fronius) introduced a spark detecting inverter at the end of last year.

As for firemen: Solar panels on a burning roof are probably, if not doomed, well insured? Knocking a few stars in the glass makes them stop producing current.

Our company installed today our 2360 th solar panel and pioneered solar from the 1970's.

Never we had a fire or even a close to fire moment.

1. Solar panels at night with full moon that produce any power are different from ours. The junctions are mainly Infra Red and full sunlight (spectrum) sensitive. These days all our inverters (about 70 pieces) go to sleep at about 6 P.M. when the sun goes down here.

That means the solar circuit is open. The panels do not even produce 0.25 watts to keep the LCD screen working.

2. The connectors for solar panels have been designed specially for solar panels, the problems that they may have to deal with and walk the 20 years warranty with flying colors. When not locked, the circuit is open and no power runs through the wires. I you want I can send some photos. Solar panels require also special wire, we use minimal 4mm2 and the wire is stranded copper with silver (no tin) coating and 2 times insulated coaxially. What is used there we don't know also.

3. There is only 1 spark detecting inverter on the market: Fronius sets the trend.

We never had to change a bad plug, and we only have one of the newest inverters installed. All the rest is conventional stuff.

4. Voltage defines the length of the spark. High voltage doesn't always mean fire hazard. Neon transformers e.g. have a current limiter in it. I have seen people running the high voltage on top of their skin. I wasn't that brave.

Sun and 10 solar panels parallel make a DC welding device when you feel the need for it.

For the firemen: do the stars in the glass. Even use your water nozzle if nothing else is available. The glass, 3 or 4 mm thick is part of the sandwich: glass, transparent impermeable foil, solar wafer(s) and bottom insulation foil (white or a variation on white). The glass is hardened but stays in the frame, bonded to the foil. ( you can see it even on the pictures of Dr Shyam) When you crack some panels, the circuit get and goes completely different routes. The wafer connection internally crack open and when the spark, they open even more.

I once had panels delivered and batteries, and the shipper had loaded the batteries on top of one panel, resulting in a splattered glass in the frame.

With a DVM it provided still 20 Volts Open circuit, but when with a faible few mA load voltage fell to 0.

A disconnect close to solar panels is useless for firemen. Solar panels in sunlight when connections are exposed (what I doubt) are like batteries or open electrical panels. No water should be used on these.

But that is not the case. You have DC voltage that is floating and is not connected to the earth and how will the circuit close with water and a fireman?

The frames are usually at ground potential, where is the fireman - once more.

There is a lot of hype going on. That is a normal phenomenon with new technologies, but are we engineers not supposed to understand and if not help each other understand?

The US is a starter on solar because energy is cheap compared to other continents. These, even Africa are way ahead. Most of the technology has been developed in Germany and Austria.

For your convenience, I took a male and female connector apart. Look at the cable's waterproof - and mechanical seal and the red O ring in the system. Though not advisable, these plugs can even swim in the gutter without problems. They are also very expensive ( $3,00 plus, in large quantities- perhaps there are some cheap imitations - we use good stuff)

Our Expert Safety Engineer keeps a better eye on our installations and implements way ahead of what the electrical code years from now will adopt. Our skill and insatllations are also insured.

The panel box has the same provisions. All these come with 15 safety labels, included your UL.

Unless these components have not been used I rule fire by solar panels out for 99.99999999999%.

The plug must be that safe because under no circumstance the technician can have contact with hot plugs (ends). Imagine what happens when you open a circuit of say 500 volts and close it through both your hands. Unless you use a nail you can not even touch the bare wire.

But please people do as you have been told. I take only responsibility for my actions. And I don't want to become political.

When fear is induced, the quality of life fades away. Best Regards. D.

dvmdsc-

Obviously you are very knowledgeable about the solar panel systems that your company produces. If they operate as you have stated and have not been part of the initial stages of a fire that is very good. Apparently, at least as what I understand you have described your systems as; they are very different than the normal system found in the USA. I am glad to see that American ingenuity has produced such a system as yours but we are not speaking of only one system. The vast majority, nearing 100%, are of the type of systems that I have described. One system does not represent all the installations. The hazards I have described are factual for almost all systems. For example, most systems will radiate energy outward during moonless nights unless properly equipped not to.

At 2360 panels in approx. 40 years (from the 1970's), 59 panels per year is not anywhere near the majority of panels installed. I stand corrected about the systems your manufacture but the vast majority does not fit into those criteria. There has been an enormous proliferation in recent years especially with the government incentives.

As for the firefighting aspects of solar panels I stand firmly on what I have said. Those are the tactics I have been taught and have experienced in actual drills and training scenarios. Most important though are the experiences of fighting actual structure fires involving solar panels and some of them started because of the solar panels. Firefighters do not have the time to investigate if the particular solar panels are of one manufacturer's design. If they did the structure would be lost before they found out which one it was. Each incident must be treated as a unique situation but the risk to the firefighters must be kept as low as possible.

I don't make the rules of firefighting at solar panel installations but I religiously follow them. A panel is never going to have a "star" opening put into it. There is live electricity in almost all sites and besides that there would be no benefit to doing so. Water and electricity don't mix, a firefighter does everything he can to avoid the two together. Of paramount importance is that on a pitched roof mounted system there is no room or safe area on the roof. The whole thing is covered with panels in most locations and they are definitely unsafe to try to sit, stand or place a roof ladder on. The fire fighting procedures you describe are only applicable to your type of system and not the vast majority, close to 100%, of the systems out there. For the majority of panels those procedures are deadly. Before making statements about firefighting tactics concerning solar panels it would be prudent to obtain knowledge applicable to firefighting from those who know firefighting. Statements from the manufacturing view point are not valid and correct in this case. They are deadly!

In order to properly fight the subject fires, extensive communication and demonstrations have been conducted by the firefighting community and the solar panel manufacturers. These manufacturers are the ones who initially and continually state that panels are not to be broken because they are electrified with power great enough to kill. I can assure you that I wouldn't want to myself or any other firefighter killed because they didn't follow prudent procedures.

Again I state, if you want to know about firefighting when solar panels are involved go to the firefighters, their trainers, their technical personnel, the manufacturers involved with these types of panels and national firefighting training conventions. It would be very informative for you and might provide more knowledge about firefighting at the vast majority of solar panel installations.

I don't manufacture solar panels. Once did many years ago for a short while but I'm no longer knowledgeable about modern systems from that standpoint. I fight fires at solar panel installations. I am very knowledgeable about it and can conduct those types of incidents. I don't confuse the two of them. Likewise, you build them and I will put their fires out. To do otherwise is dangerous and potentially deadly.

Remember the Dietz & Watson plant in Delanco, NJ, last year? It is described in one of the sites listed in my previous post. If so many people are afraid of solar panel fires their probably is some very good justification for it.

Good Luck, Old Salt

dvmdsc-

These could be of interest. They verify what I have stated previously.

http://www.foxnews.com/us/2013/10/02/firefighters-alarmed-by-dangers-posed-by-rooftop-solar-panels/

http://www.accuweather.com/en/weather-news/firefighters-danger-solar-panels/19689021

http://www.theatlanticcities.com/technology/2013/09/why-firefighters-are-scared-solar-power/6854/

http://www.triplepundit.com/2013/09/rooftop-solar-panels-really-hinder-firefighters/

http://www.reuters.com/article/2013/09/06/us-usa-solar-fire-idUSBRE9850V220130906

Good Luck, Old Salt

I've talked to a lot of guys, and they're saying, 'We've never run into it, but if we do, we're going to fight it defensively,'" Davis said.----- end quote - last link
This looks for me the most honest statement of all the links. Hype and no experience and knowledge.Tel me how it is possible when + and - of an insulated system to make a current loop through a person that cannot have contact with the 2 polarities at the same time.When the frames are grounded, the easiest way for the current to flow is through the water that covers the panels and only if and when they are defective, meaning busted, cut or whatever.
Perhaps UL should do some firefighting. TUV, Kema, and others, dealt with that years ago. I ran through a full training of firefighting at Exxon- Mobil, BP, Gamatex and Monsanto in the port of Antwerp, on solids, gases, liquids and electricity related fires. It is OK with me that opinions differ. I am getting used to that and became more understanding. Who am I ?I don't like the word firefighter.Fireman of a fire brigade sounds more educated to me.We will live and learn, that is life.Best regards. D.

dvmdsc-

Yes, we will live and learn! Wise words that I believe in also. Sometimes, hopefully few, I have to remind myself and others of the validity of it. Obviously you and I are both versed in different aspects of different types of solar panels. Both apples but one is a Macintosh and the other a green baking apple. Both are good for their intended purposes but both are apples with different properties and tastes.

I respect the complete knowledge you have for your product. No communication was intended to disrespect that. You have the manufacturing knowledge and experience of your product and I have the knowledge and experience of fighting fires associated with the more common types of solar panels. No one should every question or deny those facts.

There are several principles I make all attempts to follow in firefighting. Always have at least two people and most often 4 people do any interior work during a fire, always use risk analysis in everything you do (even if it only takes 2 seconds to do it)no fire is worth your life for, always use your accountability tags correctly and last but most important--always come home.

You certainly have impressive training credentials in firefighting. Hopefully mine would carry the same weight if you were to review all of them. I am always trying to learn more about everything I am interested in, especially firefighting and Haz Mat responses. They are two subjects that there is never too much to learn about.

The reason I use the term "firefighter" instead of "fireman" is because firefighting has become an area that many women are interested in and most can do a completely competent job at it. At the present time my fire company does not have any women but we have had in the past. As part of their training staff, I have found most of them eager to learn and any physical tasks that they are confronted with can be done by them even if it is done in a different manner. The end results are the same. I have seen several women firefighters who could do many things better than their male counterparts. One of the towns adjacent to mine has a very competent female fire chief and she has been at that level for several years.

Without different viewpoints there would be little advancement of the world and its people.

The following are good examples of a small part of the training that I initially received as part of my solar panel training.

Good Luck, Old Salt

Fire Fighter Safety and Emergency Response For Solar Power Systems

http://www.nfpa.org/~/media/Files/Research/Research%20Foundation/Research%20Foundation%20reports/For%20emergency%20responders/RFFirefighterTacticsSolarPowerRevised.pdf

A DHS/Assistance to Firefighter Grants (AFG) Funded Study

Firefighter Safety and Photovoltaic Installations Research Project

http://www.ul.com/global/documents/offerings/industries/buildingmaterials/fireservice/PV-

FF_SafetyFinalReport.pdf

Underwriters Laboratories Inc.

The Impact of Solar Energy on Firefighting

http://www.fireengineering.com/articles/print/volume-162/issue-1/features/the-impact-of-solar-energy-on-firefighting.html

Fire Engineering Magazine

Solar Panel Safety for First Responders- Part 1

http://www.youtube.com/watch?v=EaPadE2SIcI

Solar Panel Safety for First Responders- Part 2

http://www.youtube.com/watch?v=ldzJIf4j8do

Wisconsin Fire Service Training

Safety for firefighters focus of legislation

http://www.northjersey.com/news/161096295_Safety_for_firefighters_focus_of_legislation.html

The Ridgewood News

Thank you. Exchange of ideas always leads to somethings positive. Best Regards. D.

FYI- To All, this is progress in the installation of solar panels. It is especially beneficial to firefighters. The article is included in its entirety so that all will understand.

YOU READ IT HERE FIRST: Gov. Christie today signed a long-awaited bill in law establishing new protections for firefighters when they are working around roof-mounted solar panels.

The law reflects regulation updates to the National Electrical Code and Uniform Construction Code that require external shutoff mechanisms. It also calls for the creation of identifying emblems for buildings that have the systems or are served by them.

One- and two-family residential homes are exempted from having to post the emblem, and buildings that already have an emblem indicating a truss roof may combine the two into one.

The new law also requires that the specifications of the PV system be filed with the local fire department. This allows firefighters to have quick access to the information they need regarding system shutoff locations, number of solar panels, etc.

With more than 9,000 solar energy locations, New Jersey is second in number only to California.

The proposal law was launched in Trenton in 2011, then picked up momentum following a warehouse fire in Burlington County last year involving more than 7,000 solar panels that made the job extremely hazardous for firefighters.

"We may very well not be able to save buildings that have alternative energy," William Kramer, New Jersey's acting fire marshall, told the Star-Ledger after Delanco Fire Chief Ron Holt refused to send his firefighters onto the roof of the 300,000-square foot Dietz & Watson warehouse.

The greatest risk is the potential for electrocution. Even though the panels put out no more than 600 volts, that's enough to cause shock and burns. And they can't be shut off. Any kind of light, even a firefighter's flashlight, will generate continuous electricity.

They also block routes that firefighters need to cut roof holes for ventilation and make for tricky footing.

Even more menacing is the possibility of a structural collapse under the weight of the panels - as well as the potential to inhale dangerous fumes when solar batteries are burning.

Good Luck, Old Salt

Thank you for posting this.

Cutting off solar panels doesn't work. They are a source and that switch doesn't help a lot. One switch per panel is a better approach, although it has to be a very good and watertight one.

The star knock per panel destroys the output (and the panel) and also reduces the output current to a small harmless proportion.

But again, a isolated solar panel does not leak current to firefighters, unless the hold one of the poles and spray water on the other. Birds on electrical lines in the air are also not shocked or electrocuted unless they leak to the ground or a different potential.

Some regulations for protection could turn out to be more dangerous than none.

I'll keep following he evolution. Thank you.D

Ed Watts:

Good point. I am looking into this point for some feedback from house owner.

In my house built 1951, there was a bakelite switch next to the electric hot water system under the house. It was mounted on a softwood base, which in turn was mounted on a hardwood (eucalyptus) stud. The hot water went off. When I checked, the switch was charred and hanging loose, the pine base had a large burn hole in it, but the stud nary a mark, and the wire insulation was slightly damaged at the ends of the wires. Obviously a high resistance in the switch triggered the problem, unless a gecko or cockroach got there first, but no corpses.

I forgot to add that the switch used blade contacts that wiped between two other blades. New switches use compression contacts, which I don't like, I reckon they are more likely to have resistance problems with age. I replaced with a bakelite switch similar to the old one. I reckon carrying 8 Amps for 60 years before failing proved its reliability.

The wire vibrates at the frequency of the power. If the wire was run over some sharp edge like those of one of the tie plates. After time it will wear thru. This could be the cause. There could be other similar causes. Contact with a nail head, junction box, AC duct, or could have been the staple used to retain it wire was hammered in too tight.

Fortunately, my experiences didn't lead to fire.

After a few years the front porch light of my townhouse lost power. I finally tracked the problem to installation error. At a difficult spot under a stair landing, the electrician cut the corner instead of going through the corner post. The sheetrock hanger used a nail to hold the wire until the wallboard was in place. When he drove the nail, it went through the outer sheath and nicked the insulation. After a few years, galvanic corrosion parted the wire.

Later, we bought an 8-year old house. After we moved in, I noticed that the vent fan in the bathroom would slow down and speed up periodically, about every 15 seconds. The problem was caused by the electrician's not tightening the terminal screws at the switch. He just wrapped the wire around the screw and left it. About half the receptacles and switches in the house were this way and hadn't been found since the house was new.

Most residential electrical fires do occur in the attic (under the roof) because that is where most of the electrical wiring distribution and wiring is located.

Normally the wall switches and outlets report to the ceiling lighting fixture boxes or to connection boxes mounted above ceilng in the attic area.

Most electrical fires are caused by loose connections as a result of circuit overloading or improper wire nut installation whic is usually because of not enough applied torque or too many wires for the wire nut size.

Once the connection becomes loose it presents a higher impedance to current flow causing the wiring to produce arcing and heat resulting in the insulation melting.

The wiring and/or connection box will eventually reach a temperature high enough to ignite the wood rafter or wood stud the box is mounted to.

Another prevalent cause of electrical fires is the use and improper installation or improper maintenance of aluminum wiring.

Yes. The insurance company's investigating officer can. And if someone has died, then the Police and Fire services' investigating officers can.

try old age!!

what is the point of your question?

Point here is that fire took place and then fire fighters came into action much later.

Damage has already been done to the house as it had a lot of flammable material which is normally used in the construction in the zone and perhaps after electrical failure and some ignition took place, the heat insulation also failed due to large time gap from start of the fire to the fire fighting action.

Let us not argue about solar panel problem in fire fighting as that is a separate issue.

If solar panel wires get directly shorted somewhere including in the defective inverter or battery charger then entire cable will heat up and finally insulation will not only get out but will let short circuit happen and then a chain reaction may start as cable insulation is not fire proof and can finally start burning and can become a fuel by itself. Only PTFE / Teflon decomposes and most of the other insulation will burn as no one uses glass or ceramic or special insulation in house wiring as we use in industrial applications.

Solar panels perhaps did not have short circuit trip but they do have over voltage protection diodes that actually are meant to short circuit the panel voltage to partially lose the charge locally and it sure will generate some local heat in the solar panel. Not using solar panel can cause serious problem as charge will be generated and then it will be wasted in discharge diode circuits in the panel itself. This is by design in the solar panels. If roof below solar panel is hot enough to exceed 150C then solar panel circuit will also fail to protect itself as semiconductors often work below this critical temperature and perhaps up to 100C there may not be much problem and suddenly they will blow off if 150C plus is reached.Heated wood structure will also emit wood oil which can also ignite the structure.

We do have some good picture of what might have happened in this case.Now I will like to thank all participants. I think this discussion was well cooperated and there were no ugly talk anywhere. Hence credit goes to all participants here.

Thank you one and all.

Shyam

Well, it wouldn't be the first time that an extraneous rodent chewed through an electrical cable thinking it to be a water pipe.