Editor Note – This article was first published on the site in December 2004. Its being republished to the new site’s format.
I have been doing electrical and electronic installation and troubleshooting for over 20 years, and it seems like I get more trouble calls to do repairs during the winter months. You may also see this pattern with structure fires, especially fierce ones, when investigated come back with the ruling of an electrical malfunction as the cause of the fire. The sad part of this being that 80% of all electrical fires are 100% preventable if the minimum standards as set fourth in the NFPA National Electrical code are followed. Which means if an electrical circuit is not installed and designed to the minimums of the NEC a fire or accident is going to result at some point in time, this is a known and proven fact.
So lets look at some factors as to why there would be more fires during the winter months. 1st off with less daylight available people are turning there indoor lights on much earlier and using more of them for longer periods. 2nd people are using electric blankets and space heaters often on under designed circuits then what is required. 3rd the physical wood structure of a home becomes drier or moister which can contribute to electrical fires under the right conditions. 4th holidays bring with them a vast array of decorations etc that also help to increase the electrical load on circuits that may already be showing signs of deterioration. 5th poor judgment by residents who ignore warning signs and do not follow recommended codes and safety rules.
Lets start with electrical lighting fires. These can be started in many different ways. Using a 100-watt light bulb in a fixture designed for 60 watts or using a Quartz light designed for modern insulated wiring which can handle 90 degrees Celsius on older wiring which can only hold 70 Celsius. Both of these conditions causes over heating of the socket and wiring and eventual failure of the insulation in the socket. The result is often a fire after the wires to fixture become brittle, crack and their conductors lose their insulation and touch the metal case and then cause a spark or touch against combustible material. Sometimes the condition will burn open the wires causing just the lights to go out and the wiring and light fixture having to be replaced. Often times lights blinking in a house for no reason is a sign something is going wrong and needs further investigation.
Other lighting fires happen due to bare light bulbs touching up against combustible items in covert or free standing lamp. Look in the hall closet of any modern home and you will find no light installed or if there is one installed it is fluorescent and it is installed in a manner that materials can not bump up against them. If they do the fluorescent light runs much cooler than a bare 60-100 watt bulb typically used in an older home. Because of good investigation practice many of these types of fires have become less occurring because the NEC code has been drastically changed to prevent these fires. But still there are those homeowners and remodelers etc who put the wrong fixture in a closest because they are ignorant of the code or do not care to follow it.
Next lets look at heating blankets and space heaters and their roles in causing fires. The following is standard protection requirement for modern wiring circuits 1 14 #gauge wire should be fused at no more than 15 amps a 12# gauge wire at 20 amps and 10 # gauge at 30 amps. There are some minor exemptions with very old style knob and tube wiring to this but generally you should not have fuses or breakers in a service panel bigger than 20 amps unless it is serving a major appliance load such as an electric stove which has larger gauge wire to it. So lets look at a typical 1500 watt space heater at 1500 watts and 120 volts the space heater is drawing 12.5 amps. So ethnically a 14# gauge wire fused at 15 amps should be able to handle this load but take into the other part of the electrical code that a load being used continuously on a circuit can only draw 80% of the circuit. Which means the load on a 15 amp circuit running continuously can be no more than 12 amps allowing 3 amps for occasional start up surge. So as you can see the 1500 watt heater is over the safety guideline by ½ an amp. Not a big deal if you run the heater a short time and it is on a modern and well-maintained circuit. But running it continually on an older circuit with loose connections and other items at some point is going to cause a fire. This is why many space heaters have warnings on them to use only on 20 amp-dedicated circuits just as you would a window air conditioner.
Fires from space heaters are caused when this older circuit starts to heat up and connections start expanding. It could be right at the wall socket or deep in the wall somewhere. I have seen wiring move and touch against nails or metal lath when it heats up to the point were the insulation gets worn off and a spark develops. A slow smoldering fire starts slowly burning, and with dry wood conditions the fire can develop even faster till at some point it breeches the wall and there is explosive results. Even if all connections are tight wiring can still expand and contract when a large continuous load like a space heater is put on it. This is why space heaters should never be left unattended.
Then there are electric blankets, a great way to warm up a bed in a cold room. But they also contribute to many fires when allowed to get old and brittle and or damaged by being put under a doorway, rug furniture or get damaged by a pet. Especially pet rabbits for some reason love to eat on electrical wires. Then people will run the electric blanket on an extension cord that they should not use, but if it has to be necessary, the proper gauge cord with good fitting connectors and UL listed should be used. The problem with extension cords especially cheap ones is they often have not been UL tested and certified and many times the UL labels have been counterfeited. Any electrical item from overseas, in particular from China, should be closely examined before it is used. Many counterfeit electrical items of late have been coming out of China. This is particularly critical with the Christmas decorations you will buy and put up. This is what many holiday fires can be directly traced back to. Many times people use indoor only rated decorations and electrical fittings outdoor. And this is only the start of things done wrong. Never use any decoration outdoors unless it is rated to be used outdoors. This goes for timers, extension cords and adapters as well. Outdoor rated items have extra features built in to withstand severe weather conditions indoor rated items do not. Water getting in to them can cause them to deteriorate and spark causing a fire. If you put up outdoor Christmas lighting you can avoid many problems by having a properly installed Ground Fault circuit Interrupter receptacle installed outside which is controlled by a switch.
Installing lighting thru an adapter to a porch light is a bad idea. Most porch lights are only designed to handle 60 watts period and not to be used for any other purpose. Yes I know they make adapters but I strongly discourage their use. You are much safer plugging into an outlet; this is why the NEC requires an electrical outlet with GFCI protection installed front and back of all new homes. Now I know you will get some false tripping of the GFCI when it rains or snows etc. but you also may have just prevented a fire. GFCI trip out when they sense danger. Portable outdoor rated GFCI can be purchased and used in older outdoor outlets. Which brings us to our final item how too much dryness or moisture can contribute to fires.
Well unfortunately if I am right on the above statement then the floods that came on September 17 2004 are going to cause horrific events this winter. Excessive moisture allows for the break down of electrical components that are not weatherized properly. This is especially true around outdoor outlets that have not been properly sealed when installed. When items break down they begin to overheat and spark and the high moisture allows an electrical path be created to ground and a fire develops.
Take the case of a mini market fire this summer in Penn Hills. A Neon Sign that runs at 15,000 volts was not properly wired. The high voltage transformer and sign were not properly grounded and wiring was not properly sheathed to prevent it from getting abraded against the sign’s metal case. With the vibration of big trucks etc against the building and expansion and contraction of hot and cold days the insulation broke and the 15,000 volts made contact with the metal sign. Now had the metal sign been properly grounded that would have been the end of the story the high current of a short circuit would have tripped the breaker and the power to sign would have been turned off. Upon inspection by an electrician the problem would have been found. Instead the whole sign body became electrified and because it was mounted on wood with a low moisture content the wood acted as an insulator. Nothing happened until the very wet summer months came and the wood had a higher moisture content and after a particular strong downpour the sign caught fire after a path was created from the now very moist and wet wood to a metal down pout that was connected to a metal post creating a high resistance. Ground connections that started sparking and caught the wood on fire where the sparking was. Luckily the fire was caught quickly and storeowner cut power immediately when a customer came in and told the clerk there was smoke coming from the sign. This same scenario can play out with even 120 volt outdoor lights on a home when the deteriorate as well, because many of them are not properly grounded as well.
Next extremely dry wood plays a cause in fires in homes during the winter when wiring splices have not been properly made in a junction box. Often times a Romex wire is put thru the box with no clamp to keep it in place. The round wires are not used or if they are used the box itself is not grounded. Often the wires are twisted together and then just tapped instead of twisted soldered and tapped or preferred method is use of a wire nut or cap as they’re called. Because the splice has just been twisted and tapped, a high resistance can start building up in the splice and wire starts moving around till the tape is gone or melted away from the heat. The hot wire is now touching against the metal box which is fastened to the wood beam. If the ground had been attached to the box again the circuit would have tripped, but instead of tripping the wood being so dry has slowly begun to lose its insulating properties and its ignition point is drastically reduced to the point where the wood behind the box can now catch fire often resulting in dramatic fires.
So as you can see there are many ways why there are so many fires in the winter. The big question is the very home you are in this very moment. Is it a ticking time bomb waiting to go off or a well maintained safe one? If you are unsure hire only a qualified properly trained electrician to have it evaluated and repaired or suffer the consequences.
By Nick Markowitz Jr.
Member Emsworth Pa. VFD
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