A sunny day with low humidity, warm and not too windy — that seems like a perfect day to install a roof. However, while those are favorable working conditions, they can set the stage for a fire hazard. When the air is dry and still, whether hot or cold, the atmosphere is right for static electricity to build up. Certain construction materials used by a roofing crew can contribute to the static charge as well. And solvent-based products can release vapors, which the static electricity can ignite with a spark. That scenario is dangerous for your workers and can seriously damage the worksite structure.
Most people experience static electricity during cold, dry weather. Clothes cling, touching an appliance causes a shock or hair stands on end. Usually, it is just an annoyance, not a life-threatening issue. But when static electricity is present on a job site, employees are at risk.
Static electricity occurs when negative and positive charges are imbalanced. Atoms make up every object, and those atoms contain neutrons, protons, and electrons. Neutrons are neutral, while protons have positive charges and electrons have negative
charges. When positive and negative charges are balanced, all is well. Usually, objects with the same kind of charge will repel each other. However, if they rub against each other, static electricity builds up until it finds a way to release. That friction on a roofing
project can lead to a dangerous spark.
A static electricity fire might sound like a fluke, but it is not. The National Fire Prevention Association notes that fire departments respond to almost 280 industrial static electricity-related incidents every year.
Humidity is a critical factor for static electricity. The lower the humidity, the higher the chances for dangerous levels of static electricity build-up. According to findings from the National Oceanic and Atmospheric Administration, at least 89 percent of the United States experiences humidity of 60 percent or less, at least seasonally. Humidity levels can drop dramatically in a single day, such as when a cold front blows through, so safety conditions at a site can change quickly. Therefore, it is crucial to know the potential sources of static electricity and protect against them every day, not just when the humidity plummets.
In homes and offices, most people encounter static electricity when walking across a carpet or touching a metal object. However, the movement of fluid can also generate static electricity. On a construction site, this movement can happen when workers stir, pour or pump fluids.
Contractors have reported that many flash fires involve isocyanurate insulation, single-ply membranes and bonding adhesives. Crew members can create a static charge by dragging insulation boards over one another, sliding membrane sheets over insulation or removing release liners from membranes. Once static charges have accumulated, workers can inadvertently cause sparks when they allow a metal adhesive roller or applicator handle to touch a metal adhesive container. They can also create a spark just by walking across the insulation.
A single spark can cause a flame or even an explosion. Such an occurrence can injure workers, set fire to a building and jeopardize an entire project.
Most construction companies are diligent in providing employees with the necessary training for fire safety. However, it is a good idea to reinforce the basics:
■ Ensure that the building and all electrical lines are grounded. Check with the building owner as needed. Remember that metal objects are conductors, so electricity flows through them. Grounding metal objects can make the worksite safer because it allows the electricity to dissipate into the earth.
■ Take time to store flammable liquids safely. Keep containers sealed when not in use so vapors do not spread. If containers are in metal cabinets, make sure they are grounded.
■ Have workers wear clothing made of cotton. Synthetic materials such as polyester or nylon can cause static to build up more readily.
■ Train workers in discharging static from their bodies before handling solvent-based primers or adhesives and before removing release liners.
■ Instruct workers to use caution when moving insulation boards, electrical cords and membranes. Try not to drag them.
■ Be aware that vapors from solvents are heavier than the air. If working in a confined space, use a fan to direct fumes away from heaters and electric motors on the site.
■ Prohibit smoking at the worksite.
■ Make sure fire extinguishers are available and train workers to use them.
Static electricity is not visible, but it is always present and hard to avoid. Every roofing crew can benefit from learning about the potential risks and how to manage them.
Disclaimer: The information contained in this article is for general educational information only. This information does not constitute legal advice, is not intended to constitute legal advice, nor should it be relied upon as legal advice for your specific factual pattern or situation.
Trent Cotney is Board Certified in Construction Law by the Florida Bar, an advocate for the roofing industry and General Counsel of FRSA. For more information, contact the author at 866-303-5868 or visit www.cotneycl.com.
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