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Static Electricity

by Nick Gromicko

Static electricity is the buildup of electrical charges on the surface of non-conducting materials. It is called “static” because, unlike a home’s electrical system, static electricity has almost no current. Static typically forms when two materials come into contact, and some of the charges redistribute by moving from one material to the other. This leaves a net positive charge on one material and an equal negative charge on the other, both of which will remain if the two materials separate. If the net charges grow faster than a material can dissipate them, an electrostatic charge builds up. The excess charge can suddenly neutralize by a flow of charges to the surroundings, known as an electrostatic discharge or static spark. By super-heating the surrounding air and causing it to rapidly expand, the discharge is both visible and audible.

Interesting Facts About Static Electricity

Ordinary household static can have voltages many times greater than the home’s electrical system. A static shock is not ordinarily dangerous, though, because the current is comparatively low.
Scientists believe that lightning is caused by the exchange of charges between ice particles within clouds. Lightning is thus a scaled-up version of the static discharges with which we are accustomed.
During the Great Depression, swirling dust-bowl winds caused tremendous buildups of static electricity that were powerful enough to knock a person unconscious. Blue flames erupted from metal fences, electrical systems in cars shorted out, and people would drag chains in order to offset the electrostatic charge.

Static Electricity Hazards

Static may create sparks and shocks, and cause materials to cling together. These phenomena are typically merely annoying, but, under the right circumstances, they can cause significant damage to life and property. Specifically, static electricity can cause:

fires and explosions, where flammable vapors and dust clouds can occur. Static has caused deadly explosions in buildings that filled with natural gas;
nuisance shocks. While typically harmless, these shocks can cause significant distress to building occupants. In rare situations they can cause bodily harm, such as when hot fluids are handled and a static shock causes inadvertent recoil; and
damage to sensitive electronic equipment, such as computers and cell phones. One static-plagued InterNACHI member reported that she managed to disable the Caller ID feature on her phone by repeatedly “zapping” it, and she also put her microwave to sleep. Beware that even mild or imperceptible static discharges may be powerful enough to render a computer inoperable, or even erase its hard drive.

Static Limitation Strategies

There are many variables that contribute to static electricity in homes, including the physiological makeup of an individual, their walking habits and shoes, carpet materials and construction, and the amount of moisture in the air. To help ensure that static-friendly conditions are avoided, inspectors can pass the following tips on to their clients:

Humidify the living space. When the air is humid, water molecules collect on the surfaces of household materials, which prevents the buildup of electrical charges. Humidity levels of 40 to 50% are usually sufficient to prevent static discharges, and you can check the humidity with an inexpensive humidity meter from a gardening shop. Beware that high humidity levels will promote the growth of mold, which can be a far more dangerous condition than excessive static electricity. Try these other tips to increase indoor humidity:
- Use a humidifier.
- Incorporate a variety of leafy indoor plants. Plants effectively turn liquid water into water vapor, similar to a mechanical humidifier.
- Simmer a pot of water on the stove, but don’t forget that the stove is on!
Consider your clothing.
- Switch to natural fibers, since synthetics pick up more of a static charge. If you must wear synthetic fibers, do not allow them to touch; separate nylon and polyester layers with cotton, for instance.
- Wear leather-soled shoes. Also, try not to drag your feet on the carpet.
Use an anti-static hand lotion if your hands are dry.
Spray carpet surfaces with an anti-static product. Fabric softener has anti-static properties, and it may be diluted and then sprayed onto the carpet. These chemicals eliminate buildup of static electricity by making the material itself slightly conductive, either by being conductive itself, or by absorbing moisture from the air. These products may be sticky and attract dirt, however.
Wear an anti-static wrist wrap. These antistatic devices are used to prevent electrostatic discharge by safely grounding a person. They consist of a stretchy band of fabric woven with conductive fibers made from carbon or carbon-filled rubber.

In summary, static electricity can cause distress for building occupants, but it can be controlled.

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