Many people ask about shocks experienced when they touch the door, filing cabinet, lift, or other metal object. So where do these tiny bolts of lightening come from?
Static electricity is generated whenever two materials are in contact with each other. All materials are made of electrical charges in the material atoms. In the universe, there are equal amounts of negative electrical charge (electrons) and positive charge (protons). These generally try to stay in balance of equal amounts at every location.
However, when two materials are in contact, some of the charges redistribute by moving from one material to the other. This leaves an excess of positive charge on one material, and an equal negative charge on the other. When the materials move apart, each takes it's charge with it. One material becomes charged positively, and the other negatively.
If the materials are able to conduct electricity away, the charges will dissipate and eventually recombine. In this case, static electricity effects may be too small to be noticed. However, if the charges are separated faster than the material can dissipate them, the amount of electrostatic charge builds up. Eventually a high voltage, and the effects of static electricity, may be noticed.
Many people experience shocks when they get out of their car. Often they believe that the car is charged - but this is not normally so. When sitting in the car, electrostatic charges are generated on the car seat and the person's body, due to contact and movement between the clothes and the seat. When the person leaves the seat, they take half of this charge with them. As they get out of the vehicle, their body voltages rise due to this charge. When they reach to touch the vehicle door, the electrostatic discharge and shock occurs as their hand approaches the metal door.
The voltage build-up can often be avoided by holding onto a metal part of the door frame as you leave the seat. This provides a return dissipation path for the charge on your body. If you have forgotten to hold the metal door part as you leave the seat, a shock may often still be avoided by touching the glass window before you touch the metal door. The glass may be conductive enough to dissipate charge, whilst preventing the rapid discharge which is felt as a shock.
Static electricity-related incidents at retail gasoline outlets are extremely unusual, but the potential for them to happen appears to be the highest during cool or cold and dry climate conditions. In rare circumstances, these static related incidents have resulted in a brief flash fire occurring at the fill point. Consumers can take steps to minimize these and other potential fueling hazards by following safe refueling procedures all year long.
Most important, motorists should not get back into their vehicles during refueling. It may be a temptation to get back in the car for any number of reasons. But the average fill-up takes only two minutes, and staying outside the vehicle will greatly minimize the likelihood of any build-up of static electricity that could be discharged at the nozzle.
A build-up of static electricity can be caused by re-entering a vehicle during fueling, particularly in cool or cold and dry weather. If the motorist then returns to the vehicle fill pipe during refueling, the static may discharge at the fill point, causing a flash fire or small sustained fire with gasoline refueling vapors.
Motorists who cannot avoid getting back into the vehicle should always first touch a metal part of the vehicle with a bare hand, such as the door, or some other metal surface, away from the fill point upon exiting the vehicle.
Here are additional safety guidelines that will help keep you and your family safe when refueling your vehicle or filling up gasoline storage containers:
- Turn off your vehicle's engine when refueling.
- Keep gasoline and other fuels out of children's reach. Gasoline is highly toxic in addition to being a fire hazard. NEVER allow a child to pump gas.
- Don't smoke, light matches or use lighters while refueling.
- If you must use any electronic device, such as cell phones, computers or portable radios while refueling, follow manufacturer's instructions.
- To avoid spills, do not top off or overfill your vehicle.
- After pumping gasoline, leave the nozzle in the tank opening for a few seconds to avoid drips when you remove it.
- Don't get in and out of your vehicle while refueling. A static electric charge can develop on your body as you slide across the seat, and when you reach for the pump, a spark can ignite gasoline vapor.
- If you must get into the vehicle during refueling, discharge any static electricity by touching metal on the outside of the vehicle, away from the filling point, before removing the nozzle from your vehicle
- When dispensing gasoline into a container, use only an approved portable container and place it on the ground to avoid a possible static electricity ignition of fuel vapors. Containers should never be filled while inside a vehicle or its trunk, the bed of a pickup truck or the floor of a trailer.
- When filling a portable container, manually control the nozzle valve throughout the filling process. Fill a portable container slowly to decrease the chance of static electricity buildup and minimize spilling or splattering. Keep the nozzle in contact with the rim of the container opening while refueling.
- Fill container no more than 95 percent full to allow for expansion.
- Place cap tightly on the container after filling - do not use containers that do not seal properly.
- Only store gasoline in approved containers as required by federal or state authorities. Never store gasoline in glass or any other unapproved container.
- If gasoline spills on the container, make sure that it has evaporated before you place the container in your vehicle.
- When transporting gasoline in a portable container make sure it is secured against tipping and sliding, and never leave it in direct sunlight or in the trunk of a car.
ADDITIONAL SAFETY GUIDELINES
- Do not over-fill or top-off your vehicle tank, which can cause gasoline spillage.
- Never allow children under licensed driving age to operate the pump.
- Avoid prolonged breathing of gasoline vapors. Use gasoline only in open areas that get plenty of fresh air. Keep your face away from the nozzle or container opening.
- Never siphon gasoline by mouth nor put gasoline in your mouth for any reason. Gasoline can be harmful or fatal if swallowed. If someone swallows gasoline, do not induce vomiting. Contact a doctor or and emergency medical service provider immediately.
- Keep gasoline away from your eyes and skin; it may cause irritation. Remove gasoline-soaked clothing immediately.
- Use gasoline as a motor fuel only. Never use gasoline to wash your hands or as a cleaning solvent