Static electricity, the phenomenon responsible for electrostatic discharge, is responsible for everything from simple, often harmless effects like a child’s hair standing up on a playground slide to much more dangerous incidents like fires at the gas pump and even the Hindenburg disaster.
We’ve all experienced the shock of touching a doorknob—or perhaps even another person—after walking across carpeted floors, but perhaps few of us really understand what “static electricity” really is… and fewer understand what causes it.
What is Static Electricity?
“Static” electricity is latent electrification of an object. Unlike “current” electricity, which flows through substances, a “static” buildup involves acquiring an electrical charge which remains until it is discharged.
In the simplest of terms, “static electricity” refers to a positive or negative electrical charge. An object, or indeed a person, can build up excess electrons (a “negative” charge) or can lose electrons (a “positive” charge).
More specifically, the surface of an object is where this electrical charge resides.
How Does Static Electricity Build Up?
The most common means of a person or an object acquiring an electrical charge is a process known as “triboelectric” charging. Triboelectric is derived from the Greek, tribo- (‘rub’) and ēlektron (‘amber’), which is one of the earlier substances known to have been responsible for the “triboelectric” effect, and is thus the origin of the terms, “electron” and “electricity.”
As the Greek origins of the word imply, triboelectricity is often the result of rubbing, or friction. However, friction is not required to produce the charging effect.
In reality, simple contact followed by separation can produce an electrical charge in many substances. Amber and wool, for example, will produce triboelectricity when brought into contact with one another and then separated.
Other examples of substances known to produce the triboelectric effect:
- glass and silk
- rubber and fur
- hair/skin and certain plastics & vinyls
All that is needed for the build-up of an electrical charge is contact, followed by separation. In this simple example, a woman starts fueling her vehicle, then gets inside. Presumably, all it took was contact between her shoes and the vehicle’s carpet, or perhaps her skin and the fabric on the seat, to produce a buildup of static electricity:
What Causes Electrostatic Discharge?
As you can see in the video above, the woman has picked up a static charge by contact with the interior of her vehicle.
A “discharge” occurs when the object (or person, in this case) which has built up a negative or positive surface charge comes into close proximity or contact with another object that has a different charge. In the video above, the woman comes into contact with metal (either in the pump or the vehicle itself) and a small spark (or electrical arc) is produced.
Given her close proximity to the fumes of the gasoline, the results are predictable.
A similar discharge occurs when you walk across a carpeted floor in shoes in rubber-soled shoes and then touch a doorknob or other metal.
The real problem for businesses comes in when that electrostatic discharge occurs near sensitive equipment. This type of discharge can produce immediate, catastrophic failure, or even minor damage that doesn’t produce failure for a long time to come.
In future blog posts, we’ll talk about various aspects of electrostatic discharge, and why prevention is so important.
In the mean time, remember that electrostatic discharge is the reason that you always want to place your gas can on the ground before filling it up. Your truck bed or carpeted trunk is a recipe for disaster!