The human body is under an exchange of electric power difference between the atmosphere and earth, this is, it is constantly affected by electric charges that it absorbs and expels afterwards.
When two bodies are in close physical contact, there is the possibility of transferring free electrons between them. One of them gives electrons to the other, with which an attractive force is established. The energy consumed reappears in the form of an increase of electrical voltage between both surfaces. If the bodies are isolated of the medium surrounding them, the charge of both bodies occur, the one with an excess of electrons has a positive charge. If a conductor channel is put between these two bodies, the charges will immediately join again. If this conductor channel does not exist, as in the case of insulators, the increase of voltage because of the separation can reach thousands of volts, but with an insignificant intensity of amperes.
This increase of volts, the worst trouble that can make to humans is discomfort, as in electricity what is harmful for humans is the intensity, not the tension.
Although static electricity is not a direct threat for human life, an electric shock produced by a static charge can cause a shock, and if we were on a raised area, we could suffer an important lesion because of the fall.
Electricity is a source of concern in dangerous places, where a static spark may have enough energy as to create vapours and dust clouds.
Static electricity cannot be created, its appearance is due to an unequal and temporary distribution of electrons. Electrostatic charges are not created by the friction of two materials, but by separating two areas in contact. Separating two areas that were previously in connected, an unbalance of charges is produced, which creates an electrostatic field.
If the materials are insulating, the accumulated charge will not be immediately discharged, but it will remain a time. If they are conductors, due to their high conductivity, during the process of division the equalisation of charges through a contact surface will occur. After the complete division there won’t be any measurable charge excess.
It can be said that electrostatic charge is created in the following contact processes followed by division.
- Solid-solid
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Insulating-insulating
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Insulating-conductor insulating
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Insulating-conductor place at land
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- Solid-gas
- Solid–liquid
People’s charge can be so high that getting close to a conductor object may cause a sparks discharge. This would not have more importance than the discomfort that the affecter person would feel at the time of the spark discharge. Static electricity is not a direct threat for human life.
How can it be avoided?
The generation of static electricity is an unavoidable fact, the only thing that can be done is to void or alleviate its effects with some measures that void them.
The general measures are:
- Interconnection and electrostatic grounding of all conductor parts.
- Environmental humidity control
- Get people involved
- Ionisation of the atmosphere close to the material
