Humidity and electrostatics

Electrostatic charges

Humidity and electrostatics – A humidity level below 40% contributes to a significant increase in electrostatic charges on all kinds of non-conductive surfaces (such as di-electricians). This situation occurs during the heating period, when the frosty air from the outside is heated by heating devices to room temperature. As a result, its relative humidity drops sharply. The effect of excessive accumulation of charges is damage to electronic equipment, as well as the risk of fire or explosion of volatile substances. A very effective method of reducing electrostatic charges over a large area is to increase the relative humidity of the air by using a fog humidification system.

Lowering the level of electrostatics

Influence of air humidity on electrostatic charges

Humidity from the air creates a thin layer on the surface of many materials, contributing to a change in electrical conductivity. The resistivity of many materials, especially those of natural origin, such as paper, decreases by orders of magnitude as humidity increases. In the case of high resistivity of materials (in a dry atmosphere), the formation of electrostatic charges on their surfaces is intensified. Some electronic components (e.g. those most sensitive to discharge) are covered with a special polymer coating that absorbs moisture from the environment ensuring low resistivity of the material. It is assumed that serious problems with electrostatics begin at a humidity below 40% RH. That is why it is so important to use appropriate fog air humidification systems to ensure constant humidity at the right level.

In Central European climates, outdoor humidity ranges from 10% RH (during a cold winter) to 100% RH (e.g. during fog). Of course, it has a huge impact on the humidity inside the rooms, especially those with forced air exchange.

Humidity and electrostatics – Comparison of electrostatic voltages at different air humidity:

Activity Measured voltage 10-20% RH (without humidification) Measured voltage 50-90% RH (water mist humidification)
A man walking on the carpet 35,000 volts 1,500 volts
A man getting out of a car 10,000 volts 500 volts
A man walking on a carpet 12,000 volts 250 volts
A man working in an ungrounded position 6,000 volts 100 volts

See also

About air humidification