Causes of Static Electricity
Brass, stainless steel
Generation of static electricity on an object by
Rubber
rubbing is known as the triboelectric effect. The
following is a list of substances in the triboelectic
Acrylic
series. The list is arranged in such an order that when
Polystyrene foam
any two substances in the list contact one another and
then separate, the substance higher on the list assumes
Polyurethane foam
a positive charge.
Acetate
Glass
Human hair
Nylon
Wool
Fur
Aluminum
Polyester
Paper
Cotton
Wood
Steel
Acetate fiber
Saran
Polyethylene
Polypropylene
PVC (vinyl)
KEL F
Teflon®
The size of an electrostatic charge on two
different materials is proportional to the separation of
the two materials.
Electrostatic voltage levels
generated by nonconductors can be extremely high.
However, air will slowly dissipate the charge to a
nearby conductor or ground. The more moisture in
the air, the faster a charge will dissipate. Table 10-1
shows typical measured charges generated by
personnel in a manufacturing facility. Note the
decrease in generated voltage with the increase in
Nickel, copper, silver
humidity levels of the surrounding air.
Table 10-1.-Typical Measured Electrostatic Voltages
VOLTAGE LEVELS @ RELATIVE HUMIDITY
MEANS OF STATIC GENERATION
LOW 10-20%
HIGH 65-90%
WALKING ACROSS CARPET
35,000
1,500
WALKING OVER VINYL FLOOR
12,000
250
WORKER AT BENCH
6,000
100
VINYL ENVELOPES FOR WORK
7,000
600
INSTRUCTIONS
COMMON POLY BAG PICKED UP FROM
20,000
1,200
BENCH
WORK CHAIR PADDED WITH URETHANE
18,000
1,500
FOAM
10-16
