The contact current measurement is required in these cases:

• When a metal-cased object is immersed in an electromagnetic field.
• When a metal object has parts that transmits radio frequency (radio frequency gluing and drying machines)
• When a metal object has a circuit that works at radio frequency but is not isolated due to a malfunction..

In all these cases, the radio-frequency electromagnetic field produces an accumulation of electrical charges on its metal surface, which, in case of contact without precautions, can discharge to the ground flowing through the limbs and body generating associated transient currents.
Even with grounding, the problem remains, because the lower inductance L of the human body compared with that of the cable causes the contact current to flow through the operator's body.

Worker safety regulations require that instruments and objects exposed to radio frequency fields must be tested, to verify that the contact current value is within the limits, as in the table below