Direct and indirect contact
From Electrical Installation Guide
|Two measures of protection against direct contact hazards are often required, since, in practice, the first measure may not be infallible|
A direct contact refers to a person coming into contact with a conductor which is live in normal circumstances (see Fig. F2). IEC 61140 standard has renamed “protection against direct contact” with the term “basic protection”. The former name is at least kept for information.
Fig. F2: Direct contact
| Standards and regulations distinguish two kinds of dangerous contact,
and corresponding protective measures
An indirect contact refers to a person coming into contact with an exposed-conductive-part which is not normally alive, but has become alive accidentally (due to insulation failure or some other cause).
The fault current raise the exposed-conductive-part to a voltage liable to be hazardous which could be at the origin of a touch current through a person coming into contact with this exposed-conductive-part (see Fig. F3).IEC 61140 standard has renamed “protection against indirect contact” with the term “fault protection”. The former name is at least kept for information.
Fig F3: Indirect contact