Class equipment
Equipment which protection against electric shock does not rely basic insulation only,
but which includes additional safety precaution such way that means are provided for the
connection accessible conductive parts the protective conductor the fixed wiring the
. According ČSN standards the use this
class equipment prohibited the Czech Republic.2 Principal characteristics equipment according the classification.
Note: asic insulation: insulation applied live parts provide basic protection against electric
shock
Classes equipment
The class numbers are not intended reflect the safety level the equipment, but only the
means which the safety obtained. Table shows the principle characteristics the classes.FUNDAMENTAL RULES FOR PROTECTION AGAINST ELECTRIC SHOCK
36
Table 5.2.
Class equipment
Equipment which protection against electric shock relies upon basic insulation; this
implies that there are means for the connection accessible conductive parts, any, the
protective conductor the fixed wiring installation.
Class Class Class Class III
Principal
characteristic of
th equipment
No means for
protective
conductor
Protective
conductor (PE)
means are
provided
Additional
insulation and no
mans for protctive
conductor
Desidned for
supply safety
extra-low voltage
(SELV)
Precautions for
safety
Earth free
environment
Connection the
protective
conductor
None necessary Connection to
safety extra-low
voltage
Usual symbols
(according to
IC 60417)
No symbol
Application in
installations
In non-conducting
locations
according to
IEC 60364-4-41
With protective
conductor (PE) or
PEN conductor
General
application
With SELV
circuits
This table indicates also precautions necessary for safety the event failure the basic
insulation
