Parkside PSSFS 3 A1 Bedienungs- Und Sicherheitshinweise Seite 32

An inversion of the neutral and the earth conductors will not be
detected by this product .
This product is integrated with an RCD (Residual Current Device)
test function, which can be used to check the tripping function of a
30 mA RCD . It features rapid detection of correct/incorrect wiring,
fast and effective RCD test function .
Any other use or product modification shall be considered improper
use and holds considerable safety hazards . The manufacturer
assumes no liability for damages due to improper use . Not intended
for commercial use . This product is designed only for indoor use .
Always observe the regulations and laws in the country of use .
GB/IE 33