Benchtop Power Supply Question

[jiroy]

That's the anti-electro i talked about previously :

RESIDUAL CURRENT CIRCUIT BREAKER (RCCB)

Device installed in the distribution board upstream of the electrical circuits, this detects current leaks due to insulation faults and prevents any risk of electrocution by immediately cutting the power to the circuit concerned. A switch handle is used to reset it after the fault has been eliminated.