Rectifier circuits can be safe $-$ or dangerous.

$-$ A rectifier circuits is safe if the current through it never bypasses the load resistor.

$-$ A properly chosen load resistor limits the currents through the diodes to the safe levels.

$-$ On the contrary, the current that bypasses the load resistor can increase beyond limits$,$ overheating the diode, the transformer, other parts of the circuit, and potentially leading to fires and explosions.

$-$ A rectifier circuit, in which the current bypasses the load resistor even during one half$-$period of the input sine wave, is dangerous.

$-$ Dangerous circuits may be accidentally created by connections the diodes wrongly: see Module $11-4.$

$-$ Another danger is due to excessive grounding. All ground nodes are electrically connected; if the load resistor is between two ground nodes, it is bypassed.