Device including a casing formed by non-conducting material fastenable to the household appliance, electrical supply means and a lighting circuit carried by the casing, and a spark plug fastenable to the household appliance in proximity of burner means carried by the household appliance so as to be electrically connected to earth; the lighting circuit being adapted to supply a high voltage alternating current to said spark plug to make it generate a spark adapted to produce the lighting of a flame following the feeding of a combustible gas flow to the burner means; wherein the supply means are direct current low voltage generator means carried by and accommodated in the casing and supply in parallel said lighting circuit, through ac/dc transformer means, and a control circuit, through electrical disconnection means from the lighting circuit, the control circuit being electrically connected to the spark plug and to a first terminal of a LED indicator fastenable in use to the household appliance and having a second terminal connected to earth, for selectively producing the turning on or off of the LED indicator in consequence of a passage or interruption of a dispersion current to earth which flows in use to the spark plug when the flame is lit.