Use this as a guide only. Some paraffin wax manufacturers claim a 140˚C (284˚F) flashpoint for their particular waxes. Although doubtful, (I've worked with a variety of waxes at much higher temperatures), for safety's sake, follow the suppliers' guidelines.
Certain creative candles are poured at a heat of 127˚C (260.6˚F) or above. Also, hotter-than-usual waxes are the norm for overdipping candles. So, the use of a double-boiler - which prevents wax from exceeding the temperature of boiling water - becomes impossible.
Practise vigilance when you melt wax in a pitcher directly on the stove. Watch for signs of over-heating: candle wax turns brown; produces a bitter smell; smokes and sizzles, long before it approaches the point of auto ignition.
How to Put out a Paraffin Wax Fire
So, if candlewax combusts, how do you extinguish the fire? Do not pour water over burning wax. This impulsive action might be the first thing one thinks of, but this simply accelerates the fire, and causes an explosion. Instead, switch your electricity mains off. Stick a lid onto the pot with the flaming wax. This smothers the flames, and causes the fire to die down naturally.