I will have this 47k 50W wire wound resistor which will be across line and neutral which means 230 VAC rms. So the electrical power in theory will be V^2/R = 1.2 Watt.
How should one interpret this datasheet and the below curve whether a heat sink is needed? (Above which electrical power a heat sink is needed needed).
Similarly a 4.7k 50W resistor will electrically consume 1W. Can we say no heatsink required looking at its datsheet as well?
Im trying to find a method or rule of thumb ect., thats why i gave two examples-