How hot should a ballast resistor get?

A ballast resistor typically should not exceed temperatures of around 150°F (65°C) during normal operation, although some may tolerate slightly higher temperatures. The specific temperature can depend on the resistor's design and rating. It's important to ensure that the resistor has adequate cooling and is not overheating, as excessive heat can lead to failure or reduced lifespan. Regular monitoring and proper installation can help maintain safe operating temperatures.