If there is no, or little, load it should stay cold. If you leave any power supply powered up (even if with little or no load), there is a theoretical possibility that a component within it could fail, potentially causing it to 'burst into flames' (and maybe when no-one is around to see it happening). That's true whether it's a charger, a plug-in power supply for some AV/IT equipment, a TV/Sky Box, a boiler, washing machine, or anything else. However, in my personal circles, I've only ever heard of it happening once (when a colleague's unloaded laptop charger more-or-less 'burst into flames').Is that dangerous? I leave my laptop power supply unit plugged in (and turned on) all the time. As long as it isn't connected to the laptop, it remains flat cold.
Kind Regards, John