Today we find many electrical devices powered by power supplies located at the end of a power cord such as cell phone chargers or in the middle of the cord such as those used with laptop computers. Once again, none of these items should get very warm so that you cannot hold them comfortably. That would indicate a problem that is potentially dangerous. Better units have a thermo switch inside that cuts off the power automatically if the unit gets too hot. Older and cheaper power supplies still use transformers which can get pretty warm to the touch. They are also bigger and bulkier than the switching power supplies that are more commonly used today.
It is also highly recommended, when purchasing an electrical appliance or device that plugs into the wall, that it be certified by such organizations as Underwriters Laboratories Inc. (UL). The certification only indicates that the unit meets certain standards determined by the certifier. However, it does not eliminate the need to be careful about all the issue mentioned above.
Most importantly, stay vigilant and be safe. And may Hashem watch over all of us.