Your putting a electric device inside with an animal that will investigate it. Things can and will go wrong eventually. They are determined to figure it out and knock it over.

And i addressed your setup cause its off, if you need to put a humidifier inside a cage while using a heat lamp. That right there is a disaster waiting to happen and should tell you something is off. The heat lamp dries everything out, get rid of it and you wont need the humidifier.