I am an expert in this area, I also have several power port 2 units,one always went sparky. I was going to have my whole house rewired but my licensed electrician told me not to sweat it. He said it is very common with household appliances. It most likely happens when you have a phone/tablet plugged in to the cable before putting it in the wall. You have the option to exchange it if it is under warranty, I don't think it will go all "Galaxy Note 7" on you though. To be honest, my one has stopped doing it now.