LED Strip running very hot, so hot the two way tape came undone.

Hi just installed Led strips under my kitchen cabinets only to find they came undone due to the heat they produced. They are 12V LED Strips hooked to a 12 volt 2.5 amp transformer. I took a reading and the volts going to the LED Strip is 12V. Positive is connected to (Red wire) and Negative to the Black. What am I doing wrong or are these defective? How can I test them to see if they are defective assuming I connected them correctly?

It sounds like you did the right thing, but I find that these strips benefit from being stuck onto a piece of aluminium, to help get rid of the heat. The aluminium is then stuck under the cab,.