How to wire MR16 LED lights?
Electronic transformers designed for Halogen lamps will kill LEDs.

Electronic transformers are very simple switched mode power supplies. They "chop" the input 230 V/125 V sine wave in a way that will yield an average output voltage of 12 V. However, the peak voltage will be much higher and will eventually kill LEDs (that's no problem with Halogen lamps because they react more slowly). In addition, the chopped waveform may cause radio interference if the cables to the lamps are too long. The waveform may also be the reason why your voltage readings are off.

Instead of an electronic transformer designed for Halogen lamps, you should either use:


a conventional AC transformer (the heavy kind); or
an electronic DC transformer designed for LEDs.