The power path of your FX lighting system begins at your Electrical Panel (1). Inside the panel is a series of Circuit Breakers, one of which feeds 120 volts of power to the Receptacle (2) that your transformer is plugged into.
The quickest way to see if the transformer is operating properly is to take a Volt Meter or Amp clamp and test the power level at the Receptacle on the face of the Transformer (3). If your transformer has a timer, you must remove the timer in order to test the Transformer Receptacle.
Make sure your Volt Meter is set on the 200 V~ setting. On most digital volt meters, this will be two clicks to the right. If you get a reading between 115-125 volts, you will know that the transformer is getting power to it; therefore, the GFCI Receptacle (2) and the Circuit Breaker in the Electrical Panel (1) have not tripped.
If, on the other hand, you get no voltage reading, check to see that the GFCI receptacle hasn't been tripped. Note that sometimes the GFCI that protects the circuit for your transformer is NOT the one the transformer is plugged into. It may be found in the kitchen, laundry room or another location within the house. If the GFCI has tripped, reset it and test your transformer again.
If the GFCI is set properly, next check the Circuit Breaker in the Electrical Panel. If tripped, reset it and test your transformer.
If you have a Receptacle Tester (RT), insert it into the Receptacle in which your transformer is plugged into. The RT will tell you if the wiring from the Electrical Panel to the receptacle is OK or not. If it does not indicate two orange lights, something is wrong with the wiring.
Note: All high voltage side testing should be performed by a trained electrician, electrical shock can occur if testing is not done properly.