I have a plug in type 24 volt transformer. Both prongs are the same size--not retricting how it could be plugged into the outlet. I have a sensor that beeps when there is current at the sensor tip. I measure 27.5 volts across the terminals.
Here is what I don't understand----my current sensor indicates that both terminals are hot regardless of how the transformer is plugged into the outlet. How can this be? To be sure my sensor wasn't picking up a reading thru the body, I attached an 8" wire to each terminal and got the same indication that both are hot. One terminal has a "R" in its vicinity. Shouldn't the other be the neutral and no current to it?
Most household transformers (doorbell, electric shaver, model train, etc.) have secondaries isolated from their primaries, that is, neither output terminal is "automatically" connected to neutral when the transformer is plugged in.
This way, also, it doesn't make any difference which way the plug is inserted into the receptacle.
Transformer output current does not return to the main panel; rather the current just has to return to the other terminal on the transformer's output.
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