Dimmers should always be connected to line voltage (usually 120 volts). That is, when a dimmer is used to control a low voltage transformer it is always connected between the source of the power and the primary side (the line voltage side; the 120V side) of the transformer; it is never connected to the secondary side (the low voltage side; the 12V or 24V) of the transformer.
Answers & Comments
Dimmers should always be connected to line voltage (usually 120 volts). That is, when a dimmer is used to control a low voltage transformer it is always connected between the source of the power and the primary side (the line voltage side; the 120V side) of the transformer; it is never connected to the secondary side (the low voltage side; the 12V or 24V) of the transformer.