Transformers reduce standard house voltage at an approximate ratio
of 10 to 1. Consider, house current at 128 volts...your transformer
reduces the power to 12.8 volts. In the case of a home powered by
120 volts, the result is 12.0 volts. When using a multi-tap transformer,
this would be on the 12 volt tap.
Whatever the situation…transformers are not voltage regulators...
they do not restrict electric and deliver a constant 12 volts.
Most landscape lighting power packs are AC because they use
magnetic transformers to step the voltage down. By contrast,
electronic transformers are typically DC and are solid state.
Multi-tap transformers are useful in voltage control, particularly
in long runs.