Does a dimmer switch reduce electric kilowatts used when put on low??...or do you just get ambiance?

Answer 1

Yes, simply it puts a limit on the current or amps used but retains the correct voltage. Therefore, since Watts=Current x volts, reducing the current to the device or the volts will effect the wattage. Some things do reduce the voltage but current limiting is more usual Either way, the wattage is reduced.

Answer 2

Yes it does reduce power consumption when you switch to low. It works by limiting the amount of time the power is delivered to the load each cycle. At 60 Hz you have 16ms per sine wave. If you only allow the power to be attached to the load for 2ms, you have a very dim light. This is done with triacs, usually.

Answer 3

"Standard" dimmers reduces power consumption, when on a 'dim' setting.

There are other ways to dim lights that would not reduce power consumption, but I don't know anyone who makes those kind for commercial/home use. The kind you buy at an electrical supply store are the kind that reduce power consumption on 'low' settings.

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