A 40VA transformer is rated for 40 VA or volt-amps on the secondary. For a typical 24 volt secondary, this is simply using Watt’s law to calculate amperage. (For more information on Watt’s or Ohm’s laws, please check out this article HERE.)

What does 120 VAC stand for?

The household electricity our North American appliances use is delivered at 120VAC (volts alternating current) 60 Hz. … When the electric current flows it rises from 0 volts to 120 volts back to 0 volts and then it falls to negative 120 volts and rises back to 0 volts.

Is 24 VAC low voltage?

It is standard in lighting, while “low voltage (12v or 24v) lighting” is used less commonly. Line voltage lighting systems typically use 120v or 277v to supply power to lighting fixtures.