20 amp (110 - 125 Volt)
Most home espresso machines in the United States are available configured to operate on 15amp electrical connections. This connection works well for single boiler and heat exchanger home espresso machines, but with double boilers 15 amps of power is usually not enough to power the heating elements in both boilers. Manufacturers have created clever work arounds to make double boiler machines work as well as possible with a limited power supply. One common way is for the brew boiler to be favored when the machine is powered on. Once the brew boiler is up to temperature, the heating element for the steam boiler is activated. Once both boilers are up to temperature, the power is then pulsed back and forth between boilers to maintain the boiler temperatures of each. You can still brew and steam at the same time and can brew and steam without waiting in between brewing and steaming, but warm up time is longer and recovery time is longer between drinks. That is where 20 amp double boiler machines are nice to have. With a 20 amp double boiler machine, both boilers get a constant supply of energy. This makes both initial warm up time and recovery time faster. Usually about twice as fast. There are a few machines that can be operated in either 15 amp mode or 20 amp mode. And operating in either mode is a simple as switching the mode via a switch or a digital control panel and using a power cord converter. These machines are the Quick Mill Vetrano Evo, Izzo Alex Duetto IV Plus, La Spaziale Dream, and La Spaziale Dream T.