110 Volt vs 220 Volt (same as 120 Volt vs 240 Volt)

Cord Configurations and Differences

Heavy Duty 30 amp 110-120 volt
Nema 5-30 Socket / Plug

(Straight = Hot, L-shape = Neutral, Round = Ground) Appliances with 110 volt that pull more than 15 amps require a 30 amp outlet with 10 gauge wire and a Nema 5-30 plug. If 110-120 volt appliance is under 15 amps a regular 3-prong cord is used.


Regular 20 amp 220-240 volt
Nema 6-20 Socket / Plug

(Hot is both the verticle and straight)
Appliances with 240 volts require a 20 amp outlet with 12 gauge wire and a Nema 6-20 plug.


Pictured left to right: Heavy duty 30 amp 110-120 volt Nema 5-30 Plug, Standard 20 amp 220-240 volt Nema 6-20 Plug, and a standard 110 volt plug as found on most electronic appliances.

What is the difference between 110/120 and 220/240 volts and is one better.
Read below for answers. NOTE: Sometimes 120 volts is referred to as 110 volts or 115 volts and 240 volts as 220 volts or 230 volts.

Are the motors the same in the 220-240 and 110-120 versions of vacuums? No, the motors are wound differently, the transformer is different, the minibreakers are different, and the cord and wiring are different.

Can an appliance be used on SLIGHTLY more or less voltage? As a central vacuum manufacturer we use the 120 and 240 volt motors. The 120 and 240 motors will not be adversely affected if used with lower voltages. The 120 volt motor will be fine on a 110 volts. And a 240 volt motor will be fine on 220 or 230 volts. But not the other way around. A 220 volt motor would be "damaged" if used for long periods of time on a 240 volt circuit. And the same for a 110 volt motor running on 120 volts. The motors we use will also run fine in any variation of 50-60Hz.

Is one better? For the most part, our motor manufacturer has very similar performance statistics between the voltages. Our 120 volt Silent Master S900, for instance has 139 waterlift and 191 CFM with a peak of 905 Air Watts. The 240 volt version has 136.4 waterlift and 190 CFM with a peak of 866 Air Watts. These stats are extremely close. But there is quite a difference in our Silent Master S500. The 120 volt has 85 waterlift and 183 CFM with a peak of 514 Air Watts. It’s 240 volt counterpart has 95 Waterlift and 208 CFM with a peak of 722 Air Watts. That is actually a significant difference. For some homes, maximum amperage for their panel may be close so the 240 volt version offers the best benefits.

Operating Cost. The cost to operate a 240 volt vacuum can possibly be less than its 120 volt counterpart because both phases of the power are being used simultaneously. But even the 120 volt version may not be wasting much power if the opposing circuit is being used by lights or other appliances at the same time. Worst case scenario, the 120 volt version might cost a few cents per hour additional to operate.

Duration of Life. We believe the 120 volt versions of the vacuum motor will last longer. They contain a higher amount of copper and thus the heat has a greater ability to dissipate. The 120 volt motors are also much easier to find replacements for as they are a common motors in the industry. The 240 volt version motors are not used very often and vacuum shops around the country do not normally stock it. They would first stock the 120 volt motors.

What happens when 240 volt is accidently plugged into 110 volt? And 110 into 240? If you plug a 120 volt unit into a 240 volt circuit and turn the vacuum on, it will spin at nearly twice its normal RPM. If not immediately turned off the motors may disintigrate, but before that happens, the transformer will likely burn out. Normally all you need to do is replace the transformer and the system will be as good as new.

If you plug a 240 volt unit into 120 volts, it will not run correctly. Good news is the transformer or motor(s) will not be hurt. You will only be running it on half speed. In fact, this is the way you can "break-in" new motor brushes when they are changed out down the road. (Run the unit in at half speed.) Also note that the transformer will not activate the relay unless it has 240 volts.

By MD Manufacturing