Voltage drop shall not be below 5% at the load source. To find the proper wire size, one needs to know the type of conductor (copper or aluminum), the distance in feet, and the amp that are needed for the load. After you have completed that information select the wire size and then click on the calculate button. If the voltage drop percentage is 5% or below than the wire size selected is the proper size to use. Please check the bottom box for an "OK" to verify. Please Note: use of this voltage drop table is for a rule of thumb. There are many more conditions that will change the voltage drop such as the soil type, (sand, wet, clay) which will change the temperature, or if the wire will be in metal or plastic conduit all of which will change the voltage drop. Use at your own risk, we will not be held responsible for the results....
Fill in this box Load in Amps
This Voltage Calculator is for 240 AC or 120 AC volts single phase.
Fill in this box Distance in feet one way
An interesting corollary is that the line voltage doubles (240 instead of 120volts) the voltage drop decreases by a factor of 4. That means that a line can carry the same power 4 times further! Higher voltage lines are more efficient.
Pick Wire Type Copper or Aluminum
240 Volts | Voltage Drop 5% max
Pick the Wire Size AWG & MCM
120 Volts | Voltage Drop 5% max
If an OK appears in the "OK" box then the wire size is OK to use with the distance, amps, wire type, and voltage.
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