Matt Mckenzie
Member
- Location
- United States
If you install a sub panel a thousand feet from the source & you connect a 120volt pump load does that mean you have to calculate voltage drop for the 120v at 1000ft?
Voltage drop
- Thread starter Matt Mckenzie
- Start date
- Status
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
What exactly are you getting at? Distance, conductor size/type, current are going to be what affects VD.
If you have an equal 120 volt load on other leg of a 120/240 feed, your VD is basically 240 volts @ 1000 ft. But any time you would only run one of the loads at a time you are back to 120 volts @ 1000 feet.
gar
Senior Member
- Location
- Ann Arbor, Michigan
- Occupation
- EE
190703-2214 EDT
Suppose you use #10 copper which is about 1 ohm per 1000 ft, and your running load current is 10 A, then your running voltage drop is about 2*10 = 20 V (2000 ft of loop wire). Starting voltage will be very much lower than 100 V and the motor may not, probably won't, start.
You need to determine starting current at possibly 90 V and work from this to determine wire size. Starting current is possibly more than 6 times running current.
Get some values and work from those.
.
Suppose you use #10 copper which is about 1 ohm per 1000 ft, and your running load current is 10 A, then your running voltage drop is about 2*10 = 20 V (2000 ft of loop wire). Starting voltage will be very much lower than 100 V and the motor may not, probably won't, start.
You need to determine starting current at possibly 90 V and work from this to determine wire size. Starting current is possibly more than 6 times running current.
Get some values and work from those.
.
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
You can not calculate anything without a current value.
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