Voltage Drop check
- Thread starter Designer69
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3 phase VD = 1.73 x K x D x I/CMILS. Another formula you can use isKarl H said:
1.73 x Distance x R from table 9 x I /1000. WE use the 75C resistance from table 9.
From the table R 4/0 cu = 0.062/1000 ft.
VD = 1.73 x 850 ft x .0.062 x 250 amps/1000 = 22 volts.
This is usually close enough for your use.
Last edited:
Karl H
Senior Member
- Location
- San Diego,CA
Thank you BOB. I have the formulas to find VD,CMILS,D,and I. I did'nt have the R equationThey are all pretty much the same.
Here's the equation I use to adjust R for ambient and conductor temperatures...Karl H said:
View attachment 1505
Voltage drop on pole lights
Voltage drop on pole lights
This may be alittle off topic, but can anybody tell me if this is ok? I have 3 light poles that are 120 volt, each drawing about 4 amps, the 1st is 250' from panel, 2nd is bout 400' from panel, and last is about 650' from panel. Is #8 copper good enough with the voltage drop, mainly for that last one, they are actually spliced in a underground jbox about 200' from the panel. Thanks for any advice.
Voltage drop on pole lights
This may be alittle off topic, but can anybody tell me if this is ok? I have 3 light poles that are 120 volt, each drawing about 4 amps, the 1st is 250' from panel, 2nd is bout 400' from panel, and last is about 650' from panel. Is #8 copper good enough with the voltage drop, mainly for that last one, they are actually spliced in a underground jbox about 200' from the panel. Thanks for any advice.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
millspgh said:
Sorry I was responding to the op.
I responded to one of the three threads you posted your question in.
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