Crazy Voltage Drop Question

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cwdick

Member
Location
Paducah, Ky. USA
I am currently working on a project that has 4 points in the systems where we have electrical hardware.

We are using an aluminum triplex drop cable ran overhead, 480Vac Single Phase

We start at point 4 and this is the location of our 480Vac single phase source
The span from point 4 to point 3 is 2000 feet. The triplex will branch off at point 3 to a 480/120 transformer. The load at point 3 is 630 Watts
The span from point 3 to point 2 is 500 feet. The triplex will branch off at point 2 to a 480/120 transformer. The load at point 2 is 1890 Watts
The span from point 2 to point 1 is 2000 feet. The triplex will end at point 1 and will terminate at a 480/120 transformer. The load at point 1 is 330 Watts

My question is the voltage drop at each point if using a cable made by Houston Wire with specs of the following:
Aluminum Triplex Service Drop Cable
Cable Code Name: Voluta
Phase Conductor Size: 6
Phase Conductor Stranding: 7
Phase Conductor Covering Thickness: 45
Bare Neutral Messenger Size: 6
Bare Neutral Messenger Stranding: 6/1
Bare Neutral Messenger Rated Strength (lbs.): 1190
Weight per 1000 feet: 116 lbs
Ampacity: 70 amps

Thank You
 
cpinetree

cpinetree

Senior Member
Location
SW Florida
I'll take a stab at it.
I used a segmented voltage drop calculator (I believe from someone on this site, and I'm sorry I can't make proper attribution)

I get a total of 2.37% at your last point.
I don't know your actual starting voltage, so I used 480v. The end point voltage is 468v

see the att'd pic

480_VD.jpg
 
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NewtonLaw

Senior Member
Location
Honesdale, PA USA
Voltage Drop

Voltage Drop

cwdick said:
I am currently working on a project that has 4 points in the systems where we have electrical hardware.

We are using an aluminum triplex drop cable ran overhead, 480Vac Single Phase

We start at point 4 and this is the location of our 480Vac single phase source
The span from point 4 to point 3 is 2000 feet. The triplex will branch off at point 3 to a 480/120 transformer. The load at point 3 is 630 Watts
The span from point 3 to point 2 is 500 feet. The triplex will branch off at point 2 to a 480/120 transformer. The load at point 2 is 1890 Watts
The span from point 2 to point 1 is 2000 feet. The triplex will end at point 1 and will terminate at a 480/120 transformer. The load at point 1 is 330 Watts

My question is the voltage drop at each point if using a cable made by Houston Wire with specs of the following:
Aluminum Triplex Service Drop Cable
Cable Code Name: Voluta
Phase Conductor Size: 6
Phase Conductor Stranding: 7
Phase Conductor Covering Thickness: 45
Bare Neutral Messenger Size: 6
Bare Neutral Messenger Stranding: 6/1
Bare Neutral Messenger Rated Strength (lbs.): 1190
Weight per 1000 feet: 116 lbs
Ampacity: 70 amps

Thank You
Click to expand...

I used the following NEC conductor tables for impedance corrected for 40°C rating.

From #1 to #2 - Load Amps - 5.94, Vsource=480 volts, Voltage drop at 2000' with a power factor of 1.0, V drop = 17.2 volts

From #2 to #3 - Load Amps - 4.63, V driving = 462.8 V, PF=1.0, V drop = 7.8 volts at the end of 500 feet

from # to #4 - Load Amps - 0.69 amps, V driving = 454 v, V drop = 5.2 volts at the end of 2000 feet.

Voltage at point #4 = 448.8 Volts or a 6.5% voltage drop overall. This assumes the loads stay constant during the voltage drop per leg.
 
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