Voltage Drop question

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olly

Senior Member
Location
Berthoud, Colorado
Occupation
Master Electrician
Does anyone see a problem with this Install, I have already done the VD calculation it requires 500kcmil for the distance so just asking about the install.

Come out of the meter that's on a pole with 4/0 AL, to a splice box splicing into two parallel runs of 250 kcmil AL, running a distance of 320' to another splice box to step the wire back down to 4/0 AL then entering the house to hit the breaker panel.

Calculation was based off south wires online calculater

Thanks
 
olly said:
Does anyone see a problem with this Install, I have already done the VD calculation it requires 500kcmil for the distance so just asking about the install.

Come out of the meter that's on a pole with 4/0 AL, to a splice box splicing into two parallel runs of 250 kcmil AL, running a distance of 320' to another splice box to step the wire back down to 4/0 AL then entering the house to hit the breaker panel.

Calculation was based off south wires online calculater

Thanks
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Please show us all of your inputs and outputs from the calculator. This doesn't mean anything to me without the operating amps and volts.
 
Without the details, all I can say is that it is fundamentally acceptable to step up the wires in one junction box and then step back down at the other end. So if that is what you are asking, my answer is yes. But to give an evaluation of the installation, I would need to know (as has already been mentioned) amps and volts, as well as the overcurrent protection setpoint and the calculated load.
 
200a breaker 120/240 single phase panel 320' away from the meter socket. I planned on using two parallel runs of 250 aluminum 4 wire urd direct buried with a min VD of 3 percent. The reason for using 4/0 out of the socket and into the breaker panel with parallel runs of 250 in between is because it would be a pain to take two 250's in and out of a socket and meter.

The VD calculator said that's what size was needed
 
Well, I see a problem that is not related to your original question. A 4/0 AL wire is limited to an ampacity of 180 amps. You can't protect it with a 200 amp breaker, unless you have a load calculation that shows the total load is no more than 180. That issue, by the way, is the reason I had include "calculated load" in my list of the additional details I would need, in order to give you a complete answer.
 
For residential service and feeders supplying the entire load 4/0 AL at 200 amps max is good from my end.
 
What is calculated load? Just because you have 200 amp main breaker doesn't mean you will ever see 200 amps of real load. Voltage drop measured at any given time will be proportional to the actual load at that time. Many install 200 amp services to dwellings because that is what we do anymore, not because they absolutely need 200 amps of capacity.
 
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