Service feeder voltage drop..

[sick boy 73]

Trying to get information about voltage drop for a 205 ft SER feeder run..My feeder consist of three 4/0 cables and one 2/0.. it is to be ran 205 ft from the inside main lug panel to the outside 200 amp meter base.. to the best of my knowledge the cable is only rated for 180 amps .. my question is does my wire need to be upsized to carry the voltage drop from such a far distance.. the cable is XHHW rated for 600volts and is in the 90° temp column

 

[Elect117]

There are sites you can use from google or the NEC has some references in Chapter 9, Table 9.

The voltage drop requires knowing the voltage.

The 90°C temp column can be used for derating but should not be used for circuit ampacity where it terminates at equipment. UL does not test at that temperature rating. So anything listed or labeled as an ampacity, for example a 200A panel board, would be listed for use at 200A AT 75°C.

 

[sick boy 73]

There are sites you can use from google or the NEC has some references in Chapter 9, Table 9.

The voltage drop requires knowing the voltage.

The 90°C temp column can be used for derating but should not be used for circuit ampacity where it terminates at equipment. UL does not test at that temperature rating. So anything listed or labeled as an ampacity, for example a 200A panel board, would be listed for use at 200A AT 75°C.

My apologies,, this is my first post.. the voltage is 240

 

[Elect117]

Voltage Drop Calculator | Southwire

www.southwire.com

Voltage Drop Calculator

This free voltage drop calculator estimates the voltage drop of an electrical circuit based on the wire size, distance, and anticipated load current.

www.calculator.net

You need your voltage and calculated load in amps.

 

[LarryFine]

Welcome to the forum.

If you mean one cable with four conductors (SER), that's typically for use following a main service disconnect.

You do have a main service disconnect between the meter and the cable's entrance to the building, don't you?

 

[sick boy 73]

There are sites you can use from google or the NEC has some references in Chapter 9, Table 9.

The voltage drop requires knowing the voltage.

The 90°C temp column can be used for derating but should not be used for circuit ampacity where it terminates at equipment. UL does not test at that temperature rating. So anything listed or labeled as an ampacity, for example a 200A panel board, would be listed for use at 200A AT 75°C.

Welcome to the forum.

If you mean one cable with four conductors, that would be for use following a main service disconnect.

You do have a main service disconnect between the meter and the entrance to the building, don't you?

Yes sir there will be a 200 amp breaker disconnect at the meter base

 

[LarryFine]

Okay, good. Just being sure.

Voltage drop is dependent on the circuit impedance and the load current, not the system voltage.

 

[sick boy 73]

If I figured correctly I come up with 67.6 load current.. Chinese arithmetic has never been my strong suit though.. I'm really trying to find maximum distance I can run the cable.. if I figured load right is saying about 550 ft which is good.. my run is 205 ft

 

[LarryFine]

You need to calculate it using the impedance of 410 ft of your wire and the 68a of the load.

 

[Elect117]

You need to calculate it using the impedance of 410 ft of your wire and the 68a of the load.

He is probably running the calc backwards. Setting it to 5% and then getting the longest distance. Using southwire's calc, I got 450'.

Just remember to set everything properly. Like the aluminum.

I would expect to see about ~1.5% voltage drop at that distance, for that load.

 

[LarryFine]

He is probably running the calc backwards.

I see that when the wrong constants are entered, i.e., variables entered as constants.

 

[sick boy 73]

My curiosity arises from doing electrical work for over 30 years and I have never pulled a SER cable this far of a distance..

 

[electrofelon]

I depends on what the load is. Often in a residential setting the load is unlikely to ever be over 60 amps. If there is a big load like a lot of electric heat or an on-demand water heater or stuff like that you could be higher but generally it's pretty rare.

 

[Elect117]

My curiosity arises from doing electrical work for over 30 years and I have never pulled a SER cable this far of a distance..

Curiosity is a good thing. If you have a engineer you trust in the area, maybe give them a ring and ask them to just confirm your numbers. Or another electrical contractor.

I just hate to say a number with certainty. I would rather help you with the resources to your answer. You were right in thinking that voltage drop could be an issue at that length.

If there is anything you do not understand about making the calculation, feel free to ask.