Elaborating on John's Post (AKA "HotLine1"):

Understand that the "200 amp" load is a major factor. Do you know what the calculated load is for this panel??

Using my Custom Made Volt-Loss Spreadsheet, the following values were obtained across several scenarios:

FEEDER SCENARIO #1: 250 MCM ALUMINUM FEEDERSFeeder Length: 450 Feet,

Duct Material: Non-Metallic,

System: 120/240V 1 Phase 3 Wire,

E L-L at point of Delivery: 240V,

Loads: =/> 0.884PF; connected L-L...

"L-L" = Line-to-Line

"(AVG)" = Averaged

"(WCS)" = Worst-Case Scenario

1A.: 30 Amp Load: Volt Loss Percentile: 0.893% (AVG), 0.954% (WCS)

Averaged Working Voltage: 237.86 VAC

1B.: 50 Amp Load: Volt Loss Percentile: 1.489% (AVG), 1.590% (WCS)

Averaged Working Voltage: 236.43 VAC

1C.: 80 Amp Load: Volt Loss Percentile: 2.382% (AVG), 2.544% (WCS)

Averaged Working Voltage: 234.28 VAC

1D.: 125 Amp Load: Volt Loss Percentile: 3.722% (AVG), 3.975% (WCS)

Averaged Working Voltage: 231.07 VAC

------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

FEEDER SCENARIO #2: 250 MCM COPPER FEEDERSFeeder Length: 450 Feet,

Duct Material: Non-Metallic,

System: 120/240V 1 Phase 3 Wire,

E L-L at point of Delivery: 240V,

Loads: =/> 0.884PF; connected L-L...

"L-L" = Line-to-Line

"(AVG)" = Averaged

"(WCS)" = Worst-Case Scenario

2A.: 30 Amp Load: Volt Loss Percentile: 0.707% (AVG), 0.8325% (WCS)

Averaged Working Voltage: 238.30 VAC

2B.: 50 Amp Load: Volt Loss Percentile: 1.178% (AVG), 1.3875% (WCS)

Averaged Working Voltage: 237.17 VAC

2C.: 80 Amp Load: Volt Loss Percentile: 1.884% (AVG), 2.220% (WCS)

Averaged Working Voltage: 235.48 VAC

2D.: 125 Amp Load: Volt Loss Percentile: 2.949% (AVG), 3.46875% (WCS)

Averaged Working Voltage: 232.94 VAC

------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

The above figures plot High Power Factor Loads connected across the Secondary (Output) of a Single Phase Transformer, with a Center-Tapped & Grounded Secondary Winding - either Physical Tap, or Tap between X2-X3 Terminals.

Balanced L-N Loads may be figured as L-L

(i.e.: Two separate 50A L-N Loads connected A-N and B-N)

For a completely L-N Load, double the Volt-Loss Percentiles listed above.

Example: Feeder = CU, 30 Amp L-N Load:

Volt Loss Percentile: 1.413% (AVG), 1.665% (WCS)

Averaged Working Voltage: 118.30 VAC

Volt Loss results are from Two (2) Calculation Types:

a. Conductor Resistance-Only

and

b. Conductor Impedance (Resistance & Reactance).

Averaged Volt Loss Calculations are the mean of the Two, while Worst-Case Scenario is the higher of the Two.

Lastly;

If the System is "120/208V 1 Phase 3 Wire Open Wye", derived from a 208Y/120V 3 Phase 4 Wire Transformer's Output, values will be much different than the results from a 120/240V 1PH. 3 Wire Transformer.

--Scott (EE)