What Size Wire for a 200 Amp Service 200 Feet Away?
Smallest conductor under 3%
250 kcmil
240 volts, single phase, 200 amps, 200 feet one way, 4/0 aluminum.
Between 3 and 5 percent. Legal, and still worth fixing on a branch circuit that feeds a motor, a heater or a long lighting run. Going up to 250 kcmil brings it under 3 percent.
Aluminum needs terminals listed AL or CU-AL, an antioxidant compound on the strands, and a torque wrench on the lug. Most aluminum failures are the connection, not the wire.
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How that number is worked out
These are the figures this page was built with and every line the calculator produces from them. Change anything above and all of it moves.
- System voltage240 V
- PhaseSingle phase
- Load current200 A
- One way run length200 ft
- Conductor size4/0
- Conductor materialAluminum
Voltage drop3.34% on the run
Between 3 and 5 percent. Legal, and still worth fixing on a branch circuit that feeds a motor, a heater or a long lighting run. Going up to 250 kcmil brings it under 3 percent.
Aluminum needs terminals listed AL or CU-AL, an antioxidant compound on the strands, and a torque wrench on the lug. Most aluminum failures are the connection, not the wire.
| Drop | 8.02 V |
|---|---|
| Voltage at the load | 232 Vfrom 240 V at the panel |
| Smallest conductor under 3% | 250 kcmil |
| Longest run at 4/0 under 3% | 180 ftone way |
| Conductors to pull | 3including the equipment ground |
The material list this produces
| 4/0 aluminum conductor, ft | 660 |
|---|---|
| Conduit or cable, ft | 220 |
| Breaker, 200 A, each | 1 |
| Terminations and lugs, each | 6 |
One way run length compared
Drop is a straight line in length. Double the run and you double the drop, which is why the same wire that is fine in a basement is not fine across a yard.
| One way run length | Voltage drop | Smallest conductor under 3% |
|---|---|---|
| 50 ft | 0.83% on the run | 2 AWG |
| 100 ft | 1.67% on the run | 2/0 |
| 150 ft | 2.5% on the run | 4/0 |
| 200 ft | 3.34% on the run | 250 kcmil |
| 300 ft | 5.01% on the run | 500 kcmil |
What else matters here
Four aught aluminum is the standard 200 amp service conductor and at 200 feet it lands at 3.34 percent, just over the guideline. To get under, you go to 250 kcmil aluminum.
Whether that is worth doing is a real question rather than an obvious yes. Three point three percent on a service is inside the 5 percent total the NEC notes contemplate, and a 200 amp service is almost never carrying 200 amps, so the actual drop in normal use is a fraction of this figure. The calculation here is the worst case, at full nameplate load.
Where it does matter is a long run to a house that will get an EV charger, a heat pump and an electric range, because those are the loads that sit near capacity for hours rather than minutes. On a run this length, the cost of going up one size once is much less than the cost of digging the trench twice.
What this calculator assumes
- The formula is the standard one: drop equals 2 times K times amps times the one way length, divided by the circular mil area of the conductor. Three phase uses 1.732 in place of the 2.
- K is 12.9 for copper and 21.2 for aluminum, the usual figures for a conductor running warm in conduit. Circular mil areas come from NEC Chapter 9, Table 8.
- Enter the one way distance, not the loop. The formula doubles it for you, because current has to get back.
- The 3 percent branch circuit and 5 percent total figures in 210.19 and 215 are informational notes rather than requirements. Nobody fails an inspection on voltage drop alone, but motors, LED drivers and long well pump runs care a great deal.
Questions people ask
What size wire for a 200 amp service 200 feet away?
4/0 aluminum is the usual conductor and lands at 3.34 percent over that distance. 250 kcmil aluminum brings it under 3 percent.
Is 3.34 percent voltage drop a problem on a service?
Not usually. It is the figure at full 200 amp load, which a house almost never draws, and it is within the 5 percent total the NEC informational notes discuss. It matters more on a house with sustained heavy loads like EV charging and heat pumps.
Is 3 percent voltage drop actually required by code?
No. The 3 percent branch circuit figure and the 5 percent total figure live in informational notes to NEC 210.19 and 215, and informational notes are advisory rather than enforceable. Some jurisdictions adopt them as local amendments and many engineered specs require them, and motors and electronics behave badly on a long undersized run whatever the code says.
The voltage drop calculator takes any dimensions you like and hands back the same list.