Best way to run feeder 350 feet underground?

infinity said:
Not sure what your actual load is but for the minimum conductor size I ran these through the Southwire VD calculator and got these numbers for:

120 volts, 350', 3% VD, Copper conductors, (Aluminum conductors):
30 amps-#1/0 (#3/0)
25 amps-#1 AWG (#2/0)
20 amps-#2 AWG (#1/0)
15 amps-#4 AWG (#2 AWG)
10 amps #6 AWG (#3 AWG)
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Are you sizing these at a continuous load rating? Is that necessary considering the wire is undergoing derating and ampacity adjustments?
 
samhutch said:
Are you sizing these at a continuous load rating? Is that necessary considering the wire is undergoing derating and ampacity adjustments?
Click to expand...
No. It's just the minimum conductor size based on the load listed. There is no derating or adjustments required based on the parameters in the OP.
 
For those that don't know...........
A 30A RV has a single A/C unit and is fed from a 30A, 120V, single pole breaker.
A 50A RV has two A/C units and is fed from a 2-pole 50A, 240V breaker. Although it is fed with 240V there are no 240V loads. The reason for the 240V is to divide/balance the 120V loads along with the extra load of two A/C units.
Then there is the fact that a single pole 50A breaker is not a common, easily found, breaker.
 
Little Bill said:
For those that don't know...........
A 30A RV has a single A/C unit and is fed from a 30A, 120V, single pole breaker.
A 50A RV has two A/C units and is fed from a 2-pole 50A, 240V breaker. Although it is fed with 240V there are no 240V loads. The reason for the 240V is to divide/balance the 120V loads along with the extra load of two A/C units.
Then there is the fact that a single pole 50A breaker is not a common, easily found, breaker.
Click to expand...
i'm familiar with the situation. but ....... if it's as you say and just adding a second air conditioner, why isn't it just a 30a 240v receptacle? adding that second air conditioner on the second 120v leg, would fit just fine, right???

(some have electric hot water heaters)
 
infinity said:
Would it make more sense to run a 240 volt circuit and use a transformer at the 120 volt end? That would have a big impact on wire size and voltage drop.
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Maybe somewhat break even if using aluminum conductor vs cost of the transformer for only 350 feet run? Plus there is idle load of the transformer to consider.
 
Master Nater said:
i'm familiar with the situation. but ....... if it's as you say and just adding a second air conditioner, why isn't it just a 30a 240v receptacle? adding that second air conditioner on the second 120v leg, would fit just fine, right???

(some have electric hot water heaters)
Click to expand...
Just having two AC's and little other significant loads probably would be somewhat ideal to have 30 amp 120/240 supply, but some units do have more significant loads so then we would need to have the 5-20, TT30, 14-30 and a 14-50 receptacle available at RV sites and of course even more adapters out there for when you don't have what you need. I'm fine with the choices that are already standard for RV's.
 
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