RV receptacle 1200 feet from power source

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Matt Mckenzie

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When I do the voltage drop calculation to install an 30 amp 120 volt RV plug 1200 feet from the electrical service the calculation tells me astronomical large wire size. Is this even possible or do I have to build a service closer to the RV?
 
I calculated that a pair of 4/0 aluminum or 2/0 copper wires would yield 5% voltage drop. Sound familiar?
Were you to feed it with 240 volts and use a 240:120 buck transformer at the RV pad, you could downsize it to 3 AWG Al or 4 AWG Cu.
 
Matt Mckenzie said:
When I do the voltage drop calculation to install an 30 amp 120 volt RV plug 1200 feet from the electrical service the calculation tells me astronomical large wire size. Is this even possible or do I have to build a service closer to the RV?
Click to expand...

You may want to cost out (2) 5kva transformers, one to step up from either 120 or 240 to 480v with a step back down at the other end from 480v to 120. Current for 5kva at 120v will be 41.7a (plenty) and sizing the conductor between the transformers based upon10.4a at 480v.
It may be posible for you to a also compensate for any voltage drop if the transformers included HV taps.
Stepping up to 600v may also be an option.
 
templdl said:
You may want to cost out (2) 5kva transformers, one to step up from either 120 or 240 to 480v with a step back down at the other end from 480v to 120. Current for 5kva at 120v will be 41.7a (plenty) and sizing the conductor between the transformers based upon10.4a at 480v.
It may be posible for you to a also compensate for any voltage drop if the transformers included HV taps.
Stepping up to 600v may also be an option.
Click to expand...

this. trying to get 30A at 120V at the end of 1200' would give the op a rather large wire size (guessing 250-350 mcm)
 
Matt Mckenzie said:
When I do the voltage drop calculation to install an 30 amp 120 volt RV plug 1200 feet from the electrical service the calculation tells me astronomical large wire size. Is this even possible or do I have to build a service closer to the RV?
Click to expand...


Sure it's possible but it may be cheaper to have another service. Are there power lines close to where the RV receptacle needs to be.

What's really going to get expensive is 1200 ft. of trenching.
 
this sounds like a really odd install. Unless the owner has more money than God, he would likely be better off just running a generator for the little bit of run time most RVs are going to need.
 
JFletcher said:
this. trying to get 30A at 120V at the end of 1200' would give the op a rather large wire size (guessing 250-350 mcm)
Click to expand...
Yes, st 120v. But, reread what I posted, 10a at either 480v or even less at ,600v.
You may want to cost out (2) 5kva transformers, one to step up from either 120 or 240 to 480v with a step back down at the other end from 480v to 120. Current for 5kva at 120v will be 41.7a (plenty) and sizing the conductor between the transformers based upon10.4a at 480v.
It may be posible for you to a also compensate for any voltage drop if the transformers included HV taps.
Stepping up to 600v may also be an option
 
Matt Mckenzie said:
When I do the voltage drop calculation to install an 30 amp 120 volt RV plug 1200 feet from the electrical service the calculation tells me astronomical large wire size. Is this even possible or do I have to build a service closer to the RV?
Click to expand...

Calculations are correct, you cannot send 120v @ 30A over 1200 feet without huge losses
I E using 10# results in losses of 60% ? A tad high I think.
Even using 1# losses 10%.
Maybe a pair or 1# ?
$$$$

There is no easy or cheap way to do this,
You will have to step it up
Send it at higher voltage
Step it down at other end
 
A pair of Honda EU2000i generators(link) w/ paralleling cable would give you 33A@120V and run about $2100. They are super quiet gas sippers and the inverter runs computers just fine; as mentioned above, generator(s) may be the way to go, especially if the rv site is for the customer and isnt used year-round.
 
dmxtothemax said:
Calculations are correct, you cannot send 120v @ 30A over 1200 feet without huge losses
I E using 10# results in losses of 60% ? A tad high I think.
Even using 1# losses 10%.
Maybe a pair or 1# ?
$$$$

There is no easy or cheap way to do this,
You will have to step it up
Send it at higher voltage
Step it down at other end
Click to expand...

You cannot parallel #1's. Agree with stepping it up and stepping it back down.
 
Start with a pair of 120/240:600-volt transformers.
The first one puts 600 volts onto the near end of the line.
Connect the line to the 570-volt (95%) tap on the transformer at the far end. The 120-volt output will be 5% high when unloaded.
Now there can be 10% (60 volts) voltage drop in the 1200-foot line before the 120-volt output will be 5% low, and 14 AWG copper will suffice.
(not only will 14 AWG Cu suffice, it will actually provide +5%/-3% at the far end)
 
drcampbell said:
Start with a pair of 120/240:600-volt transformers.
The first one puts 600 volts onto the near end of the line.
Connect the line to the 570-volt (95%) tap on the transformer at the far end. The 120-volt output will be 5% high when unloaded.
Now there can be 10% (60 volts) voltage drop in the 1200-foot line before the 120-volt output will be 5% low, and 14 AWG copper will suffice.
(not only will 14 AWG Cu suffice, it will actually provide +5%/-3% at the far end)
Click to expand...
That output unloaded depends on what your unloaded supply voltage starts out as. It often is about 125/250 around here unloaded.

Another thing to consider is if you need to trench 1200 feet anyway - maybe see what it would take for POCO to bring their primary voltage closer. You maybe can bury 2 inch pipe for them and they pull MV cable through it and put a transformer/service at the far end. This also would be much easier to add more load to in the future where sizing for a single 30 amp 120 volt receptacle leaves you limited to 30 amp 120 volts without spending a lot to make more upgrades if that ever comes.

Also as said if this gets very limited use - a generator is going to cost less, won't be as convenient but will cost a lot less.
 
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