ajhuta
Member
- Location
- Jackson Hole, Wyoming
I have a RV Camper that needs 120 volts. 30amps at 400 feet away. What size wire should i run ? For Voltage drop
Wire size Voltage drop
- Thread starter ajhuta
- Start date
- Status
- Location
- New Jersey
- Occupation
- Journeyman Electrician
What is your calculated load a full 30 amps? Try this:
https://www.southwire.com/calculator-vdrop
https://www.southwire.com/calculator-vdrop
- Location
- Lockport, IL
- Occupation
- Semi-Retired Electrical Engineer
I clicked that link. It seems that in order to use their calculator you need to download to your phone or other device. I chose not to do that. The calculator I have tells me that you need at least a #1 AWG (copper), in order to keep the VD below 3%. If running that large a wire that far is too expensive, a couple 5KVA single phase transformers (dtep up and then step down) might prove a cheaper alternative. You should be able to use #8 instead of #1.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Scroll down, the calculator is below the app downloads.
gar
Senior Member
- Location
- Ann Arbor, Michigan
- Occupation
- EE
190508-2043 EDT
From memory #10 copper is 1 ohm/1000 ft. 30 A at 1 ohm is 30 V. 30 V change at 120 V is 25% change. For 800 ft the drop is 20%.
Do you really have a 30 A load, and does this load vary from 0 to 30 A on a cyclic basis? Suppose it does, then can you tolerate a voltage range of 120 V to 96 V at your load end or possibly 128 to 102?
If this range is too large, then what can you tolerate?
When I design equipment I use 95 to 135 V for an expected input range.
An ordinary incandescent can tolerate 0 to full rated voltage, motors without electronics will have a narrower band, and some electronic supplies can work over a very large range with some minimum voltage like 95.
What you do is greatly dependent upon the type of loads you have, their tolerance level for changes, and your tolerance level for something like light output change.
You can also put a voltage adjuster at the load end. Lowest cost I easily found for #10 copper was $95 per 1000 ft. Run two #10s in parallel, voltage drop goes to 1/2, and price doubles. This is equivalent to about #7 wire.
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From memory #10 copper is 1 ohm/1000 ft. 30 A at 1 ohm is 30 V. 30 V change at 120 V is 25% change. For 800 ft the drop is 20%.
Do you really have a 30 A load, and does this load vary from 0 to 30 A on a cyclic basis? Suppose it does, then can you tolerate a voltage range of 120 V to 96 V at your load end or possibly 128 to 102?
If this range is too large, then what can you tolerate?
When I design equipment I use 95 to 135 V for an expected input range.
An ordinary incandescent can tolerate 0 to full rated voltage, motors without electronics will have a narrower band, and some electronic supplies can work over a very large range with some minimum voltage like 95.
What you do is greatly dependent upon the type of loads you have, their tolerance level for changes, and your tolerance level for something like light output change.
You can also put a voltage adjuster at the load end. Lowest cost I easily found for #10 copper was $95 per 1000 ft. Run two #10s in parallel, voltage drop goes to 1/2, and price doubles. This is equivalent to about #7 wire.
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- Status