newman fulltimer
rv.net
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How far can i safely run 10/3 wire for a 30 service.I need to run about 65 feet.Or do i need to use 8/3 thanks for input
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donn0128
Pronounced Ore-gun
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All your answers can be found on Google.
Donn,Lorri,Max (The Rescued Lab)
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ScottG
Bothell Wa.
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65' is well within the specs for 10/3 on a 30A circuit.
Scott, Grace and Wesly
2003 Dodge 3500 4x4, 6 speed Cummins (lightly bombed),
2004 Forest River 25RKS many, many mods.
H0NDA eu2000i
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Cedarhill
Deep South
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You can run a 30A current through a 10AWG wire for hundreds of miles without burning the wire. The question is how much voltage drop you can tolerate at the far end of the cord. Of course that depends on the source voltage. To calculate voltage drop, multiply the current (30A in this case) by the resistance. 10 AWG wire has a resistance of about 1 ohm per thousand feet. Suppose you want to run your RV at no less than 110V and the supply voltage is 120V at the plugin. That means you can tolerate a 10V drop. So ...
The resistance of 65 feet of wire is 65/1000 = .065 ohms
The voltage drop will be V = 30 * .065 = about 2 volts.
No problem!
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Bit Bucket
Brookings, Oregon
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^^^^ What he said
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Dave-Sparky
Woodinville, Washington
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I also generally agree with what Cedarhill wrote with one exception and several assumptions.
You will have to get the power out and back, so the total wire length is actually 130 feet, not 65.
The assumptions are that the wire is copper, not aluminum and solid not stranded. If these are not correct they the voltage drop will be slightly higher, but still safe.
Thus, the actual voltage drop will be approximately 4 volts at full load.
Good engineering practice is to design for a worst case of 5% or with a 120 volt source 6 volts.
Dave
Dave and Colleen
Colleen's Beach House
1991 Dutchman TT 24FK
2002 GMC Safari AWD
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sljkansas
Miami Co. Kansas
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Are you making this a permenant run? if so maybe it would be better to run 8 gauge So if you move up to a 50 amp rv the wireing will be already there. You'll need 4 wires.
Steve & Linda
Son married (1 DIL, 3 granddaughters 1 grandson)
Daughter can now be called a Teacher.
Miami Co. Kansas
2004 F350 CC dually 8ft bed 6.0 PSD
2009 Bighorn 3670RL
B&W under bed hitch with 18k companion hitch
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Timothy
Wisconsin
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Dave-Sparky wrote:I also generally agree with what Cedarhill wrote with one exception and several assumptions.
You will have to get the power out and back, so the total wire length is actually 130 feet, not 65.
The assumptions are that the wire is copper, not aluminum and solid not stranded. If these are not correct they the voltage drop will be slightly higher, but still safe.
Thus, the actual voltage drop will be approximately 4 volts at full load.
Good engineering practice is to design for a worst case of 5% or with a 120 volt source 6 volts.
Dave
Don't forget to add the length of the power cord too.
Tim & Cindy
2010 Canyon Trail 35FLFT
2001 Chevy Silverado 2500HD Crew Cab
8.1 Allison
www.gsowners.com
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SailingOn
Central Texas
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One nice instruction sheet for installing 30 amp RV service is here.
It suggests #8 for over 50 feet.
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Bit Bucket
Brookings, Oregon
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Dave-Sparky wrote:You will have to get the power out and back, so the total wire length is actually 130 feet, not 65.
...only 65' would be computed in this case, out and back is not how it is done.
This is a myth perpetuated on many forums.
Formula #1 (no out and back)
Formula #2 (no out and back)
Formula #3 (no out and back)
All of these sources refer to "one way distance" or "distance from power supply to load", etc.
Those of us in the electrical field that size feeder and branch circuit conductors, etc. for engineering approval, know to use the "one way distance".
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