Gauge wire for 50amp outlet?

[paulcjhastings]

Can someone point me in the direction, or just tell me what gauge wire needs to be used for a 50amp RV type outlet? Also, what is the standard outlet for this application?

I have to reside may house due to hail damage last year and thought this would be as good a time as any to put an outlet for the bus in.

Thanks in advance.

[luvrbus]

Paul, I bought a RV box from a supply house that has 50amp ,30amp with breakers and 20amp with a GFI as for as the wire size I have no idea what size they used but it works good and has a cover to protect it from the weather.I found out later that most RV parks have these laying around from upgrades and are cheap I bought mine new and it was about $80 for the box but they had a single 50amp for $30 and they came with the plugs my large one had the breakers also

[HighTechRedneck]

6 gauge is the correct wire size for 50 amp circuits.

The 50 Amp RV plug is the 50amp range version.

Three large flat prongs vertically oriented + one ground prong that is oval with a flat side.

[bobofthenorth]

Its not quite that simple.  The NEC specifies an allowable voltage drop for a circuit.  The right way to do this is to calculate the voltage drop and make sure you are under the NEC and whatever local codes you have to comply with.  You can probably use 3% as the allowable drop but I don't have any authority with your local inspector.

http://www.powerstream.com/Wire_Size.htm
http://www.paigewire.com/pumpWireCalc.htm

I didn't look hard at this calculator - there's lots of them on the web.  Just make sure that you are using the right total length for the circuit.  Some of the calculators are based on a 1-way run and some are based on a round trip length. 

[luvrbus]

I know they used larger than 6 on mine because the main breaker was 100amp for the box and a drop in voltage for the 80ft run

[Nick Badame Refrig/ACC]

Its not quite that simple.  The NEC specifies an allowable voltage drop for a circuit.  The right way to do this is to calculate the voltage drop and make sure you are under the NEC and whatever local codes you have to comply with.  You can probably use 3% as the allowable drop but I don't have any authority with your local inspector.

http://www.powerstream.com/Wire_Size.htm

I didn't look hard at this calculator - there's lots of them on the web.  Just make sure that you are using the right total length for the circuit.  Some of the calculators are based on a 1-way run and some are based on a round trip length. 

Hi Bob,
It seems your calculator in the link you provided is for DC and has no relation to AC power requirements.
Nick-

[Nick Badame Refrig/ACC]

Hi Paul,

This chart might help you a little better.
http://www.rowand.net/Shop/Tech/WireCapacityChart.htm

Good Luck
Nick-

[paulcjhastings]

The run is around 30-35 ft. So, based on the calculator in the link Nick provided the voltage drop for 6 gauge is 1.2% @ 50amps. Is this acceptable? The drop would be less at any smaller amp draw, most of the time it wouldn't be drawing max amperage.

[HighTechRedneck]

Paul, you should probably check you local codes, but 1.2% voltage drop is within NEC allowances.

Its not quite that simple.  The NEC specifies an allowable voltage drop for a circuit.  The right way to do this is to calculate the voltage drop and make sure you are under the NEC and whatever local codes you have to comply with.  You can probably use 3% as the allowable drop but I don't have any authority with your local inspector.

http://www.powerstream.com/Wire_Size.htm

I didn't look hard at this calculator - there's lots of them on the web.  Just make sure that you are using the right total length for the circuit.  Some of the calculators are based on a 1-way run and some are based on a round trip length. 

Hi Bob,
It seems your calculator in the link you provided is for DC and has no relation to AC power requirements.
Nick-

The calculator at the bottom allows you to select the type of use.  Using that calculator, for 120v circuit a 6 guage wire on an 80' run would result in a 2.71% voltage drop and hits 3% at about 90 feet.  (these distances represent the one way distance between the distribution panel and outlet)

[JackConrad]

    I would say 6 guage is OK. The run from our house load center to our electric range is about 40' and they used 6 gauge and a 50 amp double breaker. It passed the final electrical inspection.  A longer run might require a larger wire.

[bobofthenorth]

Nick you needed to scroll down further.

I put in a 2nd link that just has the AC calculator.