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Simple electrical question please . .

Yahoo Message Number: 98653
I have to move the RV about 60'-70' from a power source. Never have asked the question. With our 50 amp service and power pole, can I safely run a 75' 50 amp cord (or longer) that far without issues?
 I can't think of any but obviously, know little about the gremlins that run up and down inside the wire, so a bit of help most appreciated.

Lon

'06 Inspire   
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Re: Simple electrical question please . .

Reply #1 –
Yahoo Message Number: 98654
As long as your extensions are 4 conductor # 8 awg wire, I see no issue.  TWI 2004 Intrigue 11731

Re: Simple electrical question please . .

Reply #2 –
Yahoo Message Number: 98655
Yes, use at least a 6 AWG cord. Since you are running it that far I would  limit the load to 40 amps or so on each leg.

Mikee

Re: Simple electrical question please . .

Reply #3 –
Yahoo Message Number: 98671
Yes it will be OK  Try not to run both AC at the same time

On Sunday, December 7, 2014 12:25 PM, "Mbaul@... [Country-Coach-Owners]"  wrote:

Yes, use at least a 6 AWG cord. Since you are running it that far I would limit the load to 40 amps or so on each leg.

Mikee

Re: Simple electrical question please . .

Reply #4 –
Yahoo Message Number: 98672
We don't know the length or size of the wire running from the main box for your home to the plug-in (on the side of your home), We know the approximate length of the connecting cord.

The main issue is voltage drop along this total length. Voltage drop = Current (amps) times Resistance. The smaller the wires and the length of the run determine the resistance. When combined with the current (10A, 20A, 40A, 50A, ?), you get the voltage drop. Voltage drop also means heating of the cord.

So, take a volt meter into the coach, and measure the voltage with no load (probably around 120V). Increase the load. When it drops to 110V on either leg, that would be my limit for the load for the wire and length you are using.

Obviously, if you were running 14 gauge (has more resistance per foot - of course not recommended), and 50A load, the voltage drop would be significant, and the wire would be melting the snow it was laying on!!!!

BTW, if you measure the voltage at the plug-in vs in the coach, the difference will be the voltage drop of the cord for that particular load (amps).

Herb

CCO Group Moderator

Re: Simple electrical question please . .

Reply #5 –
Yahoo Message Number: 98674
As many have already commented... it depends! :-)

You really need to know the gauge and type of wire you are using.  If you are talking about the flexible black cable that most of use us to plug in our coaches, (typically #6 SOOW type) it is really only rated at 50 amps up to 50' and then 40 amps up to 100'.  Mikee's recommendation to stay at 40 amps if at 75' is a good one.  If you go to #4 then you would be fine at 50 amps up to 100'

This table may help.  http://www.stayonline.com/reference-circuit-ampacity.aspx

Typically flexible multi conductor cables (extension cords) have less capacity than an equal size wire when permanently installed in conduit.  Of course the wire type (and insulation) is also different.  The #6 in your flexible cable is OK for 50 amps.  A #6 THHN is good for 75 amps when installed in conduit!  It is a wire that is rated for a 90 degree temp rise.

This table show typical wire types and ampacities.  This is for individual conductors installed in a conduit or raceway and does not apply to flexible cords.

http://www.usawire-cable.com/pdfs/nec%20ampacities.pdf

For distance and voltage drop, the calculation is a bit more complex, but the rough rule of thumb used on the street is the the above ampacities are good for up to 100'.  If over 100' then move up one wire size (move to a smaller number - from #6 to #4 if 50 amps and over 100')

The best solution for your installation, (particularly if this is a permanent move) would be to extend the outlet using conduit and THHN or better wire.  This is by far the safest solution as well and what I would recommend.

Good luck and let us know if you need any more information!

Dan

2006 Allure 430 with tag
#31344

Re: Simple electrical question please . .

Reply #6 –
Yahoo Message Number: 98678
You can't use the 90 degrees for the wire if the supply breaker is only rated at 75 degrees, you have to go with the lower.

Jim Logan

06 Inspire #51668

On Tuesday, December 9, 2014 10:56 PM, "danspangenberg@... [Country-Coach-Owners]"  wrote:

As many have already commented... it depends! :-)

You really need to know the gauge and type of wire you are using.  If you are talking about the flexible black cable that most of use us to plug in our coaches, (typically #6 SOOW type) it is really only rated at 50 amps up to 50' and then 40 amps up to 100'.  Mikee's recommendation to stay at 40 amps if at 75' is a good one.  If you go to #4 then you would be fine at 50 amps up to 100'

This table may help.  http://www.stayonline.com/reference-circuit-ampacity.aspx

Typically flexible multi conductor cables (extension cords) have less capacity than an equal size wire when permanently installed in conduit.  Of course the wire type (and insulation) is also different.  The #6 in your flexible cable is OK for 50 amps.  A #6 THHN is good for 75 amps when installed in conduit!  It is a wire that is rated for a 90 degree temp rise.

This table show typical wire types and ampacities.  This is for individual conductors installed in a conduit or raceway and does not apply to flexible cords.

http://www.usawire-cable.com/pdfs/nec%20ampacities.pdf

For distance and voltage drop, the calculation is a bit more complex, but the rough rule of thumb used on the street is the the above ampacities are good for up to 100'.  If over 100' then move up one wire size (move to a smaller number - from #6 to #4 if 50 amps and over 100')

The best solution for your installation, (particularly if this is a permanent move) would be to extend the outlet using conduit and THHN or better wire.  This is by far the safest solution as well and what I would recommend.

Good luck and let us know if you need any more information!

Dan

2006 Allure 430 with tag
#31344

Re: Simple electrical question please . .

Reply #7 –
Yahoo Message Number: 98682
"You can't use the 90 degrees for the wire if the supply breaker is only rated at 75 degrees, you have to go with the lower.

Jim Logan

06 Inspire #51668"

Jim is correct, if you are going to the higher amp rating of that wire then all components have to be rated at the higher temp (90°)  If that #6 wire is used at the more common 50 amp rating then it is perfectly acceptable when used with a 50 amp breaker and receptacle.

My point was that not all #6 wire is the same, it depends on it's use and how/where it is installed.

Dan

2006 Allure with tag
#31344
 

Re: Simple electrical question please . .

Reply #8 –
Yahoo Message Number: 98706
No disrespect intended, but I have never seen so many apples and oranges crammed into a basket of pure cow manure. The electrical code defines the minimum wire size and minimum insulation temperature rating for a particular circuit breaker rating. If you have a 20-amp breaker rated at 75 degrees C, it can feed a circuit with 20-amps. You can use #12 wire with an insulation temperature rating of 75 degrees C. However, if you really have a desire for overkill, you can use #4-0 wire with an insulation temperature rating of 1000 degrees C (but it will be really expensive). If the load exceeds 20 amps, the breaker will trip unless the breaker is defective. Insulation temperature ratings are on wires to allow the user to ensure that the insulation will not break down, catch fire, or melt unless the environment that the wire is in exceeds the rated temperature. If the wire is going to be laying next to a metal oven that could be operating at 500 degrees F, use use wire that has a temperature rating greater than 500 degrees F (preferably at least 750 degrees F. But for normal household or RV applications, a high temperature rating is not required unless the wiring is going to be located in the engine compartment For example, a #12 wire will NEVER get hot enough to melt the insulation that is on the wire as long as the current is limited to 20 amps at normal ambient temperatures. Start trying to use it to carry 200 amps and all bets are off.
 In a nutshell, saying that if a breaker is rated at 75 degrees, then the wire attached to it has to be rated at 75 degrees and no higher is exactly what you have left over after a bull processes a load of feed and deposits the remains. If you have 90 degree C rated wire, but only a 75 degree C rated breaker, USE IT AS LONG AS THE WIRE IS AT LEAST THE MIMINUM AWG FOR THE BREAKER.

John

2006 Inspire Da Vinci #51905