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Extension Cords And Loss Of Amps/Voltage


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#1 akadeadeye

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Posted 24 January 2011 - 03:00 PM

I am going to need to buy a 25-foot extension cord for an upcoming camping trip. Our coach is 50-amp. We will need a 30-amp extension cord. I already have a 50- to 30-amp adapter.

My question is this: Do we lose any voltage by having what will end up being a 52-foot cord with a dogbone in the middle? And if we do, how much? We will already be giving up some amps. I don't want to lose voltage as well.

Thank you.

Don
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#2 wolfe10

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Posted 24 January 2011 - 03:10 PM

Don,

Part of that depends on the gauge of wire you get in that 30 amp cord. Smaller gauge wire and higher current draws show larger voltage drops.

Said another way, buy the 30 amp cord with the largest gauge wire you can find. You can look at the gauge wire used in your 50 amp cord as a benchmark.

Another option would be to buy a 50 amp cord and just use the 30 amp male to 50 amp female at the outlet box-- a good idea if you anticipate high current loads.

Brett
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#3 akadeadeye

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Posted 24 January 2011 - 06:32 PM

Don,

Part of that depends on the gauge of wire you get in that 30 amp cord. Smaller gauge wire and higher current draws show larger voltage drops.

Said another way, buy the 30 amp cord with the largest gauge wire you can find. You can look at the gauge wire used in your 50 amp cord as a benchmark.

Another option would be to buy a 50 amp cord and just use the 30 amp male to 50 amp female at the outlet box-- a good idea if you anticipate high current loads.

Brett

Of course. I might need the 50 amp extension someday anyway. Why didn't I think of that. (probably because of cost). Definitely a semi-senior moment.

Thanks, Brett.

Don
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#4 Guest_BillAdams_*

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Posted 24 January 2011 - 07:24 PM

We have both. A short 25' 50amp cord and a longer 30' 30 amp cord. I prefer to park close enough to power to use my existing shore power cord or the shore power plus the 50amp extension cord (with or without the 30amp adapter). If that's not possible I will use the coach 50amp cord plus the 30 amp cord to get me where I need to be. If I can't make one of those 2 combinations work I will either move or run my generator for that night.

#5 JMonroe

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Posted 24 January 2011 - 07:30 PM

I bought a very good quality 36' 50 amp cord off ebay last fall for right about $100, including tax and shipping. This was about half of what I could find elsewhere. It seems just as robust as the OEM cord on our Revolution.
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#6 TBUTLER

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Posted 25 January 2011 - 09:17 AM

Camping World has 15' and 30' cords in 50 amp size. Watch for sales, I think I paid something less than $100 for the 15 foot cord when I bought it on sale. The 30 foot cord was $129 on sale as I recall. Check them for current prices. With this combination I can use as short an extension as possible but also have a total of 45 feet of extension.
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#7 hermanmullins

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Posted 25 January 2011 - 10:06 AM

I am going to need to buy a 25 ft. extension cord for an upcoming camping trip. Our coach is 50 amp. We will need a 30 amp extension cord. I already have a 50 to 30 adapter.

My question is this. Do we lose any voltage by having what will end up being a 52 ft. cord with a dogbone in the middle? And if we do, how much. We will already be giving up some amps. I don't want to lose voltage as well.

Don, look at your 50 amp cord. The wire guage will be stamped or imprinted every 12 to 18 inches. Check the extension you wish to buy for the same information. Then take a trip to your local electrical suppy house and ask them what size guage stranded wire you would need to carry 120 volts/50 amp power 52 feet. They can tell you the guage size you would need.
Also, as was said, you could buy a 50 amp extension cord. I have both and for the addapter I made my own out of the same guage size of my 50 amp cord.
No matter what size you have, when you have a heavy load, go and check each plug and cord for heat. That will tell you if your cable is too small.
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#8 akadeadeye

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Posted 25 January 2011 - 11:35 AM

OK, thanks for the suggestions. I have another question.

I looked at a 50 amp 30 ft. extension cord today and it showed 6/3-8/1 STW. Are these numbers the wire gauge?

Don
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#9 mrboyer

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Posted 25 January 2011 - 11:39 AM

Yes, 6/3 means 3 conductors of #6 gauge wire and the 8/1 is 1 conductor of #8 gage. The #6 conductors are for the neutral and two hot wires. The #8 is for the ground which should not carry any current.
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#10 mrboyer

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Posted 25 January 2011 - 11:42 AM

Yes, the 6/3 is 3 conductors of 6 gauge wire and the 8/1 is one conductor of 8 gauge for the ground. As other have said I would buy a 50 amp cord and add the 30 amp adapter at the end if needed.
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#11 akadeadeye

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Posted 25 January 2011 - 06:50 PM

Thanks to all. Camping World does have a sale now, but the price is $136. Not bad considering the price at my local RV store is $177.

Don
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#12 wemrdave

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Posted 04 February 2011 - 01:06 PM

I stopped at a automotive junk yard that had a few junk motorhomes in the back and pulled out a 50 amp cord for just $20. Did have to buy a 50 amp female plug and now I've got an extra 36 foot 50 amp cord at a good price.
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#13 halberstadt

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Posted 04 February 2011 - 03:03 PM

In the discussion of 50 A and 30 A extension cables, it should be noted that there is one combination that actually presents a fire hazard and not just a reduced voltage problem.

If you have a 50 A coach and a 30 A extension, the pedestal has a 50 A outlet, and you can't reach the pedestal with just your 50 A cable; you might be tempted to use this combination: Your 50 A cable, then a 50 A to 30 A adapter, then your 30 A cable, then a 30 A to 50 A adapter so that you can plug into the pedestal's 50 A outlet. Bad idea!

Starting from the pedestal: the 50 A male to 30 A female adapter will connect one of the two 50 A pedestal circuits to the single hot lead of the 30 A cable. The next 30 A male to 50 A female adapter will connect the 30 A cable's single hot lead to both hot leads of the 50 A cable, and thus to the two 50 A circuits in your RV.

At your RV, you could attempt to use a total load of up to 100 A (the two 50 A circuits). For any load higher than 50 A, the pedestal's breaker should trip, but anywhere in the load range between 30 A and 50 A, nothing will prevent overloading of the 30 A cable.

In this situation make sure you do not use a 50 A male to 30 A female adapter at the pedestal end, and just use the pedestal's 30 A outlet (if available). Or you may just have to get closer to the pedestal.

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