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Old 07-16-2012, 04:08 PM   #1
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voltage issue

My fifth wheel is at home and plugged in to a 15 amps unit witch also have 119 volts.
Now at the end of my extension cord i also have 119 volts, but when i plug it in to the trailer i only have 102 volts inside the trailer.. Does anyone have a clue of what is happening with my voltage loss????
Fifth wheel is flagstaff 8524 rls 2009
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Old 07-16-2012, 04:16 PM   #2
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Quote:
Originally Posted by micalo
My fifth wheel is at home and plugged in to a 15 amps unit witch also have 119 volts.
Now at the end of my extension cord i also have 119 volts, but when i plug it in to the trailer i only have 102 volts inside the trailer.. Does anyone have a clue of what is happening with my voltage loss????
Fifth wheel is flagstaff 8524 rls 2009
Voltage loss through small electrical cord.
How long is your extention cord?
How long is you camper cord?
If your extention cord is 14 or smaller gauge it won't do.
Your a/c alone draws 18 amps to start and 12/14 amps to run.
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Old 07-16-2012, 04:39 PM   #3
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Easy way is to remove all loads by stripping all ac circuit breakers including the converter (DC charger and supply) You now have 119 VAC. Add your loads one at a time until you have what you need. A shorter larger cord will also work but sounds you only want maintenance power correct?
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Old 07-16-2012, 04:43 PM   #4
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Voltage loss is a function of current and resistance.
A voltmeter draws a tiny fraction of an amp to measure the voltage, so there is almost no loss with just the meter.

Once you add load to the circuit the amps being pushed against the resistance of the wire drops the voltage.
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Old 07-16-2012, 06:20 PM   #5
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The answer to this one is simple... Overall cord/cable too small gauge, or too long, or both. When it comes to power to your RV, voltage drop is one of your worst enemies.

Assuming you only want 15 amps to your 5th, you need a minimum #14 gauge extension cord. Some are only #16 gauge.

Too minimize your voltage drop, you may need a #12 gauge ext. cord. The wiring wiring inside your house for your 15 amp receptacle will be #14 gauge. You need to consider the overall wiring run length from the panel in your house to the panel in your RV. You could easily end up with a 100' run overall or sometimes, even much longer. I just wired up a 30A outlet in our carport with a total run of about 130' from the panel and I used #8 wire. Copper sure ain't cheap nowadays either!

You can calculate your voltage drop using the calculator on this site (via a link posted by Herk). For example, if you had an overall run of #14 100' long, with a 15 amp load, you would have an 8.1% drop, which is too high by NEC. If you had a #16 gauge extension cord 100' long, you would have a terrible voltage drop. If you have mixed gauges (#14 + #16, eg.) in your run, you'll have to do a detailed calc. by hand, unless someone knows of a calulator online somewhere.

Don't forget, you are already going to have a 25' 30A power cord out of your 5th which will contibute somewhat to the voltage drop. In your case, you *could* have a section of #10, #16 and #14 gauge wire to consider.

Don't overlook to make sure that the plugs and connectors on your cords (and wall recept.) are clean aand free of pitting. This can also add resistance.
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Old 07-16-2012, 06:32 PM   #6
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Look burn marks or signs of arcing at all of the plug connections. If something was left "on" when the unit was plugged in, there was bound to be some arcing, which can cause a voltage loss.

If you are plugged into a 15a home circuit, and the circuit was wired with 14 gauge wire, this might also cause a voltage drop. If that is the case, what might REALLY scare you is to turn some heavy power users on in the TT, then go inside the house with a digital thermometer, and see how much warmer the circuit breaker is compared to the others in the house.
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