I need to manufacture an extension cord for a travel trailer to power the AC and refrigerator when staging the unit before trips. Ideally I would like to be able to power the trailer to the full 30A load potential.
What is the minimum gauge of wire that should be utilize to provide 125V,
30A service with no voltage drop for a distance of 100 feet?
There is no such thing as zero voltage drop in a current carrying conductor. In a practical sense you can run 100 feet of #8 at 30 amps and only drop about 3.8% which gets you in the ball park. I doubt you really use all 30 most of the time anyway. With the price of copper I doubt the payback from going to #6 (1.5% drop) will be there in any reasonable period.
Again, an engineers response to a general electrical question is overly complicated. Simply use a #10 cord (good for 30 amps) and it will be just fine. In commercial and industrial applications, voltage drop is not normally a big consideration until you get to 300 to 400 feet. Even then, the voltage drops a little and raises the ampherage a little no big deal.
AEC Electric & Controls Michael R snipped-for-privacy@sbcglobalremoveme.net
In a practical sense you are right. That trailer might as well get used to running on low voltage. Most campgrounds are notoriously underwired.
commercial and
It's interesting comparing NEC and CEC (US and Canadian electrical code) rules for campgrounds - in Canada you can't start derating for diversity of load until you pass 5 receptacles , and generally the derating is less than the NEC rules until you get to a huge number of receptacles on one service. The assumed value of loading per receptacle is higher in the CEC, too, and you must count each receptacle (not two receptacles on one spot as one receptacle). Maybe the NEC rules were devised before the land-yacht recreational vehicles with 50 Amp services and dual air conditioners became so common? I speculate that AC load is a bigger part of RV loading than heating load.
Bill ( who had to review some drawings for a campground not long ago...)
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