Extension Cord

[salem]

I plug in my trailer a couple of days before a trip so we can stock the refrigerator/freezer. The trailer is a 30 amp. system. I run an extension cord from a regular house outlet to the trailer using an adapter. I believe it's a 15 amp. adapter. May turn on a light occasionally. We don't try running the air conditioner, microwave, etc. What gauge wire ext. cord do you suggest would be the safest? Thanks

[time2roll]

IMO the coiled up is not a huge deal unless you are running close to continuous max such as two air conditioners. Otherwise for normal use you are averaging half the rating or less.

[OldRadios]

Never had a problem with keeping the 30A cord coiled and it's never got warm let alone hot. When I run the generator it all stays coiled inside the compartment. So if I plug it into the generator I should let it all hang out? When I'm plugged in at the house I use a smaller gauge extension. That would heat up before the larger 30A coiled up inside the compartment and it's never gotten warm either.

[tomman58]

pianotuna wrote:
Hi RJF,

That's why many of us "cut the cord". It made my (cold weather) life much much easier than trying extract a frozen cord through a small hole, let alone trying to stuff it back in at -30 c.

-22F to us yanks. I makes the cord harder than a newly weds ...........

[pianotuna]

Hi RJF,

That's why many of us "cut the cord". It made my (cold weather) life much much easier than trying extract a frozen cord through a small hole, let alone trying to stuff it back in at -30 c.

[jfkmk]

RJsfishin wrote:
Even us not elect tech dummies know that a coiled 30 amp cord adds a little resistence, but we also know the is all factored in. I have never heard of anything so ridiculous as to completely uncoil a 30 amp cord before pluggin it into the generator, or anywhere else. Some of yous just love making RV'n complicated !
And I dint get old by being stupid either.

Complicated? It's not really complicated, it takes me less than 5 seconds to pull the cord out. I did a mini risk assessment weighing the effort needed to pull the cord completely out (no effort) against the big warning printed in the manual, and it was a no brainer. No offense to you, but I'll take the manufacturers warning against your word any day.

[RJsfishin]

Even us not elect tech dummies know that a coiled 30 amp cord adds a little resistence, but we also know the is all factored in. I have never heard of anything so ridiculous as to completely uncoil a 30 amp cord before pluggin it into the generator, or anywhere else. Some of yous just love making RV'n complicated !
And I dint get old by being stupid either.

[wa8yxm]

Why do the cords need to be unwound...

Two primary reasons, though one does not apply all that well to 30 amp cords.

First: All wires have multiple current ratings,, ONE of them is "Free Air"
Another is "Coiled" and yet another is "in a wall" This has to do with how well the wire can cool off when current heats it up. Somewhere I once saw a chart fo the coiled capacity but frankly, that was long ago. With the wires in a coil air does not circulate around the cable as well and it gets hotter.


Second is induction.. Coils offer "inductive" resistance (R sub j if I'm not mistaken, is the symbol) and like regular resistance I^2 R applies.. If you have one ohm of Rsub J and 20 amps, that's 400 watts of HEAT.

[jfkmk]

Wayne Dohnal wrote:

You should always pull the entire length of the trailer cord out whenever you plug in.

Why?

Verbatim from my owners manual: "WARNING: The power cord must be fully extended when in use and not left coiled in the electrical compartment or on the ground. If the power cord is left coiled, it may potentially create enough heat to melt its protective casing."

[fla-gypsy]

I always use the 12 ga for cooling the fridge before a trip.

[pianotuna]

Hi Wayne,

I know that the cord in my previous RV would "heat" when I did not pull it all the way out. I never bothered to measure the temperature--but from then on I always pulled it clear of the RV.

While it probably doesn't make much difference I believe that the shorter the cord to shore power, the better it is, provided such a cord can safely carry the number of amps being used.

[myredracer]

One big reason adapters fail is because people plug them in without turning the power off first. If plugging the adapter and shore power together while live, the plug blades and inside of the connector will get pitted and dirty (from converter inrush current) leading to high resistance, and ultimately heat and a meltdown. I've had two 15 amp extension cords go up in smoke because I was too lazy to turn the power off first (at breaker) and did not think damage could occur that fast. We now have a proper 30A RV outlet in the carport along with a disconnect switch beside it which I was planning anyway. You should always turn the power off before plugging in, either at the source (house panel or pedestal) or the main breaker in your panel.

It's always a good idea to periodically check the plug blades on your shore power cord and clean as needed.

The dogbone style adapters are better because if the basic/cheap "monoblock" adapters are pitted and dirty on both ends, there is little physical separation from the input to output side and more heat *can* be generated.

I would take an extension cord you already have of the length you need, and see what the voltage is at your camper with the fridge and any other desired loads operating. If the voltage is reasonable, there's no need to spend money on a 20A 12 ga. extension cord or 30A cord (providing no AC running) unless you intend to run a long extension cord.

I would also consider cutting off the stock connector that comes with an extension cord and installing a good commercial grade one. The commercial spec ones have a much higher contact pressure which can reduce the chances of heating. I often find that retail grade cords have connectors that weaken in time and eventually won't even hold the plug of an appliance or power tool in place.

[Wayne_Dohnal]

I'd still like to hear why the trailer cord needs to be unwound. There are thousands and thousands of 30 amp motor homes out there that have the power cord plugged into an outlet powered by the generator. The cord is usually wound in a very small space (mine is about a foot square), and I highly doubt that anybody unwinds the cord when running off of the generator. Air conditioners are routinely run for hours at a time via these coiled cords. I've never heard of a problem or incident with this setup. I always thought that 30 amp trailer cords and 30 amp motorhome cords are the same. So what's the problem?

[wa8yxm]

The Dogbone type (the adapters with the cord) do not strain the outlet as much.. With the "puck" type (All one piece) the 30 amp cord has "Leverage" and physically strains the outlet.

now.. If you are using a 10 or 12 GA extension cord and putting the adapter on the ground.. Don't matter.. only matters if the outlet is in a wall.

I use a Puck with a 3 light tester to see how badly the park technician screwed up the box.

[salem]

I've never posed a question and not received excellent responces. Again, you guys (and gals) are the greatest. Thanks. I have to admit, I had never heard the comment before about always unwinding the trailer cord all the way out in case of over-heating. That's why I like this forum. I always learn something.