Melting extension cord

[Claybe]

I will be taking our first big trip soon and we will need the air conditioner. We usually boondock and never use the AC. I have only used it at home a couple of times and when I did the extension cord got really hot and the converter adapter plug from 220 to a 110 plug was almost melting. I will only have 110 available at the houses I will be staying at and need to use the AC. What should I do???

[myredracer]

MEXICOWANDERER wrote:

Reading the voltmeter while switching on the A/C...

If voltage dips to 105

The show's over. Your calculation is belly-up. Time to retrofit.
Or make -real good- friends with your RV air conditioner seller.

Eso es correcto, muy bueno... 🙂

Here is an owners manual for Dometic AC units as an example. Duotherm

Starting inrush current of motors is typically around 6 times the full load running current (FLA) for a fraction of a second. Taking a look at the 13.5K unit with compressor FLA of 12.1, the locked rotor current (inrush starting current) is 59.0 amps (ignoring the fan current)!! That is why it is so important to keep all wiring back to the supply panelboard as short as possible and as heavy gauge as possible. In a house, you could easily have 50-100' of wire to the receptacle you're plugging into. If you are attempting to get the AC to run off a 15 amp circuit, you'll have #14 wire trying to provide 59 amps for a short time period. If it's also supplying other loads, the situation is even worse. Even though you have a #10 shore power cord, that will also have some voltage drop at around twice it's rated current. You could calculate the voltage drop if you know all the overall wire lengths and gauges and voltage at the supply panel. Depending on the neighborhood a house is in, voltage drop quite a bit at peak usage times.

Note the manual says min. 20 amp breaker is required and wire size is min. #12 gauge up to 24'. Cheapo 15 amp extension cords are usually #16 gauge, unless you buy a heavy duty one. Imagine trying to pull something like 60 amps through one of those... :E

With no loads on at the panel in your RV, the voltage may *seem* perfectly fine, but when you start the AC, the voltage can drop outa sight. That's why generators can struggle to handle starting of an AC. In marginal cases, a capacitor hard start kit may help because it reduces the starting inrush current. The voltmeter you are using probably won't indicate the actual amount of the drop, but if you see the needle kick towards zero, that's not good.

All electric appliances and equipment are required to have a data plate with electric, model. no. and other info. on it. I believe they are behind the shroud. Even if the power is off, do NOT touch any electrical parts inside as the capacitors hold a charge.

Don't forget to report what the eventual outcome is!

[Claybe]

2oldman wrote:

Sam Spade wrote:

Claybe wrote:
I will also take the shrouds off of the AC and test the load and see what I get.

Only do the shrouds if necessary.

What does this mean.. the shrouds?

The plastic covers that go around the AC on the roof. I could not find the plate with all the info on it inside the RV.

[2oldman]

Sam Spade wrote:

Claybe wrote:
I will also take the shrouds off of the AC and test the load and see what I get.

Only do the shrouds if necessary.

What does this mean.. the shrouds?

[MEXICOWANDERER]

As a "final" check...after you muse, calculate and decide...

Plug an ACCURATE AC voltmeter into your rig. An outlet. Wait until 6:00 PM peak energy use hour.

Turn on ALL the stuff you're going to be normally using while on the road.

Reading the voltmeter while switching on the A/C...

If voltage dips to 105

The show's over. Your calculation is belly-up. Time to retrofit.
Or make -real good- friends with your RV air conditioner seller.

[Sam_Spade]

DrewE wrote:

A standard electric dryer outlet is not a 50A outlet, but a 30A outlet. If you're meaning a 30A RV to 50A RV adapter, it will not fit in a dryer outlet.

Oops. Brain cramp.

Haven't I seen "standard" adapters that have a 30 A male dryer plug on one end and a 30 A female RV plug on the other ??

Or maybe it was the 4-wire electric range type of plug ??

I would encourage 99 percent of the RV'ers out there to NOT make their own adapter for something like this; too many chances for a REALLY BAD outcome.

[DrewE]

Sam Spade wrote:

IF you are going to make up a 100 ft, 10 gauge extension cord, then also get a 30 A to 50A adapter. That should plug into a "normal" dryer house circuit and use one 50 amp side.....which would be plenty to feed your 30 amp service.

A standard electric dryer outlet is not a 50A outlet, but a 30A outlet. If you're meaning a 30A RV to 50A RV adapter, it will not fit in a dryer outlet. It will work with a normal electric range outlet (of recent vintage), but that's usually not so convenient to use when visiting someone.

Be aware that many existing houses have three wire dryer outlets that do not have a safety ground connection (forcing the neutral return to do double-duty as a chassis ground), while new installations now have four wire dryer outlets with separate neutral and ground connections. If you construct or buy an adapter for a dryer outlet, you need to know which style you'll be dealing with, and be sure to wire it properly for RV usage. You should use only one of the two line connections and not the other in either case so as to provide 120V to the RV rather than 240V. Doing it incorrectly will lead to much damage to the RV 120V devices.

[Sam_Spade]

2chiefsRus wrote:
You also need to know what else is running in the sticks and bricks house on that circuit you are plugging into.

Which is a second good reason to use an electric dryer outlet and 30 amp adapter. You can be sure it has enough capacity AND you can be sure that there is nothing else on that circuit.
(Well almost sure. Never underestimate the ability of morons to screw things up !!)

[Sam_Spade]

Claybe wrote:
I will also take the shrouds off of the AC and test the load and see what I get.

First look for identification plates or labels in the places that are easy to get to. There should be one somewhere that lists the power consumption. Hopefully you won't have to take too much apart to find it. Remove the grill and intake air filter first. Only do the shrouds if necessary.

[2chiefsRus]

You also need to know what else is running in the sticks and bricks house on that circuit you are plugging into. We ran into a problem when plugged into a friends house. The homeowner didn't even know that his freezer in his basement was on the same line as the outlet in the garage. When the freezer kicked on, the breaker would flip if our AC in the RV was already running. The homeowner was SURE there was nothing else on that line but turned out he was wrong.

[Claybe]

Thanks for all the advice. I will order the 10 gauge RV cords as suggested with the dog bone adapter. I have some time before the trip to test all this out and will do so at home first. I will also take the shrouds off of the AC and test the load and see what I get. Excited to make our first big trip in the RV!!!

[joebedford]

You make me nervous when you say "extension cord". Don't try to run any heavy load with an "extension cord". As far as cord-heating goes, you should be fine with a cord designed for RV use. If you ARE using an RV cord and it gets hot, something is very wrong and you're tempting a fire.

[ford_truck_guy]

You could always get one of these - adapter

and buy one of these cords - cord

But I would not go and leave it unattended.. only use AC when needed , and use nothing else while doing so..

Or something similar to plug into the dryer outlet

[Sam_Spade]

Claybe wrote:

I am assuming that just using a regular household outlet will handle my air conditioner.

Several of us have been trying to tell you:
YOU SHOULD NOT ASSUME ANYTHING. Find out what the wattage requirement of your AC is. Divide that by 110 for a rough estimate of the current draw.

My guess is that a 20 amp circuit with nothing else on it would work.....,but that a 15 amp one might not. But you should not guess.

IF you are going to make up a 100 ft, 10 gauge extension cord, then also get a 30 A to 50A adapter. That should plug into a "normal" dryer house circuit and use one 50 amp side.....which would be plenty to feed your 30 amp service.

[westend]

Claybe wrote:

Sam Spade wrote:

Claybe wrote:
but need to figure out how to plug into a house while we are on the road. Thanks!!!

You make SURE that the house is properly equipped BEFORE you get there......or resign yourself to NOT using the air conditioning.
There really is no middle ground.

When it comes to extension cords, the fewer connections the better.

I personally wouldn't do a 100' run at 30 amps with 12 gauge, especially not with multiple connections involved.

I am assuming that just using a regular household outlet will handle my air conditioner. I have a small 25 foot RV and read earlier that I would be okay to use a 10 gauge RV extension cord with a dog bone style adapter and plug into any outlet. Am I wrong in thinking this?!?

I'd suggest to try it at home before leaving. If it operates the AC, like myredracer outlined with respect to voltage, you should be good at other locations. Some of that will depend on the local conditions of the place you're parked.

[myredracer]

Another thing you must always do is keep your plug blades clean and shiny and do not plug into a pedestal or receptacle at home if the power is on. If you don't turn the power off, the result is pitting on contact surfaces leading to resistance and heat. 15 amp, 120 volt extension cords that are old, have been left out in the elements for a long time and/or have been well used and abused are candidates for poor contact, heating and in some cases a meltdown. I've had a couple of cheapo 15 amp extension cords go up in smoke in our driveway. I eventually installed a dedicated 30 amp recept. and disconnect switch in the carport for our TT and no more extension cords overheating.

Notwithstanding whether or not you can run the AC unit with what you have, you should monitor the voltage. You want it as close to 120 volts as possible at the AC unit (and it's 120, not 110). When the voltage goes down, the current draw of an AC unit goes up, putting an even greater strain on the supply cords, plugs and recepts. If low enough, can lead to damage to the AC unit and it can have trouble starting and may trip a breaker. If the voltage gets below 105, shut it off.