Heavy Duty Extension Cord versus Power Cord

[gordonhks]

I have purchased an adaptor that allows me to convert my three prong 15 amp connector to a standard 3 prong extension cord. My motive for doing this was to keep from having to drag out the heavy and thick 15 amp cord. It is a real pain to re-roll and store, especially in wet/muddy conditions.

I have attached the adaptor to a typical extension cord, but I am concerned that it will not handle the load if I run the air conditioner or the microwave for extended periods of time.

I am no considering purchasing a 12 gauge 15 amp extension cord to use with the adaptor. One like this http://www.amazon.com/2883-Heavy-Duty-C ... pd_sxp_f_r

Has anybody else been through this exercise with success?

[gordonhks]

In looking at this more closely, it appears that what I am asking is this...Will a 12 gauge 15 amp power cord work well enough to run the air conditioner OR microwave compared to the standard 30 amp power cord that comes with most RV's?

[markopolo]

Maybe.

Do you have a kill-a-watt meter? If not check with your local library. The library here in town lets you borrow one to check the electricity consumption of appliances. You'd be able to determine how much current the appliances you mention use.

I said maybe because the answer depends on your appliances. If you have a 11,000 BTU A/C then I think it could run on a 15 amp circuit if nothing else was running. I doubt that 15,000 BTU A/C would run. Most microwave ovens would run on a 15 amp circuit. My microwave oven consumes 900 watts so about 7.5 amps AC. Some convection microwave ovens come with a 20 amp plug.

I had a 10,000 BTU window air conditioner in a house that would just run on a 15 amp household circuit. The cord would get warm though

I use a 15 amp cord all of the time but my A/C is only 5,000 btu. I can't remember the last time I used the 30 amp cord.

The big problem with using the 30 to 15 amp adapters is that you essentially lose the protection of the circuit breaker at the camp site pedestal. You end up with a 30 amp circuit breaker protecting a 15 amp cord. You could pull 20 or 25 amps through the 15 amp cord and the camp site pedestal circuit breaker would not trip. That is not good. You really have to know what your appliances draw before using one of the 30a to 15a adapters.

Remember, other appliances might be running automatically when you plug in such as your converter/charger and your fridge.

The more I type the more I think you should stick with the 30 amp cord if you need to run the air conditioner.

[gordonhks]

Marko,

Thanks for the detailed reply. Some clarification is in order. The 30 - 15 a converter attaches to the receptacle on the RV and then a standard power cord attaches to that, so that the power is drawing from the 15 amp receptacle at the camp pedestal or home outlet. In that case I believe that I have protection from a 15a circuit breaker.

Still think that I should stick with the 30 A cord?

[Davydd]

Gordon,

We use our B's 30 amp cord with a 30A to 20A adapter and then a heavy duty extension cord to plug into 20 or 15 amp circuits. We did so just this weekend at a cabin. We needed the extension cord to reach the plug in source. You can run your refrigerator, microwave and coffee pot but not your air conditioner with only 20 or 15 amps.

Speaking of the Great West Van Legend of course.

[markopolo]

Edit: I see Davydd already replied with good advice while I typed this but I'll post it anyway.
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Plugging a 15 amp cord into a 15 amp outlet is safe. Your A/C (or other appliances) would trip the breaker if the circuit gets overloaded.

I think of adapters as follows: (this is just how I describe them - don't know if it is correct, I might have the descriptions backward )
15A (plug) to 30A (outlet) - allows you to plug a 30A RV cord into a 15A outlet
30A (plug) to 15A (outlet) - allows you to plug a 15A cord into a 30A RV outlet

The way I think of it would mean that you'd have a 30A (outlet) to 15A (plug). Using that adapter at the RV inlet rather than the campsite power pedestal outlet like what you've purchased is a good idea

For myself, I'd try what you are doing if you have an 11,000 BTU air conditioner. I don't think I'd go so far as to recommend it though when it comes to running the air conditioner. You're more likely to have success at home with a dedicated 15 amp circuit. Campgrounds can be iffy - amp draw goes up as volts drop.

The fridge, converter/charger and microwave (not in convection mode) etc. should all be fine. The air conditioner is still going to be a maybe. Running too many things at once obviously won't work.

This past week I used a 30A (plug) to 15A (outlet) adapter at the campsite power pedestal outlet often because some campsites only had a 30A RV type outlet and I wanted to use my 15A cord.

[Davydd]

No guessing on my part. Gordon and I essentially have the same B. I know from experience you can't run the air conditioner acceptably and if you could you'll blow the breaker with anything else on. With the refrigerator running you can use your convection/microwave oven in convection mode or your coffee pot. I don't think we have run our coffee pot and convection/microwave at the same time. You can add up your loads if curious. This past weekend I'm not sure if the outlet we plugged into was 15 amp or 20 amp. It didn't have the T shaped plug-in for one of the prongs so it might have been only 15 amp. We plug in the way I previously described at three different family households on our travels.

The optional breaker plug in at campsites is usually 20 amp. We rarely encounter a 20 amp service only campsite but have used the circuit for plugging other stuff in, not the B.

[gordonhks]

Mark/David, as always thanks for your sage advice. We are selling our home in Missouri and most if not all of our furniture, and do not plan on leaving until the end of August. Once the beds are sold, I was hoping to be able to plug into the home 15A circuit and run the air while we parked overnight in the drive.... So that plan is shall we say ... (pun intended) tripped up?

[gordonhks]

Ok, I have tried this and it appears to work. I purchased this

http://www.amazon.com/2883-Heavy-Duty-C ... acket+2883

Cord from Amazon. I have it plugged into may garage receptacle. At the female end it is then converted with a 30 amp plug.

The AC runs just fine. The cord is a little warm, but not hot. I checked the homes circuit breaker for that outlet and it is a 20amp circuit breaker.

Am I (like the Molly Hatchet song) Flirting with Disaster, by running a 15 amp cord on a 20 amp circuit? Otherwise the AC runs fine. Just to tempt fate, I also turned on the refrigerator (on AC) while the AC was running all seemed to be just happy.

[gordonhks]

This is the adapter that I use. I purchased it from a physical West Marine store.

http://www.westmarine.com/webapp/wcs/st ... hk712TF2zA

[markopolo]

Originally Posted by gordonhks

Ok, I have tried this and it appears to work. I purchased this

http://www.amazon.com/2883-Heavy-Duty-C ... acket+2883

Cord from Amazon. I have it plugged into may garage receptacle. At the female end it is then converted with a 30 amp plug.

The AC runs just fine. The cord is a little warm, but not hot. I checked the homes circuit breaker for that outlet and it is a 20amp circuit breaker.

Am I (like the Molly Hatchet song) Flirting with Disaster, by running a 15 amp cord on a 20 amp circuit? Otherwise the AC runs fine. Just to tempt fate, I also turned on the refrigerator (on AC) while the AC was running all seemed to be just happy.

You won't find anyone that will recommend it so you are on your own with the decision. I can provide some info though.

I had a 10,000 BTU window type a/c in a house that came with a 15 amp plug. It would occasionally trip the 15 amp breaker even though it was dedicated when I used a 3' extension cord.

This source https://wikis.utexas.edu/display/comm/N ... lectricity indicates that:

12 gauge stranded copper wire is rated for 18-20 Amps.

The startup surge on an 11,000 btu Dometic a/c (I don't know what you have) could be something like 63 amps. Running amps on the 11,000 BTU unit I looked up was listed as 14 amps. The plugs and adapter are all rated 15 amps. Some circuit breakers are rated 100% and some are 80% derated.

I'd check the AC voltage in the coach. Ideally it won't drop below 110 volts. If it is too low then you could burn out the a/c compressor. If the plugs get too hot they could melt. I don't know the fire risk. You'll be exceeded the length of 12 gauge (24') Dometic spec'd in the manual I looked at - that was for the wiring in the coach.

You can see it is all maxed out so don't add to the load with the fridge etc. No more tempting fate Your converter/charger is going to be running also.

[arrveedogz]

Originally Posted by gordonhks

Am I (like the Molly Hatchet song) Flirting with Disaster, by running a 15 amp cord on a 20 amp circuit?

Don't forget your 25' cord is plugged into a house receptacle that is itself some distance from your 20 amp breaker. It's the total run that determines the voltage drop over any length of wire; depending on where your breaker is located, that could be significantly more than 25'. Here's a voltage drop calculator: a total of 100' of 12 gauge drawing 15 amps costs you nearly 6V. Doesn't sound like much, but all it takes is a little voltage drop at your supply and you're flirting with serious undervoltage.

Great song, although it may be more appropriate for 5th wheelers:
"We're travelin' down that lonesome road.
Feel like I'm dragging a heavy load. "

[gordonhks]

Well, here are the final results. I purchased a Kill a Watt meter from (of course) Amazon. http://www.amazon.com/P3-International- ... ill+a+watt

AC 14 amps
Refer on electric 3 amps
Microwave 10 amps.

So it appears that the experiment is a minor failure. Technically the AC will run on the 15 amp cord and a 15 amp circuit, but only if the food is slowly getting warm. I still hate "wrastlin" that big 30 amp cord.