15 AMP TO 30 AMP QUESTION - Page 2 - Fiberglass RV

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Old 07-03-2006, 06:41 AM   #15
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Our Scamp is not a 15 Amp connection, it is a 30 amp connection and it breaks out to 15 amp branch circuits at the breaker pannel.

Here is a test you can try: Run the air conditioner with other stuff turned on such as tv and the other normal things then turn off the air conditioner, wait 5 seconds and turn it back on. Will it start up or just hummmmm and will it pop a 15 amp breaker that your extension cord is pluged into.

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Old 07-03-2006, 06:48 AM   #16
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Name: Patrick
Trailer: 2007 Casita Liberty (Sold 2011)/ Honda Odyssey
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Turning on an air conditioner again without letting it sit for 2 minutes is a good way to break it. Not a good idea. The $20 thermostat I used in my A/C Thermostat project actually has such a timer built into it.

I think the heating up of the extension cord is a good test, although all of the info I've seen would indicate that a 14 gauge, 50' cord should work just fine for our 8 amp A/Cs.

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Old 07-03-2006, 09:19 AM   #17
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The real problem here is the possibility of too low of a voltage at your camper to start your air conditioner compressor.

If you are running your A/C while at home, the voltage at the outlet the camper is plugged into is probably pretty good - at least 115 volts, possibly a bit higher. The voltage drop across a 100 foot 14 AWG extension cord carrying 8 amps is about 4 volts. At home this is no big deal, as you still have about 110 volts at the camper.

If you try to run your A/C in a campground where you start with the voltage at the outlet is around 110 volts (or maybe even less...), you end up with 106 volts running your air conditioner - not a very good situation.

This is one reason why it is important to monitor the voltage being supplied to your camper.

If an 8 amp load causes your extension cord to become warm, throw it away. It is probably a 16 or 18 AWG extension cord, which most certainly is not adequate for the job.

And finally, don't do as someone suggested above and turn on your A/C within a minute or two of shutting it off. The pressures in the compressor will be much too high to allow it to start, no matter what size or length extension cord you are using. What happens when this is tried is you trip the overheat protection in the compressor motor, resulting in no cooling until the compressor cools off. This usually takes longer than it takes for pressures to equalize, and when the compressor cools it resumes normal operation.

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Old 07-03-2006, 10:55 AM   #18
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Trailer: Amerigo 16 ft 1972
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Somewhat along the same lines - I recently purchased a 1972 Amerigo and here's the wiring situation. Incoming 30 Amp to circuit breaker box containing two 20 Amp breakers. One breaker is connected to the converter and one is wired throughout the camper for normal 120V use. I smoke-tested the converter last weeked (literally) - so it's no good.

What I'd like to do is keep the 12V/120V sides apart and use a 120V/1.5A battery tender on the battery and keep the 12V side alive. I don't see any big deal with this, but please advise!

Here's the problem on the 120V side:
Dometic frig = 2A
Microwave = 9A
A/C = 8A
Battery Tender = 1.5A

So you see I'm already over 20A... I haven't gone and physically looked at the wiring yet, but some info I found in the camper's paperwork indicating it's 12/3.

My proposed mod is to disconnect/switch off the 20A breaker supplying the converter and leaver the converter switched to the battery (everything works fine right now) and replace the other 20A breaker with a 30A breaker to power up the appliances. Any problems you see?

Thanks in advance for any help - just found/joined this site a week or so ago and have learned quite a bit! Also, I'll try and get some pics up soon.
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Old 07-03-2006, 12:22 PM   #19
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Trailer: Boler (B1700RGH) 1979
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...My proposed mod is to disconnect/switch off the 20A breaker supplying the converter and leaver the converter switched to the battery (everything works fine right now) and replace the other 20A breaker with a 30A breaker to power up the appliances. Any problems you see?
Since I understand 12-gauge wiring to be inadequate for 30A service, I would not use a 30A breaker on any circuit in this trailer (or mine, which is generally similar).

If the 20A breaker which currently feeds the converter is not to be used for that anymore, why not use it to supply a separate circuit for the air conditioner? The original 20A breaker would then be left to supply the other AC appliances for which it was intended. This would require running a cable from the breaker panel to the air conditioner outlet.
1979 Boler B1700RGH, pulled by 2004 Toyota Sienna LE 2WD
Information is good. Lack of information is not so good, but misinformation is much worse. Check facts, and apply common sense liberally.
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Old 07-04-2006, 07:34 AM   #20
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Trailer: Amerigo 16 ft 1972
Posts: 23
Thanks much for the reply - and a damn good idea! That's what I'll do; there's already a piece of triplex running to the trunk for the A/C and battery tender so I'll just move that to the other breaker and leave the converter alone.
Have a good 4th,

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