20 amp Circuit & A/C?

scbwr wrote:
OK...I've ran AC on a 15 amp circuit many times, but only with the heavy duty cord from the trailer and a matching extension cord (same gauge, etc.). Recently we moved to a new home here in Ohio and with the trailer parked in front of the house, I had to use an additional cord in order to reach the nearest outlet. Well...it didn't work too well...blew out the capacitor for the motor for air circulation. So...very shortly, I'm having a dedicated 20 amp line run to the front of the garage to prevent any further problems! Be careful with extension cords...my mistake cost me more than the cost of having a new line installed!

why not put in a 30 amp outlet? won't cost much more than a 20.
bumpy

OK...I've ran AC on a 15 amp circuit many times, but only with the heavy duty cord from the trailer and a matching extension cord (same gauge, etc.). Recently we moved to a new home here in Ohio and with the trailer parked in front of the house, I had to use an additional cord in order to reach the nearest outlet. Well...it didn't work too well...blew out the capacitor for the motor for air circulation. So...very shortly, I'm having a dedicated 20 amp line run to the front of the garage to prevent any further problems! Be careful with extension cords...my mistake cost me more than the cost of having a new line installed!

myredracer wrote:

RoyB, the prongs on that 30 amp plug are damaged from plugging the cord in live all the time. When you plug in live, the converter causes a momentary inrush current that causes a snap, crackle and pop when you plug in and you will see a flash in the dark. That pits the metal and in the long run causes high enough resistance to overheat the plug or receptacle and cause damage and even a fire. NEVER plug your RV cord live into a receptacle or extension cord. At home, you'll need to shut the breaker off.

Glad you told me that. I wondered about that "snap". From now on I will shut the breaker off if I can. When I can't I have found that if I shut off the breaker to my power converter when I plug in the "snap" doesn't happen. Then I flip the breaker for the converter back on. Breakers, and switches, are designed to snap over quickly and do less damage to the contacts. (I knew that and should have been doing this all along. Sometimes my brain doesn't snap over that quickly either)

A compressor will not necessarily be ruined running on low voltage, depending on how low the voltage is. The digital controlled marine systems that I sell, install and service do not shut down on a low voltage fault until it senses 103 volts for three minutes, so evidently, Dometic is not real paranoid about it. That said, I wouldn't recommend running one for an extended period on low voltage,

Any 15K BTU rooftop unit should run fine on a 20A circuit provided there are no addition draws. That's what is in the trailer. A 15A source could be iffy and you could get nuisance trips at the breaker panel. I had a marine unit that was an OEM installation that drove me nuts until I installed a 20A breaker.

If you have to use an extension cord, be sure it is constructed with #12 wire and keep it at 25'. if you have to go to 50', I would recommend that you go a size larger on the wire.

Most of us have 15amp circuits at home. I do and I got a 10/3 100ft extension. 10/3 will prevent any meaningful voltage drop on a 15-20 amp circuit over the 100 feet. It is this drop (which heats the cord) that will affect your RV voltage.

I may be wrong, but most air conditioners have cutoffs that will shut the compressor down if the voltage is too low (actually if the compressor starts to overheat due to the low voltage) and will reset after cooling off. I was unaware that any modern A/C would get permanently damaged by low voltage. Consider brownouts and high usage power conditions when line voltage can drop below 108.

My A/C runs cheerfully on my household circuit. Originally, I had a 12/3 100ft cord, but it bothered me that there would be appreciable voltage drop, so I got the much more expensive 10/3. Nothing seems different, but I have more peace of mind.

Advice of 3 posters is right. It's the voltage that is very important. The general rule of thumb is anything below 105 volts is bad and time to shut everything off in your RV. A SurgeGuard protector shuts off at 103 volts. The last AC manual I looked at, a Coleman, said anything below 103.5 volts can damage the AC unit.

Two things can lead to low voltage at your RV. One is the supply voltage in your house. That will be a nominal 120 volts but can vary depending on the time of day, part of the country you are in and temp. out (ie., lots of AC units on). The second is the length and wire gauge of the extension cord (which maybe is what OP asked?). An AC unit has a high startup current so even if the running voltage is okay, you are better off with a heavy duty extension cord, meaning higher gauge wire, not more substantial jacket on the cable. If the no load voltage at your RV with a smaller gauge and long extension cord *seems* okay, it can struggle to start and be damaging. A minimum #14 gauge cord is better but a #12 gauge is best. For longer runs like say 100' overall, go with #12. You can easily have 50'+ of #14 inside your house.

If your AC is still struggling, there's always the hard-start capacitor mod. that would help. Not expensive and a good idea anyway for longer comp. life. Info. here: Hard start capacitor mod.

RoyB, the prongs on that 30 amp plug are damaged from plugging the cord in live all the time. When you plug in live, the converter causes a momentary inrush current that causes a snap, crackle and pop when you plug in and you will see a flash in the dark. That pits the metal and in the long run causes high enough resistance to overheat the plug or receptacle and cause damage and even a fire. NEVER plug your RV cord live into a receptacle or extension cord. At home, you'll need to shut the breaker off.

clarkgriswold wrote:
We just bought a new-to-us Funfinder Travel Trailer and need to check out the A/C. Unfortunately I don't have a 30amp receptacle at the house. Does anyone know how long I can run the A/C on 15/20 amp circuit?

We ran our AC unit for hours on end using an extension cord plugged into the exterior outlet on our doublewide in Arizona.
I purchased a 12-gauge extension cord from a big box store to avoid overloading the standard extension cord we had available.
The heavier gauge extension cord will reduce current loss and heat build up. Check Costco for best price.

Let me list what I do here to power up my two 30AMP trailers in my backyard. Maybe it will trigger what you may want to do on your end connecting up to the house/garage.

I run two 120VAC drop cords from my garage to power up my 30Amp fifth wheel and 30Amp OFF-ROAD POPUP trailer when parked here at the house.

One receptacle in the garage is a stand alone receptacle that was installed to run an air compressor at one time and this is the only thing on its circuit. I use this to feed my fifth wheel. My OFF-ROAD POPUP uses a 120VAC receptacle that located near the garage door and is on a different circuit breaker then the one I am using for the fifth wheel trailer.

Before hooking up to the Garage 120VAC receptacle I would use a circuit tester from LOWES -WALMART that looks like this

Do not use the garage 120VAC receptacle if it does not check out "CORRECT" by the correct position of the tester lights...

What I do is use two 10-GAUGE (10-3) HD Contractor type 50-foot that run out towards both trailers. I have used a 12-gauge (12-3) long extension cord with out any issues but would never use the 14-16 gauge "RED ORANGE" smaller size extension cords you find at LOWES-WALMART. They are just too small to handle the trailers.


Out in the middle of the yard I use a RV30A-15A DOGBONE STYLE long adapter plugged into the 50-foot extension cords. These come from WALMART and look similar to this...


I could never use the small round black type RV30A-15A adapters as they always tend to get hot me when used just a short time...


What you don't want to happen is for the adapters to heat up your shore power cable which might end up looking like this and will need to be replaced.


Now all I do is plug the 30AMP trailer SHORE POWER CABLE into this RV30A-15A long adapter laying in the middle of the yard.

To insure the 120VAC power source is safe to use I will use one of these RV PLUG IN 120VAC AC voltmeters (AMAZON) plugged into a receptacle inside the trailer that is in a good view spot so you can glance at it when you need to. This will check the 120VAC level coming from the house. The part I like about this meter is it has a safe zone "GREEN" printed on the face and if the AC voltage is within this safe limit then is ok to use the power - even for one roof mounted air conditioner unit.


I will turn a few thing on inside the trailer for 10-minutes or so and then back outside and check all of the connection points to see they are not getting warm to touch. This includes the garage 120VAC receptacle.

This is pretty much what we do here for our two trailer that is hooked up to the 15AMP service from the garage.

We can run just about everything inside the trailer we want to run but have to watch sometimes what is on at the same time. i.e. we can never run the air conditioner and the high wattage microwave at the same time otherwise it will trip the breaker in the garage.

We sleep in both the trailers all the time when sitting in camp back yard and of course this is where I get to do all my mods and fix up things for the every changing OFF-ROAD POPUP configurations for my emergency radio operations I am connected with. Its a great get away just sleeping over in the back yard sometimes. Wifes gets to use the fridge to supplement her kitchen fridge. Good spot for my beers too...

ALot of folks will warn you about about all kinds things that might happen when only connected to a 15/20AMP service but if you follow some good guidelines like I have listed here you should be ok. Has worked good for me over the past few years.

We use the extension cord and RV30A-15A long adapter when on the road alot. You never know when we may need some power sometimes. Works great when visiting family - I just hookup outside their house and we sleep in the trailer.

Hope this helps

food for thought
Roy Ken

With a reasonable extension cord you can run it forever on a 20 amp circuit - that's probably what it is on inside the trailer. I ran mine for days on a 15 amp circuit at home, dedicated with a 10 gauge cord but it would blow the breaker on start-up with another 15 amp circuit. Advice about voltage is dead on.

Brian

Is the circuit 15 amp or 20 amp? if 20 amp I would think you could start it up to see if it cools, then immediately shut er down.
bumpy