Fifth wheel 50A on 30A?

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Phil Hyde

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Sep 5, 2011
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Well we finally encountered our first RV park with no 50A hook ups. Actually there was a site with a 50A plug but my Surge Guard indicated reverse polarity. Nice save and very glad I had it!

So another save was made by having a 50 to 30 adapter.  Yay me!  OK, we'll enough cheer leading.

What limitations should I expect running the fifth wheel on 30A?  We won't be running the A/C units so besides the microwave I don't think we have any more high amp appliances.

Thanks for any suggestions or reassurance!

Phil
 
My rule of thumb has always been:

15 amp:  Lights, TV, fans, etc. all you want.  Maybe use the microwave, the coffee maker or a hair dryer one at a time if not much else is on. Put the refrigerator and water heater on gas only.

20 amp:  Same as above plus a little extra to run the refrigerator on electric.  Or leave the fridge on gas and have enough reserve to reliably run the microwave, or a room heater, or maybe one A/C.

30 amp:  Lights, TV, fans and any two major appliances.  Or one major appliance and one A/C.  Two A/Cs may work if the refrigerator is on gas but is pushing it.

Watch the voltage when using an A/C on a small connection.  A/Cs can't stand voltages less than about 109 volts.  Other appliances are much more tolerant of low voltages.
 
Elaborating a bit, when on 50A service you have a total of 100 amps available - 50A on each of two power wires. On 30A, the total is still 30 and it is spread across your two power lines in any proportion, as needed. So, there are two limitations: 30A total and no more than 30A on either "half" of your RV's wiring. You are likely to find that the bulk of your galley appliances, the front a/c and most wall outlets are all on one of the two power source wires, so you may bump into the 30A limit that way. For example, if the microwave is on,  a toaster or coffee maker in use and somebody turns on a hair dryer in the bath area, you  will probably trip on 30A whereas 50A would handle all that and more.

If the fridge and water heater are in electric mode, they cycle on/off via their thermostats and that makes their amp consumption unpredictable. One moment you may be doing fine and then suddenly the breaker trips. That's often because the thermostat cycled on at an inopportune moment.
 
Thanks, all.

We are in Northen California so not running the ac and really only using a space heater.  Tv microwave and lights. Fridge runs on auto and water heater run on electric mode.

Sounds like we will be ok appliance wise.  Any concerns with battery charging? Currently I have 2x6V.
 
In what you show you are using, I see the following:
Space heater: big user, can be up to 15 amps in some cases; 
TV: small user; 
Microwave: could be a BIG user depending on its size;
Fridge on Auto, means it will be on electric, not propane, if 120V is available - big electric user but on demand  (5 Amp 600 watt) Note: could be left on propane as Fridges only sip propane;
Water heater on electric: could be a medium to high user but on demand. Could be on left on propane in many cases.
Lights, relatively small 12V user if careful but your converter (120V to 12V) has to supply it and charge the batteries. 

Timing could be everything i.e. space heater and microwave, running at the same time: not a good thing
 
Even on 50A I tried to be careful not to run the space heater at the same time as, say, boiling water with the electric pot.  Same outlet.
 
Currently we are in a VERY old KOA campground in Texas and the row we are parked has only 30 amp service.  In fact it doesn't even have breakers just glass fuses.  Our stay here lasts a total of six months and last year when we first stayed here we learned a few lessons the hard way, one was that going out at night to change a glass fuse in the dark wasn't fun.

Power management is the key and it can be pretty simple really.  If needed a single AC unit can be run without any problem but flipping on the electric water heater at the same time will result in an eery silence from the roof.  To eliminate potential damage to our fridge from fluctuating power we run the fridge on propane only.  The space heater in the living area only runs on low (750-1,000 watts) and will operate fine with the electric water heater or the microwave but not both.

Since we do a lot of boondocking when we can, power management really isn't an issue for us.
 
If you ever want to try and calculate how many amps you may be using at once take the rating of the power source i.e. (most space heaters are 1500 watts) divide that by 120.  this equals 12.5 amps.  Space heaters will use always all the available amps that a 15 amp breaker has so be careful.  Most electrical products have wattage ratings on them.  Most rv microwaves are 900watt so 900/120=7.5.  So if you have the space heater on and run your microwave at that moment you are pulling 20amps.  It adds up quick so be careful.  The good thing is if you have most of your lights on, tv, dish/cable box, plug in clocks, computer, phones charging, all that adds up to just a couple of amps.  Hope this helps.
 
Since my stick and brick home is my boondock palace I'm a wizard when it comes to saving every last watt I can. (Solar, Hydro, Battery power house). So I'll I do is take the very same technology and take it out to the RV and I can stretch a pair deep cycle batteries quite a period. As for AC requirement Mine is only a 30A RV but I'd be hard pressed to even use that much. Being normally I'm without hookups and using a small 2Kw (15 Amp) genny.
 
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