[Nesrad]

I'm converting a toy hauler (a big enclosed trailer) into a *******'s RV. I'd like to install a small water heater, an electric range, and a refrigerator. The three appliances together would peak at over 30 amps, but each of them separately would consume under 15 amps. I intend on using a regular household outlet to get power to the trailer. Most outlets are rated at 15 amps, and regular extension cords are rated at this amperage too. So I need some kind of way keeping all the appliances from turning on at once and of prioritizing which appliance gets the power. The stove would get first priority, then the fridge, then the water heater. I need a relay that's able to disconnect two of the three circuits whenever one is in use, while respecting an order of priority. Does anyone know if this exists? I know motor homes use an "Energy Management System," but I have been unable to find one, and I suspect they cost too much anyway.

 

[joecaption]

I'm converting a toy hauler (a big enclosed trailer) into a *******'s RV. I'd like to install a small water heater, an electric range, and a refrigerator. The three appliances together would peak at over 30 amps, but each of them separately would consume under 15 amps. I intend on using a regular household outlet to get power to the trailer. Most outlets are rated at 15 amps, and regular extension cords are rated at this amperage too. So I need some kind of way keeping all the appliances from turning on at once and of prioritizing which appliance gets the power. The stove would get first priority, then the fridge, then the water heater. I need a relay that's able to disconnect two of the three circuits whenever one is in use, while respecting an order of priority. Does anyone know if this exists? I know motor homes use an "Energy Management System," but I have been unable to find one, and I suspect they cost too much anyway.

Use a gas stove instead, not going to get an electric stove that runs on 110 and 15 amps.
Same with the water heater.
It would be far better to find a ref. that can run on 110 or gas.
One way to get all this stuff cheaper is check around at car junk yards and places that sell campers. Any bigger dealer will have older trade ins there parting out.
If you use all gas then you do not have to be at a camp ground to use the trailer.
You could also picked up a converter and install double bulb lights so they will run off of a battery or 110.

 

[joed]

http://www.imdb.com/title/tt0592812/

 

[Nesrad]

Use a gas stove instead, not going to get an electric stove that runs on 110 and 15 amps.
Same with the water heater.
It would be far better to find a ref. that can run on 110 or gas.
One way to get all this stuff cheaper is check around at car junk yards and places that sell campers. Any bigger dealer will have older trade ins there parting out.
If you use all gas then you do not have to be at a camp ground to use the trailer.
You could also picked up a converter and install double bulb lights so they will run off of a battery or 110.

Thanks for the tips.

I have already found a small water heater that draws under 15 amps @ 110vac and I'm pretty sure those little double burner counter top stoves that plug into a household outlet draw 15 amps or less.

Yes, I will use gas when electricity isn't available, but propane costs a lot more than electricity where I live.

As for the lights, I'll probably use 9w 110vac cfl bulbs and run them off an inverter when off-grid. Total power consumption with the inverter is not so different from a far more costly 12v system. This setup has worked great for me in my cabin with solar panels.

 

[joecaption]

Big mistake to do it that way and your going to have to have a big battery bank to supply enough power.
At least install a small breaker box, 20 amp breakers and go with a minimum of a #12 supply line with 12-2 wiring.

 

[Nesrad]

Big mistake to do it that way and your going to have to have a big battery bank to supply enough power.

I'm not planning on running anything but the lights on batteries (please check the edited version of my post).

At least install a small breaker box, 20 amp breakers and go with a minimum of a #12 supply line with 12-2 wiring.

Yes, of course, and maybe 15 amp breakers, since I wouldn't want to trip the breakers inside the house if the outlet being used is on 15. And yes I'm planning on using no 12 wiring, and a contractor grade extension cord.

 

[Nesrad]

I just thought of one possibility: using a dpdt switch to direct power either to the water heater/fridge or to the range, but not both, assuming the heater and fridge won't trip the breaker since they'll both kick in at the same time as soon as you throw the switch, and also assuming you remember to flip the switch back after using the range.

Apparently refrigerators have huge surge requirements. Is there anyway to limit the surge? I seem to remember hearing something about using capacitors for this purpose.

 

[mpoulton]

You really need to use gas for all heating. There are good reasons that electric heating is just not used without permanent utility power. Gas will be cheaper (both to install and to use), and work much better. You will find that a decent electric cooktop uses at least 1500W per unit. A two-unit portable hotplate probably has one 1000-1200W unit and one 800-1000W unit, which is a LOT of electrical load, but still not really good enough for cooking. Any gas cooktop, no matter how cheap, will be twice as good. A cheap toaster oven uses 1500-2000W. A regular toaster is about 1000W. A water heater is a few thousand watts. These heating loads add up really fast.

A typical RV hookup is 30A at 120V, and that is intended to supply no heating loads, only the other loads of the RV. RV's use gas for everything they can - often including the fridge.

 

[Nesrad]

Gas will be cheaper (both to install and to use), and work much better.

Where I live, electricity costs about 6 cents/kwh, and you don't have to fill up propane tanks, and risk fire and CO poisoning.

A two-unit portable hotplate probably has one 1000-1200W unit and one 800-1000W unit, which is a LOT of electrical load, but still not really good enough for cooking.

So they're not good enough for cooking. What are they good for? I suppose all those meals I ate as a cash-strapped student weren't really cooked.