Forum Discussion

rookie_rv's avatar
rookie_rv
Explorer
Aug 29, 2016

Finding Out Generator Load Maximum

Rookie Rver :C here! How do I find out how much (maximum) load I can put on (house) generator safely? Is there a technique or process to find out let's say running the air conditioner, two tv's, laptop, interior lights, etc....

(Generac 5500)

10 Replies

  • With ambient air temps say around 75, your Genny will run all electrical load in your rig. No problem.
  • I've got a Onan 5500 and what I did was fire it up and turned on every electrical device in the coach except the furnace.

    Sat like that about 15 minutes with no problems so now I know where I stand.
  • Mr.Mark wrote:
    We have a 20,000 watt genny. .
    Wow. That's a big one.
  • Good to know how to figure amps.

    We have a 20,000 watt genny.

    20,000 ÷ 120 = 166.67 × 80% = 133.33 amps. We could do pretty good with that.

    In a compartment on the driver's side about 2 back, we have a 30 amp buddy plug for a guest if they need power too.

    MM.
  • rookie_rv wrote:
    Rookie Rver :C here! How do I find out how much (maximum) load I can put on (house) generator safely? Is there a technique or process to find out let's say running the air conditioner, two tv's, laptop, interior lights, etc....

    (Generac 5500)


    determine the maximum wattage of the genny. once you know the wattage it's a simple math problem. AMPS = WATTS/VOLTS. so, if you have a 5500-watt genny then the maximum amp load would be 47.82-amps (assumes 115-volt system). some will argue that 110-volts is nominal, other 120-volts. for your purposes they're distinctions without a difference since the resulting math is essentially the same.

    the other poster is correct in that 80% of load is about what you can expect without tripping breakers. some AC appliances will consume additional amps for a few seconds at startup before settling down into "cruise" mode.
  • I have a control monitor in my RV. It is 50 amp and says when running Generator..
    line one 30 amps Line 2 30 amps.. 40 amps total,, i went over once and it shut down one of my air conditioners..
  • A 5500 watt generator that outputs it's rated wattage will have little difficulty running the entire rig in your profile. Most RVs with a single AC come specked from the factory with a 4000 watt onboard genny, RVs with 2 AC units normally come with a 5500 watt version. Heck, even a high quality 3000 watt portable inverter genny outputting rated wattage will run the items you listed, at least that is what I've experienced.

    As mentioned above, you have about 45 amps to utilize, which if coach has been properly wired should easily power a single AC unit, laptops, TVs, even a microwave oven at the same time. Most onboard generators with such low hours usually will require some TLC since they were severely under-used, our 9 year old Onan has nearly a thousand hours and purrs along powering our rig as if plugged into shore power.