What's your experience with 7500 watt generator?

[Steelstring]

I just bought a Generac 7500 watt generator under duress this morning due to an extended power outage. I've been planning to buy a larger generator for a while and this finally pushed my over the edge.

So here's the question: What have you been able to successfully run on a similar size genset without overloading?

I would like to run the following (with estimated wattages from the genset manual):

- 1.5hp submersbile well pump - 2800 watts
- Fridge - 1000 watts
- Freezer - 1000 watts
- Septic lift pump - 2000 watts
- Microwave - 1000watts

These obviously won't all be on at the same time, but there will be some combination of those at any given moment. The question really lies in the startup surge of the motors. The manual says to assume 3 times the running wattage of your largest motor and add that to your base load. I know that start-up surge can be a lot, but three times seems like a lot.

What's your experience?

 

[Car Doc]

I think you are ok I need a bigger one close to a 10k minimum spec wise but I have a 5500 and a 2100 and we have gotten along just fine its a matter of sacrifice you do what you have to bigger generators use more fuel etc.

 

[General Lee]

I have a 5500 watt and ran the well pump, oil furnace, 3 fridges and a freezer and all the lights I needed to run. Oh, and the TV . I did shut the breaker off for the well pump when the bladder filled and cut it back on when I needed to fill it. I had no issues.

 

[grsthegreat]

i used a 7500 watt on a 4000+ sf home. could rund all lights and frige, freezer, microwave.

didnt have a well or sewer pump though. but i never overloaded the unit. oh also ran the tv, bathrooms and all exterior xmas lights (just happen to fall on a circuit i was controlling).

personally its the well that i have the biggest issue with. those start with a load and take the most starting amperage.

 

[Travelover]

Similar setup here. Like the others, my generator only grunts when the well pump starts up. I'd just turn the well on and off with a separate switch or breaker when you know that no other major loads are running. Your fridge and freezer should be much less than 1000 watts.

 

[dex3361]

I would be concerned about the motors they can draw up to 6 times the full load current depending on the type of motor.

 

[merrickvilleguy]

- 1.5hp submersbile well pump - 2800 watts
- Fridge - 1000 watts
- Freezer - 1000 watts
- Septic lift pump - 2000 watts
- Microwave - 1000watts

These obviously won't all be on at the same time, but there will be some combination of those at any given moment. The question really lies in the startup surge of the motors. The manual says to assume 3 times the running wattage of your largest motor and add that to your base load. I know that start-up surge can be a lot, but three times seems like a lot.

What's your experience?

Those are your starting watts ... (1.5HP == around 1000W ...)

your fridge and freezer run under a couple hundred watts each after they are going

my suggestion is to get a kill-a-watt and get some real world numbers for your different appliances

we use a 7500 for the whole house (less water heater), lights, well pump, sump pump, fridges, freezer, tv/stereo computers/network gear comfortably

 

[Steelstring]

Those are your starting watts ... (1.5HP == around 1000W ...)

your fridge and freezer run under a couple hundred watts each after they are going

my suggestion is to get a kill-a-watt and get some real world numbers for your different appliances

we use a 7500 for the whole house (less water heater), lights, well pump, sump pump, fridges, freezer, tv/stereo computers/network gear comfortably

That's assumes 100% efficiency though. 1 hp = 746 watts at 100% efficiency. Most decent motors are maybe 40% efficient, probably more like 30%. I think that's how they came up with those numbers. Of course this is also assuming you are actually asking 1.5hp out of the motor too. I think real life load factors are much less than full-on all the time. That's why I was asking about real life experiences. Looks like from the posts and your experience, I should be fine.

I have a kill-a-watt....didn't even think to use it! Great idea!

 

[Gale Hawkins]

This spring we have used our old 7500 watt (run rating) Coleman PowerMate more times than in the past three years.

It is the well pump that is the hardest to start. I have some of fluorescent lights in the basement that will blink off when the pump starts but the other bulbs just dim a bit.

O would like a 10K watt generator but can hardly fee the 7500.

Keep in mind the marketing folks play with the meaning of the numbers.

To be on the safe side reduce the stated engine HP by 10% and divide the result by 2 to get the real rating of the generator when you are computing what it will start.

In our case 90% of 18 HP is about 16HP/2 = 8000 watts

It is rated 7500/8000 run/surge on the name plate.

This is due to physics more than anything else.

Just remember you MUST have two true HP to produce 1000 watts of output.

 

[merrickvilleguy]

That's assumes 100% efficiency though. 1 hp = 746 watts at 100% efficiency. Most decent motors are maybe 40% efficient, probably more like 30%. I think that's how they came up with those numbers. Of course this is also assuming you are actually asking 1.5hp out of the motor too. I think real life load factors are much less than full-on all the time. That's why I was asking about real life experiences. Looks like from the posts and your experience, I should be fine.

I have a kill-a-watt....didn't even think to use it! Great idea!

Another thing to look at is how you are hooking up. Our place had one of those hated double male dryer cords which we promptly cut an end off. We have since put a generlink switch in and makes the whole process easier. Just need to leave the water heater off and there is no need to worry about what breaker does what just use the switches like you normally do.

especially considering we're the only one on the transformer around here its a big pain to keep steady power