# Load testing today - whole house



## FlyFisher (Jun 30, 2018)

I fired up my 15kw unit today and load tested it on running the house. 

I do not have a way to measure both poles correctly combined so I am not sure on wattage/amperage numbers. I could put a meter on each pole individually, but I have both 120v and 240v loads so the numbers wouldn't be accurate if I did measure each individual pole. If all I ran was 120v loads that would be one thing, but 240v loads throw the readings out the window.

That having been said, the main loads I had running were:
1 central AC
1 room AC 
2 refrigerators

On top of that I had every circuit on in the house - of course, not every device in the house was on/running. We run ceiling fans in most rooms (all rooms have them, not all are on but most are). With every circuit on there were certainly some miscellaneous loads like wall-wart power supplies, the internet stuff (modem, wireless router), etc, etc.

All heating loads are gas here - furnace, water heater, range/oven. 

The only lugging on the engine was with the start up loads of the AC's and I will say that even that "lugging" was surprisingly subtle. My other generators have a much more pronounced "lug" with a load.

What I did not do was try to run a microwave with the 2 AC's running. However, I can cut the small AC if need-be for what ever duration a microwave needs to run if need-be if it even gets to be an issue.

Overall the outcome of the test was with the power available on the generator we won't have power outages. The question came up earlier today if we should scrutinize what is plugged in when we're on generator power - IE - to drop the draw on the generator. Easy answer - nope! 

Yeah, we can reduce fuel consumption somewhat by dropping loads, but the reality is the generator is fuel-hungry no matter what. A 4-500 watt difference in having some miscellaneous loads running or not isn't going to significantly change the fuel consumption. What will is if we go from, say, a 4,000w running load to a 10,000w running load. So the affect that the start up loads of heavy loads (compressors - AC's, refrigerators - for example) when they do start and run is going to ramp up the fuel consumption. The engine needs to crank out a lot more HP for those periods of time and thus the higher fuel draw. A few thousand watts running is going to be on the low end of the fuel consumption so there won't be much of a difference down that low anyway. If we don't draw any wattage from the generator just having the engine running is going to burn a base line fuel rate. So whats a couple hundred extra watts??? 

Now, if we were tickling the peak of what the generator could output then cutting draw wherever we could would be important. Thats the point of my comment above that if the power goes out and this thing fires up we have no power outage - we have all the power we need with flying colors. I wasn't quite expecting that, in all honesty. I knew with a fair amount of certainty the AC loads would run on the unit, but I didn't expect to have as much head room. And I am judging "head room" based on the sound of the engine. The alternator will handle the power (the same alternator is on some units up to 18kw starting/15kw running) so the limiting factor is the HP of the engine, that or the circuit breaker. The engine held the loading fantastic and we never tripped the circuit breaker. 

I will be curious to do another load test to see what does give out first - the circuit breaker tripping or lugging the engine enough to approach stalling. 

Generator details:
Engine - Honda GX690 (RHVXE2)
Alternator - Mecc Alte S20F - 230/2
Fuel - Gasoline
Rated 15kw starting/13.5kw running


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## Browse Deweb (Jan 16, 2021)

Do you have a soft starter on the large AC? Have you tried the setup on any other fuels?


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## drmerdp (Apr 10, 2018)

> I will be curious to do another load test to see what does give out first - the circuit breaker tripping or lugging the engine enough to approach stalling.


Worse off nothing trips, the engine continues to maintain 3600, and the alternators voltage plummets. Damaging all sorts of things. 

That’s the case with my old champion 7000w. The alternator is the weak link on that unit. I only ever experienced it attempting to run the central AC but it caught be a bit by surprise.

Certainly not an apples to apples comparison, just throwing it out there.


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## FlyFisher (Jun 30, 2018)

Browse Deweb said:


> Do you have a soft starter on the large AC? Have you tried the setup on any other fuels?


No soft starts on either AC.

I am not sure what the whole house AC specs are off-hand, just that its on a 40a breaker.

I have run the generator on propane and natural gas, not with the whole house load yet, though. I am working on getting a better gas access for the generators - with a valve right up close to the gas meter (swapping the 1st elbow to a T with a valve on the additional port). Once that can happen I am hoping to have enough gas available to get the regulator to run correctly. 

With the natural gas port the grill runs off of I can only get the big generator to run with the primer button pushed in - bypassing the regulator. My assumption is there isn't enough gas flow to get the pressure behind the regulator for it to do what it needs to do how it needs to do it.


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## FlyFisher (Jun 30, 2018)

drmerdp said:


> Worse off nothing trips, the engine continues to maintain 3600, and the alternators voltage plummets. Damaging all sorts of things.


The alternator on my unit is capable of 15kw continuous. The unit I have is rated to 13.5kw continuous - 1500w under the rating on the alternator. So I have some head room in the capacity of the alternator. That gets back to my point about the engine and circuit breaker being the next "weak link".

If the alternator were the "weak link" then an appropriately sized circuit breaker should be installed so the breaker trips before the load gets to the point of damaging the alternator. In this case - the engine would have the power to run the alternator harder than the alternator can go, so the breaker would have to be the "weak link" to protect the system. 

If I can drive a load hard enough to break the 50 amp breaker on the generator then the next question is if I up the breaker size to 55 or 60 amps do I start stalling the engine? I'm not to the point of wanting to necessarily try that yet - from what I've seen thus far I have plenty of power through the 50 amp breakers. If I add a microwave load with the 2x AC units running then I might get closer to popping the breaker. We'll see. 

The largest current draw of anything I have right now is a transformer welder (old round top Idealarc 250 AC/DC). I am sure I could get the 50a breaker to go with it cranked up. It will put out 300 amps weld power, I think the most I've run is around 275 amps which blew the 50a circuit. If the voltage/frequency tanks under that heavy load the welder won't care - theres nothing sensitive in there. One of my many jokes with it is if the world blew up the only 2 things left would be cockroaches and transformer welders.

I can try monitoring the frequency and voltage and see how that compares to the lugging sound of the engine as its being loaded to see what happens.


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## drmerdp (Apr 10, 2018)

FlyFisher said:


> No soft starts on either AC.
> 
> I am not sure what the whole house AC specs are off-hand, just that its on a 40a breaker.
> 
> ...


Im a big proponent of soft start units. Even though your big generator is up to the task without it, It would reduce the stain on the generator, and the compressor alike.

Certainly seems you do not have enough volume of gas at the grill port. Grill gas lines are usually sized to only about 30,000btu.


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## Browse Deweb (Jan 16, 2021)

drmerdp said:


> Im a big proponent of soft start units. Even though your big generator is up to the task without it, It would reduce the stain on the generator, and the compressor alike.


100% agree.


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## Bursident (9 mo ago)

The electric power unit is a very necessary thing for a house indeed. I plan to build my own custom home and am currently looking for all the necessary equipment. I have already fulfilled several steps from the article about how to build a house. I know what I need to do next, and the only problem is finding cheap materials. I need cheap wood and cheap sand. Do you know where I can get that in Maryland? I really need these materials to continue my project. Otherwise, I will have to freeze it because I don’t have much money. Thank you for the suggestions!


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