# Generators



## iceeyes (Jun 25, 2012)

I have no clue abt generators and am looking for one that will carry a load that includes 2 freezers and a fridge. I understand that they do not have be to plugged in at all times and to rotate if possible. Someone plz help! Thanks!


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## smaj100 (Oct 17, 2012)

If those are the only items you are running, your safest bet is to look on the back of each appliance and figure out how many amps it draws and startup amps each device has. If you take voltage x amps = watts since most generators are labeled power output in watts.

So if your freezer has a startup amp of 15, and is 120 volts then you would need 1800 watts surge. If you wanted a very small generator you could get by with running one item at a time or simply get a normal sized generator of 5000-8000 watts.

Hope that helps.


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## helicopter5472 (Feb 25, 2013)

I can give you a little info. The best type of generator is a "inverter" type. This produces a pure sine wave electrical power and is like your general grid power. All your items you plug in will last longer with this type of power. Stuff like your computer and TV and DVD player ect. really need this type of power. The draw back is these "inverter type" are more expensive. Next comes the choice of gas or diesel...Diesel last quite a bit longer than gas engines do but again more expensive. Then what size, To start with newer appliances are more energy efficient meaning they use less electricity. Each appliance has a tag usually showing that they are 60Hz and 120volt and how many amps they operate at. If you take the amps and multiply it by the volts (120) you will get the Watts needed to run your frig/freezer ie: 8.5 amp X 120= 1020 watts. Get all three items add them together this will give you the amount of running watts you will need. But these appliances when they first start up require a little more to get started. Most generators are rated this way. The generator will say 3000 watt but 2500 watt running voltage this way you have the 500 watt extra surge to start up the appliance. Rotating each appliance is OK but a pain to remember to change. It also gets costly to run a gen day and night. Your budget sort of dictates how much you can spend. To start with I would probably get a 3500 watt inverter type gas one. Other people here can throw in their two cents worth to help ya too. My system consists of batteries, inverters, generators, wind generator and hopefully soon solar panels, so the whole house runs day and night and the generator comes on only during the day (programmed). Hope this helps a little..Evan


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## mosquitomountainman (Jan 25, 2010)

smaj100 has good advice. Also be aware that you get what you pay for with generators. We've seen a lot of the cheap ones that won't begin to pull their rated amp/watt output.

Don't forget to store enough fuel and to properly treat it for long-term storage.


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## readytogo (Apr 6, 2013)

helicopter5472 has good advise, inverter generators are safe for electronics, more expensive, a good generator will work find but you have to include power surge, voltage drop for long extension cords if use. Total wattage of appliances divided by voltage will give you amps needed; generators have an amp rating, and please *ground the generator* if you calculated wattage, add a power surge percentage to it.


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## cowboyhermit (Nov 10, 2012)

helicopter5472 makes good points but I would like to clarify one point, regular (non inverter) generators output an ACTUAL true sine wave (thought there may be variations in frequency and voltage due to load etc.)
"True sine wave" inverters and inverter generators on the other hand do not actually produce a true sine wave (I know this sounds crazy but it's true) they produce a stepped sine wave that is much closer to perfect than a "modified sine wave". They may provide less frequency and voltage fluctuation than a regular generator though.


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## helicopter5472 (Feb 25, 2013)

Thanks everyone, I have learned more, I do know that I used to have a battery backup for my computer, it was plugged into normal grid, when the power went out it would take over for a short while. If I turn on the generator it would not recharge the backup and the unit would beep a different sound. I tried several different generators and 3 different brands of backups, all the same. I borrowed an inverter gen and that worked...Today I have several generators but they charge only the bank of batteries that power my "true sine wave" (maybe not so "True" as you said) set of inverters. I think by now we probably have confused Iceeyes


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## cowboyhermit (Nov 10, 2012)

I certainly hope I didn't add any confusion, inverter generators are great and often have "cleaner" power. This can be important for electronics in particular. For inductive loads like a fridge or freezer (anything with a motor) this is not so much of an issue, however the sine wave IS and a "modified sine wave" inverter is not the best.

In practice "sine wave" inverters work great, especially compared to "modified sine wave" inverters, which actually work adequately with most things anyways.
For running a fridge or freezer though, a regular generator should work fine as well.

One thing I have found helpful for people new to electronics is to come up with a few numbers that are easy to remember. For instance almost anything in North America that is designed to plug into a standard plug and is intended to run for significant periods of time will not exceed 1500watts. There are some exceptions but most people won't have them in their house, in fact if the draw is 1500 watts continuous then it often must be wired in or it may damage the plug.
The ways to calculate surge loads etc above that others already provided are more accurate but in most cases if you use the 1500 watts for each major appliance and round up you will be fine. For instance two freezers will run fine on a 3000 watt generator, for 3 a 5000 watt would be ok. 
Always start the generator with no load, run for a minute and then start turning on loads one by one.


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## readytogo (Apr 6, 2013)

*Tri-Fuel Generators HELP.*

Is very easy to install, if you have natural gas at home the generator can be attach to it, propane will last forever and fuel which is the must dangerous 
needs care.
http://www.priproducts.com/consumer_products.cfm 
*http://www.propanecarbs.com/*


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## farmers (Jul 28, 2012)

Have a 5000 watt generator, gas powered, very noisy, loud. We have a large propane tank. Is propane quieter? We have been looking to buy 2 more. What kind do we get? Have 3 large freezers 2 refrigerators. Clueless on what we are doing on generators.


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## cowboyhermit (Nov 10, 2012)

Propane is no quieter, they use the same motors as gasoline, though the compression may be tweaked a bit.
There is certainly variation from model to model though.
To get a significantly quieter generator at a certain wattage your options are pretty much some sort of enclosure and soundproofing (as part of the generator or added after the fact), or ideally imo a lower rpm generator. Low rpm diesel engines are great for a lot of reasons but noise is certainly one of them.
Another option would be to have a generator charge a battery bank and then run the fridges from inverters, this could cut the run time of the genset a lot. However, for 5 units that setup would be pricy.


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## farmers (Jul 28, 2012)

I forgot to mention I also have a well pump 3 HP to run. So diesel, which brands do you recommend. Thanks so much for your help.


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## cowboyhermit (Nov 10, 2012)

I am not really up on the brands, maybe Linctex or someone else will chime in. I know Onan has a good reputation but they don't come cheap.


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## labotomi (Feb 14, 2010)

I'll have to disagree with some of the statements here or at least what I think is being stated.

Generators are better than inverters in generating a sine wave. It's how rotational generators work. Inverter type generators are designed to try and reproduce this but that reproduction isn't always accurate.

The sine vs modified sine isn't as important as many will try to get you to believe. Small household motors can *potentially be damaged by a modified sine inverter. It shouldn't be an issue unless you buy a real cheap inverter *and* the motor is over 20 or 30 years old *and* the motor is located over 100ft (cable distance) from the inverter.
Insulation on newer motors is better in regard to capabilities as well as application techniques, cheap inverters use extremely low switching frequencies and longer cable lengths are a cause of impedance mismatch between the inverter and the load and this is the root cause of reflected waves.

If you want info on this, look up "reflected waves" of the electrical variety. You can also read about pulse width modulation which is the actual technology used for the modified sinewave inverters.

Another option if you still aren't comfortable is using an line inductor on the output of the inverter such as one of these.
http://www.clrwtr.com/TCI-Line-Reactors.htm

Contrary to what many say, most electronic equipment isn't going care if it's a modified sine or true sine wave because the incoming AC is converted to DC of varying voltages and possibly to AC again. The first conversion (from AC to DC) effectively nullifies any differences between modified and true sine waves.

I have to say this even though it's probably unlikely that anyone here would attempt to do this; 
If you have an inverter that allows you to adjust the frequency output (variable frequency drive) or a generator that you can adjust the speed... 
*DO NOT EVER RUN AN AC MOTOR AT A LOWER FREQUENCY INPUT THAN SPECIFIED*. I don't want to go into details, but halving the input frequency to a normal induction motor increases the heat generated by a factor of 4. 
Of course this comes with a disclaimer that if you have a variable frequency drive inverter capable of vector controls and have knowledge of what you're doing, this can be done safely but I can't think of a reason why anyone would want to do this in their home.


I also disagree on the statement to ground portable generators. Even the NEC states that portable generators are not to be grounded in most instances. Grounding a portable generator can potentially cause more danger. I once had a easy to understand document showing why. I'll try to find it and edit this later to include it if I can.

*Edit to add PDF showing potential dangers from grounding portable generators.*


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## LincTex (Apr 1, 2011)

farmers said:


> I forgot to mention I also have a well pump 3 HP to run. So diesel, which brands do you recommend. Thanks so much for your help.


The start-up current loads on that well pump are *very significant.* You will need something with a very high surge rating. You will need a heavy duty 12Kw or larger unit to handle that load or it'll trip the breaker, and that is if you have the generator near the well head. I have a Pramac 14,000-Watt gas generator with Honda GX630 engine and I seriously doubt it could handle your well.

If you need something that big, look into the 2-71 Detroit Diesel powered generators for the best bang for the buck, like these:

http://www.emerson2-71gm.com/

http://www.ebay.com/itm/USED-20-KW-...91593664?pt=BI_Generators&hash=item3a586c44c0

http://affordablepower.com/generators/12-5kw-and-20kw/

http://www.smokstak.com/forum/showthread.php?t=107661

Also, you can look for a diesel Kubota powered Onan generator from a motorhome. Very high quality.

http://www.practicalmachinist.com/vb/general-archive/ot-well-pump-generator-80749/

http://www.doityourself.com/forum/electrical-c-d-c/291934-emergency-generator-well-pump.html

http://www.smokstak.com/forum/showthread.php?t=72510


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## LincTex (Apr 1, 2011)

ANOTHER THING

"Portable Generators" only put max power out through the 240v plug, if it has one. The 120v outlets each only get *HALF* of the rated output!!

http://www.preparedsociety.com/forum/f16/your-6000-watt-gen-only-puts-out-3000-watts-11918/


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## labotomi (Feb 14, 2010)

LincTex said:


> ANOTHER THING
> 
> "Portable Generators" only put max power out through the 240v plug, if it has one. The 120v outlets each only get *HALF* of the rated output!!
> 
> http://www.preparedsociety.com/forum/f16/your-6000-watt-gen-only-puts-out-3000-watts-11918/


The 120v outlets get half the rated power *each*. The generator will still put out 3000W, just divided between the two outlet "pairs".


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## readytogo (Apr 6, 2013)

labotomi said:


> I'll have to disagree with some of the statements here or at least what I think is being stated.
> 
> Generators are better than inverters in generating a sine wave. It's how rotational generators work. Inverter type generators are designed to try and reproduce this but that reproduction isn't always accurate.
> 
> ...


Thus, rather than connect to a grounding
electrode system, such as a driven ground
rod, the generator's frame replaces the
grounding electrode.
If these conditions do not exist, then a
grounding electrode, such as a ground rod,
is required.OSHA
directs (29 CFR 1926.404(f)(3)(i)).


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## Tribal Warlord Thug (Jan 27, 2009)

or ya can just git a few of these.............
we have 4 (MEP016B) of 'em right now and we also have 1 gas powered 6500 watt unit.....ya cain't beat the lil' Yanmar diesels for longevity and reliability........they're also surprizingly quiet compared to the gas unit...


























hell.....if they're good e'nuff fer the .mil folkz..they be good e'nuff fer me.....


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## labotomi (Feb 14, 2010)

readytogo said:


> Thus, rather than connect to a grounding
> electrode system, such as a driven ground
> rod, the generator's frame replaces the
> grounding electrode.
> ...


Re-quoted:


> Even the NEC states that portable generators are not to be grounded *in most instances.*


What is the purpose of a connecting the frame of a generator to a ground rod if the generator is not internally grounded?


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## LincTex (Apr 1, 2011)

labotomi said:


> The 120v outlets get half the rated power *each*


Ummm.. I did say that.


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## labotomi (Feb 14, 2010)

LincTex said:


> Ummm.. I did say that.


Sorry. I wasn't meaning to sound like I was correcting your statement. I was emphasizing something that looked like it could get lost in the interpretation.


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