What size generator

[zeke08]

What size generator would you use for back-up power and why? Would you use a diesel or gas? Would you hard wire it into your box or use extension cords? If you were worried about SHTF and have a underground shelter would you place the generator underground where its secure an plumb the exhaust topside? What other than freezer what is considered a must for running off the generator if power is lost? Thanks in advance

[PowPow]

My generator is a portable 5 kW (240 volt 20 amp) from Home Depot or Lowes and is more for post storm, rather than post apocalypse.
Based on the previous generator I had, the important features were large gas tank and large muffler(low noise).  
This powers a breaker box that includes all 120 volt devices and plugs in my house, which includes 2 friges and a freezer (1/4 hp random start each), and a gas furnace blower wired to run conitinuously on low speed.
It will also run a temporary 5000 BTU window unit in our bedroom end of the house, instead of the furnace, if need be; it uses a lot more gas, but its cheaper than sleeping at a hotel.
I do not run all the lights in my house in that situation, only task lighting.
We use the microwave and grill, in lieu of the 240 volt stove/oven.
Washer is 120, dryer is 240 so we hang dry.
We have used it for as long as 5 days, at about 5-7 gallons per day w/o a/c.

Our house had a 240 volt breaker box that fed a 120 volt subpanel, so I put a manual double pole switch with a 30 amp extension cord on the 120 box. Powers goes out, roll the generator outside, start it, plug the cord in, throw the switch.

I have no plan for an underground shelter, but if I did, I would not have a generator in the occupied space.
I don't think its possible to fully seal off all possible CO leak points.
Every electrical device in the space would need to be explosion-proof.
Also the noise would run you out of there.


 

[guzzijohn]

You really have to figure out what you would have to and/or want to power with the generator and then look up the watts rating on each item. Also remember many items draw more power when first starting up, that rating is what you need to go by. Do a trial run and see how things work. For example, for some unknown reason my microwave only operates at about half power even if it is the only thing online. Better quality generators will be quieter, hold more fuel and vary the rpm according to load instead of running wide open all the time. It is worth the money to have a double throw switch installed so you can plug into that and not have to hassle with cords, etc. They do use a lot of fuel.

[Bigeasy]

I am by no means a generator expert, having had only small, portable ones for use on camping / hunting trips, and to power my floor freezer full of wild game during power outages, but one thing I might consider is a propane powered generator.  Depending on how its stored, gas and diesel can go bad in time, and jugs of gas can be dangerous.  I would think large cylinders of propane would be easier to store, and be more long term stable.  I have a cabin that is totally propane powered - lights, fridge / freezer, stove, and heat; and it works well.  Having a duel power system in your shelter - propane and elec. might be a good idea.

Larry

[powderman]

We've had several outages lasting a week. my main concern is my freezer, we can get by without anything else. If all I ran was just my freezer how big a genny would I need??? I'd probably only run it an hour or 2 a day to keep things from spoiling. POWDERMAN. 

[Pat/Rick]

http://www.kohlerpower.com/residential/solutions/sizingcalculator.htm?sectionNumber=13561&nodeNumber=1&contentNumber=103#

I am electrically challenged at best. This should give a good place to start. I have two BIL's that are electricians so i have a nasty habit of relying on them. Good luck!

[PowPow]

...If all I ran was just my freezer how big a genny would I need???...

That Kohler link is for summing up a lot of loads for a whole house generator; looks like thier smallest is 8500 Watts (8.5 kW).

Freezer is only about a 500 watts, so a 1200 Watt or 1800 Watt generator will be plenty, but you will spend about $ 500 anyway, so consider getting a 5000 Watt (5 kW) and running some other stuff. Its nice to have some lights, a microwave, and the TV on.

Gas vs propane - I like gasoline because they sell it at most beer stations. I don't store it. When the power goes out, I go buy 5 or 10 gals. If I don't use it, I dump in in the car. Only concern of an impending snow or ice storm would cause me to buy in advance. When the conern passed, I would dump it in the car.

[charles p]

I live on the outer banks of NC - hurricane central.  My first generater was a small 2500 watt model that powered a lot of stuff.  I was surprised.  My next is a 2 cylinder Honda at 12KW.  It will power my entire house if I only run one AC unit at a time.  It is loud and burns a lot of fuel.  Puts out a lot of heat also.  Propane is an option and you can even get a tri-fuel model (gas, natural gas, or propane). 

I have a 220V pigtail under a covered deck.  I roll my generator out of a workshop door and plug in the pigtail.  I have to go to my electric meter an throw two switches that disconnect the grid and connect the pigtail to my two 200 amp panels.  I also have a disconnect where the generator will operate.

I chose to use a generator that can be rolled into my shop and then rolled outside when needed.  I picked this setup because I live where salt air is a problem, and rust is a guarantee.  Generac makes a stationary model but it will rust out in no time at the coast.

My 95-yr old mother lives with me and I need a dependable energy source.  She needs the elevator to go between floors.
I usually keep about 20 gallons of ethanol free gasoline in the fall months (hurricane season).  After November, I pour it into my truck and consume all but about 5 gallons.  I also use Seafoam in my fuel and empty fuel tanks.

I have a

[FourBee]

My set-up was similar to charles p , but I up-graded it some.  It is an 8K gasoline (noisy) Generator.  I could use a little larger one.   Power was off for more than a week one winter.  It saved our frozen and  refrigerated foods, and kept the family comfortable.  Connection to the house is a pigtail to the Breaker Box ~ via ~ an all weather box at the house, and inside a Generator Transfer Box that breaks from the pole to Generator at the flip of a switch .  Got tired of rolling it back and forth to the Shop, so set up this trailer rig plus some extras.  Now I can hook it to my ATV or truck and take it to the field for maintenance on  farm equipment, corrals, etc.
  

[Lloyd Smale]

for most people that just need emergency power for a few days something like a 2500 watt generator is fine. Go any bigger and your just burning more gas for potential your not going to need. A generator like that will power your frige and freezer and water pump as long as your not going to expect them all to start at the same time. If its a long term thing you need to look at the wattage rating on everything you will need to run and add about 50 percent to that figure as startup amperage for a motor is much higher then running amperage. For a generator i would want to count on for long term use or a survial situation id look at a diesel. there alot cheaper to run and alot more flexable as to what you can use for fuel.

[zeke08]

So freezer, lights (task), microwave 5000kw would be good. I have heard good things about how quite the Honda's are but do they last??

[FourBee]

zek08;  As long as you keep them up.  That is, once or twice a year start the motor, let it run wide open, hook up a power tool or light to operate the generator itself and let run for 15 minutes or so.   If the fuel is getting old go ahead and run it out or replace with fresh fuel.  Mine is 12 years old from Northern Tool.  It starts with a pull rope.  Takes one to two pulls and fires right up.  
4B

p.s. the 'Pig Tail' mentioned in my previous post is a 240 volt rig supplying the house Breaker Box.

[Drilling Man]

What size generator would you use for back-up power and why? Would you use a diesel or gas? Would you hard wire it into your box or use extension cords? If you were worried about SHTF and have a underground shelter would you place the generator underground where its secure an plumb the exhaust topside? What other than freezer what is considered a must for running off the generator if power is lost? Thanks in advance

  First of all, in a SHFT situation, you better have yourself in a lot better shape than needing a genset!  You better have dry and canned food storage, not be trying to keep freezers ect. alive with electricity.  You need to learn how to survive without everything electric,  cause sooner or later you WILL be without it, no matter if you have a genset or not.

  After having said that:  Over the years i've had many different gensets, and still have a few around.  BUT, i have two right now that are what i settled on as "keepers".

  First one is a Honda 2000 "inverter" genset.  I use it fairly often with a batt charger to start equipment.  To run an electric impact wrench and for other small jobs.  It will run my freezer or fridge for tempory power, and is quite useull to have around.  It's VERY quiet, and uses less fuel for it's output than any other generator i've owned.

  My second genset is a PTO powered one that i run with my diesel tractor.  That works out perfectly for me, as i don't have to keep an extra motor "fresh", i use my tractor regularly, so it's always ready to go.  Being diesel, it's the cheapest way to run a generator, and being a tractor it already has a large fuel tank, and can run longer times between oil changes.  Also, the tractor is VERY handy to have around for MANY other jobs.  At 15,000 continous watts, so it will run my whole house, or run my welder away from the shop.  It will easily run anything i will ever want to run, and i can use a small tractor to run it, to save on fuel cost.  Running it with a small tractor also means i just can't get more out of the generator than the smaller tractor has power to run, so for bigger loads, i have to run it with a bigger tractor.

  PTO generators cost less than buying a diesel genset, as the pto genset doesn't have a motor with it.  Also, a cheaper diesel genset won't be the quality of a pto generator either.  They also will power bigger loads for longer peroids without over heating, as they are made to run bigger heavy loads.

  As for storeing fuels, propane is the easiest to store, diesel is second, and auto gas is last.  It makes propane sound pretty good, but there are some negatives to a propane genset.  First off, you have to size the genset BIGGER when it's running on propane, so if it's a 5kw generator on gas, you won't get 5kw out of in on propane, and even less yet on natural gas.  If it's hooked to propane, it's not near as portable either.

  So, your best choise is to learn how to live on waaaaaaay less electricity.  Learn to can, dry and preserve foods, and how to collect water to use.

  For a generator for "temporary" use, but a SMALL Honda (not just Honda powered) genset, and use it to keep your fridge/freezer going.

  If you really want a long term genset, a good diesel genset is the way to go, but it's an EXPENSIVE way to go too!

  DM

[powderman]

I clicked on the link and marked freezer but it didn't give me any info. We have a coleman stove, plenty of non perishables, oil lamps, candles, kerosene, and a gas heat stove. Plenty of flashlights, and batteries and severa btty op radios. All I want to do is save my meat in the freezer. Will a 1200 watt be enough to start the unit??? POWDERMAN. 

[PowPow]

I clicked on the link and marked freezer but it didn't give me any info. We have a coleman stove, plenty of non perishables, oil lamps, candles, kerosene, and a gas heat stove. Plenty of flashlights, and batteries and severa btty op radios. All I want to do is save my meat in the freezer. Will a 1200 watt be enough to start the unit??? POWDERMAN.  

Here is what I got from it:

Your Power Requirements
Total Running Watts: 500 W
Total Starting Volt-Amps: 2000 VA
Home Square Footage: 0 Square Ft
Appliances:
Refrigerator   Significant use   500 W   2000 VA

Please consider the output of this program to be an approximation. As always, the best way to determine your specific power needs is to consult one of the local KOHLER Power Professionals. They will analyze the actual electrical load for your home, then specify and install the proper KOHLER residential backup system.

Here is a logic check:
A 1200 watt generator provides 10 amps at 120 volts.
See what the starting amps (LRA = lock rotor amps) on your freezer is. If it is 10 or less, you are good to go.
  

[Lloyd Smale]

Im a retired lineman and a few years before i retired we put power into a guys home that he had been powering with a 5000 watt honda. He told me that he ran it all day everyday. they shut it off when  they went to bed and started it in the morning. He said it had been used like that for 2 years and still ran like new and didnt burn a drop of oil. Im sure running it on propane helped as theres very little crap that gets in the oil when using propane. Its much cleaner burning then any other fuel but it does show you that there very reliable units.

So freezer, lights (task), microwave 5000kw would be good. I have heard good things about how quite the Honda's are but do they last??

[glock fan]

You are asking about two very different scenarios, in my mind, if I understand your post correctly.  If you're asking about backup power requirements for a storm outage, where normal grid power is likely to restored in hours or days, then a reliable 6500 watt generator using heavy duty extension cords and power surge protectors should be adequate to run your freezer and refrigerator.  You will likely have to unplug either or both temporarily to run other household items like lights or a coffee maker, toaster, microwave, PC, etc.  The most important household items, regardless of scenario, in my mind are; refrigerator, freezer, hot water heater, washer/dryer (dryer when conditions are very rainy or freezing cold), fans, room heaters, etc.  If you're looking @ a SHTF prolonged scenario then your backup system becomes your primary/solo system and must be much more robust.  I would go propane and with a Kohler or Generac household size generator.  They generally come with a protective housing to shield the unit from the weather.  Coupled with a bank of batteries, you could turn the generator off and use battery power @ night to power lights, fans, PCs, TVs/VCRs, etc.  Batteries coupled with solar or wind and set up for DC power is the most efficient type system for very basic SHTF needs.  DC appliances are generally more expensive than AC appliances.  However DC is a very effective venue for lights, fans, PCs, TVs, coffee makers, microwaves, etc.  Some people swear by DC refrigerators too.  If possible and especially if I was using propane to power my generator, I would get a gas dryer and water heater.  Of course if you had solar power, you could definitely use solar for your water heater.  Sorry for rambling here.  The good news is you have alot of options and you just need to decide, based on your climate, usage & budget what is best for you.  Good luck with your project!                   

[nhnef]

If you are really concerned about power outages I wouldn't buy a generator.  I really like the new whole house battery backup systems that are available.  They come on immediately, provide power for a couple of days and can be backed up with Solar.  Plus no gas fumes or refueling to do.  Remember gas generators can provide really ugly power, I've known quite a few locals that fried computers and TV's during the last ice storm.  At the very least consider a line conditioner.  The other benefit of a battery backup is that you can go off grid any time you want by just flipping the switch, when the batteries go low switch back and let your solar panels recharge the batteries.  Kind of pricey but a great combination in my opinion.


http://www.wholesalesolar.com/back-up-power.html

[FourBee]

nhnef; I like the idea of the battery back-up system, but the cost is so beyond reason for two outlets.  My Generator set-up has a Gen/Trans Switch set-up with 6 15amp reset fuses, and 6  (A thru F) FlipSwitch connections to the household system.  You can switch any single or all connections on or off at anytime. It has two (Watt Meters / Volt Meters) for monitoring the 6 electrical household systems, plus a 3way OFF GRID/ NEUTRAL/OFF GEN Switch .  You can turn on each A-F switch and  watch the voltage output   to make sure you're not overloading the generator.   Although I have a battery back-up for my PC, I've used generator power and stayed online for days with no side effects to the PC.  I'll have to stay with this type set-up until the solar and battery prices come down.

[nhnef]

Yeah, It is expensive but does have it's advantages as I don't think you need to be home for it to auto switch.  I know that some backup gen systems will also auto switch and fire themselves up, but those too are very expensive.  I used to manage a small factory in Tijuana, Mexico.  The power there was so unreliable and expensive we just used a 30kw Diesel gen set and ran the whole place with that.  Uninterrupted Power supply backup and line conditioners will help keep sensitive electronics safe so it sounds like you are all set.  This system really only works for folks who have nothing and are looking for a new system, plus it may be eligible for a 30% tax break, and you can use it to power the house and reduce your electric utility bills.  At least for a day a week.

 

[Drilling Man]

and you can use it to power the house and reduce your electric utility bills.  At least for a day a week.

  And, at $3 to $6.00 per hour for fuel to run it, we will really be lowering those utilities bills, won't we?   

  DM

[Winter Hawk]

I think he was referring to the battery system with solar chargers.

-WH-

[Drilling Man]

I think he was referring to the battery system with solar chargers.

-WH-

  OIC, on that note, the folks i know who are using batts and collectors tell me that isn't so cheap either, as the batts only last an average of 6 to 7 years, and the collectors about 15 years.  On top of that, two of them had lightening fry their controlers, and they had to buy all of that over.  Then, how about all that maintance they have?  Pretty much an PITA as far as i can tell.

  DM

[FourBee]

Winter Hawk is right.  
I don't expect to save anything with my rig but the food in my fridge and freezer, and have a little light to see by till my gasoline supply runs dry.     Living in this rural area for nearly 50 years, you can expect outages at anytime.  Although it is getting better than in the past.   We still have to contend with the wind, lightning, and ice damages.

[zeke08]

Great Ideas but here in TN they don't give you hardly any incentives for going green. TVA and the local power companies don't want lose there big profits. You only get a one time tax cut and its not very much and the power company will only pay 7 cents per kWh you put back in the grid. I checked on solar, for a system that produces 15-20 kw was 23,000 yeah cant afford it and wind is not an option here. So I was looking at generator's. Goes to show nothing is perfect lol

[efremtags]

Read up on incentives. Tax break federal is 30%, I would not consider that trivial.

Grid-sell back systems do not interface well without generators.

If you have a generator an the grid, there is little point in having a battery based solar system, it is cheaper to run the genset when needed.

A battery based system makes sense if off grid though, as you can run your genset a 1/4 of the time and get the same amount of energy from it,  extending the life of the genset.

[Lloyd Smale]

for long term use id look into a fuel cell. Our power company was pushing them for a while for isolated locations. I dont know if they ever sold a single one but what they are is basicaly a very small gas turbine that only need to be fueled once or twice a year and were supposidly reliable for up to 30 years with very little maintance. they werent cheap but were said to be the cheapest way available today factoring in initial cost and fuel costs and upkeep costs to provide constant power for the long haul.

[tacklebury]

Set your system up with a split manifold which has an alcohol carburetor on one side and gas on the other.  Then you can convert anything green/plant matter into alcohol and avoid a lot of the cost of fuel.  I saw a small solar alcohol still made from old windows which would produce about 3 gal. a day, so a larger setup would produce a good amount.  Another bio fuel often overlooked is Methane.  There was a gentleman who set up a methane production tank and filled tractor tire inner tubes to store the methane and then used a weight system sandwich with plywood top/bottom and a small winch to regulate the pressure it produced and ran his whole farm system with a pinto engine with it's carburetor set up to run methane.  The fuel can come from many sources if you're into researching the options.    A wood gas system would be another option if there is a surplus of wood in your area. 

[gypsyman]

DM, in your post number 12, you mention a genset that runs off the pto of your tractor. Could you give a name or manufacturer of what you have. My tractor has a pto that has 3 speeds,540rpm, 780 and I think 1100 rpm. I always wondered if I could make up a bracket to run a belt off it, and power a wood chipper,generator,etc., off it. PTO hp is 18. gypsyman

[Drilling Man]

DM, in your post number 12, you mention a genset that runs off the pto of your tractor. Could you give a name or manufacturer of what you have. My tractor has a pto that has 3 speeds,540rpm, 780 and I think 1100 rpm. I always wondered if I could make up a bracket to run a belt off it, and power a wood chipper,generator,etc., off it. PTO hp is 18. gypsyman

  Mines a Winpower, 15,000 continous 18,000 surge.  I run it with a small diesel tractor 99% of the time, as i'm not pulling much out of it.  When i have a big load like my shop, then i power it with a bigger diesel tractor.

  It takes very close to, two pto hp to make one thousand watts.  So, if your tractor has 20 pto hp, you can make 10,000 watts with it.  For "continous duty", you should never take more than 80% of your tractors max rated pto hp.  You must have a smaller tractor, as normally only the smaller ones have 3 speed pto's, and these days 1 or 2 speeds is normal.

  As for your idea to belt up the pto speed, yes you can do it, but it takes a huge pully to get the tool up to speed, and that's why pto powered tools have a small gear box to do that.  All the smaller pto gensets are made to run close to 3,600 and that's a long ways from 540 that all small/medium size tractors are rated at.

  As for you using one of your higher speeds on your tractors pto.  Keep in mind, as you use the higher pto speeds on your tractor, your pto hp goes DOWN.  So, you may have 20 pto hp using the 540 setting, but you will have less as you use the higher speeds.

  DM

  I wanted to [edit in], i just reread your post, and NOW i see that you said your tractor has 18 pto hp.