# Whole house generator



## curtis (Dec 24, 2015)

We just had a huge wind storm here and lost power for the first time in 5yrs. Problem is they said it will probably be a few days before the power is restored. I know it's too late now to get a generator hooked up to the house but I'd like to be ready for next time. I would like to get a stand by generator so that it will switch on automatically. My wife stays home with our daughter and I'm at work 10-12 hours a day. Having something automatic that she dosent have to do anything with would be ideal. Our house is about 1000sf and we have all appliances electric. Our heat is a garn 1500 running through a heat exchanger in the furnace that is fuel oil. We also have central air but having that run is not a priority. I tried to size one online and got sizes from 8kw to 20kw. Does anyone have an idea of how much I'd need and what brand to go with. I would probably have a propane tank brought in for fuel to run it.


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## jharkin (Dec 24, 2015)

For the cost of one of those permanent automatic standby setup you could go to a 4 star hotel during the next 200 outages.  I would think long and hard if its really worth it to spend 5 figures to protect against a once a decade issue.


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## BrotherBart (Dec 24, 2015)

Yeah after their first multi-day outage in twenty years one of the neighbors put in a whole house Generac and 500 gallon propane tank to the tune of twenty grand. It has been around six years and the only time it has been fired off is for regular upkeep runs. 

Get an interlock kit installed and buy a 8,500 or so watt gas generator with electric start. All she would have to do is plug in a cable, flip the interlock and push the start button. What my other neighbor did at the same time and only has had to watch under $2,000 worth sit there and do nothing.


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## claydogg84 (Dec 24, 2015)

BrotherBart said:


> Yeah after their first multi-day outage in twenty years one of the neighbors put in a whole house Generac and 500 gallon propane tank to the tune of twenty grand. It has been around six years and the only time it has been fired off is for regular upkeep runs.
> 
> Get an interlock kit installed and buy a 8,500 or so watt gas generator with electric start. All she would have to do is plug in a cable, flip the interlock and push the start button. What my other neighbor did at the same time and only has had to watch under $2,000 worth sit there and do nothing.



This is exactly what I did 8,500 Generac, a socket outside, and an interlock switch on the panel. I wheel it out to the deck when I need it, hit the electric start button and I'm off to the races. It's not rated for the high end electronics like your flat screen TVs, but it powers the whole place.


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## jharkin (Dec 24, 2015)

When our basement flooded that year we had record spring rains (10?)  I got a 3200 watt portable, wired in transfer switch to be able to power the pump, septic, fridge and a few key circuits.  I also got a large battery backup sump pump in case it went out while we are at work. All of that was under a grand.

We have not had an outage longer than 2 hours since, other than hurricane Sandy (that one was 10 hr).


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## BrotherBart (Dec 24, 2015)

Yeah. I got tired of hanging cords through a window for my 3200 watt genny and cut a hole in the wall and just ran 12 gauge cords into the laundry room and added a second 3200 watt to the genny shed. Then I put 825 amp hours of solar maintained batteries in the basement and five UPS units in the house. Now we have gone for the first three years without at least a 3 day outage in the 30 years that we have lived here.

But I love the 3200 watt gennys. They just sip gasoline. My 5,500 watt used to drink twice as much powering the same loads. If I need extra juice I just fire the second one as needed.


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## velvetfoot (Dec 24, 2015)

If you have a deep well, that can take a lot of juice.
I don't know about you guys, but when the power goes out, I kinda dread dragging out the 8kw generator and the not-light cordset and figuring out what to do if it's raining, etc.  If the mere purchase of a standby generator will stave off future outages, why not?


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## jatoxico (Dec 24, 2015)

I have a 5500 watt w/ a transfer switch that will run most of the house but it is LOUD. Keep wanting to get a Yamaha inverter/generator for running some lights, the frig, TV, fans etc. The low draw stuff that you want on for hours at a time. Their about as loud as a dishwasher and use about 1g of gas for 10hrs of run time.


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## BrotherBart (Dec 24, 2015)

velvetfoot said:


> I don't know about you guys, but when the power goes out, I kinda dread dragging out the 8kw generator and the not-light cordset and figuring out what to do if it's raining, etc.



My generator shed attached to the wood shed right behind the garage took care of that. Should have done it years ago.

And the battery bank and inverter means letting the sun come up before I have to mess with it.


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## jharkin (Dec 24, 2015)

The one time we had a long outage I only ran the generator for an hour or so twice a day.  Just long enough to make hot water for a shower, chill the fridge and recharge some flashlights.  Cooking via gas stove, heat from the woodstove.  The rest of the time we read books and used candles.   Fridge will keep cold for 12 hours or more between runs if you dont open it.

The only reason I would ever need to keep that genny running all day is if we had another basement flood even and the batter backup ran out.


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## BrotherBart (Dec 24, 2015)

I fire it at sunup and shutdown when I go to bed. Every October I buy 25 gallons of gas and what doesn't get used goes in the equipment or the truck over the Summer. Sure was expensive gas I burned this Summer compared to what I could have bought it for at the time.


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## HSBull (Dec 25, 2015)

My 8500 westinghouse runs 100% of what I need.  1000.00 well spent.


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## burnham (Dec 25, 2015)

It's hard to size a generator without knowing the actual loads being used in the house.  You can get a transfer switch that will cycle things on and off (like the AC) based on load, so you don't need to size the generator to handle 100% of  the load.  Probably get away with an 8-12KW generator.  

http://www.electricgeneratorsdirect.com/Images/Generac-RTSW200A3/i50712.html


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## Husky (Dec 25, 2015)

I've been using a 7.5K generator since 1999, buy for the Y2K scare that never happened. Looking back I am glad I have it. Used this generator in two different houses now. First house I was dependent on well water and had 3 kids under the age of 5. In the house I'm in now I have basement flooding problems if the sump is off for more than 30 minutes. I would never invest in a whole house standby unit unless I lost power very often. Most can get by with a portable and in my case I have a battery backup sump system that will run for about 6 hours in case I am not home when power is out. If I had the money to burn I guess I would do the standby for the convenience but the portable is easy enough and does the trick. I lose power about twice a year for around 3-6 hours. Once several years back I was out for 3 days but that has only happened once in 13 years.


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## Retired Guy (Dec 25, 2015)

We put in a 10K whole house standby NG generator a few years ago. Cost about 5K. Went the portable route for 20 years, keeping enough fresh gasoline around was a problem. 15 Gallons in the garage made me nervous. A 4 day outage in Feb. with temps on the 0 degree range was the deciding factor. Very happy with the unit.


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## xman23 (Dec 25, 2015)

A wood stove and a 2000 watt gas powered sine wave inverter runs the whole house. I to don't see why you need a high priced automatic generator for the rare long term power outage .


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## Seasoned Oak (Dec 25, 2015)

My wood stove is my emergency heat ,light and cookin appliance. I dont even bother with a generator. I could go quite a long time with just the wood stove and no power. I do have a small generator, that if it would start in an emergency is doubtful. So why bother.


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## firefighterjake (Dec 25, 2015)

Lost power For 14 days several years back in an Ice Storm ...,last year lost it for 3 days in the winter... a small portable generator meets our limited needs ... cooking on gas, heating with the woodstove and shower at work.


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## maple1 (Dec 25, 2015)

Have a 3500w inverter Genny here. Does all we need, sips gas. Our well pump is 120v.


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## rwhite (Dec 26, 2015)

curtis said:


> We just had a huge wind storm here and lost power for the first time in 5yrs. Problem is they said it will probably be a few days before the power is restored. I know it's too late now to get a generator hooked up to the house but I'd like to be ready for next time. I would like to get a stand by generator so that it will switch on automatically. My wife stays home with our daughter and I'm at work 10-12 hours a day. Having something automatic that she dosent have to do anything with would be ideal. Our house is about 1000sf and we have all appliances electric. Our heat is a garn 1500 running through a heat exchanger in the furnace that is fuel oil. We also have central air but having that run is not a priority. I tried to size one online and got sizes from 8kw to 20kw. Does anyone have an idea of how much I'd need and what brand to go with. I would probably have a propane tank brought in for fuel to run it.


Go out to your breaker box and determine which circuits you will absolutely need to run and add all the amps of those breakers up.  Multiply by 120. This will be the optimum size but may be cost prohibitive. For what is considered "whole house" you will want a generator that will power about a minimum of 20% of your panel rating, so for 200 amp service you will likely need at least a 40amp generator which is around a 10KW.


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## maple1 (Dec 26, 2015)

I think if most people looked at their power bill, and figured out their daily consumption from that, they would realize how much of an overkill a big genny is for emergency use.

Mine works out to 700 watts. Triple that to try to account for nightime low-use, that's 2100 watts. Right now looking at my energy monitor, we're using 600 watts. Only using what is necessary, one thing at a time (not unreasonable in a 'semi-emergency' outage situation), I get my well pump using the most. That's maybe 2000 watts. So I've got lots with 3500 watts.

As usual, personal preferences & priorities comes in sideways to this too though....


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## mass_burner (Dec 26, 2015)

Been using my Prius for the last few outages. 1500 watts covers fridge, and recharging my rolling battery bank with 2 70ah agm batteries. Gas cooking, but I have an indoor wood oven if needed.


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## Wooden Head (Dec 26, 2015)

Here is my list of things I run off my 120V, 300SI Honda Generator(quite).
2-Freezers
Refrigerator
CPAP (needed for sleeping)
2-Pellet Stoves
Ceiling fans
Lighting
Propane water heater
Propane stove/oven
2-TV's (news and weather reports)
Computer(power outage reports)
Telephones(no cell phone service)
These all run just fine on this generator. This generator gets about 12-14 hours on 1 tank of fuel(5 gallons)

To run other things, I need my Rigid 6500/8500 watt, 220V /120V generator(LOUD).
Well pump (showers, toilet, dish washing, drinking water)
Propane Forced air furnace (120 volt motor draws high amps)
Clothes Washer (same high amp draw)
Propane clothes dryer(same high amp draw)
Micro Wave
This generator gets about 7 hours on 7 gallons gas.
I run the Rigid for these and the go back to the Honda for runtime, fuel savings and quite.

Hope this helps.


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## sportbikerider78 (Dec 28, 2015)

For me, the only thing that has to stay running is the fridge and a few lights.  Woodstove for heat and we are all set.

I grab my little inverter/generator and put it on the deck and run an extension cord to the fridge about 20 ft away.  

Power outtages are intolerable w/o cold beer.


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## curtis (Dec 28, 2015)

claydogg84 said:


> This is exactly what I did 8,500 Generac, a socket outside, and an interlock switch on the panel. I wheel it out to the deck when I need it, hit the electric start button and I'm off to the races. It's not rated for the high end electronics like your flat screen TVs, but it powers the whole place.



Im going to look into that, I just didn't want to get a portable and then have a bunch of extension cords running through the house. But being able to just plug it in to a outside wall socket and turn breakers on from inside sounds like a good plan.


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## maple1 (Dec 28, 2015)

Keep remembering though that you were talking about a once-in-5-years event. I don't mind using a couple of cords a couple times a year. That's me though...


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## moey (Dec 28, 2015)

You should be fine with a 8kw standby system. Sounds like money is not a issue so by all means get the best. 

I have a 3500watt loud generator to power our well pump. And use a 2000w inverter to power 5 circuits in the house via a 120v transfer switch. Fridge some lighting and our pellet stove. Works well have to refuel about every 6 hours but uses minimal gas.


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## claydogg84 (Dec 29, 2015)

curtis said:


> Im going to look into that, I just didn't want to get a portable and then have a bunch of extension cords running through the house. But being able to just plug it in to a outside wall socket and turn breakers on from inside sounds like a good plan.



Me either. I wired the generator outlet in when I was renovating the downstairs (all new Sheetrock) so it was fairly easy. Also, with the interlock switch I can energize the entire panel and turn off certain stuff if I wanted to.


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## Highbeam (Dec 29, 2015)

claydogg84 said:


> Me either. I wired the generator outlet in when I was renovating the downstairs (all new Sheetrock) so it was fairly easy. Also, with the interlock switch I can energize the entire panel and turn off certain stuff if I wanted to.



I also took the opportunity to upgrade to an interlock panel from Siemens when I replaced my old Zinsco panel. I only use a 3500 watt 240 volt genset that will easily run 12 hours running my essentials. It's a champion power equipment generator and everything runs fine except the ceiling fan humms louder than usual so we shut it off.

I also own a 3000 watt inverter genset but those only make 120 volt power so it gets a little tricky to backfeed the whole panel. That's a problem with the interlock route, you need a 240 genset.


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## pen (Dec 29, 2015)

Lots of good advice.

I'll add, you need to have a keen sense of what you really need.  For example, I need a bit more than most since I have a well.  As such, I went with a 5500 watt portable unit, with a single hook up (as others mentioned) and it feeds a transfer switch box that gives my well the 220 volts it needs, and also feeds 4 other 110 volt circuits in the house that I chose.  These circuits feed each of the fridges and freezers, and I may need to move a few lamps around for light, but the things that need to run, will run.

For my parents, I could do similar for them, be they no longer have a septic and are hooked to a sewage system that unfortunately loses power the same as they do,,,,, in other words, by numbers he should need enough electric to run the well and grinder pump, but by reality he needs to poop in a bag now   Folks around him last power outage that didn't know better, had bad fluids flowing up in their yard as a result of thinking their power to their grinder pump meant things would move away from home.

In all, the first five years we lived in our house, we were without power for several hours a day, monthly,,,,, going 12 hours without power was basically a 2 to 3 time a year event.  Then, 4 years ago, we had a storm that put us out for days and I finally broke down and bought a generator.  Since, we haven't been without power for more than 2 hours in the worst of weather,,,,, simply because they did some tree trimming.

In all, it's good to be prepared, but unless you are disabled, or have a setup that somehow does not allow a portable unit to make ends meet on a minimal level, many people are going overboard with the whole house generators.

pen


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## firefighterjake (Dec 30, 2015)

pen said:


> . . .
> 
> In all, the first five years we lived in our house, we were without power for several hours a day, monthly,,,,, going 12 hours without power was basically a 2 to 3 time a year event.  Then, 4 years ago, we had a storm that put us out for days and I finally broke down and bought a generator.  Since, we haven't been without power for more than 2 hours in the worst of weather,,,,, simply because they did some tree trimming.
> 
> ...



Similar experience here . . . we would lose power for a few hours until the Ice Storm of 1998 hit . . . leaving us without power for 14 days (well technically leaving my wife without power for 14 days since I left to go to a two week training seminar at Day 7 or 8 I think it was).

That Summer the tree trimming crews came through and until recently we haven't been without power for more than maybe 3 hours . . . we did have a storm a while back though that did leave us without power for 3 days.


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## velvetfoot (Dec 30, 2015)

firefighterjake said:


> technically leaving my wife without power for 14 days


How did that work out? Did she mess with a portable generator?  I trained my wife on using the snow blower when I was laid up once, but....


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## firefighterjake (Dec 30, 2015)

velvetfoot said:


> How did that work out? Did she mess with a portable generator?  I trained my wife on using the snow blower when I was laid up once, but....



Oh it gets worse . . . on Day 2 or 3 I think it was we opted to go into town to eat . . . and in the dark she stumbled over the ATV plow I had left out, fell and ended up breaking her wrist so she was basically left one handed.

To answer your question . . . she did OK . . . she was able to start the generator (which we had hooked up to the oil boiler and a couple lights) one handed and with help from her daughter could refill it with gas. She's an incredible woman . . . my true soul mate.

These days we're in a much better place . . . having a woodstove is nice since we know we'll always have heat at least.


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## velvetfoot (Dec 30, 2015)

She sounds like a real trooper, to carry on one-armed like that!


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## firefighterjake (Dec 30, 2015)

velvetfoot said:


> She sounds like a real trooper, to carry on one-armed like that!



She also has to put up with me . . . and I can be difficult sometimes.


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## jebatty (Dec 31, 2015)

I'm like a few others who have come to understand how simple life can be and how little emergency electrical power is actually needed to cover a grid outage, even one lasting several days. Following a big windstorm in the early 1990's which left us without power in the heat of summer for 4 days, I obsessed over emergency electrical power, looked at gas, LP and diesel units, portable and whole house, etc. Then the common sense of my situation finally sunk in: what is really needed vs what is wanted during a long term or a short term outage, winter or summer. 

Heat: Since our primary heat is the wood stove in the living room, which can keep the house main level very comfortable and can keep the lower level basement walkout well above freezing, electricity for heat is not needed. AC too is not a real need, even in the heat of summer. 

Drinking water: the well pump is 220/240VAC, and well water can be a real need, although since we live on a lake, simple water purification filter systems can meet the need for drinking water. I've use those for camping for many years, and the ones available today are simple and inexpensive.

Other water: water for toilet flushing can come with a bucket full from the lake. The septic system is gravity, so need for electricity here either, although we have a lift pump for the walkout level bathroom but that does not need to be used in an emergency. Water for bathing or hot showers is a luxury, and the lake is available from late May through September, sometimes into October. Otherwise a pot of heated water and a sponge bath work just fine. It wasn't too long ago that the weekly bath was a reality, not a joke.

Cooking: with an otherwise all electric house, the cook-top and oven would not be available, but also not really needed. For camping we have a rocket stove, and a few sticks, summer or winter, will cook a large pot of anything, including heating water for that sponge bath. 

Lighting: when I think of camping, dawn and dusk mark the days. Up a little before sunrise and to bed after sunset. Very little lighting actually is needed in an emergency. But with LEDs available today, a lighting circuit with LEDs will easily be powered from a small generator if dawn to dusk is too burdensome.

Refrigerator/freezer: electricity for these probably is a necessity, but once again, today's units take very little electricity. This is where the small generator for LED lighting, and now refrigeration, is entirely adequate.

Telephone, DSL, cable box, computer, chargers for handheld smartphones/electronics: used conservatively, these all are minimal electric draw devices; small generator works here too.

Conclusion: live simply, have a small generator with a transfer switch to run refrigeration, lighting and electronics, and "enjoy" the adventure of a power outage.


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## jharkin (Dec 31, 2015)

jebatty said:


> I'm like a few others who have come to understand how simple life can be and how little emergency electrical power is actually needed to cover a grid outage, even one lasting several days.
> 
> Conclusion: live simply, have a small generator with a transfer switch to run refrigeration, lighting and electronics, and "enjoy" the adventure of a power outage.




+1 well said.


The primary reason I bought a generator is because we live in a 200 year old house with a leaky stone basement on a high water table.  The year we had those record march rains (was it '09 or '10 ?)  and got something like 10 inches of rain in a couple days at one point my sump pump was on continuously for 2 days (not cycling, just running) and the water was starting to inch out onto the basement floor.

I got the smallest generator that could handle the startup load of the sump after that - a 3200watt generac.  And a battery backup unit, in case the power ever went out during work, and to give me a secondary pump to handle that overflow load.

Mostly as a fun project I wired in a transfer switch so I can also use it to run the septic pump (needed if we had an outage over the 3 day standby  capacity of the pump tank) and a few other circuits like the kitchen (fridge) and boiler (for hot water).


We have the woodstove for heat.
You can open a window for cooling 
Water is city.
Kitchen stove is natgas... or if by some disaster that was shutoff there is the grill.
Cold food - well in winter you can put everything outside in a cooler, or just eat the perishables first.

Light... flashlights, candles, etc.  Many of the flashlights are rechargables and I have DC chargers.

Entertainment...  I have more books lying around than I'll likely ever read , and lots of board games for the kids.
If I really need to be online we can use tablets and I can power the wifi router off my DC powerbox with an inverter for a couple days, or just use the wifi hospot on the cellphone.  (A small deep cycle battery and a car USB charger can recharge phones and tablets for weeks)


In a real long outage and basement water was not an issue I figure I'd only need to run the generator about 2 hours a day - just long enough to cool down the fridge, recharge flashlights, make some hot water for showers and top off the couple deep cycle batteries I have around for the backup pump.  with the 10 gallon can in the garage we could go at least a week like that.

----

The ironic thing is, 50 years ago the sump well in the basement had a drain pipe that ran under the road and dumped to daylight on the down slope from us.  All gravity powered, no electricity required.  Along the way some land owner decided they didn't like that and the drain was cut and plugged, requiring an electric pump.  And the septic was just a gravity well too before thee last Title V required reconstruction with pump and raised drainfield.

Ahh, progress!


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## Easy Livin’ 3000 (Dec 31, 2015)

Good question, I have the same one.  We need to power the fridge, natural gas furnace circulating pump, well pump, and most importantly, the blower on the new wood insert. We bought the insert partially because we have frequent outages in winter in this part of the world- lots of trees overhanging the power lines.  We replaced all of the light bulbs with LEDs earlier this year (thanks PECO subsidy!)  in part to lower the load.  Other than the well pump, I'm sure a small generator would suffice.  Any suggestions about how to get the "juice" needed to start and run the well pump if we are using a small generator to run the rest of the small house?  I was imagining some sort of battery/inverter setup tied in.


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## velvetfoot (Dec 31, 2015)

ED 3000 said:


> Any suggestions about how to get the "juice" needed to start and run the well pump if we are using a small generator to run the rest of the small house?


2 generators?  That's what I do.  Run the big one once in a while for water.


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## Easy Livin’ 3000 (Dec 31, 2015)

velvetfoot said:


> 2 generators?  That's what I do.  Run the big one once in a while for water.


Thanks velvetfoot.  A neighbor gave us his old generator because it would not power his well pump.  This sounds like the answer- buy a small one new for constant power, and start the other one up for showers, etc.  How do you hook them both up?


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## jharkin (Dec 31, 2015)

velvetfoot said:


> 2 generators?  That's what I do.  Run the big one once in a while for water.



Agreed. An inverter large enough to take the startup load of a 240VAC well pump is going to be very large and expensive, and will require a big bank of deep cycles wired up on large gauge cables.


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## jharkin (Dec 31, 2015)

ED 3000 said:


> Thanks velvetfoot.  A neighbor gave us his old generator because it would not power his well pump.  This sounds like the answer- buy a small one new for constant power, and start the other one up for showers, etc.  How do you hook them both up?



That's the tricky part.  With 2 generators driving the same load they have to share the load and most importantly be timed so the AC waveform of both gensets are synchronized.  Honda and Yamaha make inverter gensets designed for paralleling, they have special cables and the electronics in each unit sync together properly.

I do not believe you can just connect two contractor grade gensets together to the same load without bad things happening.  Im no expert on this so some research or talking to an electrician may be in order.


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## maple1 (Dec 31, 2015)

Could you put the well pump on a plug & receptacle setup, then when you needed to genny the pump just unplug it from the receptacle & plug it into the genny? Maybe with an extra short cord in between. A dryer plug setup should work - or a range, think they're rated for more amps. Or a genny plug & receptacle.


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## velvetfoot (Dec 31, 2015)

ED 3000 said:


> Thanks velvetfoot.  A neighbor gave us his old generator because it would not power his well pump.  This sounds like the answer- buy a small one new for constant power, and start the other one up for showers, etc.  How do you hook them both up?


I have an generator interlock on my panel.  It powers both legs through two breakers.  I have a generator inlet on the outside of the house.  I plug the big 240v. generator into it.  I can also plug a 120v. generator into the same inlet.  I rigged up a plug for the 120v. generator such that it feeds both legs.  I also throw the breakers on any 240v. appliances.  That includes especially the well pump and electric water heater which come on when they want.  I'm not sure what would happen if both legs of a 240v. load were fed by one leg:  I'm thinking nothing would happen, but I don't know for sure, yet.


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## Highbeam (Dec 31, 2015)

maple1 said:


> Could you put the well pump on a plug & receptacle setup, then when you needed to genny the pump just unplug it from the receptacle & plug it into the genny? Maybe with an extra short cord in between. A dryer plug setup should work - or a range, think they're rated for more amps. Or a genny plug & receptacle.



That's what I would do. Not try and combine the power of the two gensets but to use the big guy when needed for the big load and only for the big load while the little genset hums along keeping the rest of your home working.

It is unfortunate that the inverter generator market has not provided 240 volt generators in the low wattages. You need to buy some god awful 6000 watt, 600#, electric start, 7000$ generator to get an inverter at 240. None exist at the 3000 watt level.

When you backfeed your entire house through a panel using an interlock you need 240 volts to power both sides of the panel. This means that no 120 volt circuit will have access to more than half of your genset output. So your 3000 watt genset just became a 1500 watt genset for each half of the panel. Then the voltage regulators of non-inverter gensets do some funny things when you heavily load only the one "phase" of the 240 output.

With some sneaky tricks I plan to backfeed both sides of my panel with my 120 volt inverter genset. Superior voltage regulation, clean power, and the ability for any combination of circuits to access the entire generator output. Just no 240 stuff will work.


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## velvetfoot (Dec 31, 2015)

Highbeam said:


> With some sneaky tricks I plan to backfeed both sides of my panel with my 120 volt inverter genset. Superior voltage regulation, clean power, and the ability for any combination of circuits to access the entire generator output. Just no 240 stuff will work.


See post above. 
And, what do you think will happen if a 240v device is turned on?  My theory is nothing.


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## Highbeam (Dec 31, 2015)

velvetfoot said:


> I have an generator interlock on my panel.  It powers both legs through two breakers.  I have a generator inlet on the outside of the house.  I plug the big 240v. generator into it.  I can also plug a 120v. generator into the same inlet.  I rigged up a plug for the 120v. generator such that it feeds both legs.  I also throw the breakers on any 240v. appliances.  That includes especially the well pump and electric water heater which come on when they want.  I'm not sure what would happen if both legs of a 240v. load were fed by one leg:  I'm thinking nothing would happen, but I don't know for sure, yet.



Great post velvet. Exactly the sneaky trickery that I spoke of and plan to do. Your interlock is supposed to feed your panel through a double pole (a 240 volt) breaker and NOT two single pole breakers. I have plans and a desire to built that rigged up plug for the 120v genset to feed both legs.

You have to consider the neutral wire size. Since you can feed both hot lines with 120 power and they are both expected to use only the single neutral line you need to limit your genset to what can pass through the single neutral which BTW is not protected by a breaker. My generator backfeed breaker is a 30 amp breaker and I used 10 gauge wire so I know that my max size 240 genset is (30*240=7200 watts) but my max sized 120 volt genset limited by the neutral is only (30x120=3600 watts). I can live with that but know that no breakers inside the house will trip if I were to exceed 3600.

The thing about 240 appliances is that some use a little 120 volt power to run the electronics. You are wise to just throw every 240 breaker while using the cheater 120 volt cord.


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## Highbeam (Dec 31, 2015)

velvetfoot said:


> And, what do you think will happen if a 240v device is turned on? My theory is nothing.



I'm not going to risk it. With the floating neutral issue things get very complicated. I powered my Lincoln 240 volt stick welder with a genset once. The genset puts out 240 volts through the 4 wire plug but the Lincoln only needed a three wire input so I made a cheater cord. Depending on whether I combined the ground and neutral, used just the neutral, or used just the ground, the cooling fan on the Lincoln would work or it would not work.

So appliances don't always act like you'd think. They are too expensive to risk leaving energized with that unexpected power of inphase 120. I know I won't be using the 240 appliance anyway and it is easy to flip breakers.


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## Highbeam (Dec 31, 2015)

Highbeam said:


> I'm not going to risk it. With the floating neutral issue things get very complicated. I powered my Lincoln 240 volt stick welder with a genset once. The genset puts out 240 volts through the 4 wire plug but the Lincoln only needed a three wire input so I made a cheater cord. Depending on whether I combined the ground and neutral, used just the neutral, or used just the ground, the cooling fan on the Lincoln would work or it would not work.
> 
> So appliances don't always act like you'd think. They are too expensive to risk leaving energized with that unexpected power of inphase 120. I know I won't be using the 240 appliance anyway and it is easy to flip breakers.



Been thinking about this some more. If you have a 10 gauge neutral it will burst into flames at 30 amps. No breaker protects it. If your genset makes over 3o amps of 120 volt power, so over 3600 even on "surge", then don't do it. It is a bad idea. No breaker will protect you in the house and some gensets can run at over 100% of their rating. I get nervous.

My 2800 running/3100 watt peak inverter genset is safely below the 30 amp limit on the neutral so I feel okay doing it.

http://www.costco.com/Champion-2,80...RB-50-State-compliant).product.100139466.html


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## Wooden Head (Dec 31, 2015)

Just a couple of things to add to my earlier post.

Do not hook-up 2 generators at the same time unless the manufacturer make that option available.

Pick a generator that produces clean power. Otherwise you have the possibility of torching sensitive electronics/Computers, Televisions, pellet stove electronic boards, microwaves and audio equipment.

As I said earlier, I run a 240 volt Rigid for things that need 240 and devices that have large motors. I run a Honda 3000 invertor generator for 120 volt lower draw devices and gas savings.

I never have both hooked-up at the same time. My hook-up was recommended by my local electrician.
A 30 ft., 10 gauge RV cable with a 30 amp male connector on one end and a female connector on the other. Cut the cord 4ft. from the female end and wired to 2, 120 volt grounded connectors that will plug into the Honda. The remaining 26 ft. of cable with the male connector is wired into 2, 30 amp breakers in the panel. The male connector when not in use is inserted an cable tied  in a plastic
junction box with a cover, so it can not be removed when not in use.
When you use 240 volt you plug the male connector into the 240 outlet on the 240 generator. When using the 120 generator, you plug the 2, 120 connectors into the 120 generator and the female 240  female receptacle into the 240 male plug.

I would recommend Contacting a Qualified Electrician for advice for connections for your generators and panel.


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## Dieselhead (Dec 31, 2015)

I have a 10kw propane generac for about 5 years now, real convenient. I did the deal with the portable generator and extension cords at first, then put in a back feed circuit, finally bit the bullet and put in the real deal. Glad I did, after 10 sec no muss no fuss it transfers on its own and takes care of business. I paid around 2900 and self installed it other then the gas line my buddy did that off our existing line from 500g inground tank.


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