Generator/electrical question?

[ff347]

A friend would like to have a standby generator installed at his house, it would need to be a rather large generator as he wants the whole house to run on it. He has two 200 amp panels and because of the size and power needed would it be possible to run two generators with two stanby switches? On paper it is cheaper, reality says he is probably screwed though.

He has had a few estimates and they say he needs at the least a 20kw but because of the two panels the cost is evidently very high. It would seem that none of the electricians around really want to mess with it.

Is it possible?

Thanks

 

[HenryAZ]

I have an Onan 20kw standby. To give you an idea of capacity, the 20kw has a 90amp@240v breaker. I have the transfer wired to light up my whole 200 amp house panel, but I cannot run everything in there at one time off the genset. I can run one (of two) central AC units, all my refrig, lights, computers and so forth but no other big loads simultaneously.

Unless you are going to go a whole lot bigger than 20kw, you will need to decide what you want to run and size the genset(s) for that.

 

[Photoman]

I wonder why he would not just want to power enough circuits to get through what would be a transient situation? I have two 200 amp services and a 150 amp sub panel. I wired up a 20kw standby generator and basically power 1 panel. Even to do that I installed two 50 amp modules that can drop out heavy load circuits if the generator starts to get overloaded. (The two modules are the small boxes by the panel on the right) Also, I left out the electric kitchen range which is rated 17kw. So no stove in an emergency. BTW, the fuel source for the generator I have is either propane or natural gas and requires 300,000 btu's. Two generators that size would be 600,000 btu's. So plumbing and supplying that amount of fuel is another consideration. Transfer switch is box on the left. Picture is as I was wiring and not the finished product.
$.02

 

[ff347]

Appreciate the input, his goal is that a power outage would be a non-event on the household. I am thinking that he is going to have to scale back and have an area of the house (which is large) that they ride out the storm and pick a few important things.

 

[LAMBCRUSHER]

There is one that we installed...a v-10 powered liquid propane withdrawal 100KW ....it's enough to power your buddies situation, but the cost reflects his desires.....it was $52K plus over 5 years ago.....and burns more fuel at idle than your land cruiser at freeway speeds.....

 

[PAToyota]

Appreciate the input, his goal is that a power outage would be a non-event on the household.

That's nice, but it does come with a price. Last serious generator setup I was involved with was a municipal building. Obviously, with the police and fire and all they wanted to do as your friend wants - make loss of power a non-event. The question is whether your friend is willing to pay tens of thousands of dollars for something he's likely to use only hours (if that) a year?

Which really begs the question - how often does he lose power and for how long at a time? There are some more rural areas around here than can expect to lose power for a day or two a few times a year from either wind or snow. I'd do a dedicated generator with a transfer switch for the essentials if I faced that. Where I am in the twenty years that I've been here, other than one time I've only lost power for a few hours at a time. After that one time, I've sort of been considering a generator that I could run extension cords to the refrigerator, freezer, and furnace.

 

[HenryAZ]

The more you put into it, the less likely you will be to ever lose power again

 

[walther]

Hi Everyone,
I'm new to this site but I've tried to post a question relating to this topic, I hope someone can help me out.

Got a new generator for my mothers house and did a home brew of a connection.

used #10 wire (romex) typical locking 4 wire plugs and outlet. I connected a 2'ft piece from the panel to a free hanging outlet. conected the white and black to the main lugs in the panel and ground to the ground bar. The rest of the wire about 80' is generally a big extention cord plugged into the generator.

so, with that said we have so far: 80' #10
4 wire plugs and outlet THOUGH ONLY USED BLACK TO Y AND WHITE TO X ON THE PLUGS AND OUTLET with ground.

The Problem: fan on the furnace wont kick on and when I switched it to AC, breaker on generator tripped right away. Both generator/wire and plugs all rated for 30amps.

The main purpose of me doing this for her is so she can have heat and a/c is power goes out and here in Virginia beach, when the power goes out,,,its for days!

Any ideas??

Thanks

 

[KLF]

^^^ This sounds like a recipe for a disaster.

Please, hire an electrician, have this done correctly. Put in a proper transfer switch. How you gonna feel when the house burns down? You also need to think of the guys on the line down the road, you can possibly backfeed the mains out to the pole, and zap someone that is fixing things for you out on the street.

That's the best help I can give you.

 

[LAMBCRUSHER]

Hi Everyone,
I'm new to this site but I've tried to post a question relating to this topic, I hope someone can help me out.

Got a new generator for my mothers house and did a home brew of a connection.

used #10 wire (romex) typical locking 4 wire plugs and outlet. I connected a 2'ft piece from the panel to a free hanging outlet. conected the white and black to the main lugs in the panel and ground to the ground bar. The rest of the wire about 80' is generally a big extention cord plugged into the generator.

so, with that said we have so far: 80' #10
4 wire plugs and outlet THOUGH ONLY USED BLACK TO Y AND WHITE TO X ON THE PLUGS AND OUTLET with ground.

The Problem: fan on the furnace wont kick on and when I switched it to AC, breaker on generator tripped right away. Both generator/wire and plugs all rated for 30amps.

The main purpose of me doing this for her is so she can have heat and a/c is power goes out and here in Virginia beach, when the power goes out,,,its for days!

Any ideas??

Thanks

as stated, use a proper transfer switch. this can be done by installing a sub panel to feed the emergency circuits and it needs to have enough room to house a 2 pole main breaker, and a 2 pole back up input breaker. these 2 breakers will need to be mounted side by side and a mechanical interlock installed between them to keep either one in the off position when the other is ON. your generator feeder wires(you need 4-2 hots, a neutral and a ground from the genset. you will need to have a seperate grounding bus in the sub panel to keep all grounds and neutrals isolated. repower the fridge and heat circuits and a couple of light circuits to the sub panel. when the power goes out, you will start the genset, and then actuate the mechanical interlock between the sub main and back up input breakers to turn the sub main off and the back up input on. The way you describe things, it doesn't appear as tho you are running neutral from the gen to the loads. also not certain of your polarity, I know you said black to X and white to Y, but are they landed the same at the gen AND the panel side? again, you're not delivering a neutral to your loads. This type of mod to this type of system should not be done by yourself unless you have a COMMAND of the theory. as stated, fires are a result of faulty and incompetent wiring....not to say you can't do it yourself correctly, but please, do it correctly, and make certain your mom knows exactly how to use it. when done properly, it is inherently safe.

 

[LAMBCRUSHER]

also, your wire size needs to compare to your genset output amps...your # 10 romex with only 3 conductors in it is only capable of carrying up to 30 amps. I'd use stranded wire in conduit to a j box with the receptacle for the gensets plug and a weather proof box and cover and then a short piece of SO or SJWO cord with the correct number and size of conductors to carry the load just long enough to reach between the receptacle on the house/post/building and the genset.

 

[walther]

Lambcrusher,

Your absolutely correct and I certainly could do that but I'm not installing a back up system, just a "get me out of a pinch" situation and my mother wouldn't touch it anyway.

I figured out my problem anyway. The furnace didn't fire because the igniter happen to go at the same time. As for the A/C, My start up amperage is 72 amps and run is 18 amps and the generator is rated for 30.

Installing the sub panel is best as I know however the main panel needs to be changed anyhow but there are circumstances as to why I have not done that among other things.

I absolutely appreciate your response as suggesting to someone a way"around" something can be quite dangerous.

Many Thanks!!

 

[PAToyota]

What you have described stands the potential of backfeeding out of your house. That is not only a potential danger to yourself, but to other people outside of your house - neighbors, utility line workers, etc. This is definitely something that you DO NOT want to do half-assed.

 

[LAMBCRUSHER]

Lambcrusher,

Your absolutely correct and I certainly could do that but I'm not installing a back up system, just a "get me out of a pinch" situation and my mother wouldn't touch it anyway.

I figured out my problem anyway. The furnace didn't fire because the igniter happen to go at the same time. As for the A/C, My start up amperage is 72 amps and run is 18 amps and the generator is rated for 30.

Installing the sub panel is best as I know however the main panel needs to be changed anyhow but there are circumstances as to why I have not done that among other things.

I absolutely appreciate your response as suggesting to someone a way"around" something can be quite dangerous.

Many Thanks!!

with all due respect, I was telling a way to do it right, not recommending a way around. neglect in this area can kill PEOPLE. HTH

 

[Weedhopper]

FF, have your buddy find an outfit that specializes in generators. Companies are out there for commercial and residential. We just did a generator for my parents house. We found that electricians shy away from generators and they don't like to do the routine maintenance that a standby generator calls for.

He will need a big generator if he wants power failures to be a "non event" and he will probably be in the class of liquid cooled generator selection. Anything is doable with a large check book.

Best tip I can offer is "anything but a Generac" I saw 3 fail from catastrophic engine damage after the October snowstorm here in 2011 (Generac makes their own engines). Kohler (merged with Lennox) and Onan are two fine brands.

 

[john_eckels]

The startup wattage required for a central A/C unit is insane. You probably need around a 20 KW genset to get it going. This is just a guess. If you have electric hot water, well pump, etc. you will need even more. You can probably buy a cheap new car for the cost and installation of this kind of unit.

FF, have your buddy find an outfit that specializes in generators. Companies are out there for commercial and residential. We just did a generator for my parents house. We found that electricians shy away from generators and they don't like to do the routine maintenance that a standby generator calls for.

He will need a big generator if he wants power failures to be a "non event" and he will probably be in the class of liquid cooled generator selection. Anything is doable with a large check book.

Best tip I can offer is "anything but a Generac" I saw 3 fail from catastrophic engine damage after the October snowstorm here in 2011 (Generac makes their own engines). Kohler (merged with Lennox) and Onan are two fine brands.

 

[LAMBCRUSHER]

The startup wattage required for a central A/C unit is insane. You probably need around a 20 KW genset to get it going. This is just a guess. If you have electric hot water, well pump, etc. you will need even more. You can probably buy a cheap new car for the cost and installation of this kind of unit.

a brand new FJ cruiser....maybe only a couple of Kias if you did the work yourself

 

[Weedhopper]

The problem with standby's is that you never know when it will kick in. The house could be dark with everyone sleeping, or it could be a time when the heat is on, laundry is being done and dinner is being cooked with a full house of people using electricity. If the genset can't handle that massive startup things get fried quickly.

Around here the codes got changed and the genset has to be capable of starting everything on it's panel at once. Too many people were under sizing to save money.

Our guy told us that their smallest liquid cooled genset, installed is around 32K. A 16Kw Kohler is 14K installed, permits, transfer switch, hookup to natural gas, etc.

 

[ff347]

Well he is getting nowhere with answers locally but I appreciate all the help. I guess one of the biggest issues is the local generator installers seem to be sort of clueless because of the two panels and how things are wired between the two, and the electricians he has called want to rewire the panels. The pockets are deep but nobody seems to be able to either do the job or really want to.
Weedhopper you are right though if it's going to be a non-event you have to be able to pay for the possibility and with 3 heat pumps and all the other items.......