# How do emergency generators work? **URL:** \ **Category:** Factual Questions\ **Created:** [May 20, 2023, 10:17pm UTC](https://boards.straightdope.com/t/how-do-emergency-generators-work/984346 "2023-05-20T22:17:49Z")\ **Posts on this page:** 20\ **Page:** 3
**Author:** ![Jackmannii](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jackmannii/32/311_2.png) [@Jackmannii](https://boards.straightdope.com/u/Jackmannii)\ **Post date:** [May 21, 2023, 9:54pm UTC](https://boards.straightdope.com/t/how-do-emergency-generators-work/984346/41 "2023-05-21T21:54:39Z")
Transfer switches aren’t all that expensive compared to the price of the generator itself. For instance, Generac sells a 10kW generator without a transfer switch for $3,217. The corresponding model with transfer switch included is $3,797. ---
**Author:** ![MindsEye\_Watering](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mindseye_watering/32/3619_2.png) [@MindsEye\_Watering](https://boards.straightdope.com/u/MindsEye_Watering)\ **Post date:** [May 21, 2023, 10:49pm UTC](https://boards.straightdope.com/t/how-do-emergency-generators-work/984346/42 "2023-05-21T22:49:37Z")
Standby generators like the Kohlers or Generacs are a bit different from portable generators. They are way bigger and usually provide better quality and more stable power than portable generators. I looked hard at the 14kW to 20kW standbys but was put off by the high cost of installation and (at that time) the required service to keep the warranty in effect. You can use a portable generator as a standby by making some accommodations, but true standby generators are the “gold standard” for home emergency power. ---
**Author:** ![Thudlow\_Boink](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/thudlow_boink/32/320_2.png) [@Thudlow\_Boink](https://boards.straightdope.com/u/Thudlow_Boink)\ **Post date:** [May 21, 2023, 11:32pm UTC](https://boards.straightdope.com/t/how-do-emergency-generators-work/984346/43 "2023-05-21T23:32:06Z")
So, I’m reading the thread title and imagining a device for generating emergencies. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [May 21, 2023, 11:40pm UTC](https://boards.straightdope.com/t/how-do-emergency-generators-work/984346/44 "2023-05-21T23:40:19Z")
> [@Jackmannii](#): > > For instance, Generac sells a 10kW generator without a transfer switch for $3,217. The corresponding model with transfer switch included is $3,797. Is that an automatic transfer switch? Even if it is, $580 is awfully steep for a switch. ---
**Author:** ![MindsEye\_Watering](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mindseye_watering/32/3619_2.png) [@MindsEye\_Watering](https://boards.straightdope.com/u/MindsEye_Watering)\ **Post date:** [May 21, 2023, 11:47pm UTC](https://boards.straightdope.com/t/how-do-emergency-generators-work/984346/45 "2023-05-21T23:47:01Z")
> [@Chronos](#): > > $580 is awfully steep for a switch. It’s not just a simple switch. ---
**Author:** ![songsoflovetrouble](https://avatars.discourse-cdn.com/v4/letter/s/9dc877/32.png) [@songsoflovetrouble](https://boards.straightdope.com/u/songsoflovetrouble)\ **Post date:** [May 21, 2023, 11:57pm UTC](https://boards.straightdope.com/t/how-do-emergency-generators-work/984346/46 "2023-05-21T23:57:21Z")
> [@DPRK](#): > > If it does not automatically kick in (and function as intended), it is not much of an _emergency_ generator. “It’s 20 degrees out, my electric heating system is offline, and there’s too much snow on the ground to go somewhere warmer” is an emergency. “We need hot water to sterilize the baby bottles / we need to refrigerate someone’s medication / we need to keep a medical device running” is an emergency. All of these things can be done after 15 minutes of attaching and powering up the generator. They are emergencies, but they don’t require to-the-second kicking in of the generator. That function is, except in the most rare constructed scenarios, simply a convenience. ---
**Author:** ![DPRK](https://avatars.discourse-cdn.com/v4/letter/d/4491bb/32.png) [@DPRK](https://boards.straightdope.com/u/DPRK)\ **Post date:** [May 22, 2023, 12:24am UTC](https://boards.straightdope.com/t/how-do-emergency-generators-work/984346/47 "2023-05-22T00:24:47Z")
Fair enough. I have used those small gasoline-powered generators myself. You do need a canister of fuel ready to go. Electronic equipment that needs continuous power can and should be hooked up to an uninterruptible power supply, which should kick in instantly and is attached to or contains appropriately rated batteries. ---
**Author:** ![Francis\_Vaughan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/francis_vaughan/32/3093_2.png) [@Francis\_Vaughan](https://boards.straightdope.com/u/Francis_Vaughan)\ **Post date:** [May 22, 2023, 4:41am UTC](https://boards.straightdope.com/t/how-do-emergency-generators-work/984346/48 "2023-05-22T04:41:12Z")
> [@Chronos](#): > > Even if it is, $580 is awfully steep for a switch. This is a switch for which failure leads to lethal consequences for linesmen working on your power lines. Certification, testing, and liability insurance all get factored into that cost. The ability of the switch to operate reliably in the face of unexpected and unknown faults conditions is also going to factor into the price. A switch which welds itself closed because the line power came on at just the wrong moment isn’t great either. I can find you plenty of simple switches for use in aviation that cost much more and do much less. ---
**Author:** ![pullin](https://avatars.discourse-cdn.com/v4/letter/p/c57346/32.png) [@pullin](https://boards.straightdope.com/u/pullin)\ **Post date:** [May 22, 2023, 11:03am UTC](https://boards.straightdope.com/t/how-do-emergency-generators-work/984346/49 "2023-05-22T11:03:52Z")
> [@Thudlow\_Boink](#): > > So, I’m reading the thread title and imagining a device for generating emergencies. Such a device exists, and we’re all communicating on it now. [rimshot] As to the OPs question, I went through all this analysis and pricing a few years ago, following the Texas Deep Freeze. Our little backup generator was barely sufficient, and we discovered two old people shouldn’t be dragging a 200 lb. device out of the garage across an icy driveway to safely position it. We don’t have natural gas at our house, so all estimates included either a permanent propane tank or running a zillion feet of line from the nearest source. The best price we could find for automatic whole-house was over $15,000, so we punted. We bought a “portable” 12KW dual-fuel and got an electrician to install the necessary changes to our electrical system, including new circuits, transfer switch, and connectors. The word “portable” is in quotes, because it’s anything but. It took 3 of us to manhandle it onto a permanent covered base I built and it hasn’t budged since. We bought several 100 lb. propane tanks (which actually weigh 170 lbs!) and the necessary lines/regulators/connectors to run the generator. All this cost around $3000 (IIRC). We can manage for 2-3 weeks with the available fuel, as long as we use it sparingly. It can power one or two large appliances (dryer, oven) simultaneously, but not the whole house. It can run the main central A/C, but we retreat to a room with a window a/c to save fuel. As others have mentioned, we test it monthly by starting it and placing a small load on it for 10 minutes. Every 3 months we hook it up and actually switch the house over for a half-hour to ensure all’s well. ---
**Author:** ![cincinnatus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cincinnatus/32/7990_2.png) [@cincinnatus](https://boards.straightdope.com/u/cincinnatus)\ **Post date:** [May 22, 2023, 12:09pm UTC](https://boards.straightdope.com/t/how-do-emergency-generators-work/984346/50 "2023-05-22T12:09:18Z")
One of the best investments we made was having a very competent electrician install a 17 kilowatt automatic generator fueled from our existing propane tank. It starts weekly to test itself, and has never failed us. The automatic switchover has made our power company happy the several times linemen stopped in to check on our house being powered during a blackout. It runs the whole house easily, but we still are electrically conservative while it’s running. And we stand the annual expense to have the electrician show up for a routine service visit. Costs about $150 or $200 for an oil change, air filter and whatever else, and most importantly for him to test what electronics and magnetics that need looking after. I could do all this, but I want a pro handling it. The original package was about $8,000. We paid because during an outage we had no heat refrigeration or water. So nothing, including toilets, because we were on a well. Before that, I would haul out a 5 kw gasoline powered generator, and switch extension cords around to power what was the most imperative at the time. Wanna use the bathroom? Hang on, I’ll plug the well in. The electrician was very competent and personable. Since his demise one of his workers he trained fresh out of tech high school continues servicing our generator. ---
**Author:** ![Dewey\_Finn](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dewey_finn/32/4222_2.png) [@Dewey\_Finn](https://boards.straightdope.com/u/Dewey_Finn)\ **Post date:** [May 22, 2023, 1:09pm UTC](https://boards.straightdope.com/t/how-do-emergency-generators-work/984346/51 "2023-05-22T13:09:36Z")
Those of you with whole-house generators, do you get neighbors who want to stop by during a blackout to take a warm shower or cook their food? ---
**Author:** ![Mighty\_Mouse](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mighty_mouse/32/7776_2.png) [@Mighty\_Mouse](https://boards.straightdope.com/u/Mighty_Mouse)\ **Post date:** [May 22, 2023, 1:31pm UTC](https://boards.straightdope.com/t/how-do-emergency-generators-work/984346/52 "2023-05-22T13:31:51Z")
Well, we have a few families in our neighborhood with whole house generators who will host dinners every night the power is out. Other people will bring food there as well. We also open our house to anyone who needs a warm place to sleep. Our generator is portable, but it keeps the furnace, fridge and lights in the lower level going. We’ve had families “camping” in our basement during winter power outages during COVID when people were afraid to have close contact. And other times we’ve had families sleep over or hang out in our warm house. One thing about New England. People who don’t even like each other will help each other in the winter. There’s a recognition that a blizzard could put anyone in a precarious situation and your neighbors are the ones who will have to help because no one else can safely get to you. I’ve cleared driveways a few doors down for older neighbors. Teens will dig out cars for older people, pregnant wives of firefighters and policemen, etc. ---
**Author:** ![msmith537](https://avatars.discourse-cdn.com/v4/letter/m/d9b06d/32.png) [@msmith537](https://boards.straightdope.com/u/msmith537)\ **Post date:** [May 22, 2023, 7:35pm UTC](https://boards.straightdope.com/t/how-do-emergency-generators-work/984346/53 "2023-05-22T19:35:53Z")
> [@engineer\_comp\_geek](#): > > > [@msmith537](#): > > > > It’s not like I have to throw some big switch or anything. > > You are using “connected” in a different sense of the word. > > You still have a switch, but you have an automatic switch so that you don’t need to do anything. But when the generator automatically switches on, the main feed from the utility company is disconnected. > > So it is permanently connected in the sense that you don’t have to physically move any wires around. Everything is permanently wired in place. > > But it’s not permanently connected in the sense that that the generator and utility power are simultaneously connected electrically to your house. When your generator comes on, your automatic switch disconnects the feed from the power company and switches over to the generator. This is what @Chronos meant by it does this automatically. That makes sense. ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [May 22, 2023, 8:40pm UTC](https://boards.straightdope.com/t/how-do-emergency-generators-work/984346/54 "2023-05-22T20:40:26Z")
Having a simple automatic transfer switch requires you to have a generator with enough capacity to power your whole home, that will cost you more right there. A more complicated transfer switch can be used to activate a sub panel with limited circuits but that requires a bunch of electrical work to set up and wire a sub-panel, plus the switch costs more. So if you want an automatically activated generator that would power your home even when you aren’t there you will pay a lot more for it than for a portable. It’s not just initial costs either, you usually don’t need a permit for the portable generator, you will need several for a permanent. You’ll probably be required to bury the power line, the generator has to be located a specific distance from any door or window. The costs just keep mounting. ---
**Author:** ![MindsEye\_Watering](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mindseye_watering/32/3619_2.png) [@MindsEye\_Watering](https://boards.straightdope.com/u/MindsEye_Watering)\ **Post date:** [May 22, 2023, 8:48pm UTC](https://boards.straightdope.com/t/how-do-emergency-generators-work/984346/55 "2023-05-22T20:48:51Z")
> [@TriPolar](#): > > It’s not just initial costs either, you usually don’t need a permit for the portable generator, you will need several for a permanent. You’ll probably be required to bury the power line, the generator has to be located a specific distance from any door or window. The costs just keep mounting. Yup. I was told that whatever I pay for a standby generator, I would pay the same or more for installation. ---
**Author:** ![Hari\_Seldon](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hari_seldon/32/5173_2.png) [@Hari\_Seldon](https://boards.straightdope.com/u/Hari_Seldon)\ **Post date:** [May 22, 2023, 11:12pm UTC](https://boards.straightdope.com/t/how-do-emergency-generators-work/984346/56 "2023-05-22T23:12:23Z")
My son had a natural gas powered generator with an automatic transfer switch installed for about $10K. It powers everything except the oven and clothes drier (the two 220 appliances). One year we were there at Thanksgiving and getting ready to put the turkey in the oven when the power went out. The switch worked perfectly and my son fired up his gas barbecue to do the bird. The rest of the meal could be done on the gas cooktop, all except the pumpkin pie that had to be punted. He does invite the neighbors in if he has an extended interruption. ---
**Author:** ![GaryM](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/garym/32/241_2.png) [@GaryM](https://boards.straightdope.com/u/GaryM)\ **Post date:** [May 23, 2023, 3:42am UTC](https://boards.straightdope.com/t/how-do-emergency-generators-work/984346/57 "2023-05-23T03:42:42Z")
My situation is similar. Worth it. ---
**Author:** ![andrewm](https://avatars.discourse-cdn.com/v4/letter/a/c57346/32.png) [@andrewm](https://boards.straightdope.com/u/andrewm)\ **Post date:** [May 23, 2023, 1:55pm UTC](https://boards.straightdope.com/t/how-do-emergency-generators-work/984346/58 "2023-05-23T13:55:41Z")
> [@mixdenny](#): > > Since it only supplies 208 vac to the house instead of 240 vac I can’t use any 240 vac appliances but that is just the oven. FYI many 240V heating appliances are also rated to run on 208V, just at a lower wattage (due to Ohm’s law). Power delivery as two-of-three phases is common in NYC (and maybe some other locations) and manufacturers don’t make a special model for these cases. So if you really want to bake a cake or a pie during a power outage, you probably can. ---
**Author:** ![Uncommon\_Sense](https://avatars.discourse-cdn.com/v4/letter/u/f9ae1b/32.png) [@Uncommon\_Sense](https://boards.straightdope.com/u/Uncommon_Sense)\ **Post date:** [May 23, 2023, 2:10pm UTC](https://boards.straightdope.com/t/how-do-emergency-generators-work/984346/59 "2023-05-23T14:10:45Z")
> [@Crafter\_Man](#): > > I have a 3600 W Honda generator. It powers our house when the grid goes out, which is about twice a year. > > A long time ago I installed a 50 A receptacle near the garage door. I then built a “suicide cable” that plugs into the receptacle and generator. > > It works very well. > > I do not recommend this approach, for obvious reasons. > > Don’t do this, but it works very well for **me**. Of course, you turn off the mains when you do this. Otherwise you’d backfeed the utility. I also do this, except I run a suicide cord into the dryer outlet in the garage and backfeed the panel that way. ---
**Author:** ![Uncommon\_Sense](https://avatars.discourse-cdn.com/v4/letter/u/f9ae1b/32.png) [@Uncommon\_Sense](https://boards.straightdope.com/u/Uncommon_Sense)\ **Post date:** [May 23, 2023, 2:13pm UTC](https://boards.straightdope.com/t/how-do-emergency-generators-work/984346/60 "2023-05-23T14:13:07Z")
> [@MindsEye\_Watering](#): > > > [@TriPolar](#): > > > > It’s not just initial costs either, you usually don’t need a permit for the portable generator, you will need several for a permanent. You’ll probably be required to bury the power line, the generator has to be located a specific distance from any door or window. The costs just keep mounting. > > Yup. I was told that whatever I pay for a standby generator, I would pay the same or more for installation. Correct, as an electrician, I install them for customers. I would always recommend an automatic transfer switch for when you loose power and you aren’t home to manage things. So much more peace of mind. [Previous page](https://boards.straightdope.com/t/how-do-emergency-generators-work/984346.md?page=2) [Next page](https://boards.straightdope.com/t/how-do-emergency-generators-work/984346.md?page=4)