Emergency Preparedness

[williatw]

When the feces hit the rotary impeller I don't see central AC as the highest priority.

You may have a point hanelyp half a loaf is better than none to be sure. But suppose during a killer >100F degree heat wave in Ohio (admittedly rare), main power goes down for whatever reason and stays down for days? I suppose I could go with the cheaper more affordable portable generator, and augment with a wall unit AC (or two). Probably still for far less than than $2900 plus installation the 11KW standbye generators cost.

[ladajo]

The problem with high starting current loads like AC, fridge, freezer, pumps is when they cycle simultaneously. Even if just two go off at the same time on a 15 or 20 amp (especially aged breakers), it can be enough to trip it.
It is good policy to separate them to different circuits.

For example, I own a house in VA that I had to run a dedicated feed for the well pump. When it cycled with the freezer or garage door opener, that was sometimes enough to trip the feed.

If you really think you will want one or two window unit backups, then think about another small generator, just to run them. Or look at the start load for youtr central AC, and you may find you can run it on its own small generator. It is the kick that normally causes the problems, not the steady state.

I think option two is your best bet. You can read the starting current right off the AC motor lable plate. Then decide about a small dedicated gen for it. I bet that will still be way cheaper than the super whamidyne, and you will use less fuel when you do run it. Plus, for those majority periods that you won't, you will have a back up gen for your gen. Not a bad trade, especially when you consider it will save you probably $2K and meter out fuel usage better during crisis.

[JoeP]

With my 5KW portable gen, I've been able to run a small AC window unit along with the furnace, fans, water pump, and fridge. The small AC cools down one medium sized room where my family was able to go cool off and hang out. I still view AC as a luxury and not something you need, unless you are very old, and/or live in the desert. Some old folks cannot tolerate broiling heat well.

Running a full central air system is not really "emergency preparedness." I view that as more a luxury. If you can afford it, it is good. A couple of my neighbors have such systems and they also have a large tank of propane which will run the system for many days.

[ladajo]

Here is a for example;
Unit...BTU.....HP...Run kVA...Start Amps (Locked Rotor)...Start kVA(30% Sag)
2 ton..24,000..2.......2.4.......... 67.................................. 7.9

This is a 240V Single phase unit.

Remember Power = Current x Voltage x Power Factor
(Standard commercial Pf is .

So your start surge on this unit would be max 67amps at 240V.
Your run would be 10amps at 240V

10amps at 240V is 20amps at 120V

As an example, a 7K Gen will handle by design (30% sag) a 46amp start surge. This includes engineering margin.

So just to run this, you would need a 2500W generator.
To ensure the start cycle, you would probably need to go at least 1.5 if not 2 on the generator, so a 5K would probably handle it and they run typically $500.
You may find that your Central AC is an smaller unit, like a 1 Ton. In that case roughly halve your numbers. You could proably run it on a 3K gen. ($300ish).
It is also a trial & error thing. You may find that your AC unit has a hard or easy start cycle, and can get away with a 1.5 factor, or may need a 3 factor. The rule is the smaller the compressor HP, the easier the start surge. It is not linear. However, it also plays with compressors in particular, that smaller HP (start torque) units are cut closer on the design margin, and typically have lower, but longer duration start surges.

In any event, I think you may find that you can set up a second portable to soley run the house AC if need be. And otherwise it is your spare gen & can be used for camping and stuff as well...and this is going to be much cheaper than buying the super whamidyne all in one.

I also agree that AC is not a primary must for emergency. It is a comfort, unless Gramma ain't gonna make it. But then if she is that fragile, how long is she gonna make it anyways? Just sayin.

I think your best option is to either go without the AC, or get a second gen to run it when you need it.

[GIThruster]

Since you have fireplaces, you don't need to be concerned with heating. That's good because a camp stove will not cause enough draft for you to make use of the chimney. Should you really need to use a camp stove indoors over more than an hour or two, you should vent the room. Many fireplaces have vents that allow cold air in from outside when you open the damper so that you're not exhausting heated home air when you burn. Check to see if you have such an inlet and use it with the camp stove if necessary, but still be sure to vent the room if you cook for extended periods. Any decent CO2 monitor will let you know if you need to so vent.

There is a lot of unnecessary silliness about generators. Most people don't need more than 2-2.5kW to run the necessities in the kitchen, and these run less than $100. A small, cheap, portable generator is enough. All you need to hook it up is to turn off the breaker for the circuit that runs the fridge, and plug the generator into the wall on the same circuit. Obviously you need an extension cord for this that is rated for the proper power, not longer than necessary and has two male connections. The generator MUST be outside. You can then periodically use the generator to power the fridge, the microwave, lights--anything on that circuit. I have done this for days and it is quite safe regardless of what folks will tell you. Be sure that you're not running the fridge and microwave at the same time with a small generator as that will draw more than 2 kW. In general, if you power the fridge for a few minutes each hour and limit access to it, you can stop food spoilage for days this way. The only significant risks concern how you vent the exhaust from the generator, and refueling. Be careful the exhaust does not enter your house, and do not refill it when the exhaust is hot. Wait until you are about to start it up and it is cool, and if you spill gas, wait until it evaporates for operation.

[ladajo]

I agree with GIT, you can do it that way. If you go to a slightly larger unit, like the 3K-4K generator, then you can run stuff together and let it go. It is really a question of labor requirement verses fuel savings. I find that my 3K is just fine to let run. It does not use so much gas for idle loads, and is big enough to cycle the heavy start cycles like the fridge and freezer. I actually run two fridges and one freezer plus hotel loads off mine no problem. I paid $225 for it on sale.

In the past I have run a house on a 1.5K by limiting load and cycles. That house had a fridge and freezer.

I keep two short cord male to male suicide plugs that I made with 12/3 and 25amp rated hospital grade plugs from Home Depot, and back feed my house via heavy duty (12/3) extension cords using these. You use the male to male at the source, it helps limit voltage droop heating.

[JoeP]

I keep two short cord male to male suicide plugs that I made with 12/3 and 25amp rated hospital grade plugs from Home Depot, and back feed my house via heavy duty (12/3) extension cords using these. You use the male to male at the source, it helps limit voltage droop heating.

Is this somehow going into your panel or are you plugging the suicide cords into outlets to power certain circuits? This works, but it is a bad idea on many levels, aside from the obvious electrocution risk. There will be no protection on that circuit for overload, could cause a fire. Plus, if you forget to cut the mains you back feed more than your house. Could kill someone. Legal troubles too. Spend a little money on a sub-panel, transfer switch, or even cheap interlock, or use regular extension cords.

This guy put in a simple interlock -- pretty easy -- probably less than $100.
http://www.youtube.com/watch?v=GbtRxcb-cmA

[GIThruster]

That's an interesting vid and to be sure, it is safer than what I was suggesting. I would note too, that if you really want to go much past 2kW, you can't use the wall lines the way I was suggesting, because they're normally only rated for 20A. he ran an expensive line in addition to the interlock, and that is not cheap. Likewise, I doubt what he did is legal, since although he can add the interlock without a license, he can't add the line.

[ladajo]

I keep two short cord male to male suicide plugs that I made with 12/3 and 25amp rated hospital grade plugs from Home Depot, and back feed my house via heavy duty (12/3) extension cords using these. You use the male to male at the source, it helps limit voltage droop heating.

Is this somehow going into your panel or are you plugging the suicide cords into outlets to power certain circuits? This works, but it is a bad idea on many levels, aside from the obvious electrocution risk. There will be no protection on that circuit for overload, could cause a fire. Plus, if you forget to cut the mains you back feed more than your house. Could kill someone. Legal troubles too. Spend a little money on a sub-panel, transfer switch, or even cheap interlock, or use regular extension cords.

This guy put in a simple interlock -- pretty easy -- probably less than $100.
http://www.youtube.com/watch?v=GbtRxcb-cmA

I did not give the full long term run proceedure. But here it is, and again, if you don't know what I am talking about here, then DO NOT TRY IT;

I cut the main, isolating the house.
I have the wife and kids go around and turn off any lights they remember being on.
I jumper the busses with 10 wire. Turns the panel into a joined single phase distribution, vice a 2 phase feed. This takes about 5 minutes total, start to finish.

I then plug one cord into a circuit for the house. This does two things. One is the load on the circuit I use is minimal, and allows the panel breaker to act as protection for everything on the other side of it, in addtion to the breaker on the generator itself.

The other cord is connected to the garage fridge and freezer via a power strip.

The suicide adapters are connected one to each cord.

I spinup the generator.Set the output breaker to off.

Plug in the garage feeder. Flip the breaker. Sometimes one of the garage loads will start cycle at this point, and I let it. After this, I plug in the house feed.

At this point all is up and running, and family can use lights/tv as needed.

If you do not want to power the whole house, then you figure out which side of your panel your fridge is on, and find an outlet on that side you can backfeed. Then the panel jumper is not needed, you get your fridge, and half your house.

Generator dependant, ie. how the winding is tapped to the output plug, you can feed each buss bar independantly and get a "240V" 3 phase feed again without the jumper. To do this you need to hook the generator ground to the house stake.

The right answer is as you (and I previously) have said. Get a generator with a dedicated 3 phase output, have a three phase connector added to your panel via a load matched breaker with mains disconnect interlock for your generator. Connect the generator via a dedicated purpose duly rated cord and have at it.

I just have not gotten around to putting the box and interlock on my panel yet. So I backfeed. My choice alone, and completely not recommended for anyone who does not not what they are doing.

[JoeP]

ladajo, another thing to keep in mind is your homeowners insurance will likely be voided should you be unlucky enough to have an accident or fire related to the way you are backfeeding.

You know what you are doing, and it works so long as nothing is forgotten or changed by someone else. For example, another reason why I would not do this. Suppose I leave the house unexpectedly, or fall unconscious or something. I would not want my wife, kids, or friendly neighbor attempting to revert everything. I could see them accidentally throwing the main breaker back on before shutting down and decoupling the generator connections.

[JoeP]

That's an interesting vid and to be sure, it is safer than what I was suggesting. I would note too, that if you really want to go much past 2kW, you can't use the wall lines the way I was suggesting, because they're normally only rated for 20A. he ran an expensive line in addition to the interlock, and that is not cheap. Likewise, I doubt what he did is legal, since although he can add the interlock without a license, he can't add the line.

This is why I choose to have an licensed electrician do it all at my home. I've got a 30amp line with an external twist-lock connection that the genset hooks into. That goes straight down into my basement and into the panel. There is a transfer switch that isolates select circuits for the generator and it is all up to code. Although in many areas, it is perfectly legal to do all the work yourself -- in some cases you might need an inspection when you are done.

[ladajo]

ladajo, another thing to keep in mind is your homeowners insurance will likely be voided should you be unlucky enough to have an accident or fire related to the way you are backfeeding.

You know what you are doing, and it works so long as nothing is forgotten or changed by someone else. For example, another reason why I would not do this. Suppose I leave the house unexpectedly, or fall unconscious or something. I would not want my wife, kids, or friendly neighbor attempting to revert everything. I could see them accidentally throwing the main breaker back on before shutting down and decoupling the generator connections.

Absolutely correct. In my case my I have taught my wife what to do. But it remains that in the event someone comes along and does not know, then there is risk.

One of the things I do is I leave the panel cover off when it is rigged. And my jumper is very bright colored and obviously does not belong.

Probably I should make a tag that I can hang on the main that says "DO NOT OPERATE UNLESS GENERATOR AND BUSS JUMPER ARE DISCONNECTED" or some such.

[GIThruster]

Like I said, all manner of silliness. If you're like us here outside Atlantic City which was ground zero for Sandy, we have a serious power outage maybe once or twice a decade. All you need to do is be able to run the fridge 10 minutes each hour and fire up the stove and/or microwave a couple times/day. For that, a 2kW portable plugged into the same circuit is enough. If you're not smart enough to shut off the mains, you're not smart enough to do this.

Now if you're pumping your own water, you have a different problem and need more power generation, but that's not what william asked about. I would note too, that gas will decay into a lacquer over time, so you have to run the generator every other season, as well as replace the gas periodically even when you don't use it, or it will not be usable when you need it. Some of the additives do slow decay available in an auto or lawn care store work okay (basically lacquer thinner), but you still need to run it just like you need to run your snowblower during the summer months. The dangerous additive is Xylene. It will eat rubber fuel lines and it burns too hot for most small IC engines, so do not use more than the recommended amount. Toluene is safer.

[ladajo]

Here on the island, we lose power several times a year. Sometimes for multiple days.