oldhorseman (oldhorseman) wrote,

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Low-Nonsense Doomsteading: Backup Generator.


   Some preppers dismiss the idea of generators.  After SHTF, fuel will run out, right?  A generator will be useless.

   But I think there is a high probability that modern civilization and Cornucopian infrastructure will stutter and grind to a halt over the course of years rather than stopping all at once.  During this time, the power grid will become unreliable, and fuel supplies may become erratic.  Being able to stockpile fuel when it's available and generate one's own electricity during outages could smooth-out the bumpy road of the collapse, at least for a while.

   (Of course we're big into non-electrical alternatives where they're practical, and solar/wind electrical generation for things electricity does best.  Covered elsewhere in this book.)

   The best approach to getting a generator is to buy a proper back-up system and have it professionally installed.  The things appear to be pretty awesome.  They look like an extra heat pump behind the house.  Start automatically during power failures.  Shut down when the grid is back up.  Even do maintenance runs and diagnostics by themselves.  Owner just checks the oil a couple times a year.

   Complete with a dedicated transfer panel, these generators are safe and code-compliant.

   But they are rather expensive.  Complex installation means that you may be dependent on the professionals if service is required in the future, and who knows if they will be available then?

   The deal-breaker for us was that these systems run on propane or natural gas.  And not just a barbecue bottle.  Since we don't have gas service here, setting it up just for the back-up generator was an excessive hassle and expense.
   (In retrospect, a gas home might be a pretty good way to go for a doomstead.  A big tank full could keep the appliances going quite a while, and only a small back-up generator system would be needed to go with it.)

   A popular approach to back-up electrical power is the gasoline-powered 'portable' generator.  These are widely available, reasonably affordable, and fairly simple to operate.   Of course, you have to wheel 'em out, start 'em manually, and plug things in yourself.  And they are obnoxiously loud.  But still: POWER during an extended blackout rocks!

   The 'proper' way to use a portable generator is to set it up outside the house (the gasoline engine exhaust can kill people with carbon monoxide in an enclosed area), then run extension cords from it directly to the appliances or devices you want to power.  This reduces the possibility of electrocution, fire, and damage to electronics and household wiring.

   But there are considerable safety hazards in doing it the 'right' way.  You're going to have to leave a door or window partially open to admit the extension cords, possibly letting out heat, letting in bugs, fumes, or worse.  There's also the possibility of the extension cords being damaged by accidental closing in the door or window, creating a shock and fire risk.

   Having extension cords running across the floor in a poorly-lit house is a tripping hazard.  The most important things you may need to power could be loaded refrigerators and freezers, which often have stuff stacked on top, and are recessed into the counters and cabinets with their short power cords behind them.  Trying to drag the blasted things out so as to plug them into the extension cord can easily result in injury from strain, having the icebox tip over onto a person, or gashing a hand or arm fishing around behind for the plug.

   Making matters worse, long extension cords don't play well with 120v heavy-load appliances.  You may find your generator breakers tripping every time the fridge cycles on.  And other things you may need to run, especially your well pump, may be 240v and/or hard-wired, so you can't just plug them into an extension cord.

   Wouldn't it be easier just to connect the generator to the household electrical system?
Please review the disclaimer at the start of the book.
We're heading into sketchy territory now.
Quick Primer On Household Electricity.

Voltage: There are two general voltage standards for US household electricity.  120v is used for lighting and common wall sockets to supply power for most devices and light appliances.  240v is used for heavier demand appliances like stoves, electric furnaces, water heaters, clothes dryers, and deep well pumps.

Amperage: The load on an electrical circuit (or maximum safe potential load) is measured in amps.  Increasing amperage tends to heat-up electrical components, especially wires.  So higher amp rated cables have to be thicker and heavier to avoid melting or burning under a full load.

Wattage: Watts are a measure of the actual power being applied in a circuit (or potential maximum power).  It's basically volts multiplied by amps.  So a 60w bulb puts a 0.5 amp load on a 120v circuit.  A 1200w hair dryer puts a 10 amp load on a 120v circuit.

Starting Loads: Electrical devices and appliances usually require a spike of power to get them started, then settle to their regular operating load.  Starting loads vary between devices.  Incandescent bulbs have a fairly low and brief starting load.  Fluorescent lights take considerably more.  Pretty much anything with an electric motor (fan, pump) will take a big, long gulp of electricity to get going.  Household electrical services are typically wired to handle far more power than normal consumers would usually need just to accommodate simultaneous starting loads that might occasionally occur.

Breakers: These are switches which automatically turn off (trip) when the amperage on a circuit exceeds the rated limit.  They are usually integrated into the household service panels and the generator as well.  Breakers are there to prevent dangerous overloads. Do not circumvent them.

The Four Wires: US standard 120/240v wiring use four wires.  Hot #1 (usually black), Hot #2 (usually red), Neutral (white), and Ground (usually green or bare).

   The Hots are opposite 'ends' of your 240v circuit.  Connect red and black an appliance to feed it 240v.

   Neutral taps from the center of that same circuit, putting it 120v from each of the Hots.  Connect black and white (or red and white) to a device to feed it 120v.

   Ground is just what it says on the tin.  The green or bare wire is ultimately connected to a rod driven into the earth to provide a harmless escape path for stray current in the system.  The Neutral wire is usually cross-connected with the Ground at the household main service panel as well as at your generator.  This means that, when a Neutral connection is needed, and there isn't one available, you can usually get away with connecting to the Ground wiring instead.
Connecting a Gasoline Generator to the Household Service.

   This will require a mid-sized (5000w) or larger generator with a 12/240v socket to be worthwhile.

The Suicide Cable.

   If you have a 240v receptacle that is easily accessible from outside the house (back porch or garage clothes dryer, workshop welder, RV shore power...  Make sure it's a 240v, not just a 30 amp 120v!), back-feeding generator power into the house through a Suicide Cable may be a practical solution.  But remember that these things deserve their name.  Screw up the Order Of Operations and you can earn a Darwin Award real quick.

   A Suicide Cable is a generator extension cord that has plugs at both ends.  Nobody manufactures these, so you have to make one for yourself.  Start with a heavy-duty extension cord that fits the 120/240v outlet on your generator.  (Most take a 30 amp, 4-blade twist-lock.  Bigger generators may also have a 50 amp, 4-prong push-in.  May as well go with the more powerful one if you have it.)  Get a replacement plug for whatever appliance would normally use the 240v household receptacle.  Take the socket end off your generator cable and replace it with the appliance plug.

   If your appliance plug has 4-prongs, you're in luck.  Just be sure to get each of the four wires in your generator cord connected to the correct prong.  If the wires aren't color-coded, you may have to use a voltmeter or test light to verify.

   If your appliance plug has only three prongs, double-check to make certain we're dealing with a 240v outlet and not a heavy 120v.  For three prong 240v plugs, omit the dedicated Ground wire.

Backfeeding Procedure.
(Order is more than important!)

-   Position your generator within cord reach of the 240v household outlet.  The generator must be out in the open air, not inside the house!  Take care that there's nothing that could be melted/ignited near the exhaust pipe.  Get it leveled, grounded, fueled, and ready to start.  Nothing should be plugged into any of its outlets at this point.

-   Walk through the house and make sure all the accessible lights and devices are switched off to reduce the combined starting load when you power the house up.  It may be a good idea to unplug televisions, computers, and other sensitive electronics altogether.

-   Start your generator so that it can begin to warm-up.

-   Go to your primary electrical service panel...  The breaker box, usually outside the house, right under the meter.  SWITCH OFF THE MAIN POWER BREAKER.  (This is usually a big breaker switch at the top.  Something on the order of 100 to over 200 amps in most modern houses).  This effectively disconnects your house from the electrical grid, which is important for a couple reasons:

   It prevents your generator from backfeeding out onto the power lines.  Safety Sallys scream this will kill utility workers, but the odds of that happening are between slim and none.  What should happen is the monstrous overload of trying to power the whole grid with a portable generator will instantly trip the household breaker associated with the appliance outlet, the generator's breaker, or both.

   The biggest reason to make absolutely sure the main breaker is off is that, if it's left on, and the grid comes back to life while you're handling the Suicide Cable, you could suffer a horrible, agonizing, gruesome death.  If one end of the cable is plugged into a live socket while the other is free, the exposed prongs become like an electric cattle prod, but with very lethal current!

-   Plug the appropriate end of the Suicide Cable into the (inactive) household 240v receptacle.

-   Plug the other end of the Suicide Cable into your generator.

-   You should now have normal, but limited power throughout your house.  Everything should run, but don't try to run everything at once!  Or anything you don't really need, for that matter.

-   To go back to grid power, unplug the generator end of the Suicide Cable FIRST, then the household receptacle end.  After both ends are unplugged, shut off the generator and throw the main breaker on the household service panel back on.

   The advantages to a Suicide Cable approach are that it's relatively cheap, simple, and portable.  And, when not in use, you can coil the cable and stow it.  So you don't have to worry about a meter reader or anyone else spotting the code violation and getting you cited.

   The disadvantages include the use of an appliance outlet circuit, which could be the weakest link in your power feed.  No matter how powerful your generator is, if you're backfeeding through a 240v, 20amp circuit, you're going to be limited to 4800 watts, maximum...  Oh, and there's the whole "make one error and have most of your body cremated so quickly that the remainder is alive long enough to 'enjoy' the experience" thing.

   Note: 120v Suicide Cables are sometimes attempted.  They aren't worth the risk or effort.  Even if they work right, they'll only power some of the 120v outlets in your house (the ones using the same Hot leg as the backfed socket), won't power any of the 240v essentials, and will feed only 1800 watts max.
Our Way.

   We played catch-as-catch-can with typical, mid-sized generators and inverters for backup electricity for quite a few years.  Then the bovine aspect of our doomstead got up to speed, and we found ourselves with multiple freezers full of valuable beef and dairy.  We needed a more practical solution.

   First we considered a proper, automatic back-up generator system.  But we don't have LP or NG here, and the inaccessibility of the doomstead made professional installation of the generator and regular delivery of fuel an impossibility.

    So we bought the biggest gasoline generator we could.  In addition to having enough output to power everything we might want to run, the big generators tend to have other useful features.  Electric, push-button start.  12v DC output that can be used to charge batteries for incidental power needs.  A 50amp 120/240v socket, which can be used to channel up to 12,000 watts to the household service, rather than the 7,200 max that the mid-sized generators could provide through their 30amp 120/240v sockets.  And a toggle switch breaker on the 50amp socket, which allows it to be shut-off for safer plugging and unplugging.

   One common problem with portable generators for backup is that they almost inevitably wind up pushed into the far corner of the garage, buried under and behind a long ton of assorted junk.  Not only is it a pain to dig them out when they're needed, but you're unlikely to do it very often for maintenance...  So I laid down a heavy, rubber stall mat near the corner of the house, away from windows, and where it can be easily reached by the cables from the house, barn, milking parlor, and smithy.  Then I built an intentionally rough-looking corrugated box shed to cover the generator in its permanent location.  (Better it look like a doghouse for a redneck's really huge Rottweiler than the home of thousands of dollars worth of equipment for OpSec.)  Not having to to drag the thing out and connect the ground wire every time makes starting the generator much faster and easier, both when it's needed, and for regular maintenance.

   To connect the generator to the house, I got a heavy-duty 50amp extension cable with a plug that fits the generator's big outlet, removed the socket end from the cord, and wired it into the house's primary service panel though its own 50amp breaker, labeled "Aux In".  (No weak link from backfeeding through a 20 or 30amp dryer outlet.)  I also installed an interlock device...  A simple, sliding plate on the breaker panel that prevents the generator cable's incoming breaker and the grid main power breaker from being switched on at the same time.  This prevents anyone from accidentally energizing the generator cable from the house's end and creating a Suicide Cable hazard.

   When the grid goes down, I just raise the cover and start the generator with nothing plugged into it and the 50amp toggle breaker switched off.  Then I go to the house's primary service panel and switch off the 200amp main breaker from the grid, then switch on the Aux In breaker.  The interlock keeps me from doing this in the wrong order.  Next I remove the safety cap from the 50amp cable and plug it into the generator.  Switching on the 50amp circuit powers up the house.  The barn, milking parlor, and smithy can be plugged into the generator's other outlets so that they don't count against the wattage available to the main panel.  (This generator has plenty of capacity left-over to run them.)

   To switch back to grid, I switch off the 50amp circuit on the generator, remove and re-cap the big plug, go back to the house's primary panel to switch the Aux In breaker off, and the main grid breaker back on.  Again, the interlock keeps me from screwing up the order.  An effective interlock device is fairly easy to fabricate, and definitely worth the effort.

Bonus Round:  Generator Fuel & Maintenance.

   Generators need to be run, preferably under some electrical load, on a monthly basis.  This is one of the big problems with your typical portable generator as a backup.  The danged thing is a hassle to get to and set up, so you put it off.  Next thing you know, there's a major blackout, and your generator hasn't been run in years, and won't start or run right...  This is why I set up ours in a permanent place.  During the last week of each month, I fire it up, plug in just the barn (including the big barnyard lights) and milking parlor, and let it run for an hour while I do other chores.  No big deal.

   When shutting down after a maintenance run, or whenever I don't plan to restart the generator anytime soon, I shut off the fuel valve and wait for the engine to starve out, then turn the run/off switch off.  This gets the gasoline out of the fuel lines, pump, and carburetor, where it might thicken to clogging varnish over time.

   Check the oil every few runs.  Just in case.  Air filter, etc.  See your manual.

   The reason the dedicated, pro-installed backup systems run on LP/NG is that gasoline is a bit of a pain for this application.  It has a limited storage life, so you can't stockpile a lot of it.  Ethanol, which is common in American gasoline, shortens storage life even farther, and is murder on generators  to boot.  So get ethanol-free gas (it's around, but you may have to search), and treat it with a gasoline stabilizer for maximum storage life.

   Regular maintenance runs should allow you to top-up the generator tank frequently enough (probably every third month) to keep the fuel therein from getting stale.  Be sure to use newly purchased and stabilized ethanol-free gas for this, not the stuff that's already aged a few months in your jerrycans.  If you feel like you're not going through gasoline fast enough to keep it fresh, siphon some out and use it in your automobile, clearing room for fresh fuel in the generator tank.  When SHTF, you don't want stale gas in the generator.

   A bunch of jerrycans (stored safely in a shed away from the house and barn) may be the simplest way to keep a stockpile of stabilized, ethanol-free gasoline for the generator.  Number or position your cans, keep using the oldest stuff up in your chainsaw, mowers, vehicles, and other gasoline engines before it gets stale, replace with new gas, keep the rotation going.

Notes: There is a lot of variation in the way houses are wired.  Our house has a main service panel outside, under the meter.  This has the 200amp main breaker, and the 240v breakers for my well pump and heat pump.  (And now my Aux In breaker.)  This panel has a shared bus bar for Neutral and Ground.

   There is a subpanel inside the house that is home to breakers for all the household circuits.  This panel also has a 200amp main switch at the top...  But switching it off will not kill the current in the outside panel or anything wired directly to it!

   Some houses will have only one panel.  Locate your meter and work from there to find the real main switch for your grid power.


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Tags: #1, #2, doom, doomsteading, latoc, layman, low-nonsense doomsteading

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