September 20, 2011
IN RESPONSE TO YESTERDAY’S BACKUP-POWER BLEG, a lengthy email from reader Harry Lenchitz:
Having enjoyed about one-third of our lives on generator power, we decided to enter the discussion.
I have more than 40 years experience in electric power generation for prime power applications (seagoing vessels, forward operating bases, field hospitals) and critical standby power (healthcare facilities, emergency services, credit card transactions).
My wife has invested a similar amount of time performing research at sea, and in remote locations, on generator power.
We met shortly after 9-11, and we watched the Pentagon smolder for several weeks.
Note to deniers: It really happened!
This e-mail is my contribution to the generator discussion.
First, to all those who want a cheap, convenient way to charge their cell phones and other portable electronics: every motor vehicle includes a one kilowatt (1kw) alternator for battery charging.
Some vehicles are slightly less (a skinny kilowatt) others are quite a bit more (2kw) but all vehicles have a battery charging alternator.
The best way to charge portable electronics is to idle your vehicle and use 12 volt DC chargers.
To charge your cell phone, you do not even need to start your vehicle. Just plug the cell phone charger into your vehicle and let it charge.
To charge larger items, start your vehicle and let it idle.
To operate larger items which require 120 volt AC power, such as your computer UPS, a drip coffee maker, or a small microwave, use a 1200 watt (1.2kw) inverter – available everywhere for less than $100.
Most vehicles today will run a 1200 watt inverter indefinitely while idling, but you may need to turn on the air conditioner (which increases the engine idle) or turn up the idle speed (not legal – do not do this) to make sure the alternator is putting out full power.
Also, the family minivan (or coupe, pickup truck, or SUV) is the best survival pod ever invented – heat, air conditioning, lights, etc. You already own it, and the fuel to run it is negligible compared to buying, maintaining, and feeding a generator.
Even more important, you can drive the vehicle to a fuel point to refuel it, and charge the battery while driving to and from the fuel point.
If you need more power than your vehicle produces, then and only then, consider a generator.
We can discuss how to size a genset for home use, based on how many items you desire to run during a power outage, and how much fuel you are willing to store and consume.
You can use a portable generator, or install a standby generator.
Whatever you do, please follow all safety precautions with respect to electrical hazards, thermal hazards, and fume hazards.
If you use a portable generator, please use extension cords to power your loads – do not energize your home wiring unless you have installed an Underwriters Laboratory (UL) listed transfer switch!
I will discuss transfer switches later in this article.
If you choose to install a standby generator, and you live in an urban, or dense suburban area, a propane (bottle gas) or natural gas (city gas) powered system is the most popular and cost effective way to go. It is also the quietest.
Note well: City gas is often shut off during natural disasters. Propane is stored on your property, and can be stored indefinitely.
If you live in a rural area, you can go with a propane or a diesel unit, or if you have a tractor, a pto-driven genset.
For almost all tractor owners, I recommend a pto-driven genset. If you buy a Winco, Onan, or similar high-quality pto-driven genset, you can pass it on to your grandchildren. It will never wear out.
The beauty of a pto-driven genset is that many tractor owners are already adept at maintaining their tractors. Also, you can always find someone to repair a tractor, or, if you really need to, you can buy another tractor, new or used, almost any time.
It is extremely important to have a generator big enough to start and run your rotating loads, and to hold frequency and voltage as near constant as possible.
All rotating loads – well pump, pool pump, air conditioner/heat pump compressor and fan motor, refrigerator and freezer compressors and fan motors – require 60 hz alternating current (AC) to operate at the correct, constant speed, and require full voltage (120 or 240 depending on the motor) to operate at the correct current under load.
Incorrect voltage, and incorrect or varying frequency, can lead to failure of rotating equipment.
Let me put that more plainly – a badly regulated generator will burn up expensive motors!
Home electronics (tv, computer, etc.) are not as sensitive to voltage, and are relatively insensitive to frequency (they all have power supplies that convert AC to regulated DC) but they can be damaged by very low or high voltage.
Most important is your transfer switch.
After the transfer switch is installed, and inspected by your county building inspector, send a copy of the electrical inspection to your insurance agent – 2 reasons:
1. Liability – If anyone is ever injured or killed while working to restore power on your distribution grid, you will have proof that there is no way it was a backfeed from your generator.
2. Risk Reduction – If you ever have an electrical fire in your house, you will have proof that the transfer switch was properly installed and inspected.
My advice is to install a 200 amp (or whatever size your home electrical service is) manual transfer switch.
That way you will be able to use any lights, anywhere in your house, including in your basement, regardless of whether you power your house with a 5kw or a 50kw genset.
I do not recommend an automatic transfer switch for home use.
You want to determine that the power really is out, and will be out for more than a few minutes (or hours).
You want to start your genset and make sure it is running right – all engine gauges (oil pressure, battery voltage, coolant or cylinder temperature) and generator gauges (voltage, FREQUENCY, current) registering correctly, and then and only then transfer the load.
If the engine parameters are incorrect, you run the risk of destroying the engine. If the generator parameters are incorrect, you run the risk of destroying expensive items in your home.
Even if you never have a power outage, throw your transfer switch once a year to make sure it moves.
Also, open it once a year and blow out the insects. Leave a piece of no-pest strip or a livestock ear tag with pyrethrins in there to keep it insect free.
I recommend testing a home generator twice each month.
Just connect an electric stove or similar load to it, and run it under load for 30 minutes.
If you can start it and run it every 2 weeks, and it takes a full load, you can depend on it for a power outage when you transfer the house load using your manual transfer switch.
Takeaway – Generating your own power during an outage requires serious investment in time and money, and significant fuel and maintenance expenses.
At present prices, we spend about $90/day for fuel and oil changes during extended power outages.
We can discuss this stuff further if you like.
We have a 200 amp transfer switch to transfer our house between the electric grid and generator power, and a second 100 amp transfer switch to transfer between main generator and auxiliaries. Main generator is a 15kw 1800 rpm diesel. Auxiliaries are 25kw Winco pto unit (more power than either of our tractors can provide, but superior motor starting capability), 8.5kw 3600 rpm gasoline powered welder, 3.5kw 3600 rpm gasoline powered welder, 2kw 1800 rpm continuous rated gasoline powered genset (perfect for overnight refrigeration and entertainment loads, if we don’t need heat or air conditioning).
Well, that’s going big. The small-scale way is with the inverters. The maintenance load for a generator is why I haven’t bought one. The more expensive ones start themselves every month. But they’re more expensive. . . .