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This is a past episode of the Emergency Preparedness "Tip o' da Week". To see the current episode or any past episodes, please follow this link.

Why do we have power outages?

Before a power outage occurs, you need to have a few things ready. You will notice that they are the same items you need for just about any emergency. Power companies, like all utility companies, are quick to warn you to be prepared for loss of services for 72 hours.

The usual list, but many people forget!

• Flashlight with extra batteries
• Candles and matches
• Manual can opener
• Battery powered radio
• Wind up or battery powered clock

(we wouldn't want to be late to work, would we?)

One of our local suppliers had a run on emergency supplies when the windstorm of 1995 hit Seattle. He sold several hundred flashlights and battery sets to help restock a local hardware store that ran out. About an hour later, he got another call for several hundred more from the same hardware store! They were selling like hot cakes! There are only so many of these items in any city at any given time. Get yours today while you're thinking about it!

The supplier mentioned above also sold about 1000 road flares to the local power company. You would think that the local power company would be ready for a small disaster like that one, but they weren't!

General notes about outages:

• Cold weather is especially hard on infants and the elderly. If you loose power in cold weather, dress in several layers of clothing and be sure to wear a hat and a pair of gloves. Keep the heat in.
• Use your hot water sparingly. Your hot water heater will hold its temperature for a day or so, but remember that every drop of hot water that you use is replaced with cold water at the inlet of the heater. If you use a few gallons of hot water, the temperature of the remaining water will decrease because of the cold water that replaces it. If possible, use the hot water from a location that is close to the heater so you don't waste hot water trying to get it to the 3rd floor when the heater is in the basement.
• If possible, keep doors and windows to your house closed. But remember that if you use your fireplace for heat, it will use valuable oxygen in the house, and will require infusions of fresh air from time to time.
• Keep the refrigerator and freezer doors closed as much as possible. We hope you have read the Tip O'da Week episode that dealt with the refrigerator. There are some great tips for keeping stuff cold in a power outage.
• If you have an electric garage door opener, please take a look at it to see how to over-ride the mechanism. You will need to know how to open it!

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If you lose power:

Take a look at other houses in the neighborhood. Do they have power?

Turn off your main circuit breaker:

Motors draw large amounts of initial start up current.

Let's take a belt driven drill press as an example. If the drill bit speed is set to a slow speed, the chuck reaches its final speed a short time after power is applied to the motor. If the drill speed is set to the high setting, you can hear the drill press "wind up" until the final speed is obtained. The reason is that the drill press belt, pulleys and other mechanics have some resting inertia that the motor must overcome in order to get the works spinning. This resting inertia is larger when the gearing ratio is larger as in this example. If you were to measure the startup current for both cases, you would find a huge increase in start up current when there is more of a load on the motor (more resting inertia).

An example is an 1/8 horse power furnace motor used in many Natural gas heaters. The running current is 300 Watts, but the start up current is nearly 500 Watts. That means that you need about 70% more power to start the motor than you need to keep it running once it has been placed into motion. The same holds true for all motors. In some cases you need even more power to start a motor based on the initial load. A good estimate of the initial start current is to double the run current.

Here is a little story to help illustrate the need to turn off your main circuit breaker after power is lost.

Like in the real world, all my customers need power at the same time. They all get up at 6 AM. They all start their toy coffee pot at 7 AM, and they all go to work at 8 AM. Nobody needs my power in the middle of the day, but they all get home at 6 PM and cook dinner in their Betty Crocker ovens. At 7 PM they all turn on their toy televisions to watch re-runs of the Simpsons.

What if the toy coffee pots are run by a toy motor that consumes 1 Watt of power?

Hint: remember that motors need twice the run power to get started (start up current).

Guess what. My toy power station just tripped the circuit breaker, and nobody gets power! One of my customers must turn off the coffee pot! What happens then? Well, if one customer bows out, the remaining power needs are.... 2 Watts (start up) x 5 (customers) = 10 Watts. Now power can be restored. After the motors start running, the current demand returns to one Watt per customer for a total of...1 Watt(running) x 5(customers) = 5 Watts total. My power station can deliver 10 Watts, so there are now 5 extra Watts available. My last customer can then turn on his/her toy motor powered coffee pot and the new current is....1 Watt(running) x 5(customers) + 2 Watt(start up) x 1 (customer) which is equal to 7 Watts! Guess what again. Everyone still has power!

I know the example above is a bit silly, but I think it well illustrates the problem. Think about the real life application:

• When power is lost, all the switches in your house (for lights and such) and all the appliances that were on are sitting there ready to consume juice when power returns.
• You might even have turned on more light switches thinking that power was only lost in one room. Did you remember to turn them back off?
• If power is off for some time, the house may cool off, and the furnace thermostat might trigger to start the heater. Remember, power is still off, so the furnace motor will be sitting there ready to consume more start up current.
• The contents of the refrigerator and freezer might have warmed up, so the refrigerator thermostat might also have triggered. The motor will be sitting ready to eat more start up current.
• By this time, the water in the hot water heater might have cooled down enough to cause the water heater thermostat to trigger. The water heater element will be sitting ready to consume more power! Although the heater should keep the water warm for a day or so, we needed to stress the point!

About generators:

• Do I need 120 Volt or 240 Volt?
• How much power do I need?
• How much will it cost?
• How do I hook it up?

For now, here are some general notes:

• The smaller the better. Run time is a major concern. If you don't have power in your neighborhood, your local gas station won't either. No power, no way to pump gas at the gas station! The gas supply on hand must last as long as possible.
• All generators manufacturers rate their generators fuel consumption based on running with a load that is 1/2 the rated capacity. It's a bit misleading, but they all do it! Remember the fuel usage numbers shown below are for 1/2 the rated continuous load!
• To get a generator that has 240 Volt output requires an 8 horse power motor in most cases. Try to limit your generator choice to a 5 horse power or smaller which implies a 120 volt only unit.
• Generators with 12 VDC output in addition to 120 VAC cost about $100-$150 more than AC only units. What you are really paying for is an extra set of coils in the generator, and support electronics to rectify and regulate the DC power.

In Brief:

• Quiet is expensive! Loud is cheap!
• Long run time means low power output. High power means short run time!
• 230 volt output means 8 Horse power or larger with most brands, and short run time (small hours per gallon).

Do I need a generator?

Take a look at the table we have provided below. A few things should come to mind:
(This table might look messed up if you are not using Netscape)

Your electric range and stove are the largest consumer of your limited emergency resources. Next on the list is Electric heat, the electric hot water heater and the close dryer. All these items require lots of power. Also note that these are the only items in your house that require 230 Volts.

Most Gas heaters only require 120 Volts to run the blower motor, and control electronics.

What do you really need to power? All you really need to power is a lamp or two, a TV, or radio, the refrigerator, and a microwave oven. None of these items require a large amount of power, but they do if you want to power all of them at the same time.

Look at the total:
Item:                         Watts:   

Lamps (2 60 Watt bulbs)       120
TV (color)                    115
Radio                          75
Refrigerator                  425
  start up current (+70%)     290
Microwave                     650
Gas furnace blower 1/8 HP     300
  start up current (+70%)     210
                             -----
                             2185 Watts


Notice that it looks like the microwave is the largest user of power, but remember that the refrigerator uses about 70% more power on initial start up as discussed above. That means that for a short period of time, the refrigerator uses 425+290 Watts. That's 715 Watts all by itself (at startup). The same is true for the furnace motor which will use 510 Watts at start up.

From the above, notice that you would need a 2200 Watt (3000 Watt peak) generator to be able to run all that stuff! That size generator uses a 5 horse power motor and runs for about an hour on a gallon of gas. Remember that gas will be impossible to get in an emergency! Is it worth using a gallon of gas so all the above items can be used at the same time for an hour?

A better approach would be to use the generator to power just the items you really need on at the same time.

Think about the following:

It's all a game in tradeoffs!

• 120V or 240V
• Power verses run time
• Generator motor size verses fuel consumption
• Cost verses noise

Wattage requirements for home items:

DC to AC power converters:

If these devices are intended to provide emergency power from a battery (or bank of batteries), you must remember that they will draw power out of the battery at a rate that is in proportion to the amount of power required at their output. If power is not added back into the system, they can provide AC power for only a short period of time.

Lets look at how power conversion works:

Power = Current x Voltage.

So if we have a load that requires 140 Watts out at 120 volts, the output current is 140W/120V=1.17 Amps. For 140 Watts to be available at the output, and assuming we convert 100% of the input power to output power (in actuality, most units are only 90% efficient), that means we need...140W/12V=11.7 Amps from the 12 volt DC source!

If you have ever left your headlights on in your car, you know that your battery will die by the end of the day. Your head lamps require about 10 Amps. I hope you see that powering 120 volt items from a battery using a power converter is impractical for more than a few hours unless additional power is put back into the battery. Lots of power can be put back into a battery from the charging system of a car, but a car engine, with its hundred+ horse power, is a bit over kill for charging batteries!

Another solution to providing a large amount of DC power to the converter would be to use an alternator from a car, and a small gas powered motor. This combination can deliver over 780 watts (with a 65 amp alternator).

See our new Tip O’da Week episode for more details.

Some other notes about converting power in general:

The key is to use a device that is intended to run on the power source you have, or plan to have. If you plan to power a TV on batteries like D cells, or your car battery, then buy one that holds D cells, or has a 12 volt cigarette lighter input. You can still run it on wall current (when local power is available) with the adapter that comes with it, but if you need to run it off battery, you can!

The point I'm trying to make:

Emergency power loss lights

These little lights go on when the power goes off. The way I figured, even if the walls collapse, there would be light to help us find our way through the debris to safety. It never occurred to me how useful they would be in a normal power outage!

In the windstorm of 1995 (December) I was testing the small generator just before the large winds were about to hit. The generator was sitting there running when the entire neighbor hood went black! I looked up at the house, and saw light in the kitchen, and light in the basement! It was dim by normal standards, but was brighter than the rest of the neighborhood. I went into the house, and realized that all the light was coming from the 1/2 dozen emergency power failure lights through out the house! Every room was list up! The Christmas tree was dark, but the rest of the house was navigable!

I pulled one of the lights out of the wall and used it as a flashlight. I went in search of the 50 foot extension cord for the generator, and the candles and such. In a few minutes I had the generator hooked up to the TV, the antenna amplifier, and the floor lamp. Presto, and Bryan said "let there be light"!

The December 1995 power outage made a real believer in those silly little power failure lights! I hope I never need them for the disaster that I intended to use them in, but they sure worked well for a normal power outage!