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  In the last episode we talked about generators.  If you have decided that you need one, we're sure you have a few questions like:

• What will one cost?
• How do I hook one up?

Do I need to take out a second mortgage?

Watts:  Watts out:   Run time/gal:  Motor Size:  Volts:    Amps:    $    Brand: Model: Note:
Rating  Continuous

1000     900         3.8  hour/gal   ?           120,12   7,8     $ 700  H     EX1000  X Q
1400    ?            ?               ?           120,12   ? ,8    $ 750  H     EG1400  X Q
1750    1400         5.5  hour/gal   3   Horse   120,12   14,15   $ 550  C     1750    X
1800    1400         ?               5.5 Horse   120,12   12,8    $ 900  H     EM1800  X
2500    2100         3.0             5.5         120,12   17,8    $ 950  H     EG2500  X
2500    2300         3.1             5.5 Horse   120,12   17,8    $1100  H     EM2500  X
3000    2250         1.1             5   Horse   120      19      $ 350  C     2250    L
3500    3000         2.1             8   Horse   120,240  29,14   $1200  H     EG3500  X
4000    3250         3.0             6   Horse   120,240  27,13   $ 700  G     G4000
5000    4000         3.4             7.8 Horse   120,240  33,17   $ 850  G     G4000XL ER X  
5000    4000         ?               8   Horse   120,240  33,16   $ 450  C     4000    L
5000    ?            0.8             11  Horse   120,240  21,8    $2100  H     EM5000  ER X
5750    4600         1.3             9   Horse   120,240  38,19   $ 600  C     4600ER  ER
6250    5000         0.83 Hour/gal   10  Horse   120,240  41,20   $ 650  C     5000    L
6250    5000         0.75 hour/gal   10  Horse   120.240  41,20   $1000  C     5000ER  ER X

C=Coleman Powermate
H=Honda
G=Generac
ER=Extended run, 5 gal tank
X=extras like low oil shutdown, quieter, electric start, etc. Hard to tell the whole story!
Q=quiet
L=loud!

We have not included data for Generators exceeding 10 Horse power.

From the above data and personal experience:

• 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).

Notes from previous tip for review:

• 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.  The key is to evaluate what you really need to power in an emergency.
• All generator manufacturers rate their generator's fuel consumption based on running with a load that is 1/2 the rated capacity.  It can be 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're really paying for is an extra set of coils in the generator, plus the support electronics to rectify and regulate the DC power.  Is it worth the money to have a gas powered battery charger?

How to hook one up:

     Notice that the plug on the generator is intended to have devices plugged into it.  Also notice that it is a socket, meaning that the connections are protected from accidental contact.  The rule is that if power can be supplied at a connection, the supplying connector is a socket.  Notice that on your appliances, the connector is a plug (since it doesn't supply power).

How do you get the power from the generator to items in the house?

1. Use a heavy gage extension cord.
2. Have a transfer switch and sub panel installed.

Extension cord notes:

1. Wire has resistance.  The resistance per foot depends on the construction of the wire (number and size of strands).  The maximum amount of current that can be provided by an extension cord depends on the type of insulation used in the construction of the cord, and the number of conductors in the cord.
2. Because current is passed through the resistance in the wire, voltage across the wire drops.  This voltage drop should be kept to under 2%.  If the voltage drop is greater than 2%, efficiency of the appliance is severely decreased (and can also result in damage to some equipment). Larger wire size, or decreased current requirements can reduce the voltage drop.

From the above tables, a few things should be pointed out:

Voltage drop can be calculated using Ohm's Law which is given by... Voltage drop = Current (amps) x Resistance (Ohms).

Let's take an example where you might want to use a 200 foot, 14 gage extension cord to run a 1000 Watt flood lamp:

• Current = 1000 watts / 120 volts = 8.33 Amps
• Resistance of #14 wire = 0.00258 ohms/foot x 200 feet = 0.516 ohms
• Voltage drop = 8.33 amps x 0.516 ohms = 4.29 volts
• Percent drop = 4.29 volts / 120 volts = 3.6 %

The House wiring and generator connection:

The diagram shows the addition of the DPDT transfer switch.  Note that the loads you have determined to be necessary in an emergency must be moved from the main breaker to the sub panel.  When the transfer switch is in the normal position, power is routed through the switch to the circuits attached to the sub panel.

When power is lost and generator power is to be used, notice that the switch must be moved to the "generator as source" position.  Once the switch is moved, the desired loads may get power from the generator connection.  Even if main power is restored, the desired loads are isolated, and will continue to receive power from the generator until the switch is returned to the normal position.

Notice that there is a special connector shown on the diagram. This is the only place that you will find a plug with exposed contacts mounted on a piece of equipment in your house (except your computer). It is a connector that is panel mounted with a recessed set of male contacts (like a plug, not a socket). Remember from the text above that anything that can be the source of power has a socket. Since the opposite ends of the transfer switch are wire to connector and the source in the main breaker panel, the connector can never be delivered power from the main. 

We are going to quickly mention a very dangerous method for connecting your generator to items in your house. Our intent is to discourage you from this practice!

Its called "back feeding", and is very dangerous for 3 reasons:

1. It requires that the home owner remembers to turn off the main breaker.  Little details like that can easily be forgotten when an emergency occurs. More on this later.
2. It requires use of a very dangerous plug to plug cable!  As mentioned above, a plug has exposed contacts, and the second it is inserted into a powered outlet, the other end of the cable would have exposed "live" contacts.
3. If the home owner forgets to kill the main breaker, the power will back feed to the pole-mounted transformer and will be stepped up to lethal voltages.  A line man who wouldn't expect the line to be powered if he were working on line is sure to be killed by your generator!  In addition, if power is returned while the main breaker is on and the generator is connected......ZAPPO!

The Webmaster's baby generator:

The cost of a small generator like this one is about $500-$600.  You pay a high price for the low noise levels.  Now, just to make you sick, I wanted to tell you what I paid for this generator.  I bought it from a guy who had it sitting in his scrap pile behind his house.  He told me that a friend gave it to him because it needed a new motor.  He priced a new motor and decided it was going to cost too much.  I bought it from him for $10, and took it home to determine what could be salvaged from it.  I found that it had a large rust hole in the gas tank, the carburetor jets were clogged, and the float bowl was full of rust chunks.  A few hours later, it was up and running!

Now this little generator is nothing fancy, and requires the user to adjust the output frequency when it is first started, but I think the inconvenience is worth the $490-$590 dollar savings!

Another used generator story (or two):

I remember sanding in the gas line in Princeville on the island of Kauai the morning that Hurricane Iniki was about to hit.  A man pulled up in a truck and was trying to sell a generator to the folks in line for gas.  There were no takers!  After Iniki, the island was without power for 3 months.  I wonder if that man sold his generator that morning and if he regretted it?

The Webmaster's other generator:

     Notice the modifications that were necessary to keep the neighbors happy.  This generator is VERY loud. You pay a premium price for silence, and although this is a great value ($/Watt), the stock unit will cause you (and your neighbors) to go deaf!  What?

     I added some pipes, and a small car muffler to help reduce the noise. Also note the addition of a set of wheels and "move handles."  These additions added up to another $75 or so but were worth it!