How to hook one up:

First off, if you have ever taken a look at a generator you will find an outlet like shown. It looks exactly like your wall outlet doesn't it? In fact, it is! If the generator is a 240 volt model, it will also have a another outlet for the 240 volt power. The generator will also have a circuit breaker with a push button reset.

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 you 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?

There are only two safe ways I know of to get the power into your house.

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

The easiest way is to use an extension cord. But there are two critical notes you need to know about using extension cords.

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, a voltage drop across the wire results. 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.

Lets forget the details for a moment to examine the table below:

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 %

A 3.6% voltage drop is above our recommended 2% max voltage drop given in the table above (for 120 volt). Either the wattage of the lamp must be reduced, or a larger size wire (12 gage) must be used. The larger size wire has less resistance per foot, so the voltage drop will be less.

The House wiring and generator connection:

The only safe way to power items in your house without using an extension cord is to have a Double Pole Double Throw (DPDT) transfer switch and sub panel installed. It's an expensive proposition, but is the only legal way to connect a generator to your house wiring!

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 discourage you from using 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 them, is sure to be killed buy your generator! In addition, if power is returned while the main breaker is on and the generator is connected......BOOM!