Wiring a  Home  Generator for Emergencies

March 8, 2009
Lon Schultz, B.E.  E.M.T. B.N.H. and D.N.M.

In an emergency situation we all might need to do things we are not trained for or accustomed to doing, dangerous things that require care, like minor surgery. Electricity is no different.

Remember, if someone else can do it, you can learn to do it also.

You can do this. Just follow these instructions exactly and completely!

These instructions are for a 220 V generator only.

First, construct or have constructed an extension cord, one end with a plug that goes into the 220 V outlet on the generator. The other end needs to have a plug for a 220 V outlet in the house, air conditioner for 6KW or less or an electric dryer for 10KW or less. If possible, it would be best to have an electrician install an RV outlet on the outside of your house and make up the cord. The wattage and subsequent amperage of the generator should match the outlet in the house, but it is not necessary; however the extension cord wire must meet or exceed the rating of the generator.

This cord will have a plug on each end, and is very dangerous! If you plug it in and start the generator, so DON'T!

Here are some guidelines for cord construction:

Of course you can always use a larger wire.

Cord Construction methods: Each 220 V plug will have three or four connections, two hot, some times one neutral and always one ground. On the three pin plugs the neutral and ground are the same. The plugs might be different or the same, it doesn't matter. The pin is round and the lug is flat like a knife.

What matters most is that the ground from each plug is connected to one another and then that any neutrals are connected to one another. If one plug is a three lug and the other is a four, connect the ground and neutral together at the four pin plug. The ground and neutral are essentially the same.

It is preferred that a green wire is used for the ground and that a white is used for the neutral, again, the white and green can be connected. Most ground lugs or pins are located away from the hot lugs, at the bottom or top of the plug body, if there is a neutral it is near the ground.

The hot lugs are always a lug and the ground is usually a pin.

The hot lugs usually oppose each other and the hot wires are usually black and red. Once the ground and neutral are connected, connect the hot wires, one to either side, it does not matter which hot lug they go to.

Always use the cable clamp on the plug and pull on the cable to test it before use. If you have a multi-meter (and you should) use the ohms or continuity section to test continuity between the grounds and neutral if there is one and then the hot connections from one plug to another.

Second. Turn off the main breaker. (I can't overemphasize this) then turn off all other breakers! If you don't, someone can be killed and at the least, your generator will overload and blow breakers.

Third. If possible ground the generator, to the ground with a grounding rod or to a pipe. Then connect the cord between the generator and the house.

Fourth. Start the generator and let it warm up a little. The generator should be out side or at least in a garage, with the door cracked or open NOT IN THE HOUSE!

Fifth. Turn on one breaker to one room with lights only, like the bathroom. If all is well, turn on another breaker to another room with lights only, and then all other breakers for the lights only. This is to avoid wiring and load problems. If there are problems check your wiring! So now the house is mostly lit. Turn off any unnecessary lights.

Try this before you need it; there might be problems!

Sixth. Depending on the power of the generator, turn on other breakers to rooms with freezers and Refrigerators, one at a time with 10 to 20 seconds between. High wattage devices like electric stoves and air conditioners, or water heaters will usually overload your generator and blow breakers, so don't try and use them unless you have a high wattage generator. If this happens just turn of the device and reset the breakers.

Seventh. Shutting the system down is basically in the reverse order.

No matter what, shut down the generator before any wires are disconnected, as it is a shock hazard, otherwise.

You should go through the sequential turning on of the breakers each time you turn on the generator, with the main breaker off.

Dr. Lon Schultz has over 50 years in electricity and electronics, taught Industrial maintenance at A.T.U. and electricity for local electricians.