In my article, “Hurricane Tech – Keeping the Lights On with a Portable Generator”, I discuss the benefits and basics of having a Generator to keep critical devices such as Refrigerators, Freezers, Heating, and Communications operational in the case of a Utility Power Outage. The limitation is that a Portable Generator can only provide electricity to a limited number of devices such as those mentioned above.
If you want the ability to power most every device in your home – as if Utility Power were still present – you need a Whole House Generator that is able to produce a similar number of Amps. The average home with a 100amp electrical panel would require a Generator capable of producing approximately 12,000watts. And, with a 200amp panel, the Generator would need to produce approximately 20,000watts.
It is possible to power an entire home with a Generator producing less than the above approximate output wattage ratings if using a “Load Shedding Generator Switch.” (See my article “Hurricane Tech – The Load Shedding Generator Switch” for an explanation of how this can be accomplished.)
It is more common to use a properly sized Whole House Generator so that the average load on the Generator is between 50% and 70% of rated capacity. If you have 200amp service and a 20,000watt Whole House Generator, and assuming normal living patterns so that only selected lights and appliances are in use at any one time, the Generator should be operating in that range. Rarely are Electrical Circuits in any home at capacity but more likely at a similar 50% to 75% of maximum capacity.
The Whole House Generator is usually connected to the Main Electrical Panel of the home using an Automatic “Utility/Generator Transfer Switch” which works with the Generator to sense loss of Utility Power, Turn-On the Generator, and then switch the Power Source of the Electrical Panel to the Generator from Utility Power. (See my article, “Hurricane Tech – The Utility/Generator Transfer Switch”.)
Other than following local Electrical and Plumbing codes and using Licensed professionals for the installation, the other major decision after the sizing capacity is the Fuel Source for the Whole House Generator. The most popular use Natural Gas (NG), Liquid Propane (LP), while some use Diesel Fuel or Fuel Oil. The actual output of a Generator can be affected by the Fuel selection. NG/LP rated Generators will produce approximately 10% less output with NG. With LP, the output is closer to the actual rating. A 20,000watt Generator may actually produce 19,500watts with LP but only 17,280watts with NG
A Whole House Generator requires periodic testing/”exercising” and maintenance. Typically, a Whole House Generator will turn itself on once per week and “exercise” for approximately 20 minutes. Like any other Engine, Oil needs to be changed. For most Whole House Generators this is approximately every 100 hours or annually depending on usage. IT IS CRITICAL TO FOLLOW ALL MANUFACTURERS MAINTENANCE RECOMMENDATIONS. Failure to do so may cause the Generator to fail or not to start when it is needed most during a Power Outage.
IMPORTANT SAFETY NOTE: CONSULT WITH A LICENSED ELECTRICIAN AND GENERATOR PROFESSIONAL TO CONFIGURE AND SELECT A PROPERLY SIZED WHOLE HOUSE GENERATOR SUITABLE FOR YOUR NEEDS. ALWAYS USE A LICENSED ELECTRICIAN AND LICENSED PLUMBER TO PERFORM THE INSTALLATION. FAILURE TO INSTALL A GENERATOR, TRANSFER SWITCH, NATURAL GAS OR LIQUID PROPANE CONNECTIONS CORRECTLY MAY RESULT IN FIRE, EXPLOSION, SERIOUS INJURY, OR DEATH.