Home Generators – What Type Should You Purchase?

1. How convenient do I want this process to be when power is lost?

2. What is my primary fuel source going to be?

3. How long will it typically need to run when power is lost?    

To answer the first question, how easy do you want this process to be? When you lose power, do you mind getting up and doing the following:

• Pull out the generator
• Make electrical connections
• Make fuel connections

If you don't mind doing this during a storm or just before an event then you will be satisfied with a portable generator. It can be stored in your garage or shed until the time you need to pull it out and hook it up. Returned to storage after used.  You can also have an electrical contractor pre-wire everything so that it is more of a plug and use scenario.

If you do mind doing this then you would consider a permanent home generator with automatic transfer switch. When power is lost, the transfer switch senses a loss in load and transfers your house load(s) to the generator automatically. You don't have to touch a thing. It is all automatic with no manual operation. 

Of course! You want the convenience of automatic operation. Understand that this convenience comes with a price tag. It is the most expensive option. But by far the best option if you are looking for that convenience.   

Portable generators are typically gasoline fueled. Their gas tanks are good between 8-12 hours at 50% load. You will have to refill the tank when it runs out. Make sure you have plenty of gasoline on hand during times of possible power outages.

Permanently installed generators are either Propane (LP) or Natural Gas (NG). The gas supply is connected to the generator set at all times. If Propane (LP) is your fuel of choice, you will need to have a propane tank appropriately sized by the gas company for the estimated usage of your generator. Natural gas is piped into the generator set and is readily available when needed.

Diesel generators are available for home use but not as common. They would be supplied with a diesel fuel tank of some type. It would be sized for a determined amount of time (for example, 8 hrs, 12 hrs, 24hrs at full load). Diesel fuel would have to be brought out to the tank and filled once down to a certain level. These generator sets are far more expensive than the types we are discussing in this article.

Where you live will affect the answer to this question. Some additional questions you should ask yourself. How frequently do you lose power? Do you live in a windy area where you lose power once a week for 2 hours? Do you live where there are a lot of hurricanes, thunderstorms, etc.? Once you lose power, how long do you typically go without power?

If you are finding that it is probable that you will run your generator for extended periods of time then you should probably go with a permanently installed home generator.

A portable generator is typically not sized to run loads for extended periods of time and the fuel tanks are so small that it doesn't make sense anyway. Most manufacturers do not recommend running the smaller portable generators for any longer than 8 hours at at time. I personally have seen them run for 24 hours straight after Hurricane Isabel without problem. I would not suggest doing that often as it may void warranties.

I have selected two different models as portable home generator examples. They both have very reliable engines and in my experience have a good reputation in the market place.

Generac is the most common home generator out there today. It is also the most economical. I have selected a few of their available sizes with various options to show you what you can purchase for the price.

All of the generators come with the following:

• Pre-wired and equipped with all necessary installation components.
• Automatic Transfer Switch with weekly exercise option
• Pre-wired Conduits
• Outdoor Connection Box
• Flex Fuel Line Pigtail
• Composite Mounting Pad
• Corrosion resistant enclosure – galvanized steel or aluminum
• UL Listed

• 100Amp Automatic Transfer Switch with 8 circuit load center, NEMA 1 inside use
• Galvanized Steel Enclosure
• 30ft., 5ft., and 2ft., prewired conduits
• Outdoor Connection Box
• 1 ft. Flex Fuel Line Pigtail
• Composite Mounting Pad
• Installation Guide, Owner's Manual
• DOES NOT INCLUDE BATTERY – Requires minimum of Group 26R, 12V min., 350CCA
• Dimensions – 48” x 25”x 29”, 336 lbs.

• 100Amp Automatic Transfer Switch with 16 circuit load center, NEMA 1 inside use
• Galvanized Steel Enclosure
• 30ft., 5ft., and 2ft., prewired conduits
• Outdoor Connection Box
• 1 ft. Flex Fuel Line Pigtail
• Composite Mounting Pad
• Installation Guide, Owner's Manual
• DOES NOT INCLUDE BATTERY – Requires minimum of Group 26R, 12V min., 350CCA
• Dimensions – 48” x 25”x 29”, 336 lbs.

Intended for Whole House Use – For most traditional homes – loads must be verified before it can be considered meeting your whole house requirements.

• 200Amp Automatic Transfer Switch, Service Entrance Rated NEMA 3R outside use
• Aluminum Enclosure
• 1 ft. Flex Fuel Line Pigtail
• Composite Mounting Pad
• Installation Guide, Owner's Manual
• DOES NOT INCLUDE BATTERY – Requires minimum of Group 26R, 12V min., 525CCA
• Dimensions – 48” x 25”x 29”, 336 lbs.

This is the tricky part. There are no real rules of thumb that I would suggest sticking to other than taking a look at your actual loads that will be backed up by the generator and determine what your Starting Watts will be and what your Running Watts will be.

When starting a motor, the Starting Watts is more than the Running Watts. Take a look at some typical household loads and compare the Running Watts to the Starting Watts below. These are “typical” values. Your specific loads should be checked before you settle on a size to purchase. This can be done by looking at all the nameplate data on the devices that you are going to be backing up with the generator.

If you have problems finding this information, consult a local electrical contractor for help. A contractor is required to install the generator and can provide the sizing as part of their service to you.

                                             Running Load                      Starting Load

Television                               300 Watts                               300 Watts

Refrigerator                            600 Watts                              1950 Watts

Hot Water Heater                   5000 Watts                             5000 Watts

A/C Unit, 12000BTU                1900 Watts                             7600 Watts

You see the difference between Running Load / Running Watts and Starting Load or Starting Watts? Do NOT size your generator for Running Load. You will most likely have problems getting it to start.

1. Make sure that your generator is suitable for sensitive loads if you will have any electronic type loads connected to it. Such as your computer. Things like electronic governors are required to properly interface with sensitive loads.

2. Maintenance is recommended on the permanent home generators every 200 hours or once every 2 years. Which ever occurs first. Refer to the manufacturer recommendations to make sure the maintenance schedule is followed.

3. Maintenance on the portable generator sets are typically done after the first 5 hours of service and then annually thereafter. Refer to the manufacturer recommendations to make sure the maintenance schedule is followed.

4. Never allow your generator set to run out of fuel. It can cause damage and warranties will be voided.

5. Only a licensed electrical contractor should install the permanent home generator. It is recommended that a contractor also make connections when dealing with a portable if you do not have the experience to do so. As part of their installation price, they can also provide the service of sizing the generator for your home. Use their expertise.

6. Ask your electrician if they have any type of maintenance plan available through their company that you can sign up for at an additional fee. Let them service your generator set at the manufacturers recommended intervals. Also, with Generac, I have seen that dealing with a local contractor on the service is much easier than dealing with Generac Service Direct. You tend to get lost when dealing with them direct. Your contractor will make sure you are taken care of. Another option would be to find a local Generac dealer and sign up for a maintenance plan through them. They will make sure you are taken care of and they have to deal with the manufacturer direct. Not you.