One of the more significant projects we accomplished this past year was the installation of an emergency stand-by generator system. A major icing event occurred across the Ozarks last winter, which caused wide-spread and prolonged power outages throughout the region. As fate would have it, I was in California helping with a family medical crisis at the time, while Retta was left alone to deal with the ice storm and it’s aftermath.
One lesson we learned was that the electric company (Entergy, in our case) prioritizes reconstruction of the power grid after a disaster, and when you live “at the end of the road” in a sparsely populated area, you are placed at the end of the list (for obvious and appropriate reasons). It could possibly take weeks for power to be restored, so you had better be prepared! When the power goes off, so does the heat. So does the well pump. Without the well pump, there is no running water. Without water, there are also no usable toilet facilities. Without power, communication become difficult or impossible. Satellite television ceases to operate. The Internet disappears, as does email, on-line banking and bill-paying. Cooking reverts to camp stove cookery, while food rots in refrigerators and freezers. These things were just at the beginning of the list of hardships Retta endured until the power was eventually restored.
When I returned home from California, I promised Retta that she would not have to worry about being without electricity should an ice storm reoccur in our neck of the woods – we would install an emergency generator. So that is the genesis of this particular project.
There are many sizes and types of generators available for emergency use. We decided to purchase this QuietSource 27kw generator (pictured above), after consulting with people in our area who had tried other solutions during the ice storm. The consensus of opinion was that a permanently installed, automatic whole-house generator system, adequately sized to satisfy a reasonable electrical demand during an emergency, was the way to go. Opting for 27kw provides us with sufficient capacity so that all reasonable electrical needs will be met, while allowing the generator to run well below it’s full-load rating, saving fuel and prolonging the generator’s useful life.
The unit is powered by a 2.4 liter Mitsubishi 4-cylinder liquid-cooled engine. This engine is designed to run at a constant 1800 RPM, which compares to the 3600 RPM of it’s competitors. Operating at half the speed of most other engines results in significantly quieter operation. Another benefit, which was more important to me, was the increased fuel economy the slower running engine obtained compared to other engines on the market. The importance of this will become clear later in this post.
Because of the size and weight of the generator, the manufacturer recommends placement on a concrete slab. We opted to place the generator along the side of the carport, where you see the slab being poured.
Notice in the poured slab above that we stubbed PVC conduit through the concrete, so that the electrical service would feed directly into the generator control panel.
To power the generator, we needed to install a propane tank. After digging a hole of the proper dimensions, the cavity is bedded with sand, which is meant to prevent contact between the tank and potentially damaging rocks in the ground.
This is what the 1000 gallon underground propane tank looked like prior to filling the hole with sand, and then topsoil. Why a 1000 gallon tank? Let’s do the math. A propane tank can only be filled to 80% of it’s volume capacity. Therefore, a 1000 gallon tank will be filled with 800 gallons of propane. For a variety of reasons, our propane company recommends filling the tank when it falls to 20% of capacity. So a 1000 gallon tank provides about 600 usable gallons of fuel to the generator.
The 27kw QuietSource generator burns 2.2 gallons of fuel/hour when run at 50% load, so the 600 usable gallons of propane should last for about 270 hours, or slightly more than 11 days. Since it could easily be over a week before a propane truck could replenish our fuel supply (given our experience from this past winter), the 1000 gallon capacity propane tank was the smallest size we felt comfortable with – there is no point to installing a system like this if it runs out of fuel in an emergency.
Now we placed the generator on the concrete slab and began the process of connecting things together. We ran the propane line underground (in the trench on the lower right), as well as the electrical service (in the trench leading around the house, in the upper right).
Three PVC conduits were placed underground. The larger conduit carries the main power lines. One of the smaller conduits carries the control wiring between the generator and the transfer switch (at the utility service-entrance of the house), while the other carries 110 volt power to the generator, which keeps the generator starting battery fully charged at all times.
This is the automatic transfer switch we installed near the utility service entrance. All of the electricity that goes into the house comes from this switch. When conditions are normal, the source of power is from the utility company. When the system senses a power outage, the generator starts, warms up for a short time, and then the transfer switch automatically switches the source of power over to the generator. Thus, in a power outage, the house only experiences a power loss for a short period of time. and this all happen without any homeowner intervention.
We replanted grass over the propane tank location, and all that is visible now is the small access riser, seen in the photo above.
This is how the finished project looks, now that the trenches are filled and the grass has been reseeded. The over-sized slab allows for convenient access for routine maintenance or any repairs that may become necessary in the future.
The generator is programmed to start up automatically once a week, in an exercise mode designed to keep the system ready for use at a moments notice. Since we installed the system, we have only experienced one brief power outage (thank goodness!), but it was comforting to see the stand-by power system kick in automatically, just as it was intended to do in an emergency.