Common Sense Approach to Standby Power
by Clayton Preble, Revised June 2010
This paper has been written to help educate
homeowners, builders and other interested parties about the advances in small standby power generation. The information is based on research and personal experiences in helping consumers make good choices in
selecting the standby power generator system that is right for their needs.
Just a few years ago, standby power was available
only in large, costly generator systems, built primarily for large commercial and industrial applications. Homeowner’s options were very limited – generally a portable gasoline generator complete with
extension cord. Storage of the portable generator and an adequate supply of fresh
fuel were causes for concern. The preparation for Y2K was largely responsible
for the advance of technology and advent of today’s affordable and reliable automatic standby power generator systems.
Since the Y2K event, technology has continued to advance. Additional manufacturers have entered the standby power market, giving homeowners numerous options to obtain
reliable standby power. Whether the homeowner has a home office, medical issue,
or simply values the security of reliable power, an affordable standby power solution is now available.
Today’s standby power generators are
fully automatic, self-contained, and built to be permanently installed outside the living area. They use an automotive style muffler and sound attenuation to limit sound to approximately 70 db’s
and use environmentally friendly natural gas or propane as a fuel source. The
most popular small automatic standby generators range in size from 7kW to 20kW. Generally,
7 to 10kW generator systems are used when requiring protection of 10 electric circuits or less. The 12 and 20kW generators offer greater capacity and therefore more options for the homeowner.
Several factors should be considered when
choosing the site for the generator: access to the fuel source (natural gas or
propane), access to the primary electric service entrance for the home, and landscape considerations. Adequate clearance on all sides of the generator is important for proper cooling and servicing the generator
- as a general rule, a minimum of 3 feet of clearance on all sides.
The transfer switch acts as the interface
between utility power and generator power. When sensing an absence of utility
power, the generator starts and the transfer switch automatically and safely transfers the protected circuits to generator
power. The time between power failure and restored power by the generator is
generally less than 30 seconds. When utility power is restored, the process reverses
itself. The most common transfer switches used in residential applications include
50, 100 and 200 AMP rated capacity. Some of the 50 and 100 AMP transfer switches
include 10 to 16 built-in circuits. Likewise, some of the 100 and 200 AMP transfer
switches have enhanced functionality such as “smart” technology, which allows isolation and load management of
Understanding Your Options
There are several ways to approach standby
power for the homeowner. The following are the most common:
Whole House – When the objective is maximum convenience and cost is not an important consideration, the whole house option is the ultimate in standby power generation systems. The
advantage is that the homeowner does not experience any difference in electrical power access when the utility power fails. Disadvantages include size of the generator and costs (initial, operation, and maintenance).
Essential Circuits - While whole house standby power solutions are available
for any size home, most consumers are looking for a more affordable standby power solution that will help them meet their
essential needs when the utility power goes out. For most homeowners those essential
needs are tied to certain essential circuits.
Those essential circuits may include heating, cooking, refrigeration, lighting,
security, telephone, well pump, home office, entertainment or medical equipment. Air-conditioning
is generally not considered an essential need, primarily due to the large electrical requirements of these systems. For serving essential circuits, it is common to see a transfer
switch with 10 to 12 specific circuits. These transfer switches range in size
from 50 to 100 AMPs, and are typically used with 7 to 12kW generators. The advantages
of this option are small generator size and lower costs (initial, operation and maintenance) compared to the whole house. The disadvantages include lack of flexibility due to
having to pre-select the protected circuits. See AC Power Module option below.
Majority of Circuits – For most, the option offering the greatest flexibility with minimal inconvenience is the majority of circuits option. The successful use of this option depends
on the size of the home, electric panel size, and which energy is used (gas or electric) to serve the larger energy consuming
appliances. With this option the concept is to isolate the largest electric loads
(air-conditioning) and serve the rest of the home. As previously mentioned, one
manufacturer’s transfer switch is a “smart” switch with built-in controls, allowing isolation of large loads
such as air-conditioning. For example, in a 3,500 to 4,000 square foot home,
if the large energy appliances such as heating and water heating are fueled by either natural gas or propane, it is then possible
to isolate the air-conditioning and serve everything else in the home. The
effective use of this option requires common sense conservation. Common sense conservation means that the homeowner limits the of use non-essential loads (dishwasher, washing
machine, etc). while operating on generator power. The advantages of this option
are small generator size, flexibility and lower costs (initial, operation and maintenance) compared to the whole house. See AC Power Module and Power Management discussion
AC Power Module represents enhanced electronics that automatically manage high power items like central
air and heating, along with other essential circuits in your home. Designed exclusively for use with the 12 and 20kW Briggs &
Stratton Home Generator Systems, the AC Power Module essentially optimizes a Briggs & Stratton 12 or 15kW generators
to run a 4 ton central air-conditioner and other essential power requirements while eliminating the hassle of a standby generator
overload and shutdown. The 20kW is rated to run 5 ton AC systems.
Power Management is the process of automatically shedding larger loads when necessary to make power
available for more important starting motor loads like air condtioning. GenSpring is a leader in this area and has more
power management systems up and running than any other generator dealer in Georgia. Through Power Management we can
help you: utilize a smaller more efficient generator system which lowers your generator cost, installation cost, fuel
cost and maintenance cost. The combination is a much wiser use of materials and fuel use to produce a more environmentally
friendly generator system.
Planning a New Home
Considering a standby power generator at
the outset of planning a new home can result in substantial savings for the homeowner.
Savings can occur in two ways. First, if standby power is important, the
use of natural gas or propane for primary heating and water heating will greatly reduce the size of a generator. For example, none of the generator systems discussed above can adequately serve an electric heat pump. In addition, choosing natural gas or propane for water heating frees up valuable generator
capacity to serve more important essential loads. Second, having your electrician
incorporate the transfer switch into the initial wiring plan saves time and installation cost.
Cost is a function of the size of the generator
system required to serve the homeowners needs. In new construction $400 to $500
per kW is a good estimate. In existing construction, installed costs are somewhat
higher depending on installation issues.
After the Sale
After the sale service is as important as
purchasing the generator system. Make sure you understand the service commitment
and capability of the selling party. Is the selling party a sales and service
authorized dealer, or just a sales outlet? If only a sales outlet, who will provide
service and warranty coverage? When purchasing from an authorized dealer, you
can expect help in sizing, planning your installation, start up and of course service after the sale.
About the Author
Clayton Preble is the founder and President of GenSpring Power, Inc.
Prior to forming GenSpring Power, he spent more than 30 years in the natural gas industry. Since forming GenSpring Power in 2002, he has completed manufacturer sales and service training, and successfully
met the requirements of Master Service Technician - the highest service level expertise certified by Briggs & Stratton.
GenSpring Power specializes in standby power generator systems for residential customers in North Georgia and is an authorized dealer for Briggs & Stratton
Power Products, Generac – Guardian Power Systems, GE, Eaton Cutler-Hammer and Kohler Power.
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