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Generators

A emergency or back-up generator is a back-up electrical system that
operates automatically within seconds of a utility outage. An automatic transfer
switch senses the power loss, commands the generator to start and then transfers
the electrical load to the generator. The standby generator begins supplying
power to the circuits. After utility power returns, the automatic transfer
switch transfers the electrical load back to the utility and signals the standby
generator to shut off. It then returns to standby mode where it awaits the next
outage. To ensure a proper response to an outage, a standby generator runs
weekly self-tests. Most units run on diesel, natural gas or liquid propane gas.
Automatic standby generator systems may be required by building codes for
critical safety systems such as elevators in high-rise buildings, fire
protection systems, standby lighting, or medical and life support equipment.
Residential standby generators are increasingly common, providing backup
electrical power to HVAC systems, security systems, and household appliances
such as refrigerators, stoves, and hot water heaters.
Emergency/Backup Generators: Gasoline,
Natural Gas, Propane and Diesel
It takes a lot of
calculation to properly size a home generator, and you'll need to talk to a
installer to be sure you've got it right. In a nutshell, though, the machine's
wattage has to be slightly larger than all simultaneous loads. First, tally
the running watts of the appliances and devices you will use at the same time.
Now add the startup wattage of the largest motor—operated load liable to come
on line with the other loads. Motor wattage is three to five times greater at
startup than it is running at steady state, and your largest startup load will
usually come from a furnace fan or a well pump. (That assumes you won't be
running an air conditioner during a power outage.) Wattage is listed on a
motor's nameplate or on the electrical data plate affixed to an appliance. If
wattage isn't listed but amperage is, calculate wattage by multiplying amps by
volts. Aside from motor wattages, other loads, such as those imposed by
electric water heaters, can severely strain a generator's output. Calculate
accordingly.
The risk from carbon monoxide poisoning is not to be taken lightly, so locate
the machine to minimize that risk. The Consumer Product Safety Commission
estimates that in 2005, for 10.6 million portable generators, there were 85 CO
deaths. A rule of thumb is to keep a portable generator 10 ft. away from the
house. Permanently installed generators are much safer in this regard since
they are fueled not by gasoline but by cleaner-burning natural gas or propane.
Make sure the generator's distance from the house meets both the
manufacturer's specifications and the requirements of building and zoning
codes (it can't infringe on your neighbor's property line, for example).
The next major safety issue with generators is electrical. Don't operate a
portable generator using a homemade extension cord with two pronged ends,
connecting one to the generator and the other to a wall outlet receptacle.
Electrifying a house's branch circuit this way can create a fire and shock
hazard, especially in older homes with weak or improper wiring.
Instead, use heavy-duty exterior extension cords to plug appliances directly
into the machine, or use a single cord and connect the generator to a
power-transfer switch. This device is a specialized circuit-breaker panel that
is wired into the house's regular circuit panel. It isolates circuits to be
powered, while blocking generated current from flowing into the grid outside
the house. Current back-feed poses an extreme hazard to utility crews working
on downed lines. The reason it's so deadly is that the voltage of the reverse
flow is stepped up when it passes through the pole-mounted transformer, which
normally steps down voltage to household levels.
In addition to boosting safety, a transfer switch better enables you to power
built-in appliances, such as a furnace, that cannot simply be connected to an
extension cord.
Finally, test run the machine. In the case of a portable generator, that means
wheeling it out to the location where you intend to run it and putting it
through its paces. If you're going to run appliances from it using generator
extension cords, test run the machine with the cords hooked up so that you're
sure everything will work as intended when the power goes out. Permanently
installed generators can be programmed to automatically test run the unit any
day and time of day you wish.
You'll want to start up the machine on a regular basis to be sure it operates
properly. Add gasoline stabilizer to its fuel. This additive will prevent the
fuel from chemically deteriorating
Key Benefits
- Benefit 1: Power for crucial
medical equipment.
- Benefit 2: Power for heat
- Benefit 3: Power for cooking
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