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· ke4sky
190 Posts
Generators 101

Portable Generator Basics And Safety

If you can't recharge your batteries when the grid is down, once you have run them down, they are useless. Generators are a good solution, but are not the only answer.

If you don't know what you are doing, stay away from generators, because a screw up may kill you!

NEVER connect a portable generator to house wiring unless a double-pole, double-throw transfer switch has been hard-wired into the breaker panel.
This disconnects the house wiring from the AC mains.This prevents your generator from injuring utility personnel working trying to restore your power and also prevents "back-feed" from blowing up your equiopment when the mains do come back up. Installing a transfer switch requires an electrical permit and inspection and is a job for a licensed electrician which must meet requirements of the National Electrical Code (NEC).

An adequate earth ground is needed for any portable generator.
This is necessary to ensure your personal safety. Never run a generator in standing water or work on the generator or feed lines while standing on wet ground.

Never run a generator inside an enclosed building
This is because it is impossible to adequately ventilate carbon monoxide and fumes.

Use only UL-listed 3-wire extension cords.
Always plug cords into equipment first before connecting them to the generator feed. Medical devices and computers require clean "sine wave" 60-cycle AC power and should never be run direct from unconditioned "square wave" generator feeds of varying cyclic rate.

Gasoline generators produce about 600w at 120 volts AC for each engine horsepower.
A 100-watt HF-SSB transceiver requires about 1200 AC watts at 120 volts. Generator capacity must be sized to not only the running wattages of the equipment, but also for the starting loads. For low-loads such as furnace fans multiply running wattages x 2, for pumps or compressors you must multiply the running wattages x 7.

A 3.5 HP portable generator is the minimum recommended to operate a home emergency radio station for ACS or RACES use. It can be carried by one person, uses 5 gallons of gas every 24 hours and produces about 2 kW. It can power a modest station, such as a 100w-SSB or VHF-FM Landmobile or amateur radio, laptop PC, wireless modem or terminal node controller, several small NiCd chargers, an automotive battery charger and limited emergency lighting for the radio operatiuong position only. Don't expect 2kw generator to also power your well pump, refrigerator, hot plate and coffee pot!

Light-duty recreational generators are not rated for continuous duty, They may "quit" and not restart when hot, under prolonged disaster conditions. They should be limited to intermittent use for battery chargers, emergency lighting, cooking and limited use of power tools.

The minimum generator to power an average single-family house or an Incident Command Post in the field supporting a SAR or wildfire supression mission is 5kW. A typical commercial-grade, continuous-duty generator of this size has an 8HP engine, weighs 200 lbs., produces 32A at 120 volts and runs 8 to 10 hours on 5 gallons of gas and requires a 55-gal drum of clean fuel to be brought ot it every 72 hours of continous duty at full load. A larger generator is practical only if you have a reliable source of fuel.

It is unsafe to store more than one 5 gallon jerican can of gasoline in your barn or garden shed. F-3201.2 of the Uniform Fire Code prohibits storage of more than 5 gallons of gasoline in residential areas. Storing larger quantities in a residential area requires a hazardous use permit and storage area which meets the NFPA standard. Stored gasoline goes bad in a few months unless treated with stabilizer.

Store extra gas cans empty. When the hurricane Watch changes to a Warning, then fill your cans while there is still mains power to run the pumps, then store them under cover, and securely tied down outside! Once the generator is started, use a wooden dip-stick to check fuel level every 2 hours and top off tanks before they run out.

Generator Safety Tips From the U.S. Consumer Product Safety Commission:

Carbon monoxide hazard!
Never use indoors or in attached garages!
Set up OUTDOORS in a well ventilated, dry area
Away from HVAC air intakes
Under a canopy, open shed or carport

Electrocution Hazard!
Adequate grounding of generator and equipment!
DO NOT connect or plug into household AC!
Plug only individual devices into generator
UL-rated cords of wire gage adequate for load

Explosion / fire hazard!
Fuel vapors can travel along the ground and be ignited by sparks, arcs from switching equipment, or pilot lights from appliances!
Store fuel outdoors in a ventilated shed
Use Fire Marshall approved containers

If a backup generator is to be connected to a building electrical service, NEC requires that it be equipped with a double-pole, double throw transfer switch.
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