Residential Generator Safety Guidelines
Disclaimer: This list was written and compiled by Carl Wahl from multiple sources
between 8/2019 and 2/2022, plus input from Stuart Tom. Still, the below should not
be considered as a comprehensive list.
The numbering is non-prioritized.
This list covers both portable and standby generators. A number of the items would
not apply to properly installed standby generators.
- Outdoor use only:
Generators should only be used outdoors in a well ventilated area.
Generators should never be run in a garage, even with the garage doors open.
The above applies to all outbuildings as well.
- Generators should rest on a stable, fire-resistive or noncombustible surface such
as a concrete, asphalt, gravel, soil, or similar surface clear of leaves and/or other
combustible debris. Maintain a leaf and debris-free 5-ft. radius area around the
- Keep the generator dry. Don’t operate the generator if your hands are wet or if
you are standing in water.
- Backfeeding is both illegal and deadly. A power transfer switch is mandatory (if
one is not exclusively using the generator’s receptacles). Simply put: Never plug
a generator’s output into a wall outlet. This is an electrocution hazard for utility
workers and your neighbors. Also, backfeeding can instantly destroy your
generator when power is restored.
- If you install a manual safety transfer switch, try buying one that has the ability to
lock the cabinet (or one that can be retrofitted to lock). For 200A service, there’s
48kW of live electricity inside.
- Assure the generator is properly grounded. See pp. 73-78 of the “Generators for
Your Home” seminar under the “Resources” tab on SWC’s website at
saferwestcounty.org for info on how to check for, and how to correct, this often
overlooked (or improperly made) connection.
- Have a qualified electrician familiar with generator installations install your generator
backup power system.
- Never modify a generator without manufacturer approval.
Of particular note are modifications made to reduce noise. Never encase a generator.
Always maintain proper clearances. Fires have started by people placing boxes over
their generator, or otherwise shielding them, in an attempt to reduce noise. If noise is of
great concern, buy a “quiet” generator (like an inverter).
- Carbon monoxide: Most generator-related deaths are due to carbon monoxide
When in use, keep the generator outside and at least 10-feet from doors and
window openings. (Also: Read the second bullet under Number 14 below.)
Again, don’t use a generator in a garage. Wind gusts can trap high levels of
CO inside, which then may seep into the home.
Install a CO alarm in the area closest to the living space where the generator
will be running.
Per the CDC, never look for the source of a gas leak. If your CO alarm goes off,
go outside and call 911. Seek medical attention if you are dizzy, light-headed, or
nauseated and suspect carbon monoxide poisoning.
- Never attach or detach a generator cable while the generator is running.
- Shut the generator off and let it cool before refueling.
- Keep extra fuel, and any other flammable fuels, at least 10-ft. away from the generator.
- Gasoline fuel line leaks:
The proximity of the generator gasoline fuel line to the exhaust and/or muffler
may pose a fire safety issue.
Most gensets have the fuel tank positioned over the engine to allow the fuel to
gravity feed the carburetor. The fuel line is almost always made of rubber
and, over time, deteriorates (due to a combination of heat, UV light, and the
fuel itself). Periodically check the fuel line for small cracks—especially in
older units. Often too, the fuel line becomes brittle due to heat. In either
case, immediately replace the fuel line. Gas dripping onto a hot engine or
muffler will almost assuredly cause a fire.
- Propane or natural gas fuel line leaks:
Whenever attaching a fuel hose, check for gas leaks after tightening the fittings.
Use soapy water, or similar, to test for this. (Brush the solution onto the fittings
and check for bubbles.) That said, do not over-tighten compression fittings.
- Generator clearances (generator proximity to one’s home or outbuilding):
There appears to be no agreed upon clearances, nor any related California codes,
addressing this topic. Written opinions vary wildly. This is understandable.
Due to the multitude of generators, and generator types and sizes available,
follow the manufacturer’s recommended clearances for your
genset—including the minimal overhead clearance. If not stated in the
product literature or owners manual, contact the manufacturer and obtain this
information (ideally in writing).
From a carbon monoxide standpoint, the CDC recommends a clearance of 20-ft.
between the generator and the home. Other sources cite different clearances.
(One recent development: Many new generators now include automatic shutoff
All this said, engine exhaust should always be directed away from windows,
doors, and any combustibles.
- Periodically inspect the muffler’s spark arrestor screen for burn holes, carbon buildup,
deterioration, and proper positioning. If it is missing or damaged, replace it.
- Undersized generator cable(s):
Overloaded generator power cables can overheat and cause fires. The cable(s)
must be capable of handling the maximum generator output(s). This also
requires matching the wire gauge to the cable length. (See the two “Wire
Size Selection” charts posted at the end of the of “Generators for Your Home”
seminar under the “Evacuation” tab at firesafeoccidental.org.)
If using extension cords, use only undamaged outdoor-rated cords, and assure
they are of adequate gauge for the lengths and likely maximum loads.
When in doubt, use the next higher gauge (i.e., use a cable with the next lower
- Keep generator cables out of the way so they don’t present a tripping hazard.
Never run cables under rugs or carpets where heat might build up or where damage to
a cord may go unnoticed.
- Undersized generator:
This is a hazard that can damage or destroy the generator and/or potentially
anything connected to it. Proper power management may mitigate this issue.
Power management information and generator power sizing are discussed on
pp. 28-33 in the “Generators for Your Home” seminar under the “Evacuation”
tab at firesafeoccidental.org.
To properly “size” a generator for your needs: Calculate the maximum
amount of both running/continuous watts and startup/peak watts needed for
the items you wish to power. Then add about 10% to those figures for
“future-proofing.” Use a generator whose output at least meets those power