Generator Safety: Power Up Without Getting Knocked Out.

Inexpensive gas generators are a big favorite in the amateur radio community. Everyone seems to love these effective albeit cheaply made power plants! As they became more popular, the law of averages kicked in and there was an unfortunate but not unexpected increase in accidents and deaths related to small gas generators. In an effort to prevent a tragedy, we’ll be going through gas generator safety. I’ll also show you how to more effectively use your generator.

If you’re the kind of person who thinks you don’t need to read the dorky generator safety stuff, then you’re probably exactly the kind of person who should.

Have a plan before you need a plan.
Most accidents occur due to haste or lack of planning. Don’t be the mall ninja who just buys stuff and stashes it away. Plan out how you will use your generator and run practice drills as often as needed to make sure your plan will actually work.

Issues that need to be addressed include: Where will the generator be stored, and where will it be used? How easy is it to move from one spot to the other? Do you have the correct length and type of cords to power your equipment and where will these items be kept? How much fuel can you store and how will it be dispensed?

Imagine that it’s the middle of night and the grid goes down during a heavy storm. It’s pouring rain and the basement will quickly flood if you don’t get the generator on line real soon. This is not the time to be running around looking for an extension cord, or digging the generator out from under all the clutter stacked on top of it, or realizing the five gallon fuel tank has about two cups of gunked up old gas in it.

While none of these things are an inherent generator safety hazard, they do incite haste & carelessness, which in turn increases the probability of an accident. No one wants to be running around in a storm trying to solve problems that with some simple forethought could have been avoided in the first place.

So the first step to generator safety is to be prepared. Decide where your generator will be stored. If the storage spot is different than where it will be when running, then consider how easy it is to move between the two places under adverse conditions.

Cables, cords, and other generator supplies should be centrally located and easily accessible. I store mine in a large plastic tote. These items are dedicated to off-grid generator use only and are not “borrowed” for any other purpose. When the need arises, I can grab the tote and be confident that I won’t have to hunt around for anything. I also suggest having a supply of motor oil, a spare spark plug, a spark plug wrench, and an air filter.

Having everything staged and ready to go will eliminate the anxiety that comes from disorganization and reduce the opportunity for an accident. In a grid-down situation you’re going to be plenty stressed without added distractions.

Making the right connections.
The easiest way to use your generator is to simply plug into the outlets on the generator and go. Extension cords are fine as long as they are used within their rated load limits. Stringing two or more extension cords together is not acceptable generator safety practice!

generator safety

Common NEMA connectors found on larger generators: Two L-series twist lock plugs and two 5-15 common 120 volt plugs. OFF GRID HAM ORIGINAL PHOTO ®2017

Your generator should have a ground lug somewhere on the frame. When an electrical cord is run directly to a generator that is isolated from earth ground, the ground prong on the cord and the safety purpose it serves is disabled. It becomes just an extra unused wire. You have to complete the bond by running a wire from the lug on the generator to an earth ground. The earth ground does not need to be anything elaborate. A simple metal spike temporarily pounded into the dirt is fine. This will give you the same level of safety as if you were plugging into the outlets in your house.

Omitting the ground is not the most horrible generator safety violation in the world, but it should be used whenever possible. Grounding the generator will also help reduce RFI in your radio equipment.

Transfer switches.
Installing a hard wired transfer switch in your house provides an additional layer of generator safety because it eliminates the need to run extension cords all over the place. The other big benefit transfer switches offer is that all the outlets and devices in your house will work as they normally do. Transfer switches cost from a few hundred dollars for basic manual models up to the thousands for a fully automatic version. Also, factor in the cost of wire & materials beyond the switch itself.

generator safety

A six-circuit transfer switch. A 240 volt feed is split into two 120 volt branches with three circuits on each. OFF GRID HAM ORIGINAL PHOTO ®2017

Installing a transfer switch often requires a building permit. The rules vary depending on where you live, but in general, a permit is not needed for a transfer switch if it A) is manually operated, and B) will be used on a portable generator that is not permanently connected to an electrical circuit. This is the legal loophole I used to install my transfer switch without getting the government involved.

I did my own switch install, but be warned this kind of project is not for the casual do-it-yourselfer. Transfer switch installation requires advanced skills; if you want to go this route and you’re not completely fluent in home electrical wiring, including working around hot circuits, do yourself a huge favor and hire a pro. Part of generator safety is knowing your limits and not exceeding them.

As always, do not rely solely on internet advice, even if it does come from a credible source such as Off Grid Ham! Do your own due diligence and comply with local codes and/or NEC standards. Never take shortcuts with electricity. The electricity will always win.

Power cables for transfer switches.
A standard extension cord cannot be used to connect a generator to a transfer switch. Expect to spend good money for a correct cord.

Most transfer switches use an L-series NEMA male plug with either three or four prongs, and most larger generators have a corresponding female plug. Shop carefully because there are different types of connectors in use, and you may need a different type of connection on each end. The nomenclature works like this:

L = round twist lock
5 = 125 volts max
6 = 250 volts max
20 = 20 amps max
30 = 30 amps max
R= receptacle (female)
P= plug (male)

EXAMPLE: An L6-30R is a twist-lock, 250 volt, 30 amp female connector.

generator safety

An L-14-30P feed to my transfer switch. In my area, a permit is not required for this type of setup. L= locking plug, 14= either 125 or 250 volts, 30= 30 amps max, P= plug (male). OFF GRID HAM ORIGINAL PHOTO ®2017

The “Big C”: Carbon monoxide.
According to the Consumer Product Safety Commission, over 80% of non-fire related carbon monoxide (CO) deaths are from the improper use of gas generators. That’s not a typo. Generators alone cause four times more CO fatalities than all other CO hazards combined!

One would think that running the engine in an outdoor, well ventilated area is as instinctive as breathing itself, but as the CPSC statistics show, a lot of people are not listening to their inner voice. Every time there is a large storm that causes widespread power outages, reports of carbon monoxide deaths increase dramatically due to failure to follow this most rudimentary & obvious of generator safety guidelines. The fatalities are 100% preventable.

We will not spend many lengthy paragraphs discussing this because there should be no need to. Use a little sense! Generators should never be operated in attached garages (even with the door open), enclosed porches, crawl spaces, or near open windows, doors, or air intake vents.

Since I know a lot of my readers are going to ignore this generator safety advice, please at least have one or more carbon monoxide detectors in your home so you will have early warning when your lack of instinct catches up with you.

Can you hear me now?
Generators are low priced because the manufacturers cut corners. One of the most obvious shortcuts they take is at the muffler. With only a few exceptions, generators are dangerously LOUD! Hearing protection is inexpensive and very effective, so there is no good reason not to use it when near a running engine. Hearing loss from excessive noise usually occurs incrementally, sometimes over many years, and is irreversible. You may not notice until it is too late.

Many radio amateurs lack awareness of hearing conservation as it relates to generator safety, but the problem is very serious and also easily 100% preventable.

“Clown Cords,” or, things you should never, ever do. 
There are two common DIY connection methods that technically work, but are so outrageously hazardous that it’s hard to believe that people actually do this:

Trick #1 ”The Cheater Cable : This is a custom made extension cord with a standard household NEMA 5-15 male plug on both ends. One side plugs in the generator, and the other plugs into any outlet in the house. The power will then be backfed to every outlet in the house connected the same breaker panel.

The danger is one end of the cord will have exposed energized contacts. On top of that, the power from the generator will also backfeed into the main power grid and endanger electrical workers trying to restore service. The hazard to power company employees can be eliminated by shutting off the main breaker, but anyone who would use a “cheater cord” is probably not going to care enough to take that precaution.

Trick #2 “The Jack In The Box”: A custom cord is made with a male plug on one end and bare wires or spring loaded clamps on the other. The cord is plugged into the generator, and the bare ends/clamps are terminated on the main bus in the breaker box. I’ve even heard of people doing this with automotive jumper cables! This trick creates the same problems as #1.

There are a variety of other shortcuts and questionable solutions. If it looks and feels unsafe, it probably is. All of these hacks are extremely dangerous and are among the worst generator safety violations out there. If anyone gets injured or killed from a “clown cord”, the responsible party will for sure be in a world of legal trouble in addition to the emotional trauma of having been the cause of a totally avoidable accident.

If you plan with the right stuff, there will be no need to resort to the wrong stuff!

Key Points-what you need to know.

  • Always store your generator and accessories in a way they can be quickly & easily accessible under adverse conditions.
  • Always use the correct type and size cables/cords to power your equipment from a generator. Never plug two extension cords together.
  • Generators should be bonded to earth ground whenever possible.
  • A transfer switch is the best and safest way to connect a generator to multiple loads.
  • Generators are the #1 cause of non-fire related carbon monoxide poisoning deaths. Use some basic sense to assure you won’t be a statistic.
  • Hearing protection should be used when around running generators.
  • “Clown cords” are extremely dangerous hacks and should never, ever be used to connect a generator to home wiring, or anything else.


This Off Grid Ham Article from 2015 gives additional info about generators.

For the truly nerdy, here is a PDF report from the Consumer Product Safety Commission about carbon monoxide fatalities.

Here is a printable info-graphic about generator safety that can be distributed at a ham radio club meeting or hamfest.

This really cool chart from Interpower is a superb, one-page reference describing NEMA connector nomenclature.

The Better Hearing Institute has useful information about hearing loss prevention.

Generator safety & use is admittedly not the most exciting topic in the world, but it is important. The rules are not complicated or hard to follow. A power outage elevates the possibility of an accident; the competent off grid ham will have the right equipment, the right frame of mind, and the right plan to get through it without becoming their own safety hazard.


4 thoughts on “Generator Safety: Power Up Without Getting Knocked Out.

  1. Mitch

    While expensive, I use a Whole-House backup generator that kicks in automatically and as the name implies, powers the whole house. I also keep a 2 KW inverter Generator. Since 2 K is not enough to power the house, I have a have a plan that centers on the radios, pellet stove, and refrigerator. I have tested the inverter on the generator and pellet stove thus far. The main radios are fed by a large AGM storage battery. The secondary radios and scanners are powered by the power supply, which also keeps the battery charged. End result is the main radios and computer never go down. While the two mains may draw 40 amps total if transmitting at the same time, the battery draws about 10 amps max to charge. In testing, I ran it for 48+ hours during an exercise using solar to charge the battery incase all else fails. One of the radios has a high transmit cycle as it runs a radio mail system on HF. This give me plenty of time to get the inverter set up, which is used if the whole-house generator fails,. The solar system is already set up – just need to disconnect the power supply.

    The beauty of the system is that I can always keep the radios up; keep the house warm about 60% of the time, and the inverter and solar system are transportable for my back-up/deployable emergency radio system.

    1. Chris Warren Post author

      Hi Mitch, thanks for stopping by Off Grid Ham. I didn’t get into whole house generators because that’s a little beyond where I wanted to go with this article. I will point out that whole house generators are usually fueled by natural gas, so they are not truly “off grid” and will run only as long as the gas company is on line. You did the right thing by coming up with a separate stand-alone solution and testing it before it will be needed. You set a great example; this is the kind of forethought I want all my readers to have.

  2. randall krippner

    Nicely written, as always. Those safety instructions of yours should be required reading for anyone even thinking of buying a generator!

    One thing a lot of people seem to neglect is test running their generators on a regular basis. The result is that when an outage does happen, either the thing won’t start, or even more sad, there is no one around who knows how to run it or start it. A lot of them can be a real pain in the neck to start, especially if they haven’t been run in a while.

    Even more annoying is that gasoline has a shelf life that is measured in weeks, not months, really. Ideally that gasoline in the tank should be drained or used within a couple of months of being put in the tank. Putting a fuel stabilizer additive into the gas will help, but even that’s not a sure thing. Test running them on a regular basis (a minimum of an hour, preferably more) will help too. Ideally the gas tank should be drained every three or four months and fresh fuel put in, but it’s unlikely many people will do that. So at the very least some kind of fuel stabilizer should be used.

    Just starting the things can be an issue. Unless they are test run on a rather frequent basis, they can be a bear to start, especially if people can’t read instructions, and most seem to be unable to read the starting instructions written right on the machines. With pictures… Sigh…

    One thing I wanted to bring up is that I’ve heard that some modern furnaces will not work properly without “clean” power, i.e. an inverter, not a generator. I’m not sure if that’s true or not. I have a 2KW inverter that is more than enough to run the furnace if necessary, but I haven’t tested it with the big 9KW Generac we use to power the rest of the house. I’m afraid I’d wreck a $6,000 furnace :/


    1. Chris Warren Post author

      Hello again, Randall. You are right: Test running a generator at least every quarter and rotating the gas should be a part of the plan. There are a lot of opinions on how long treated gas will last; I don’t let mine go more than 6-8 months and have had good luck with that cycle. Also, when test running a generator, make sure it is under a load of 1/3 to 1/2 of the total capacity of the generator (portable electric space heaters are ideal loads). There is no benefit at all to having an engine spinning freely doing nothing, and it can even damage the device over the long term.


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