Running a Generator in a Detached Garage

Running a Generator in a Detached Garage

How to Run a Generator in a Detached Garage

If you live in an area where power outages are common, you probably have a generator on hand, maybe even two. Generators are incredibly useful for having a back-up power supply for your house. If you live in the middle of nowhere, you may even use a generator to power equipment and machinery away from the main house.

If you run a business in a place where it gets deadly cold in the winter, you may want a generator handy to keep the lights on, just in case. But what do you do if you want to run a generator in your detached garage or shed?

As handy as generators are, they are better off used outside. You really shouldn’t be using a generator inside any enclosed space, detached or otherwise. It’s a terrible idea. Gas generator or electric generator, they are both going to produce hazardous carbon monoxide, which can kill – and pretty darn quick.

If you start a gas generator in the garage and leave it running with the doors and windows closed, all that toxic carbon monoxide is going to build. If you happen to be inside at the same time, the toxic gas will literally suck the oxygen out of your lungs. It’s like standing at the lip of an active volcano. 

How to Use Your Generator Properly (Running Generator in Garage)

There are some important safety tips you need to be aware of before pulling the starter of your generator. If you’re using it to power the electricity in your house, turn the main power off. This is true even if there is an outage. Turn your house’s power off before plugging into the generator. This will prevent backfeed. On another note, make sure you have a professional wire your house’s electrical to the generator. Don’t do it yourself or you could end up with a dangerous and unreliable setup.

You never want to overload your generator. This is a nasty idea. If you’re plugging a few things into it, obviously that will be okay. If you’re using it to generate all the power of the house, maybe don’t turn on all the freezers, TVs, electric stoves, and hot tubs that you can find.

Take it easy or you could overload your generator and cause problems. In an emergency, you always want to prioritize what you’re using the generator for. Essential electricity is first. 

Try to use heavy-duty extension cords with your generator. For that matter, use clean and functional extension cords, no ratty ones with holes in them or rusty inner cables. Keep them out of the way to prevent tripping and pulling out the power unexpectedly. You probably shouldn’t cover them with carpet, nor should you tape them to the ground.

When you are refuelling your gas generator, turn it off. Never fill up the gas tank while the generator is still running. This is begging for trouble.

Turn the generator off, let it cool down, then pour in the fuel. The last thing you want is fuel catching fire as you’re pouring it into the machine. That would be a literal disaster.

Always keep your kids and pets away from the generator and away from the fuel. 

Related – How to Get Gasoline Smell out of Your Garage

Is It Ok to Run the Generator in Garage With Door Open?

Ventilation is incredibly important. Because the exhaust is pumping out deadly carbon monoxide, it is ideal to only run your generator outside, preferably sheltered by an awning of some sort.

You can use the generator in the garage but be sure to leave the door all the way open. A cracked window or cracked garage door is still going to allow the carbon monoxide to build up.

If you need to use your generator in a detached garage, keep reading.

How to Run a Generator Inside a Detached Garage

You have already been warned about the dangers of carbon monoxide poisoning and to never operate a generator inside an enclosed space, like a detached garage. However, if you must, there are smart and safe ways to go about it. One of the best ways is by simple ventilation.

Ventilation is key. You need to keep your detached garage ventilated. Because you are unlikely to have a big enough chimney, and unless you are only going to run the generator with the door wide open – assuming you have a large garage door in the first place – you will need to make some venting.

Before you vent, decide where the generator is going. You don’t want it flat on the ground, so build a base with some 2x4s and a sheet of plywood, kind of like the base of a fireplace. In fact, this whole setup is a lot like installing a fireplace. Once your generator is on the base, you can figure out where to open a hole.

Generator Garage Exhaust Hose

The hole should be close enough that your exhaust isn’t going to be too long. Open a hole in the side of your garage, through the siding and wood and everything.

Next, you want to get a vent cap. Stuff your vent cap through the hole in your detached garage. the size of your vent cap and hole really depends on the size of your exhaust extension and hose that you are going to use.

Also don’t use plastic or cheap aluminum hosing, as this will likely melt or be a fire hazard. To attach the hose you would need to make or buy a coupler that bolts or screws directly to the generator exhaust/muffler and attach a flexible metal exhaust tube(such as what is sold at auto parts supply stores) with muffler clamps.

Or, if the generator has a nipple on the muffler, attach and clamp the tubing to that, being sure not to restrict the exhaust by making too long a run.

Here is a video making an exhaust extension that would work, and then you can attach the extension to your ventilation system.

It’s not 100% safe, so don’t go tinkering in your detached garage with the generator running. If you can’t make a vent out of the garage wall, leave all the windows open and try to pipe it out of a window. Either way, none of this is all that safe. You want to use the generator outside if possible. If not, always vent! It’s only the carbon monoxide that is dangerous. Get that outside and up into our lovely atmosphere and you will be okay. 

Also make sure you use a CO2 monitoring system in the garage while you are working in there and also running the generator.

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