After experiencing one too many power outages, we decided to install a small gas generator at our home. (We chose a 3200 Watt model with 4000 watt peak). Since we have a detached garage – it made the most sense to mount the generator on an elevated wooden shelf (our home is in close proximity to a bay which can flood during severe prolonged storms). Next we decided that porting the exhaust outdoors so that we could enter the garage while the generator was running (for re-fueling etc…) Note: do not install a generator in an attached garage – many people die each year from inadvertent carbon monoxide poisoning from generators placed in the wrong area.
I drilled out some 2” plumbing cast iron threaded end caps with hole saws. One with muffler port clearance (7/8”) and the other end cap 1 -1/4”, which allows clearance for a zinc plated EMT conduit threaded fitting. I also needed to drill an access hole in the side of the end cap on the muffler side so I could tighten/loosen the internal clamp collar on the muffler port. I then connected the two end caps with a piece of aluminum flexible tubing. (The generator’s engine moves around on its rubber mounts and thus requires a non-fixed exhaust hose.) Support the middle of the aluminum hose with a piece of metal wire, to further reduce stress on the hose. Clamp collars hold everything in place.
I drilled out some 2” plumbing cast iron threaded end caps with hole saws. One with muffler port clearance (7/8”) and the other end cap 1 -1/4”, which allows clearance for a zinc plated EMT conduit threaded fitting. I also needed to drill an access hole in the side of the end cap on the muffler side so I could tighten/loosen the internal clamp collar on the muffler port. I then connected the two end caps with a piece of aluminum flexible tubing. (The generator’s engine moves around on its rubber mounts and thus requires a non-fixed exhaust hose.) Support the middle of the aluminum hose with a piece of metal wire, to further reduce stress on the hose. Clamp collars hold everything in place.
Next we decided to get a 30’ long 220v extension cord so that we could power our breaker panel. On the outside of the house, we installed a 30 amp outdoor rated quick disconnect box to a piece of Azec. Next we ran some 6 gauge wire (though only 10 gauge is required) from the disconnect box to a 30 amp double pole breaker mounted in the upper right most position inside of our panel.
Lastly, we fabricated a mechanical breaker interlock out of ¼” Lexan. The interlock ensures that you will never have the main breaker in the on position while the generator is in the on position. There are kits available for purchase online for almost any panel if you are not feeling ambitious. In order to make the Lexan, you will need to make a slew of measurements and make a template out of cardboard. Lexan is much easier to cut and trim than steel, so it is totally doable. The kits that you get online come with UL certification sticker, a homemade kit does not. So proceed accordingly. The tricky part of making the Lexan for our 150Amp Cutler Hammer panel, was getting the generator lockout tab to fit in-between the 30 amp double pole handle and the breaker below when in the “generator on” position. The slots and where you drill the holes in the dead front panel are also key - take your time and measure twice.
When switching between main breaker and the generator power, ensure that you switch off the branch breakers to eliminate damage to your electronic devices.
Lastly, we fabricated a mechanical breaker interlock out of ¼” Lexan. The interlock ensures that you will never have the main breaker in the on position while the generator is in the on position. There are kits available for purchase online for almost any panel if you are not feeling ambitious. In order to make the Lexan, you will need to make a slew of measurements and make a template out of cardboard. Lexan is much easier to cut and trim than steel, so it is totally doable. The kits that you get online come with UL certification sticker, a homemade kit does not. So proceed accordingly. The tricky part of making the Lexan for our 150Amp Cutler Hammer panel, was getting the generator lockout tab to fit in-between the 30 amp double pole handle and the breaker below when in the “generator on” position. The slots and where you drill the holes in the dead front panel are also key - take your time and measure twice.
When switching between main breaker and the generator power, ensure that you switch off the branch breakers to eliminate damage to your electronic devices.
In order to fit the double pole breaker, I had to move some circuits from singles to tandem breakers. Tandem breakers are very useful for times like this, when you need to get more circuits into a panel that is maxed out. Another note I picked up from an electrician - I always label each black wire going into a breaker with a small piece of Romex, it makes your life much easier when it comes to identifying circuits and labeling the dead front panel.
Our home has lots of LED lights, a high efficiency fridge and a tankless water heater – so fortunately, the 3200 watt generator has enough power to keep our whole home running. Keep in mind, running an oven, microwave, and other high wattage devices simultaneously will not work with a 3200 watt generator – you will need a generator with more power and a larger input breaker.
Good luck with your generator installation project. Witnessing your home running off generator power for the first time is pretty sweet. If your budget permits, you might consider a natural gas generator or an automatic transfer switch – but we wanted to show you how to get a system up and running as simply as possible.
Our home has lots of LED lights, a high efficiency fridge and a tankless water heater – so fortunately, the 3200 watt generator has enough power to keep our whole home running. Keep in mind, running an oven, microwave, and other high wattage devices simultaneously will not work with a 3200 watt generator – you will need a generator with more power and a larger input breaker.
Good luck with your generator installation project. Witnessing your home running off generator power for the first time is pretty sweet. If your budget permits, you might consider a natural gas generator or an automatic transfer switch – but we wanted to show you how to get a system up and running as simply as possible.
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