It feels like the power grid for our subdivision in Houston is extra sensitive and the slightest wind can knock out the power. After reviewing options for standby power solutions, I decided to go with a simple gasoline powered portable generator. The little generator was able to power the entire house including both ACs and coffee maker (barely, more on that later). Hurricane Beryl hit us as a Category 1 on Monday around 1 AM and by 5 AM the power was knocked out. The gasoline generator powered the house for 4 days until the power was restored on Thursday at 9 PM.
List of Components and TLDR
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TLDR. Make sure your breaker panel has room for 1 more dual pole breaker. Then, get an electrician to install the Inlet, Mechanical Interlock with new 30 amp breaker and Soft Starter for the AC.
Champion 8750-Watt Generator I chose this generator because it has enough power for my needs (2 HVACs and refrigerator) and it produces Clean Power with less than 3% THD. Less than 5% THD is needed for powering sensitive electronic equipment like the HVAC.
30 Amp Power Inlet Box NEMA L14-30 Any 30 Amp inlet box will do.
Eaton 30 Amp breaker Make sure to get the one for your panel type.
4 Prong 30 Amp 75 Foot Generator Extension Cord I needed a really long cord because the Inlet box is on the front corner outside wall of my house on the other side of the breaker panel and I wanted to put the generator far into the backyard away from the house. Generators produce carbon monoxide and needs to be far away from any windows and walls.
Mechanical Interlock for my breaker panel. I have the Cutler Hammer / Eaton type. There are other types, like this Square D brand mechanical interlock. The sticker on the breaker tells what type to get for the interlock.
EasyStart Micro-Air 386 Soft Starter The HVAC system’s compressor uses a surge of power from not running to running. This generator has a 30 Amp output. That means the instantaneous draw should not be much more than 30 Amp for too long or the generator will trip. The EasyStart device reduced the 4 ton unit’s LRA from 117 to 43 (63% reduction) and the 2 ton unit’s LRA from 58 to 26 (55% reduction). This was enough to start the compressors without tripping the generator. More details below.
All the Details
Breaker panel
Make sure your breaker panel has room for 1 more dual pole breaker.
This is a dual pole breaker.
This is a single pole breaker.
This is what the Breaker Panel looks like with the dual pole breaker installed with the mechanical lockout. The new breaker is installed on the top right, right under the main on off switch. The point of this sliding metal piece is so both the generator inlet breaker and the city power switch cannot be in the On position at the same time. In order to flip the inlet to On, the city switch needs to be off then the metal interlock can slide up to allow for the Inlet breaker to be flipped to On. This is a safe guard against accidentally powering the city line with the generator if both breakers are in the On position. It is unsafe to send power down the city line because a city electrician could be servicing the line expecting no power on it and instead get zapped.
Inlet Box
The Inlet box looks like this.
I hired an electrician to drill a hole through the breaker panel to the outside wall to connect this inlet box. Installation and parts cost $737.10.
HVAC Compressor soft start modification
I have a 4 ton unit and a 2 ton unit. Here are the labels on each of the units.
The Locked Rotor Amps (LRA) shows 117 for the 4 ton and 58.3 for the 2 ton. This is the amount of instantaneous current spike that is needed to start the motor. The 30 Amp generator output cannot give an 117 Amp spike. The soft start device is directly connected to the motor to gradually increase power until the compressor starts. I had just enough room in the compressor to mount the EasyStart device. The electrician can install this also.
After installing the Micro-Air’s EasyStart 368. I measured the inrush current.
The 4 ton reduced from 117 to 43.6 and the 2 ton reduced from 58 to 26. I knew I could start the 2 ton from these measurements. I was disappointed the 4 ton unit didn’t reduce to under 30. When the hurricane hit and left us without power, desperate times call for desperate measures. I tried starting the 4 ton unit on the generator and it worked! It turns out that the instant spike was so short, the generator did not trip. Hooray! I could start one AC, let it run, then start the other AC and have both AC’s running at the same time. This was pushing the generator to its limits and I ended up running one at a time. When the 4 ton unit was running and I started the coffee maker, the generator tripped. So I had to restart the generator and before starting the 4 ton unit, make the coffee.
Generator and Connections
The generator looks like this.
The 30 amp output is connected with the 4 prong cord to the wall inlet.
That’s it. Whole house power for about $2,500.
Generator was about $900. Inlet and breaker $737. The 75 ft cord was $170. Soft Starter was $350 (times 2 because I have 2 ACs).
Closing Thoughts
The generator was able to power all the electrical outlets, the lights, the ACs, the kitchen fridge, and the garage fridge. The only hassle was to get gasoline once everyday. I bought 10 gallons each day. The generator’s 4 gallon tank needed to be filled every 8 to 10 hours. It ran for almost 4 days straight. I did give it a little 2 to 3 hour break everyday. Even though our Comcast router had power, it wasn’t connecting to the upstream. I guess there is Comcast equipment in the neighborhood that was unpowered. Our router was able to get a connection immediately when the city power was restored. Future improvements to this setup could be to buy the natural gas conversion kit and install a natural gas line close to the area I would put the generator so I wouldn’t have to fight the crowd to get gasoline everyday.
Backup Power Options
I considered several options.
Solar Panels with Power Walls — $40k to $60k
Permanently attached whole house standby generator — $15k to 20k
Gasoline or Natural Gas Portable generator — $2k to 3k (parts and installed)
Being a tech guy, the solar panels with power walls option is the most appealing. But after considering the downsides, I decided against it. I got several quotes with different panels, inverters, and battery storage. The solar panel companies have a 20+ year warranty, but there is no guarantee the company will even exist in that timeframe. It just seemed like too big of an investment.
Permanently attached whole house generator would be the next level down from solar panels. It is more hands off than the portable generator, but it does require a maintenance contract. I was willing to do my own servicing of the portable generator to keep it working.
Great post. Check out the Champion 201176 Tri Fuel generator. If I was going with a permanent stand by generator, I would probably pick the Cummins RS13A. The engine is oversized for the output, and is quiet.
Awesome writeup. I just bought the same generator, post-Beryl. I plan to convert it to Tri-Fuel with the NashFuels kit.