Whole House Standby Generator

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After several near misses by hurricanes and listening to the experiences of people who had no power for days or weeks, I decided to install a Guardian 30,000 Watt standby electric generator that runs on propane or natural gas to power the entire house.

Choosing a Whole House Generator

I considered a less expensive portable gasoline generator but dropped the idea because portables are very loud, require large amounts fuel (who wants to haul and store 50 gallons of gasoline to keep it running for a week?) and is too small to power the electrical appliances I want to use – especially the central air conditioner.

The factors in my decision making were:

  1. A mold deductible of $50,000 in my homeowners insurance policy. Mold damage happens quickly with no air conditioning and high humidity in Florida.
  2. The probability that power would be out for days or weeks after a hurricane.
  3. A standby generator would provide electricity for power tools to make emergency roof repairs.
  4. Power for the well pump for water.
  5. Comfort.

A whole house generator met my requirements:

Guardian 30KW Standby Generator

Whole House Generator Cost

After extensive research, I decided to buy a Guardian 30KW liquid cooled generator. My final costs were:

  • $9,055 generator and automatic transfer switch
  • $2,600 electrician services (2.5 days of work)
  • $2,700 for the gas company to bury a 500 gallon LP gas tank, gas hookup and fuel
  • $160 for 32 bags of cement mix
  • $55 for electric cement mixer rental
  • $200 for landscaping rock and stone curbing
    $14,770 total installed

I framed and poured the 4ft x 7ft x 8in concrete pad, placed the generator on the pad and installed 3/8 inch anchor bolts myself.

Generator Capacity Sizing

One method of sizing a whole house standby generator is to add up the loads for all the electrical appliances you want to run simultaneously. Note that there are two types of loads: resistive loads such as lights, ovens and TV; and inductive loads (things with motors) including the central air conditioning system, pool pump and well pump. Resistive loads are the stated value (e.g. 100 watts at 120 volts). Inductive loads will create momentary startup surges, drawing perhaps 150% more amps than the ‘steady run’ rating as printed on the motor.

The second method is to pick a generator large enough to operate the central air conditioning system – which was my #1 objective – with everything else turned off – and rotate services. e.g. Run the air conditioner for 1 hour, turn it off, and watch TV or run the Microwave and lights.

The surest way to determine your load requirements is to have an electrician place an amp meter on the mains and measure the actual load of the devices you want to operate. The peak load value is found by measuring the startup current draw when the air conditioner and other inductive loads are turned on.

The specifications for the Guardian Model 4988 generator I purchased are:

  • 30KW at 120 volts steady load, equals 250 amps
  • 45KW inductive load momentary surge
  • Ford V6 3.0L liquid cooled engine

As it turned out, this easily powered all of my house electrical needs (including the central air, pool and well pumps) with no special power management techniques.

Automatic Transfer Switch

An automatic transfer switch (ATS) contains electronics and a huge switch to that senses when the utility power is lost, automatically disconnects the utility mains and connects the generator inputs to the main circuit breaker distribution panel. I highly recommend an ATS it allows the generator to kick in without making trips outside to switch over to generator power.

Hiring an Electrician

Finding an reputable and honest electrician turned out to be challenge. The good ones were backlogged and would only do the job if I purchased the generator from them. (At the time, the housing market was still booming.) Several electricians were willing to do the job, but unwilling to provide a written and itemized fixed price proposal. More alarming was that several licensed electricians, including some listed on the Generac web site, said no building permit was required! I called the county building department to verify. The building dept. said a building permit is absolutely required and my homeowner’s insurance wouldn’t cover fires or damage from unpermitted work. Furthermore, I could be held responsible if my generator back fed electricity into the utility grid and electrocuted a lineman. I called Generac and provided the names of the ‘approved’ dealers/electricians who gave me this false and dangerous advice.

Eventually, I found an electrician that:

  • Was licensed and insured.
  • Had installed many of the Guardian generators.
  • Said a building permit is required without prompting for the correct answer.
  • Provided a written, itemized, fix price quote that included initial turn-up testing and customer hand-off procedures.

This particular electrician did an excellent job and handled follow-up warranty service directly with the factory.

Try www.kudzu.com for finding a generator sales and service businesses in your area with customer reviews.

Buried Propane Gas Tank

The local propane company was pleasure to work with. They buried a 500 gallon liquid propane tank, installed the gas underground lines, converted the carburetor from natural gas (factory default) to liquid propane and filled the propane tank.

I chose a 500 gallon propane tank as this was sufficient to operate the generator for about 10 to 15 days, depending how I managed my electrical demands. The generator spec. sheet states the cubic feet gas consumption at various operating loads, which I used to calculate the expected runtime for a given tank capacity.

Generator Installation

After checking prices with several local retailers, I found the best deal by ordering from Home Power Systems. The generator was dropped shipped from the Generac factory (owner of Guardian brand) and arrived on a tractor trailer. Home Power Systems and the truck driver called me a couple of days in advance to schedule the delivery.

The truck driver used a pallet jack to move the generator into the garage until the outside preparation were complete. The generator weighs about 1500 lbs with the crate and fortunately my driveway was level with the street, so getting it inside was not a problem.

Generator in the Shipping Crate

Generator in the Shipping Crate

Concrete Pad

The generator sits on a concrete pad. I prepared a 4 foot by 7 foot by 8 inches deep pad using thirty two 60 lb bags of cement. I did this by digging 6 inches below grade with a shovel, leveling the base and framing the sides with 2×4 lumber. The top of the 2×4 frame is set 2 inches above grade for the final height of the pad. The 2×4 frame is held in place by wooden stakes around the exterior held in place with screws. I also laid a wire mesh in the concrete for extra strength. A portable electric concrete mixer rented from Home Depot made the mixing and pouring of concrete manageable. The concrete was finished using a hand towel and bull nose edger. Remember to call the kids so they can write their names in the corner, too! Overall, this was a good days work.

Placing the Generator on the Pad

The generator is big, bulky and heavy (1350 lbs). The pros use a forklift maneuver the generator onto the concrete pad. I didn’t have access to one, then I came up with an idea from the ancients. I rolled the generator into position on wood fence posts. With a couple of neighbors helping, we kept placing fence posts in front, pushed and moved the back post to the first position. It worked great! It helped that I had a very level yard so there was no danger of the generator running away.

Here’s the generator bolted down to the concrete pad. (The unit is level, only the camera is tilted.) Gas and electric hookup is next.

Generator placed on the Concrete Pad

Generator placed on the Concrete Pad

Propane gas hookup, manual shut off value, and pressure relief regulator. Duct tape covers the underground electrical conduit against the wall that was set into the concrete for a neater installation.

Propane Gas Hookup

Propane Gas Hookup

The gas company buried the propane tank in the yard and installed the gas line, shutoff valve, regulator and connected it to the generator. Notice the black rubber section of fuel line for a vibration isolator to minimize the chance of a fuel line connection working loose:

Whole House Generator - Gas Line Regulator and Shutoff Valve

Whole House Generator – Gas Line Regulator and Shutoff Valve

View of the generator gas line plumbing. The black rubber fuel hose vibration isolator is denoted by the yellow arrow. The generator is about 15 inches away from the house. My intention was to locate the generator 18 inches away from the house but I made a measurement error locating the J anchor bolts in the concrete pad when I was studying the generator drawings before the generator arrived. This made for a tight squeeze when servicing the generator. Next time I’d place the generator 3 feet from the house for comfortable maintenance access:

Whole House Generator - Rubber Gas Line Vibration Isolator

Whole House Generator – Rubber Gas Line Vibration Isolator

Generator and gas hookup view from the other side:

Whole House Generator on Concrete Pad

Whole House Generator on Concrete Pad

The gas company buried the white PVC regulator relief vent line to safely vent the propane gas around the corner of the house away from the generator and potential heat/spark sources. The regulator relief would activate only if there were an usual overpressure event:

Whole House Generator - Gas Regulator Relief Vent Line

Whole House Generator – Gas Regulator Relief Vent Line

Another view of the propane gas generator hookup. The red lines on the wall were for locating the generator electrical hookup, which is waiting for the electrician:

Whole House Generator - Gas Regulator Plumbing

Whole House Generator – Gas Regulator Plumbing

The Automatic Transfer Switch (ATS) was placed in the garage next to the main circuit breaker panel.
A = 200 amp Main Circuit Breaker Panel.

B = Automatic Transfer Switch

C = Utility power lines

D = Generator power lines

E = Generator control signal wiring conduit

Automatic Transfer Switch Installation

Automatic Transfer Switch Installation

The 500 gallon propane tank was buried for two reasons:

  1. So it couldn’t be damaged in a hurricane.
  2. An above ground silver tank is very ugly.

All you see above ground is the inspection hatch!

Buried 500 gallon Propane Tank

Buried 500 gallon Propane Tank

I’ve had the generator for over a year now and am very satisfied. The family has grown dependent on the generator, enjoying power during thunderstorms and other short term blackouts. Fortunately, no hurricanes… yet.

Bob Jackson

Copyright © 2018 HandymanHowTo.com   Reproduction strictly prohibited.


  1. Paul February 1, 2013 at 3:01 pm - Reply

    This is a very helpful article. I just received my Generac 8K and was trying to figure out how to get it to the back of the house from the side porch. The round timber transport will come in handy.
    I live in a very rural area and didn’t think about the permits needed. With the possible danger to a lineman I will definitely get all permits an a licensed master electrician.
    Thanks for the valuable information!


  2. Bill M September 21, 2014 at 3:38 am - Reply

    Thanks for the article Bob. How did you size the generator for your use. It looks like you have a 200amp service, but you are installing a 30kW generator.

    • Bob Jackson September 21, 2014 at 4:29 pm - Reply

      Hi Bill,
      When the automatic transfer switch is activated, the power source changes from the electric company power feed to the whole house generator which feeds the 200 AMP rated circuit breaker panel. How big of a generator you have determines how many and what size loads can be powered. Depending on what generator you buy, it could be a smaller unit that can support only 15 or 30 AMPs of load. (We’re talking AMPs here but generator capacity is specified in Watts because the loads might be a mix of 110V and 220V devices.)

      As explained “Generator Capacity Sizing” section of the article:

      “One method of sizing a whole house standby generator is to add up the loads for all the electrical appliances you want to run simultaneously. Note that there are two types of loads: resistive loads such as lights, ovens and TV; and inductive loads (things with motors) including the central air conditioning system, pool pump and well pump. Resistive loads are the stated value (e.g. 100 watts at 120 volts). Inductive loads will create momentary startup surges, drawing perhaps 150% more amps than the ‘steady run’ rating as printed on the motor.

      The second method is to pick a generator large enough to operate the central air conditioning system – which was my #1 objective – with everything else turned off – and rotate services. e.g. Run the air conditioner for 1 hour, turn it off, and watch TV or run the Microwave and lights.”

      I was living in South Florida at the time and mainly concerned about sustained power loss caused by hurricane damage. Living in a subtropical climate without air conditioning is almost unbearable.

      See the Generator Sizing Calculator by Generac to estimate how big a unit would suit your needs. It basically boils down to what are your priorities for backup power.

      Let me know if I’ve answered your question.


  3. Al Walker July 15, 2015 at 12:53 pm - Reply

    I noticed you seem to have the generator located pretty close to the house. I was trying to find out the minimum distance that a 27kw liquid cooled generator could be placed from the house and Generac told me 3 feet on liquid cooled and 18 inches on air cooled. How close is yours to the house? Also, I’m trying to figure out if the 500 gallon propane tank that I have now will work. The supply line from the tank is buried already and looks like 1/2 inch line going to the regulator (50 ft run) but coming out of the regulator the pipe size is 1 inch. What size did your gas company use coming from the tank?

    • Bob Jackson July 16, 2015 at 8:28 pm - Reply

      The generator is closer to the house than I intended. My goal was 18 inches away from the house but I misinterpreted the generator drawings in the user guide (downloaded it before I received the generator) and misplaced the J-bolts in the concrete pad. The electrician grumbled because it was a tight squeeze to get between the generator and the wall for servicing. I’d set it 3 feet back from the house if I were to do it again for comfortable service access with enough room to squat down.

      The 1/2 copper gas line runs all the way from the propane tank to the generator.

      I updated the article with several new photos although I don’t have a photo of the buried tank connection. A propane tank company could advise you if your tank and gas line will work.

  4. Sue July 24, 2015 at 4:20 pm - Reply

    Check your local codes before placing generac generator. Generac said 18 inches, but our local code says 5 feet. It’s been 9 months and we still can’t use generator. Still doesn’t pass local inspection. If we hadn’t gotten permit, we would have been fined. ( They check).

  5. George Williams January 19, 2016 at 7:26 pm - Reply

    I installed a 8.5 K Kohler in my home. I back-fed the main panel using a 40 amp breaker. This breaker is interlocked mechanically so the generator breaker and the 200 amp main cannot be on at the same time. This system eliminated the need for an ATS. I used a similar method to move the generator. I got 4 pneumatic wheels and installed an axle in the lifting holes in the frame. I rolled the 400b generator across my backyard to then pad.

  6. brad August 14, 2016 at 11:59 am - Reply

    Yes, without a forklift you must use “Critical Path Analysis” get it into place.
    Just like the Ancient egyptians.
    I’d say it’s worth the money it to have someone move it for you
    Unless you’re writing a DIY: Workers’ Cemetery Article

    • Bob Jackson August 14, 2016 at 4:56 pm - Reply

      It was easy and safe enough to move it that way in sunny and more importantly, flat Florida. I would need a forklift where I live now in hilly North Georgia!

  7. William Rahm November 10, 2016 at 7:23 pm - Reply

    Bob, did the generator’s proximity to a wood fence present a code problem? I am considering backing a 22kW generator 18″ from a vinyl fence.

    Our building code here in Central Florida will allow me to situate a generator 18″ from any non combustible wall. Not certain how the inspector will feel about a vinyl fence.


    • Bob Jackson November 13, 2016 at 12:14 am - Reply

      The generator is located about 7 or 8 feet away from the wood fence. Notice the Trane condenser unit is between the fence and generator in this photo.

  8. dick williams II September 11, 2017 at 1:41 pm - Reply

    Bob, great piece & most helpful sir! i wonder how that unit’s holding up now for *new* homeowner in FL? sure bet that it’s been a blessing given Irma’s wrath down there. i see you’re in “hilly” N. GA mountains now. did you install another Guardian 30KW up’aire as well? we’re down/ over here in W. Cobb GA area & have been kicking around the idea of adding such a unit. thanks for the most helpful info., tips, tricks, advice, counsel, replies, etc. – you saved us a helluva’ lot of time & heartache. cheers!

    • Bob Jackson September 11, 2017 at 2:00 pm - Reply

      My former Florida home has been sold twice since I moved to GA and I don’t know if they’ve kept the generator maintained and fueled. Because devastating wide area weather events and long term power outages are rare in North Georgia (I’m 1000 feet above sea level here) there hasn’t been a compelling reason for a whole house generator. We’ll see if that holds true with the remnants of Hurricane Irma moving through.

      One thing to remember is if structural damage occurs to homes in your neighborhood the utility company will shutoff the natural gas to minimize fire hazards and your generator won’t work. Burying a liquid propane tank is the most reliable method.

      I do have a two APC X750 UPS battery backup units powering my home network. If Comcast can do their part my WiFi and Internet stay up 24 hours or more. Power outages in north GA aren’t so bad when watching Netflix on a laptop or iPad.

  9. dick williams II September 12, 2017 at 12:58 am - Reply

    roger that. i have an APC myself (though not quite as sophisticated as the X750) for our home network as well. the rest of that sort of lost me at the, “My network has almost 30 IP connected devices ranging from PCs to smart TVs to Internet of Things (IoT) which are notorious for poor security safeguards…” bit. lol.

    that said anyway, you’re clearly a fellow who’s interested & committed to a ‘plan’ & i dig/ respect that immensely. speaking of said, two days ago, i heard a man on Weather Channel make a statement (metaphorically/ allegorically) about a Mike Tyson quote; something about “… plans are good until you get punched in the face” and it really made me stop and pause for a minute. i think i’m still thinking about it actually.

    when you mention the utility co. shutting off nat. gas & recommending LP tank, were you referring to something akin to the one you had buried in FL? i assumed so but maybe i’ve misread. thanks again, Bob.

    • Bob Jackson September 12, 2017 at 1:38 pm - Reply

      That Tyson quote is a variation of “No plan survives contact with the enemy.

      The 500 gallon propane tank was buried to protect it from wind and weather. Coastal Florida and North Georgia have very different backup generator planning and risk factors.

      Coastal Florida:
      * Subject to hurricanes causing widespread structural damage.
      * Natural gas supply will be shutoff by the utility company in the expectation or event of widespread structural damage to prevent fires.
      * While your home may not be damaged, if homes/buildings in your neighborhood are your generator might not have fuel.
      * A buried propane tank is the most independent and survivable option.
      * However, a natural gas generator would have been operational in most areas during Hurricane Irma, such as Dade, Broward and Palm Beach counties that had minimal structural damage but numerous power outages due to downed trees.

      North Georgia:
      * Seldom sees widespread structural damage.
      * Tornadoes, severe thunderstorms and rare snow/ice are the most likely events, but damage is usually limited.
      * Power outages are repaired more quickly because the electric company is able to focus resources.
      * A natural gas generator is probably a better choice for North GA. It’s practically an unlimited fuel supply from the gas company.


  10. Chris ENglish October 13, 2017 at 4:31 pm - Reply

    Hi Bob, did any of the electricians try and tell you that you HAD to use a transfer switch with circuit breakers? I want to hook mine up identical to what you did (which is a very straightforward installation) but am being told I have to do it differently because my generator is only 20kw.

    • Bob Jackson October 13, 2017 at 6:45 pm - Reply

      If I understand the question, you bought a transfer switch doesn’t have built-in main circuit breaker, correct?

      The surest answer is to contact your local Building Dept as they’ll be signing off on your electrical & mechanical permits.

      Generators must comply with NEC 445.12(A):

      “Generators, except AC generator exciters, shall be protected from overloads by inherent design, circuit breakers, fuses, protective relays or other identified overcurrent protective means suitable for the conditions of use.”

      445.12(A) doesn’t specify where the over current device (e.g. main breaker) is located. You should be code compliant by installing a separate main breaker box next to the transfer switch to protect the generator, but a transfer switch and breaker combo is convenient and makes for a simpler installation.

      The following reference may help (bold emphasis added):

      Generac: Understanding NEC Code for Standby Generators: Cabling, Sizing, Startup and Disconnect
      “Is a disconnect required on the generator?
      NEC 445.18 shows a preference for the generator to be equipped with a disconnecting means but does allow that disconnect (typically the generator breaker) to be removed provided the generator can be readily shutdown, can be locked out from restarting, and does not operate in parallel with other sources. Though the NEC does allow the generator to be provided without an output breaker, standard industry practice is to typically include this disconnect.”.

      Let me know what the Building Dept. says.

  11. Curtis July 14, 2018 at 4:10 pm - Reply

    Another thing to keep in mind is the exhaust coming out of the generator. If you have it to close to the house it is possible to get exhaust into the soffit vents filling the house with carbon monoxide. You may want to extend the exhaust pipe higher then the roof.

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