Loading... Please wait...

Generac Guardian 5875 20kW Standby Generator (Aluminum) Pre Packaged 200 Amp Service Rated ATS

Generac Power Systems Generac Power Systems
Model#: 5875
This product is no longer available for purchase.
To see the product that replaced this model or one
similar in specifications click on the button below.
New Model
This product is no longer available for purchase.
To see the products that replace this model or ones
similar in specifications click on the button below.
New Model
This product is no longer available for purchase.
There are currently no similar or related products that replace it.
We have kept the model's documents available for download:

Maintenance Kits, Replacement Parts & Accessories

Generac Power Systems 6212 Details and Specifications

The Generac Guardian Series of standby generators are designed to start and operate automatically during a power outage. The Generac Model 5875 package is a popular standby generator with a Nexus Controller sold by Norwall Power Systems and includes a 20-kilowatt generator packaged with an 200 amp, service-entrance-rated automatic transfer switch.

Fuel choices

All Guardian generators operate on either natural gas or on LP gas. Availability and cost are the main factors in choosing between the two fuels, but the fuel choice also affects the power output of the generator. The 5875 can produce a continuous 20 kilowatts of power using LP gas, but that is reduced to 18 kilowatts for natural gas. Fuel consumption at fifty percent load runs about 1.9 gallons per hour for LP gas and 2.9 gallons per hour at full load. Natural gas use is 206 cubic feet per hour at half load, and 294 cubic feet per hour at full load.


The engine is Generac's own overhead valve industrial engine; the only engine designed specifically for use in a generator. The design of the V-twin, 999 cc engine allows for extended operation with an extended maintenance cycle twice that of most generators. It runs cooler and smoother with less vibration and easily switches from natural gas to LP gas in the field.

The engine senses low oil levels and shuts itself down to prevent damage. Pressurized lubrication helps keep the engine operating smoothly and for extended periods without interruption.

Transfer Switch

The Generac Nexus Smart Switch is a UL rated, automated transfer switch that handles the changeover from utility power to the standby generator in the event of a power outage and incorporates load management for high demand appliances. The switch is normally mounted close to the existing service panel for ease of access, installation and convenience.

The Smart Switch incorporates load management for high demand appliances through a load-shedding controller and manages one or two air conditioners without additional equipment, and up to four additional high demand appliances with the addition of Demand Load Management modules.

Nexus Controller

The Nexus Controller is an integral component of all Guardian generators and manages generator functions. Once a week it starts the 5875 generator and exercises it for 12 minutes. When the generator is not in use, the controller monitors and charges the battery to ensure it is ready when needed and alerts the owner to replace the battery when it will no longer hold a charge.

When a power outage occurs, the controller senses the outage and waits to ensure it was not a momentary interruption, then starts the generator after ten to thirty seconds (programmable). During operation, it monitors generator voltage continuously and adjusts it for utility quality power, and also controls the frequency to keep it at a steady 60 hertz. When utility power is restored, the controller instructs the transfer switch to change back to utility power, but continues to operate the generator in a cool-down mode for up to one minute before shutting it down.

The controller also senses incorrect/improper wiring to alert the user and prevent damage to the system. If the any part of the system shuts down, it can notify the homeowner through a general alarm displayed on the generator control panel. The optional advanced wireless remote controller sounds an audible alarm if a malfunction is detected.

Generator Unit

The alternator or generating unit is the heart of the system that produces electricity. It utilizes an efficient revolving magnetic field and a stationary armature with skewed stators that keep the current output smooth, clean, and free of spikes and noise. The unit employs automatic voltage regulation for continuous, unvarying power and also helps to provide for the momentary high inrush currents required by electric motors during startup.

Appearance and Noise

The overall appearance is clean and unobtrusive, with a smooth, protective case. The entire unit stands 28 inches tall, 47 inches wide and 25 inches deep. The aluminum cabinet resists rust and is covered by epoxy paint for a long lasting finish. The engine's muffler is located within the cabinet to guard against burns and injury and keeps the generator's noise level to 66db or lower. The 5875 package includes the fascia and trim kit normally sold as an accessory.

20kw Generac Generator 5875 Includes:

200 Amp Service Rated Nexus Smart Switch with Digital Load Management Technology Nema 3R Rated #RTSD200A3, Flexible Fuel Line Connector, Composite Mounting Pad, Base Fascia
USA Engineered & Built

Generac $50/$50 Referral Rebate, Click Here

Product Specifications

Model Number 5875
Manufacturer Generac Power Systems
Made In USA Yes
Rated Watts 20 kW
Rated Amps 83LP/75NG
Voltage 120/240V Single Phase
A/C Ton Rating 5 Tons
Enclosure Aluminum
UL Listed Yes
Decibel Rating 66 db(A)
Starting System Electric/Automatic
Low Oil Alert Yes
Idle Control No
Hour Meter Yes
Battery Requirement Requires 12Volt, Group26R-525CCA
Mounting Pad Composite (Included)
Product Weight 451 lbs.
Dimensions (Inches) 48L x 25W x 29H
Engine Brand Generac
Engine Size 36 HP/999 cc
Engine RPM 3600 RPM
Cast Iron Sleeve Yes
Cooling System Air Cooled
Alternator Type Brushed
Frequency 60 Hz
Auto Voltage Regulation Yes
Fuel Type LP/NG
NG Power Capacity 18kW
LP Power Capacity 20kW
NG Consumption @ Full Load 294 cu.ft/hr
NG Consumption @ 1/2 Load 206 cu.ft/hr
LP Consumption @ Full Load 2.90 gal/hr
LP Consumption @ 1/2 Load 1.89 gal/hr
Transfer Switch
Transfer Switch Model RTSD200A3, Nema 3R, Outdoor
Transfer Switch Amps 200 Amps
Transfer Switch Circuits Whole Panel, Service Entrance Rated, Nema 3R, Outdoor Rated
ATS Poles 2 Poles
Warranty Information
Consumer Warranty 3 Years Limited
Commercial Warranty 3 Years Limited
Shipping Weight 572 lbs
Shipping Dimensions 45H x 50W x 27D
You need to be logged in to write a review.
Write A Review

Product Reviews

Previous | Showing reviews 11-20 of 44 | Next

  1. Would not be without a Generac

    Posted by Fred B on 17th Dec 2012

    I purchased my first generac unit, a 14 kw 6 years ago. It has been perfect. After Sandy I decided to upgrade to a 20 kw Model 5875. I had my 14 kw unit reinstalled at my business. they both work perfectly. Great service-great price. A very good experience. Several friends have now bought the same unit and feel the same way

  2. Delivered when I needed it

    Posted by Tom V. in CT on 9th Dec 2012

    Sandy took out utility-supplied power to my home for more than 7 days. Thanks to my Generac 20kW generator I had heat, lights, TV, and everything I wanted and needed during the outage. It ran my air conditioning during a 1-day outage over the summer. I am not the only one in my neighborhood who has one, but those who don't sure wished they did. And I've recommended Generac and Norwall to everyone for their great products and customer service.

  3. Excellent purchase and delivery

    Posted by Shawn M on 6th Dec 2012

    I was interested in getting a Generac whole house generator and had been procrastinating, then hurricane Sandy hit our area and I decided to get one. Norwall was the only place that had the 20 KW whole house auto generator available with no wait time. I was shocked as the price was cheaper then anywhere I had looked. Free delivery and no tax were the icing on the cake. I was still skeptical but decided to get one. Order process was easy. Delivery was on time as promised. Norwall sends tracking #'s and UPS called day before to confirm time. My driver moved generator inside my garage and even refused my tip. My contractor friends could not beat the price I paid for the gen. Gen arrived with no damage and all documentation. I highly recommend Norwall.

    As for the gen itself, it hasn't needed to run yet but I did extensive research on this make and model and reviews are all mainly positive.

    As for install $. This is where I had alot of questions as I had to outsource everything (I am not that handy). For anyone looking to install here is what I paid: Electrician- $1240, this included set up and testing of gen, 200A transfer switch install, all wiring and panels etc. Natural gas- $1040, this was all piping, new regulators and new gas meter. Also paid about $150 in misc fees (permits, batt, etc)..

    Hope this review helps. I live in Reading PA and used UGI for gas work and Waldman elect for gen install, I was happy with install price as it was cheaper than what I had researched.

  4. Is that all you got

    Posted by Brian D on 20th Nov 2012

    After the two storms here in the Northeast in 2011 we were without power for 2 weeks.I decided i was never going through that displacement again.We purchased a 5875 20 kw from Norwall(they were great,knowledgeable and very professional)I in stalled a 500 gallon propane tank and we were ready to roll,when our power went out 3 weeks ago the generator started about 15 seconds later and ran for 5.5 straight days and amazed me when I calculated my propane fuel usage to 1.2 gallons per hour.I felt bad for the people without power.but still managed to climb into my 6 person hot tub on the deck,by the way,didn't burn 1 drop of oil after running for 135 hours straight.(I use blue purple syn)So back to my headline,my wife saw a commercial for generac with a women outside during a windstorm saying (is that all you got)and said if that were a man it would be you.Thank you Norwall for making the purchase a pleasant experience and thank you Generac for making a quality product that functioned with perfection.Afterall anything that runs at 3600 rpm's for 135 hours is like a car traveling almost 10,000 miles without stopping and had no oil consumption that is just amazing.

  5. 20kw Stanby generator

    Posted by John M. Hill on 6th Nov 2012

    This is a great Generator i had a 14 and a 20 kw it delivers great service.

  6. 20K all the way!

    Posted by Mike G on 5th Nov 2012

    Generac and Norwall are a great combo. The sale, delivery and install went as smoothly as could be expected. The generator and transfer switch performed flawlessly when Hurricane Sandy turned the lights off for 72 hrs and 16 mins. My family was in darkness for the 30 seconds it took for the systems to do exactly what they were designed to do. 20kw powered my entire 3400 sq. ft. home and met all the needs of my family and those who took refuge with us. I would and daily do recommend Generac and Norwall. If you've read this far waste no more time and just place your order. Finally I and my family thank both Generac and Norwall.

  7. Great Product

    Posted by Anthony on 5th Nov 2012

    After installing the 5875 back in august 2011,It got its first use this past week from hurricane sandy. It Ran for 6 days straight with no breaks and I did not have one problem.With the 20kw you can do anything you would normally do on a daily basis. My wife was baking doing laundry i had every light and electronic device on. The transfer when power is restored is flawless I didnt even notice I got power back until I walked outside and didnt hear the generator running. the only issue I have is generac does not have customer service you have to call a dealer or service company and they dont give any free information. So if your a DIY guy like myself this may be an issue

  8. Hurricane sandy was its first test

    Posted by Todd in Clinton CT. on 4th Nov 2012

    After installing this generator in February, it got its official use this past week with Hurricane Sandy. I ran it for 15 hours a day, and shut it off at night. (No sense in wasting propane while we're sleeping) We used it for five days in a row, and it ran perfect for the entire time. It burned no oil, and when the well and furnace kicked on, there was no dimming of any lights. Oh, and speaking of lights- we had more lights and electronics on than I care to admit. I definitely would recommend getting the 20k model. I mean if your going to hard wire in a generator to your home, it makes no sense to get a lesser model when the 20k only costs a few hundreds more. Do it ONCE the right way. Just my .02 cents.

  9. The only way to go is Norwall.

    Posted by Matt P on 3rd Nov 2012

    In August of 2012 I decided to buy a generator for my new home. After speaking to a trusted electrician friend I decided that my generator purchase would be with Norwall Power. The sales person was helpful, knowledgeable and had several suggestions to help my purchasing experience along. Once ordered the generator arrived in 6 days. When dealing with Norwall your price is your price. There was no additional cost for shipping or taxes. I used a check routing number and received an additional discount that more than covered the cost of the battery.
    Now lets get to the important part.

    After having this Generac 20Kw generator for only a couple of months we experienced our first power outage. Hurricane Sandy came ashore just north of my home and dumped over 11 inches of rain on my house to compliment all that fancy wind. If I had now generator, i would still have water in my finished basement. Thanks to Norwall Power and my perfectly operating Generac generator all is well and dry. refrigerator kept cold food and cold beer, lights, TV, internet and yes even the prized Xbox all online.

    In closing, you will not find a better combination of product and service anywhere.

  10. happy camper

    Posted by Tom G. on 1st Nov 2012

    Can not be happier after install.Used about 2 times since purchase.Hurricane Sandy came through and was praying for power outage.Got my wish as electric went off for 3 hrs.Didn't miss a beat.Neighbors asking loads of questions about generator but hesitant on spending the money.Oh well their loss.Did install by my self and saved on labor expense.

Previous | Showing reviews 11-20 of 44 | Next