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

Generac Power Systems Generac Power Systems
Model#: 5875
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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
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Product Reviews

Previous | Showing reviews 41-44 of 44

  1. This is by far the best on the market

    Posted by Jeffrey L on 22nd Jul 2011

    I have bought 9 of these units over the past 2 years. I am fixing to buy a 10 unit, and as you can see, this is definitly my choice of Generators. I have done extensive research in the competition and none have even come close to the performance of Generac. During Hurricane Katrina and Gustov, I had to run my generator for 3 weeks after Katrina, and 2 1/2 weeks after Gustav. Both times, I had absolutely no problem at all. All i did during each hurricane was have spare oil and maintenance kits, and did the maintenance as required to keep the unit healthy. I have been dealing with Norwall for a few years now, and no one beats the service and price they offer. Great people and very friendly. I will be dealing with Norwall and Generac for many years to come as orders come in for more Generators in my area. Thanks so much for your support and service Norwall...

  2. top quality..great service

    Posted by Brad on 3rd Jun 2011

    I was very impressed with the quality of this generator. We use 3 commercial Generac's at work and I saw how well and simple they were made so I bought one for my home. Norwall has the best price by several hundred dollars. Home Depot and Lowes were about 500 dollars or more. I hooked it up and it started first crank. I use Propane so I had to buy a step down gas regulator to deliver the proper amount of fuel. It cost $50 from my local propane dealer. Install on the regulator was 30 minutes. Install costs for plumber and electrical hookup was about $1500. Your cost may be much lower since my situation was complicated by the locations of my utility electrical connection. I had to take it from one side of my house to the other side through the attic. I used 3/4 inch pipe for the fuel but think a 1/2 inch will work. It runs fairly quiet. I would like to see Generac have a quiet kit for the muffler so it could be more quiet, but as it is, it's not objectable. I highly recommend this generator. I bought it a little over-sized to make sure I could power my whole house.

  3. 20K does the trick

    Posted by Wally on 26th May 2011

    Best investment due to power failures and ice storms it could be a week without power. Since the purchase it was only used twice during power failure due to a bad storm. Great peace of mind and best price from Norwall. Only go with a 20 KW smaller may not be enough. Now we are ready for the next bad storm.

  4. Second purchase of this generator in 3 weeks

    Posted by Jeff from New York on 12th Mar 2011

    I bought the first one for myself, then bought one for my mom and dad. Now my uncle wants one. Norwall has the best pricing along with the most informed sales staff. These are not kids toys and you have to know what you are talking about. Sharon was the one that I talked to first, then a Karen. Both had the answeres to all of my questions and if they said they would call me back, they did... This comapny IS the best at what they do.. The Product has worked everytime we needed it. 5 times so far this year....

Previous | Showing reviews 41-44 of 44