There are few 12KW jobsite generators that can hold up to the Cat RP12000E. Designed and built with contractors in mind, this mighty generator is also a great option for homeowners seeking reliable backup power. Read our updated review for 2020. 

The Caterpillar brand covers a wide range of products and services. Though, I think most of us associate Cat with industrial grade site equipment. Form large excavators to generators of every size and description, Cat has an undeniable presence and a reputation like few others. I have a childlike awe for these machines. So, it should come as little surprise that I’m delighted to be reviewing the Cat RP12000E 12,000W generator.



Cat RP12000E 12,000W Gas Generator ǀ The Complete Review


  •  15,000 peak power; 12,000W rated power
  • 670cc V-Twin engine (EPA certified)
  • Electric starting
  • Removable lifting eye
  • Low THD (<5%)
  • Durable frame and wheel kit

Cat RP12000E Review

At a first glance, anyone can see that the Cat RP12000E is intended to handle tough working conditions. The seriously thick metal frame that extends to protect the steel gas tank, chunky robust wheels with metal rims and all-terrain tread, and the super-tough fold down handle are clear indications that this is no ordinary portable generator. It’s the kind of industrial grade design one would expect from Cat.

The 670cc V-Twin engine has me quite amazed. It’s a mighty powerful beast with pressurized lubrication. This means that, unlike most generators with splash lubrication, the Cat RP12000E has an oil pump – like a car engine. This offers improved performance and reliability. Like most modern engines, it will shutdown if the oil pressure is too low, thereby protecting the engine from damage. It has an electric starter and is a breeze to fire up, even on the coldest winter morning.

As is to be expected, this huge, powerful engine is quite a thirsty beast. To keep it running for a good length of time, the Cat RP12000E is fitted with an enormous steel gas tank – 13.2 gallons. This should keep you going for a full workday, providing 11-hours runtime at 50% load. That’s an average load of 6,000W. In its standard guise, the Cat RP12000E is only EPA compliant. A separate (CARB certified) model can be ordered. So California residents can rest assured. The Canadian (CSA compliant) 502-3701 model has a lower continuous output of 11,000W.

In keeping with the needs of professional contractors, the Cat has OSHA compliant GFCI 120V 20A outlets. Another great safety and durability feature are the tough rubber covers protecting all the outlets. There’s plenty of them too. The industrial style metal control panel incorporates 2 X duplex 120V 20A outlets; 2 X 120V 30A outlets, a 120V/240V 30A outlet, and a 120V/240V 50A outlet. This is great for contractors who use a bunch of high-powered tools. All of these outlets are protected by individual circuit breakers. If one circuit trips, the entire jobsite doesn’t come to a standstill. These outlets are also ideal for homeowners who want to use a transfer switch to connect power directly to their house wiring. You can make full use of the 12,000 running watts and 15,000 starting watts by utilizing multiple high-amp outlets. This is advantageous when you consider that the peak output at 120V is 125A – far more than a single 50A transfer switch can handle.

The control panel also has a number of useful extras, like LED backlighting. If you want to check the Cat RP12000E in the dark, it has a switch that will illuminate the full panel. It also has a multi-display LCD digital screen (voltage, frequency, running hours), and a 12VDC battery charging outlet. The choke is conveniently located on this panel, as is the fuel shutoff valve and electric start switch. The fuel gauge is on the gas tank.

Now, onto the superb copper alternator. This impresses me no-end. Mostly, I like the low THD nature of this generator – less than 5%. Most conventional generators (without an inverter) will usually exceed 20% THD at high loads. This makes them unsuitable for electronic devices. The Cat RP12000E is rare in its ability to produce low THD that is safe for electronics. This low THD spec is not only great news as far as clean power goes, it also indicates a high level of design and build quality. This generator should be able to handle high loads continuously for a long time to come.

Of course, high-grade metals are heavy and the Cat RP12000E is packed with the heaviest of metal components. This durability has its disadvantages when it comes to easy portability. The CAT RP12000E is one of the heaviest portable generators, at 350 pounds. On the bright side, the generator has a great double-hinge loop handle, with foam padding and incredibly tough all-terrain wheels. This makes it easy enough to move across a rough and tumbled jobsite. It also has a heavy-duty removable lifting eye to assist when loading the generator onto a truck.

A heavy-duty generator, like this one, is unavoidably expensive. Add the Cat brand into the mix, and the RP12000E becomes one the most expensive in its class. This doesn’t surprise me. I know the value of a product like this. If you expect a generator to work hard, no matter what the conditions, you are going to have to deal with a high price tag. In the end, it’s worth it. The Cat RP12000E is as reliable as it gets and is built to last. It comes with a standard 2-year warranty. If you register your generator on the CAT website within 30-days, the warranty is extended to 3-years. I’d think it’s certainly worth the effort to do so.

If the Cat RP12000E seems too expensive, you should consider the. This is also a heavy-duty 12KW jobsite generator and I’m really impressed with the affordable quality that Westinghouse generators offer.


Link to Amazon

Cat RP12000E Downloads:

Cat RP12000E Spec Sheet [PDF]

Cat RP12000E Quick Start Guide [PDF]

Cat RP12000E Owner’s Manual [PDF]

Cat RP12000E Service Manual [PDF]

Cat RP12000E Warranty [PDF]