Running parallel generators is a relatively new trend that is based in common old school mathematics. Power rates and equations are simplified and once you understand the numbers behind what your generator is putting out and what you are demanding from the generator, running parallel generators may be the answer you didn’t know you were looking for.
A single power source (in this case, a portable generator) puts out power at a constant rate. This is the number in the manual or most likely in the model number itself. If you are running an 1800 watt generator, you are likely getting 1800 watts surge and around 1500 watts running power. This difference is what the generator is capable of in moments of short demand draw such as when motors kick on and require that initial pulse of power to get started but can run at a lower rate once they get moving.
By adding a second power source and running parallel generators, you can increase that wattage and run larger appliances. Wattage is the measurement of how much energy flows from one place to another. So if your generator is running but you don’t have anything plugged into it, you have plenty of potential, but are not drawing any watts.
When you plug in a device, it draws the required wattage to run that device. You can do the math and add up your devices’ watt draw until it nears the capacity of your generator’s running watts rating. Putting a second generator in parallel typically doubles that running watt rating.
Some numbers won’t change beyond the minor fluctuations inherent in portable generators. You’re still putting out the same voltage, but you have increased the amperage capability and allowed more electricity to flow through the circuit thereby increasing the wattage rating. If all this seems too mathematical for you, the good news is that many manufacturers make it easy for you with simple parallel generator kits.
Why To Parallel Generators
So you might ask, why would I need to run parallel generators? When is it beneficial for me? Well the important aspect of running a parallel generator system comes in having the increased capacity for current draw, and wattage throughput. Taking two generators both running 120VAC, and connecting them in parallel will increase the amperage on the combined output.
This is why you might see two generators each having a maximum 30A connector be connected through a manufacturer’s parallel generator kit and have a 50A connector on the board. If you have a large RV that has a 50A connection plug, you wouldn’t be able to run it off of a single generator but you can make the simple connection after installing the parallel generator kit.
Your RV may also be pushing the limits of your single generator’s wattage capacity. If you’re running the refrigerator, television, lights, etc… and when the air conditioner kicks on, the start-up surge may be enough to put you over the generator’s limit.
You’ll hear the engine sputtering, brownout the existing electrical possibly causing damage to some of your more delicate electronics. Running parallel generators will boost that upper limit well beyond that critical point and you won’t have any more failures.
The Benefits of Paralleling Generators
If the benefits of increased amperage and wattage while running a parallel generator set up is so good, why not just purchase a larger generator and avoid the trouble of maintaining two generators and go through the parallel generator setup? This is a matter of usefulness. If you are running a large RV all the time, then maybe a larger generator is the better choice for you. However for most of the consumer market, parallel generator operation offers the freedom that a single large generator can’t.
- First off, the sheer size of the large capacity generators are difficult to maneuver. Smaller units can be picked up quite easily and transferred from place to place with ease.
- Secondly, cost is a factor. Two smaller generators can still be cheaper to purchase than some of the larger capacity generators. Those big machines can come with a hefty price tag.
- Third, you may not need that large capacity for your normal generator usage and running the large generator would be a waste. It’s easier to run the single when you want and break out the parallel generator when you need that extra power.
- Lastly, running two generators in parallel offers convenience for the large draw appliances, but in the event you have a problem and a generator fails, you still have a single generator to run the necessities while you repair or refuel the second machine.
Safety Precautions When Paralleling
You can run parallel generators with any two generators but extreme caution should be taken when you go off manufacturer brand and recommendations. Most generator brands will tell you that you can only run their brand generator in parallel with another of the same brand, make and model.
This is not a money making scheme, they are looking out for your best interest with the maintenance of your generator and more importantly your personal safety. If you don’t know what you are doing with electricity it is wise to stick with the manufacturer’s recommendations.
However, electricity does not really care about which brand of generator it is coming from. It cares about compatibility. Both generators are putting out 120VAC, they can be placed in parallel and will aggregate their amperage and give you an increased watt rating allowing for those surge motors to start up with extra power without disrupting the rest of your electrical draw.
Any connections must be set up safely and securely, and it is highly suggested that the two parallel generators be rated close to one another’s specifications in wattage capability, but mathematically, you could technically run any two generators in parallel no matter how varied their wattage rating is. We just wouldn’t recommend it unless you are a licensed electrician.
How To Successfully Parallel Generators
To run your two parallel generators successfully, make sure you have the appropriate connections set up. This can be done through a direct parallel port connection, an external parallel generator kit, or a carefully laid out home-created system.
Some manufacturers include a special cable that plugs into a “parallel” slot on the control face of their generators. These connectors are commonly proprietary and are keyed in such a way that they will only plug in the right way into the right machines. Trying to use the parallel cables from one brand to another is unlikely to work.
These kinds of direct connect parallel generators are most often found on the newer inverter generators. If you are looking to purchase two new generators for parallel use we do like the inverter generators. They are quieter, more compact, efficient and is the easiest, simplest, and likely the safest way to boost your power from your portable generators.
Other generators are advertised as “parallel generator ready” but require the purchase of an external connection kit that brings your two generators into a single power source. These are common among the middle capacity open frame portable generators and you are less likely to see this style on a newer inverter style. These parallel generator kits can be purchased separately from the generator itself so if you don’t need to run your in parallel but later find a need, you can pick up these kits after the fact.
Staying within brands again, this style kit is more flexible and will allow you to make a connection between two generators that aren’t identical. Feed from generator “A” and the other feed from generator “B” will be connected and the breakout board will have the combined connection points on it for the parallel generator’s feed. This will often be a combination of a high amperage plug such as a 50A or so, and the addition of one or two conventional 30A household three prong plugs.
Final Thoughts and the DIY Route
If you do not have a manufacturer’s parallel generator kit, or a pair of newer generators that are specifically manufactured with parallel ports built in, all is not lost. You can still run any two generators in parallel, but it will take some more ingenuity. At this point we’ll throw in the important “do not try this at home unless you REALLY know what you are doing” disclaimer.
Playing with electrical connections can be dangerous and if you aren’t absolutely positive you know how to do this work, you’re better off purchasing generators designed to run in parallel or at the very least, have a licensed electrician prepare your parallel generator set up. They can build it and approve of its function and its safety.
Landing two electrical sources at a single point is an easy task that any of us can do, but knowledge and wisdom in the electrical trade is required to make certain the connections are running in sync and not creating any kind of backflow problem that could damage the weaker generator. Not only could this eventually destroy the smaller generator, but it could pose a very real health hazard to anyone near the parallel generators or using the services when the failure occurs.
Running two parallel generators is a convenient and safe endeavor, until you attempt to reach beyond your skill set and you could end up damaging more than you saved.
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