Portable generators and what you need to know about hurricanes and power outages.
Before you just go out to a store and buy a generator, you need to know what size you need. So you'll need to know a few facts first:
- Why do you need a portable generator?
- What appliances you want to run?
- How many amps do this appliances use?
- Do they use less electric after they are started ?
- How long do you expect to continuously run the generator for?
Using the generator for camping or on your boat, or for normal power outages, is one thing. If you're going to buy a generator for the hurricane season is another. Here you will be using the unit 24/7 for God knows how long.
Most of us here on the Treasure Coast where without power for 4 weeks back in 2004, and about 2 weeks after Wilma. So our needs are quite different than someone buying a genset for a few hour power outage. We would be using the genset 24/7 for about two weeks. This is no normal power outage, so you cannot use the guide lines that some generator manufactures use in determining the size generator you need. If you drive your car with the gas pedal to the floor all the time the car is not going to least as long. The motor is under full load all the time.
A 3800 watt generator will produce 3800 watts at its peak capability, but it cannot sustain this load for more than a minute or two. This size generator should produce 3000 watts of continuous power. This does not mean 3000 watts for 24/7. It means for 3000 watts for 8 hours. Then the genset should be turn off and allowed to cool down to normal room temperature, normally 4 hours.
Now let's see what 3000 watts really is. 1000 watts is equal to about 9 amps, so 3000 watts equal about 27 amps. A modern refrigerator will use about 3 to 4 amps after the compressor is running. It will use between 6 and 9 amps to start the compressor; this is the surge rating.
If you plan on running just this refrigerator and a few lights, let's say 3 60 watt bulbs, for the hurricane you would think that a 1200 watt (1000 watt continuous power) generator would work out just fine. Well it would be fine for the camping trip but not for 24/7. The genset is at it's maximum capacity and cannot produce this power 24/7 without the windings over heating.
Let me explain. The winding in the genset will run hotter as the generator produces more power. The more load placed on the genset the hotter the windings get. They can get hot enough to burn the vanish coating off the wire windings that keep them insulated from each other. Then they short out the unit, these is known as "throwing solder" because the solder connections heat up enough to melt the solder. This is why the genset can only run for 8 hours at a time.
To prevent this you would need to purchase two 1200 watt units or a 3800 watt unit. The 3800 can run at a very low load for it's capability, about 850 watts. So running 24/7 means that the windings will not heat up to the point on burning off the vanish coating. If you chose two 1200 watt units, you will be pushing the units to their upper limits when you turn on a few lights or TV set. You would need to run one unit for 8 hours, turn it off and run the second unit for 8 hours, and so on in order to not burn up the generator.
Remember, it is not the engine that runs the generator that you need to worry about, it is the generator unit itself that you need to consider.
I would not recommend you buying two 1200 units, I would tell you to purchase two 1800 watt units with a surge of about 1500 watts, or larger. The larger genset will run cooler and longer in the above example. Now if you are going to use more appliances then we just discussed, you would need even a larger genset.
If you where going to rely on just one generator during a hurricane power outage, I would recommend getting at least a 3800 watt unit for the above example. The genset will run much cooler for the 24/7 usage. You will only need to turn it off for a short time to cool down before refueling it. Hot engines and gasoline spills are dangerous.
I have three generators myself. A 3800 watt unit for the day time and a 5500 watt for the night time, and a 4800 for my pool.
During the daytime I use the 3800 to feed the house. A refrigerator, a freezer, a computer, coffee maker, and a few ceiling fans. It supplies ample power for my daytime needs, as the freeze rarely kicks on. So I will run the 3800 watt unit for 12 hours, since it is almost always on less than 1/2 of it's continuous capability(3000 watts).
The 4800 watt unit is a WildFire used just for the pool pump, just runs a few hours per day. And it serves as a backup should one of my others stop working.
Then in the evening I start up the 5500 watt unit. This allows me to watch TV and have a windows A/C unit on in the bedroom. The Refrigerator will kick on less at night as no one is in and out of it. Here again, it is running at less than 1/2 of it's continuous capability, except when I turn on our hurricane 6 gallon water heater. The water heater is only 1200 watts and the genset can more than handle the load.
So it will run all night till the morning. Not only am I saving the genset, by not having it work to it's upper limits, but I am saving on gas. The lower the load on the genset the less gas it burns. My 3800 watt unit will burn about the same amount of gas as the 1200 watt unit burns in the above example.
As a side note, if I only had one genset and no pool, I would have a 7000 watt unit. This would allow me to run it 24/7 except for refueling and oil changes every two days. The genset would stay cool as it is hardly working. However, I would burn a little more gas than with the two smaller units.
Most engines will burn about 1/3 of a gallon per hour with no load, the 1200 watt unit has a much smaller engine so it may only burn 1/4 gallon per hour under no load. But when you load up the 1200 unit, it will burn about 1/2 to 5/8 of a gph. A 7000 watt unit will burn between 1/3 and 2/5's of a gallon per hour with on low load. My 3800 unit and 5500 unit on a low load, about 1/2 or less of it's continuous capability, will burn about 1/2 gph. Now if we I pushed the unit to its max, it would burn quite a bit more gas.
I want to mention one more thing, sound. My 3800 watt unit is a Wildfire with just 69 db noise level, it is real quiet. We keep in on the patio and the sound level does not stop us from seating outside near it in the daytime. Unfortunately my 5500 watt unit is not a Wildfire, it is a Coleman with a Briggs & Straton engine and it's quite loud. So at night we put the genset on the opposite side of the house from our bedroom. I feel sorry for my neighbors. Maybe this year I'll get a Wildfire generator to replace it.
If you are unsure about what size genset you need, come on in to our showroom in Port Saint Lucie and I'll help you get the right size for your needs.
In my next editorial I will discuss how to back feed your house with your portable generator.