Home Generator 101: How to Power On When the Power Goes Out
Here are 10 basic generator questions people asked PM, and their answers.
1. How Big a Generator Should I Get?
We’re not talking physical size, but, rather, a generator’s electrical capacity. This size depends on the sum of the electrical loads you want to power simultaneously, measured in watts. First, add up all the loads you know you want to be able to run simultaneously. Then, as a precaution, figure out which electrical item in your house requires the most electricity to start its motor and add that to your total. The reason for this is that large items like air conditioners tend to use a lot of juice when they start up—two or three times what they use while they’re running. You want to make sure your generator can accommodate that extra electricity requirement; that way, larger items won’t overload the system if they start up.
Every generator has two wattage ratings: running wattage and surge wattage. Generators are rated for surge wattage because they should have some excess capacity in case the load you need is temporarily larger than what you’ve calculated. When you buy a generator, choose the size based on the running wattage and its surge wattage should automatically fall into line with what you need. If you’re worried about needing more surge wattage, buy a larger generator.
2. What Loads Should I Consider Powering with the Generator?
PM contributor Pat Porzio installs generators for a living. He’s a mechanical engineer, a plumber and an electrician and is HVAC (Heating, Ventilation and Cooling) manager for Russo Brothers Plumbing in East Hanover, N.J. Here are the circuits he typically powers:
First-floor bathroom
A couple of lighting circuits
Refrigerator
Furnace
Garage door opener
Well pump
Other loads to consider are a sump pump, a sewage ejector pump or a circuit into which you can plug a window air conditioner.
3. How Do I Calculate All This?
Generator manufacturers and retailers post helpful sizing worksheets or wattage calculators on their websites to help you figure it all out; Honda’s is a good example.
4. Do I Need to Hire an Electrician to Set Up a Generator Safely?
The safest way to run a generator is to plug it into a piece of electrical equipment called a transfer switch. This is a combination switch and electrical subpanel. It’s wired directly into the house’s service panel, and the generator is plugged into it. When you throw its switch, it does two things. First, it disconnects the house from the grid outside. This prevents power from the generator from flowing outside the house, where it can injure or kill a utility worker. Second, it sends power only to house circuits that you’ve designated. That way, the generator won’t be overloaded.
Unless you’re an experienced amateur (you have previous electrical and mechanical training but lack an electrician’s license), it’s best to have a licensed electrician install a transfer switch.
5. Can’t I Just Plug My Generator into a Wall Outlet?
No!!! This is known as backfeeding, and it’s blatantly dangerous for a variety of reasons. For instance, if someone forgets to throw the main circuit breaker to electrically isolate the house from the grid, then the generator could send electrical power beyond the house and out onto the grid. When that happens, the electricity you’re generating could injure or kill a utility worker who has come to repair the downed grid.
Read more at: https://www.popularmechanics.com/adventure/reviews/a11855/home-generator-101-how-to-power-on-when-the-power-goes-out/