When You are Ready for that Generator V
Part 5 of 6
Fifth of a series of articles that will run through the ins and outs of buying a generator
Last Time
Last time we covered Permanent Home Standby Generators, if you missed it here is a link.
Getting Power into Your Home or Business
Separating Load for Part Home Backup
If you have chosen only to back-up part of your home, next is how do you want to do that? With manual equipment you have options. You can simply choose to keep everything in the main panel, and just turn off the breakers to circuits you don’t want to power. This is the least expensive option and gives you the ability to change your mind about what you are powering. This is great if it’s always you who are making the switch to the generator.
If you are choosing an automatic option or just want to make things simple, you can add a dedicated sub-panel for generator powered circuits. This is a little more expensive up front but makes it easy to have someone with limited training turn on the generator and power those circuits. (There is a little more on combo auto transfer switches later in this article)
Connecting a Portable to Your Home
Safety briefing, you have heard it before, don’t use a suicide cord. For those that don’t know what they are, they are a cord with a male plug on each end, it doesn’t take a rocket scientist to figure out its super easy to electrocute yourself. If you know what you are doing it works, but very few do, and it’s extremely easy to make a mistake. So just don’t!
Point of clarification here, I am talking about any generator that moves, that includes PTO generators that are not permanently mounted. This even works with standby batteries if they have a 120/240-volt outlet, many do not. You will want to have a “power inlet box” installed. Just google that term and get a visuals. It is just a connection box containing a male electric plug, usually twist lock, that you have wired to a breaker or device that you’ll be using to transfer power between generator and utility. Nearly all of these inlet boxes are rated for either 30 or 50 amps, choose the one that matches your generator outlet. Many of these inlet boxes also come with a generator cord, make sure the cord will fit the largest outlet plug on your generator.
With the advent of EVs, 120/240 60-amp outlets (NEMA 14-60) are becoming increasingly popular. Unfortunately, no one makes a 6o generator inlet box, or a male 60-amp plug with mounting flanges that could be used in a generator inlet box.
So, in those cases where you need 60-amps of power input, the cord would have to be hard wired on the building end. Many of the PTO generators use connectors made by Anerson Power, a manufacturer of high current plugs. Anderson does make panel adaptors, so theoretically you could have a generator inlet plug installed with their products, but your contractor would have to build it. Otherwise, you can just hardwire it similar to the 60-amp.
Manually Switching Your Home/Office between Generator and Utility
For a manually started and/or connected generator, there is no point in investing the money in an automatic transfer switch. There are a few options to switch your panel over to the generator feed and back:
By far the cheapest and most popular is the breaker interlock. The generator breaker is installed as close to the panel main breaker as possible; both have to be in the same panel. The interlock is usually a sliding metal plate that prevents both the generator breaker and the panel main breaker from being closed at the same time. The switch occurs when you open one, so you can slide the plate to close the other, simple, and effective. GenInterlock (https://www.geninterlock.com/) makes interlocks for the majority of electrical panels made, and are the industry go-to. Even manufacturers often just defer to GenInterlock rather than build their own. GenInterlock also sells inlet boxes and generator cords if you want to one-stop shop.
Geninterlock sliding interlock plate installed in a electric panel If you prefer, or it simply works better for you, you can use a manual transfer switch. All the transfer switch manufacturers will be happy to sell you a manual model for a fair bit of coin. But you really don’t need something that fancy. Unless you have a commercial three phase service, all you need is a double pole double throw (DPDT) switch rated for the same amperage as the panel it will be feeding. For three phase you need a three-pole double throw (3PDT) switch. You will need to have a contractor install it at an accessible location in the main feed to the panel you are switching. There must be a customer owned breaker somewhere in the wires on the utility side of this manual switch to be legal. In other words, you cannot put it between your meter base and your panel without adding a breaker such as a meter main, or using a service entrance rated manual switch that has its own breakers (not sure they exist).
Manual DPDT transfer switch If you really don’t want to tear into your house wiring, or it’s not yours to tear into, a company named Global Power Products makes a transfer switch that plugs in between your meter and your meter base. They make automatic switching models under the Genlink label and manual switching models under the Trifecta label. They come sized for 30 amp or 45-amp generator inputs only. These switches are pretty expensive for what they are, but they fill a niche market. Some utilities will provide you one for free (usually the 30-amp model), some utilities will not allow you to install one at all. So do your homework. Probably the best advantage is if you are in a rental, you can have it removed and take it with you. Here is a link https://www.globalpowerproducts.com/transfer-switches/ .
Global Power meter base transfer switches
Automatic Transfer Switches
You should only be dealing with an automatic transfer switch if you are installing a permanent, fully automatic home standby. It should be part of the quote that your installer gives you, so it will come with your generator package. Here are some need to know things when you are looking at the quote:
You only need a service entrance switch if you are installing between a meter base and the main panel. A service entrance (SE) switch has circuit breakers inside that increases the price, so don’t let the installer sell you one just because he wants to. A lot of installers will only stock SE switches, you can always make them give you one for the non-SE switch price. Now in the world of options, at least one manufacturer offers a meter SE transfer switch all in one combo if that fits your need. It’s a pretty compact package, it may save you some money over a traditional meter base and transfer switch if you need both. I had a meter main, so I did not get an SE switch. FYI starting with the 2020 version of the National Electric Code section 230.85 requires a disconnect on the exterior of homes. Homes built before the rule are grandfathered, but as people remodel and new homes are built, you will see the old meter base disappear.
Don’t buy a 200-amp switch to feed a 100-amp panel. This is the next item to watch, the amperage rating of the switch must be at least the same as the breaker that feeds it and is generally the same size as the panel it feeds. Don’t pay for a 200-amp switch protected by a 100-amp breaker feeding a 100-amp panel. Now sometimes the main breaker is smaller than the panel. I purchased a 225-amp panel to get more breaker spaces, but it is protected by a 200-amp meter main. I have a 200-amp transfer switch.
If you are going to move circuits off to a sub-panel so you only power part of your home/business, most manufacturers make a combination transfer switch and sub-panel all in one unit. These really help if you have space restrictions. They may also save you some money. It never hurts to run the numbers to see which one works better, a traditional sub-panel and traditional transfer switch or a combo.
Combo transfer switch offerings from several manufactures Residential grade transfer switches are very brand specific, a Cummins residential switch will only work with a Cummins residential generator, a Generac residential switch, will only work with a Generac residential generator, and so on. This is largely because the switch controls are quite simple which makes them very inexpensive, usually under a thousand dollars. Most of the brains for these switches live in the generator. Commercial grade ($$$) transfer switches of any brand will generally work with any brand of generator including residential. There are several commercial grade manufacturers who only make automatic transfer switches.
That winds up what I can tell you about planning your purchase. Hopefully you are fully armed to venture out and starting a conversation.
Up Next
In our last article we will talk about miscellaneous items like fuel handling and storage, fuel piping issues, extended warranty and other off topic items.
Recommendations
I strongly recommend you bookmark PowerOutage.US. Great website for tracking power outages with a clickable map. You can drill down into a state and then into a county if you want. There are links to the websites and utility ran outage maps for most electric utilities. If you are in Canada or Great Britain then go to Poweroutage.com and follow the link to your country. Poweroutage.eu is in the works.
How do you know when power is restored? My solution was to install a 120v siren on one of the service phases that I switch on during a power outage.