My brother isn’t easy to shop for, so finding the right Christmas gift is always a challenge. This year, I decided to get him a portable generator. It’s small enough that he can take it to a small cabin for the weekend, but it’s big enough to be able to power some pretty useful gear.
Then I remembered that my brother lives in a city with a lot of trees, overhead power lines, and the year-round possibility of severe storms. In short, he can count on a power outage or two every year. A couple of times, he’s been without power for a few days – both in the middle of summer and the middle of winter. I thought it would be great if he could connect that generator to his home in the event of a blackout. But as it turns out, you can’t just plug a generator into an outlet.
Here’s what I learned: A home’s electrical system is designed to receive power from the local utility. Power is distributed through the electrical panel; this panel features circuit breakers that can instantly disconnect a circuit in the event of overload. Problems can occur if and when power is received from another source, such as a portable generator. When the panel is bypassed, circuits (and the devices connected to them) are no longer protected from overloads; damage to wiring and electronics can be the result.
And that’s not all. There’s another danger called backfeed – the term for when power flows in the opposite direction to the one intended. Plugging your generator into your outlet also connects it to the utility line. Generator power can travel backwards up that line until it hits a transformer that will greatly magnify the voltage. This voltage can cause damage to electronics; more importantly, it can cause severe injury or death to any utility worker making outage repairs.
If you want to plug a portable generator into a home, you need to do so properly. (Read: After the local licensed electrician sets everything up according to code.) You’ll need to install a device that prevents backfeed, and which doesn’t allow your electrical system to connect to generator and utility power at the same time. You’ll need something called an interlock kit.
Interlock kits are attached to the electrical panel, and provide a proper point for connection between generators and household electrical systems. By using an interlock kit, generator power travels through an electrical panel properly, with the usual circuit breaking safeguards in place.
Interlock kits also require you to choose whether your home is powered by the generator power or by the utility line. If you opt to use generator power, you’ll disconnect the circuit from the utility line; opt to use utility power, and the generator is disconnected. This eliminates the possibility of damaging and dangerous backfeed.
Now that I know what has to be done to connect a generator to a home, I’ve already made arrangements with a local electrician to install an interlock kit on my brother’s home right after Christmas. (I had my nephew identify the electrical panel for me, so the panel-specific kit could be ordered in advance.) A generator and interlock kit may not be the most exciting gifts, and few could be more valued the next time power goes out.