Interlock vs. throwing the main circuit breaker for generator powering a house

[JFoy]

Is there a difference in safety if I just turn off the main 200amp circuit breaker versus having a generator interlock installed? My understanding is the danger of backfeeding power to the outside power pole and transformer.

Thanks,
JFoy

 

[Oldoak]

They both will accomplish the same thing. However, an interlock is your safest bet. An interlock eliminates the chance of human error by forgetting to turn off the main breaker.

 

[RNeumann]

Yes major difference- “just throwing the breaker” requires a manual sequence of events to prevent damage or injury. While the interlock is designed to be in either/or position with one move.

IMHO it’s short sided to setup something that your spouse, neighbor or child couldn’t easily do.

 

[aczlan]

Is there a difference in safety if I just turn off the main 200amp circuit breaker versus having a generator interlock installed? My understanding is the danger of backfeeding power to the outside power pole and transformer.

Thanks,
JFoy

If you don't want to buy an interlock switch, there are companies who make an interlock plate that goes on your existing breaker panel and makes it so that one of the top Breakers cannot be turned on at the same time as the main breaker is on.

Aaron Z

 

[marchanna]

I don’t have an interlock, I wish I did. But because of my particular electrical layout, it was not practical. My wife knows that she should not even attempt to switch it over, and it would be very difficult for someone to figure out if he power we’re to go out, layered safe guards , which I have done intentionally.

 

[RickB]

A legitamate transfer switch interrupts the neutral bond to the electrical grid. Opening a circuit breaker does not. That is a huge safety concern for utility personnel and a major reason that most codes require a transfer switch.

 

[aczlan]

I don稚 have an interlock, I wish I did. But because of my particular electrical layout, it was not practical. My wife knows that she should not even attempt to switch it over, and it would be very difficult for someone to figure out if he power we?*e to go out, layered safe guards , which I have done intentionally.

Look at a trapped key interlock. Something like this: KIRK KEY INTERLOCK QTY 2 (228) "NEW" | eBay

One goes on the main breaker, the other goes on your generator breaker. One key gets locked up as a spare, the other is locked into one lock (that is installed so that it keeps the main breaker off when the key is removed). The other lock is installed so that it keeps the generator breaker off when the key is removed.
To turn on the generator, you turn off the main breaker, lock the interlock to keep it off, remove the key, unlock the generator interlock with that key and turn on the generator breaker.

Aaron Z

 

[marchanna]

That’s a brilliant idea.

 

[dieselcrawler]

My power system is also layed out such that in interlock won't fit the bill. Main breaker is at the house, generator feed is at the barn, which is fed from the house. Things are clearly marked, wife and oldest son understand the process and order of events clearly. We likely have a better understanding of the safety risks than most, as I have 20+ years of electrical background, and have installed many very nice back-up generator systems with auto-transfer switches, and hope to have my own someday.

The point I state clearly, every time we have a power issue, is turn off the main breaker FIRST, and save the life of the guy out in the cold/rain/snow trying to fix the power outage, then go to the barn and hook up the generator, start it, and very last turn on the breaker for generator feed to the barn panel.

 

[Jstpssng]

If you don't want to buy an interlock switch, there are companies who make an interlock plate that goes on your existing breaker panel and makes it so that one of the top Breakers cannot be turned on at the same time as the main breaker is on.

Aaron Z

It looks like this...
Mine was installed when I bought the building, but I have never used it. If my power ever does go out for a long period of time I will have to build a cord before using it.
Until reading RickB's comment below I never really thought about how mine worked; but I have heard that this can still allow power to feed back into the utility line.