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

[aczlan]

I have a 400 amp service to the house. My shop 200 ft from the house is fed from one of the 200 amp breaker boxes at the house. Interlock wouldn't work in my application. I have to turn off both breakers and some of the other 220 breakers.
The power company here assumes people will have generators connected, so they work an outage with that in mind

Sounds like a trapped key interlock would work for you, you would need a double key one for the generator and a pair of single key ones for the 200 amp breaker boxes in the house.
Double key interlock for generator:
I.T.E. Imperial Corp. Kirk Interlock F2 45-62915, Yale Key, Lock, Double | eBay

Single key interlocks for house panels:
KIRK KEY INTERLOCK QTY 2 (228) "NEW" | eBay

These particular ones are not keyed alike, so they would not work for you, but that is the style that you would need.

Aaron Z

 

[MossRoad]

I have a 400 amp service to the house. My shop 200 ft from the house is fed from one of the 200 amp breaker boxes at the house. Interlock wouldn't work in my application. I have to turn off both breakers and some of the other 220 breakers.
The power company here assumes people will have generators connected, so they work an outage with that in mind

You could easily put in a kirk key as described earlier in this thread and that would make everyone safe.

 

[MossRoad]

You could easily put in a kirk key as described earlier in this thread and that would make everyone safe.

Like he said.... :laughing:

 

[buickanddeere]

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

National Electrical Code, Insurance Companies and utilities mandate use of the fool proof interlock system that Can Not connect the generator to the utility grid .
They didn't make the rule because they are mean and nasty.

 

[kenmac]

well, since I'm the only one here. I'll be the one doing all the work connecting the generator and flipping the switches . I really don't see how they would help me.
I could see using something like these if there were many different people involved making connections and flipping switches. I have been doing it so long, it's as simple as getting in the truck, turning the keys to start the engine.

 

[buickanddeere]

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.

Depends if the generator has a floating or bonded neutral if the transfer switch also switches the neutral.
Only way a neutral is going to send power back to the utility is an incorrect installation.

 

[buickanddeere]

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

Only works IF the generator is Hard Wired to the electrical service .

 

[buickanddeere]

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.

Still doesn't make it right, safe or legal.

 

[buickanddeere]

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.

How ???

 

[BHD]

it not only protects from back feeding,
but it protects your generator, as well, as if the grid comes back on and one flips the breaker on and the generator is still hooked up, most likely it is fried,