If you will notice the sub-panel…the one on the right in the photo…
At the top right you will see a 100 amp breaker. It is fed with 3 awg (2 wouldn’t be too much) through the pvc loop you see below the panels.
This breaker controls all power going to the sub-panel…ie…if this breaker is not made (turned on), there is no power getting to the sub-panel, short of an act of God (lightening strike perhaps).
Now, below that you will notice a 60 amp breaker…this is the breaker that will power the sub-panel with generator power once it is made. Closer inspection will reveal that it is “tied” to the 100 amp breaker from the house buss via a “rocker switch”. That is, when one is off the other is on…and vice versa.
When the 100 amp breaker is on…everything is normal. All of the circuits you’ve moved to the sub-panel to provide power to vital circuits when the power goes out…all work perfectly normal. After all, they’re being powered by the house buss at this point.
Uh-oh….powers out! Well, we fire up the generator, and plug that bad boy into the wall outlet we installed… that feeds (has a big wire that goes into) the sub-panel, through that 60 amp breaker.
Now, we need to go make the switch! When we flip the main 100 amp breaker off…or the 60 amp generator breaker on…the other one moves by itself via the aforementioned rocker switch! How cool! No mistakes.
Now, given that there is a direct disconnect between the sub-panel and the house panel (the 100 amp breaker was turned OFF when we made the switch)…there is no way current can feed between these two…other than the aforementioned act of God.
In my case, I moved the well pump, furnace, hot water tank and a few house circuits to the sub-panel…I didn’t include the AC, electric stove or clothes dryer.
You’ll notice in the photo…I had to add a box to complete some of the circuits, the yellow wires in the photo.
This install is up to code…I had it inspected for insurance requirements…but…I did cheat one 110 feed through the pvc that houses the 3 awg…not allowed…but he let me slide. I knew, but figured I did such a fine job on everything else…
I have can lights in the kitchen controlled by only one switch….we turn this switch on when the power goes out, then we know when it comes back on. Again…COMPLETELY SEPARATE CIRCUITS! The generator and the house power can work in unison forever. They are separate entities.
I post this because this is fairly easy to do…and to clear up any misunderstanding surrounding a transfer switch.