I got the interior secondary panel/breaker box installed and wired in. It has a big electro-mechanical switch at the top that has heavy #4 wire feeds coming from a dual-pole 70 amp breaker in the primary breaker box (through the lower conduit) and from the generator outside (through the upper conduit.) Then that switch feeds down into a dozen breakers.
Then it has a series of a dozen wires running from those breakers out through the lower conduit back into the main breaker box, where they're tied into the hot wires that lead out to the key circuits that the generator can carry. For example, my HVAC condenser used to be fed by a dual pole breaker in the main box. Now it's fed by a dual pole breaker in the secondary box. And that breaker is normally fed by the main breaker box, but during an outage, the generator starts itself up, cuts over the big switch, and then begins feeding that HVAC breaker and all the other secondary breakers from the generator.
It's an ingenious design.
As of now I'm feeding my HVAC, kitchen, internet closet, basement lights, master bedroom, and garage (door opener) from the secondary panel. I still have an empty breaker or so, so during the next outage I'll take some amperage measurements and maybe try to decide which circuits I "miss" the most, and then cut them over if I have capacity. I already plan to run my shop's welder/phase converter circuit off of it, but I'm waiting for the breaker I've ordered.
I already know that it can't carry both the hvac and the welder at the same time, so I'd only use it during the cool season when the AC isn't turned on.
To test it, your just flip off the 70 amp breaker that feeds the secondary panel. After a few seconds you hear the generator outside start up. And 10 seconds or so later, those secondary circuits all light back up. It's really cool to see it happen.
I've tried to do the work in a fashion that is completely compliant with codes and regulations. And I'm pleased with it. I think it looks pretty good too.
Bob
