Wire Gauge does power "direction" matter?

[Alchymist]

THanks Elf, I almost understand. I have an interlock (a slidy thing) that shuts off the main power from the grid to my main panel. Interlock engaged = no grid tie but all breakers in the main and sub are connected still. The shop subpanel is fed from a breaker in the main panel. If I backfed an outlet in the shop, through the subpanel, it seems to me that both the main and supanels would be enrgized since they are all still connected and the only thing disconnected in the grid feed.

I think it will work electrically as KPSquared states. What do you think is happening that would stop electricity from feeding both panels from my subpanel?

The lineman argument is irrelevant since the main breaker is shut off.

You are correct in what you say. The fly in the ointment is the interlock does nothing to insure that mains and generator power are not on at the same time. (You can power the generator and feed the subpanel without the mains interlock being thrown). In the usual scenario the mains interlock interlocks the main breaker with the backfeed breaker in the main panel so only one can be on at a time. There is no interlock between the main breaker in the main panel and the backfeed breaker in the subpanel in your scenario.

 

[Highbeam]

Oh, now I get it, the interlock tab works with the official "generator" breaker to be sure that they are not on at the same time but is not linked to the breaker that feeds the subpanel. This is true, a safety issue only, but it is true. I can still be sure that the main is shut off but there is no fail safe when using an outlet on the subpanel as there is when using the official generator breaker. Thanks Alchy.