Originally Posted by k_buz
There is no issue with two breakers. Its done all the time. The only downside is you have to check two locations if one trips.
One thing to check is if the neutrals and grounds are separated in the first panel. The way you describe it is the original panel is now a sub panel. It is possible that when the new main panel was added, they didn't separate the grounds and neutrals.
You're right, the grounds tie into the neutral bus. In fact there is no grounding rod on this panel. This place is so old it apparently had a generator backup as it has one of those A or B input switch boxes with the blades. Sorry I don't know the name but here is a picture of the power coming in, neutral in middle, and two hots either side.
You can see that these 3 wires go out the bottom to a meter panel being used as a sub panel for a few lights in this old pump house. A second set of 3 go out to the "outside" (panel on another building) I was writing about which is picture #2, and you can see the ground connecting to the neutral bus.
The old circuits in the trailer don't have a ground wire anyway, but the new romex ones do
Please refer to my other post about the voltage swings between the two 125v feeds. Could this be due to ground wires connect to neutral bus as well as no ground rod?