Some pics, for reference. Used phone....sorry for quality (or lack thereof). Georgia currently using 2011 NEC with no state-specific amendments
Main panel w/cover removed - the red and black coming out of the top of the main breaker lead to the top left knockout and over to the subpanel.
Close-up of the neutral and ground bus bars. You can see some are doubled- and tripled-up. This is legit??

Also, is it legal to use wirenuts inside the panel?
Sub-panel - I believe this goes to a sunroom addition added in the 90s. If so, it only feeds a rarely-used PTAC, 2 ceiling fans, and 6 duplex outlets of which we only use 1 for a TV and sat box.
