In article , stryped wrote:
I am building a detatched garage about 75 feet from my attached
garage. I have my main panel and a sub panel beside each other in my
attached garage. The sub panel only has my small upstairs heat pump/
air conditioner for a bonus room hooked to it as well as a 50 amp plug
for a small welder I almost never use. Can I run a sub panel in my new
detached garage/workshop from the sub panel in my current attached
garage?

Maybe. What type of cable (size, material, and number of conductors) runs from
the main panel to the existing subpanel? What is the rating of the existing
subpanel? Is the subpanel connected to a breaker in the main panel, and if so,
what is the rating of that breaker?

If so, do I need another ground rod at the detached garage?

Yes.

If it helps, I can remove the 50 amp welding plug because I only plan
to wel in the detached garage anyway.

Do so.

I have 200 amp service in my main panel. I think the sub panel next to
it I bought was either a 50 or 100 amp panel

That makes a BIG difference.

but like I sais, the only
thing on it is the 1.5 ton heat pump. It is usually turned off as the
upstairs is a play room for the kids.

I added the sub panel because all of the breakers in my main pannel
were almost full.

IMO you're much better off hiring a licensed electrician. The questions you're
asking -- and the fact that you failed to gather such elementary but crucial
information such as the rating of the existing subpanel -- strongly suggest
that you do not possess the knowledge or the skills to do this safely on your
own.