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oups.com...
If I am wiring a 100 amp subpanel in my detached garage with 240 using
2-2-2-4 AL, I am carrying the ground from my house's main panel (60 amp
breaker). Does NEC require that I have a grounding rod at my detached
garage? If that is the case, should I only be running 2-2-2AL?
thanks. Any arguments for using copper? The AL seems like it may be
overrated, but cheaper in the end.


Grounding is done at the electrical service. Any installed panel after the
service (meter location) is considered a sub panel. Sub panels must have
seperate hots neutral and ground conductors. Using the earth as return path
can be dangerous. ( ya I know lots of places do it and are installing it as
I type, still wrong).

A supplemental ground rod at the garage is confusing and complicated. I
encourage you to go to the library and find the "Soars book on Grounding"
Simplified explanations for a complex subject. Lots of good pictures and
illustrations.

2-2-2-4 is correct, better check your 60 amp breaker, I will bet you have
trouble landing #2.


As long as you understand AL and work to its needs there is nothing wrong
with the wire. Every problem I have seen in 20 plus years of electrical work
with AL can be attributed to the workmanship. Utilities seldom use copper
any more. Cost and weight is their issues.

Some jurisdictions require grounding at remote buildings. Best check
anonymously before you go to far astray.