Sub panel cable

[StevenW]

First-time poster here...

I am running a 100 amp service to a sub panel in my detached garage. I have a 125 amp box in the garage which is 70' from the main panel in the house. The local electrical supply sold me 2-2-4-6 aluminum, direct bury, mobile home feeder.

I have searched and found similar scenario's but I still would like reassurance that this is acceptable.

Thanks in advance.

[HayZee518]

2-2-4-6 is ok. the #2 is used for the feeders, 4 is a reduced neutral and #6 is for the auxillary ground. the neutral bonding screw is NOT used in the sub panel.

[StevenW]

Thank you. Should I drive a ground rod at the building?

[HayZee518]

you can if you want - it'll terminate at the aux ground strip.

[StevenW]

you can if you want - it'll terminate at the aux ground strip.

So it's ok to have the ground rod terminated at the aux ground strip in addition to the #6 ground from the main panel? Also, the garage is a steel building, should I have the building itself tied to a separate ground rod?

[HayZee518]

Ideally all vertical forming beams should be individually grounded and bonded to the enclosure or auxillary ground. if you have a grounding grid then a ground wire should exo thermally bonded to the frame work. horizontal purlins should be bonded together.
Structural Metal
Exposed structural metal that is interconnected to form a metal
building frame and is not intentionally grounded and is likely to become energized shall
be bonded to the service equipment enclosure, the grounded conductor at the service, the
grounding electrode conductor where of sufficient size, or the one or more grounding
electrodes used. The bonding jumper(s) shall be sized in accordance with Table 250.66
and installed in accordance with 250.64(A), (B), and (E). The points of attachment of the
bonding jumper(s) shall be accessible.

[StevenW]

Thanks for the edit HayZee518. So would a 6' ground rod with #8 copper to the enclosure and bond the building to the enclosure be acceptable?

[HayZee518]

8 foot ground rod 5/8" diameter copper clad steel driven full length into the ground. #4 bare, stranded copper to the structure and ground rod.

[StevenW]

Done. Thanks again.