ECN Forum Forums Code Related Discussion NEC & other Code issues sub panel detached building

i have a sub 50 amp sub panel that i want to put in a detached maint/gar building.
to save money on wire i am going to run two #6's for the lines and one #8 for the neutral(derating the neut)along with a #10 ground. my question is does this sound code compliant, we derate neutrals for the service feeders and this is going to be a feeder so it seems very complicit to me.

am i on the right page? any codes that i am missing which would forbid this derating?
thanks guys,
h20

oh yea it is a metal building which i will bond the beam structure and will drive two ground rods down at the building too.

By not knowing what your load is, I can't tell you that you can or can't derate the neutral. Also, I would be interested in how you terminate the neutral and ground wires in the sub panel. Where do you connect the Grounding Electrode Conductor in the sub panel?

There's no need to install ground rods if you run a separate equipment grounding (bonding) conductor (E.G.C.) to the detached garage.

See more about this topic here: https://www.electrical-contractor.net/ubb/Forum1/HTML/006874.html

And here: https://www.electrical-contractor.net/ubb/Forum2/HTML/002417.html

Hold on. You must ALWAYS install a grounding electrode system for a detached building with more than a single multiwire branch circuit. It doesn't matter if your have three or four wires; with or without an equipment grounding conductor.
see 250.32

The neutral may only be derated if there is sufficient straight 240 volt loads to warrant it.
see 220.22

If your neutral busses are specifically listed at 75C and you use 75C rated wire, then #8 copper is fine for a 50A feeder because that wire is still rated at 50 amps.

My bad.

Yes, a grounding electrode MUST be installed on any detached building.

...that is fed with a feeder.
If you only run a circuit no rod is needed.
See: 250.32